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WO1993025567A9 - Production de polypeptides recombines par des especes bovines et des procedes transgeniques - Google Patents

Production de polypeptides recombines par des especes bovines et des procedes transgeniques

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Publication number
WO1993025567A9
WO1993025567A9 PCT/US1993/005724 US9305724W WO9325567A9 WO 1993025567 A9 WO1993025567 A9 WO 1993025567A9 US 9305724 W US9305724 W US 9305724W WO 9325567 A9 WO9325567 A9 WO 9325567A9
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WO
WIPO (PCT)
Prior art keywords
transgene
sequence
bovine
transgenic
milk
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Application number
PCT/US1993/005724
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English (en)
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WO1993025567A1 (fr
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Publication date
Application filed filed Critical
Priority to EP93915365A priority Critical patent/EP0652889A4/fr
Priority to JP50179494A priority patent/JP3670003B2/ja
Priority to AU45373/93A priority patent/AU4537393A/en
Publication of WO1993025567A1 publication Critical patent/WO1993025567A1/fr
Publication of WO1993025567A9 publication Critical patent/WO1993025567A9/fr
Priority to US10/170,221 priority patent/US20030192068A1/en
Priority to US10/987,587 priority patent/US20050198698A1/en

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Definitions

  • the invention relates to the production of recombinant polypeptides by transgenic bovine species and to methods for producing transgenic non-human mammals having a desired phenotype.
  • transgenic sheep (Nancarrow, et al. (1987) Theriogenology 27:263 (transgenic sheep containing bovine growth hormone gene) Clark, A.J. et al. (1989) Bio/Technology 7:487-482 and Simons, J., et al.
  • Human tissue plasminogen activator reportedly was produced in transgenic mouse milk at the levels between 0.2 and about 0.4 ⁇ g/ml when a cDNA encoding a human t-PA with its endogenous secretion sequence was expressed under control of a 2.6 kb 5' sequence of the murine whey acid protein gene.
  • Subsequent experiments using the same or similar construction reportedly produced t-PA in different mouse lines arranging from less than 20ng of t-PA per ml of milk to about 50 ⁇ g/ml.
  • U.S. Patent No. 4,873,316 issued October 10, 1989 discloses the use of 9 kb of 5' sequence from the bovine ⁇ S1 casein gene including the casein signal peptide and several casein codons fused to a mature t-PA sequence.
  • the transgenic mice obtained with this construct reportedly produced about 0.2-0.5 ⁇ g/ml of a t-PA fusion protein in their milk.
  • WO88/01648 published March 10, 1988 (transgenic mouse having mammary secretory cells incorporating a recombinant expression system comprising a bovine ⁇ -lactalbumin gene fused to interleukin-2); European Pat. Pub. No. 0 279 582 published August 24, 1988 (tissue-specific expression of chloramphenicol acetyltransferase under control of rat ⁇ -casein promoter in transgenic mice); and PCT Pub. No. WO88/10118 published December 29, 1988 (transgenic mice and sheep containing transgene encoding bovine ⁇ S1 casein promoter and signal sequence fused to t-PA).
  • transgenic bovine species which are capable of producing recombinant polypeptides such as human milk proteins and human serum proteins in the milk of such transgenic mammals.
  • transgenic bovine species which are capable of producing recombinant polypeptides which are maintained intracellularly or are secreted extracellularly. It is also an object herein to provide transgenic bovine species which are capable of producing recombinant polypeptides such as human milk proteins and human serum proteins in the milk of such transgenic animals.
  • transgenic bovine species containing such recombinant polypeptides.
  • food formulations supplemented with recombinant polypeptides from such transgenic milk such as human infant formula supplemented with human lactoferrin.
  • transgenes which are capable of directing the production of recombinant polypeptides in the milk of transgenic bovine species.
  • the invention includes transgenes for producing recombinant polypeptides in the milk of transgenic bovine species.
  • the production of such transgenic bovine milk containing one or more recombinant polypeptides is desirable since it provides a matrix wherein little or no purification is necessary for human consumption.
  • the transgene comprises a secretory DNA sequence encoding a secretory signal sequence which is functional in mammary secretory cells of the bovine species of interest and a recombinant DNA sequence encoding the recombinant polypeptide. These sequences are operably linked to form a secretory-recombinant DNA sequence.
  • At least one expression regulation sequence functional in the mammary secretory cells of the bovine species, is operably linked to the secretory-recombinant DNA sequence.
  • the transgene so constructed is capable of directing the expression of the secretory-recombinant DNA sequence in mammary secretory cells of bovine species containing the transgene.
  • Such expression produces a form of recombinant polypeptide which is secreted from the mammary secretory cells into the milk of the transgenic bovine species.
  • the invention includes methods for producing such transgenic bovine species.
  • the method includes introducing the above transgene into an embryonal target cell of a bovine species, transplanting the transgenic embryonic target cell formed thereby into a recipient bovine parent and identifying at least one female offspring which is capable of producing the recombinant polypeptide in its milk.
  • the invention also includes transgenic bovine species capable of producing recombinant polypeptides in the milk of lactating females of said species, the milk from such transgenic bovine species containing such recombinant polypeptides and food formulations containing the transgenic milk in liquid or dried form, as well as food formulations supplemented with one or more recombinant polypeptides from such transgenic milk.
  • the invention includes transgenes and transgenic bovine species containing transgenes that are capable of producing a recombinant polypeptide.
  • transgenes are similar to the aforementioned transgenes for milk secretion and are characterized by having an expression regulation sequence which targets the expression of the DNA encoding the recombinant polypeptide to a particular cell or tissue type, e.g. expression of human serum albumin in the liver of a transgenic bovine species.
  • a secretory DNA sequence encoding a secretory signal sequence functional in the particular targeted cell or tissue is operably linked to the recombinant DNA sequence encoding the recombinant polypeptide, e.g. secretion of human serum albumin from bovine liver into the bovine circulatory system.
  • the invention includes methods for producing transgenic non-human mammals having a desirable phenotype. The method comprises first causing the methylation of a transgene capable of conferring the desirable phenotype when incorporated into the cells of a transgenic non-human animal, e.g., by transforming an appropriate bacterium, such as E.
  • the methylated transgene is then excised and introduced into fertilized oocytes of the non-human animal to permit integration into the genome.
  • the oocytes are then cultured to form pre-implantation embryos thereby replicating the genome of each of the fertilized oocytes. Thereafter, at least one cell is removed from each of the pre-implantation embryos and treated to release the DNA contained therein.
  • Each of the released DNAs are then digested with a restriction endonuclease capable of cleaving the methylated transgene but incapable of cleaving the unmethylated form of the transgene formed after integration into and replication of the genomic DNA.
  • Those pre-implantation embryos which have integrated the transgene contain DNA which is resistant to cleavage by the restriction endonuclease in the region containing the transgene. This resistance to digestion, which can be detected by electrophoresis of the digest after PCR amplification of the DNA and hybridization with a labelled probe for the transgene, facilitates the identification of successful transgenesis.
  • the invention also includes a method to produce a population of transgenic offspring having the same genotype.
  • This method utilizes a specific embodiment of the above method for detecting early transgenesis.
  • a methylated transgene is introduced into fertilized oocytes which are cultured to pre-implantation embryos. Thereafter, each pre-implantation embryo is divided to form first and second hemi-embryos. Each of the first hemi-embryos are then analyzed for transgenesis as described above.
  • the second untreated hemi-embryo which contains the integrated transgene, is cloned to form a multiplicity of clonal transgenic blastocysts or hemiblastocysts, each of which have the same genotype.
  • the transgenic embryos are thereafter transplanted into one or more recipient female parents to produce a population of transgenic non-human mammals having the same genotype.
  • Fig. 1 depicts the DNA (Seq. ID No.: 1) and amino acid (Seq. ID No. : 2) sequence for a human lactoferrin clone derived from a human mammary cDNA library as described herein except that the sequence between nucleotides 1557-1791 and 2050-2119 corresponds to the previously published sequence (Rado et al. (1987) Blood 70: 989-993).
  • Fig. 2 depicts the complete DNA (Seq. ID No.: 3) and amino acid (Seq. ID No.: 4) sequence of human lactoferrin including 5' and 3' untranslated sequence as well as the complete human lactoferrin signal sequence.
  • Fig. 3 is a restriction map of a clone of a 5'-flanking region of bovine ⁇ S1 casein gene.
  • Fig. 4 is a restriction map of a clone of a 3'-flanking region of bovine ⁇ S1 casein gene.
  • Figs. 5A, 5B and 5C depict the construction of pSI3'5'CAT and pSI5'CAT.
  • Fig. 6 depicts pMH-1.
  • Figs. 7A through 7F depict the construction of expression vectors containing sequences encoding human lactoferrin.
  • Fig. 8 depicts the genome of human serum albumin, the fragments used to generate transgenic mice contained in this genomic DNA and the identification of the fragment sizes which would be obtained upon the digestion of genomic DNA from a transgenic mouse with the restriction enzymes BstE-II and Nco-I or with Nco-I and Hindi-III.
  • Fig. 9 depicts an alternate pathway for the construction of a transgene of the invention encoding human lactoferrin.
  • Fig. 10 depicts the construction of a plasmid pPC containing a transgene encoding Protein C.
  • Fig. 11 depicts the DNA sequence for a hybrid intervening sequence used in a preferred embodiment of the invention.
  • This hybrid sequence comprises a 5' portion from an intervening sequence of bovine ⁇ S1 casein and a 3' portion from an intervening sequence of an IgG intervening sequence. The juncture of the 5' and 3' portion is the HindIII site shown.
  • Fig. 12A is a restriction map of a bovine ⁇ S1 casein promoter hLF cDNA transgene.
  • Fig. 12B shows a Southern blot analysis of DNA isolated from various bovine and murine tissues using an hLF cDNA probe.
  • Fig. 13 depicts restriction maps of hLF genomic clones 13.1 and 13.2.
  • Fig. 14 depicts the BamHI fragment from genomic hLF subcloned into plasmid pUC19.
  • Fig. 15A depicts a restriction map of the 8hLFgen9k or 16hLFgen9k construct containing the 8 or 16 kb ⁇ S1 casein promoter, a ClaI-ApaI synthetic linker and the 9 kb (i.e., 8.9 kb) ApaI-SalI genomic hLF fragment.
  • Fig. 15B depicts the DNA sequence of the ClaI-ApaI synthetic sequence shown in Fig. 15A.
  • Fig. 15C depicts the IVS and the structure of exon 1 and part of exon 2 of the genomic hLF construct shown in Fig. 15A through Fig. 17.
  • Fig. 16 depicts the coinjection of the NotI-SalI fragment from the 8hLFgen9k or 16hLFgen9k construct (as shown in Fig. 15A) with the 3' ClaI fragment of genomic hLF.
  • Fig. 17 depicts the generation of a genomic 8hLF transgene by linking the NotI-MluI fragment from the 8hLFgen9k construction (shown in Fig. 15A), the MluI-ClaI fragment from clone 13.2 depicted in Fig. 13 and a ClaI-NotI linker.
  • Fig. 17 also depicts the DNA sequence of the ClaI-NotI linker.
  • Figs. 18-20 depict the generation of the ⁇ LG-hLFgen and ⁇ LG-hLFgen37 constructs.
  • Fig. 21 depicts the design of the 16,8hLZ expression vector.
  • Fig. 22 depicts the design of the 16,8hLZ3 expression vector.
  • Fig. 23A-23E depict the pathway for the construction of plasmid p16,8hLZ.
  • Fig. 24 depicts a comparison between the DNA of bovine ⁇ LG and sheep ⁇ LG.
  • the top sequence represents the bovine sequence.
  • Fig. 25 shows the linker GP 278/279.
  • Fig. 26 depicts the p16,8A hLZ3 expression vector.
  • Fig. 27 depicts the 16,A hLZ3 expression vector.
  • non-human mammals comprise all non-human mammals capable of producing a "transgenic non-human mammal" having a "desirable phenotype".
  • Such mammals include non-human primates, murine species, bovine species, canine species, etc.
  • Preferred non-human animals include bovine, porcine and ovine species, most preferably bovine species.
  • Desirable phenotypes for transgenic non-human mammals include, but are not limited to, the production of recombinant polypeptides in the milk of female transgenic non-human mammals, the production of animal models for the study of disease , the production of animals with higher resistance to disease (e.g. diseases of the mammary gland such as mastitis) and the production of recombinant polypeptides in the blood, urine or other suitable body fluid or tissue of the animal.
  • transgenic bovine species are disclosed which are capable of producing recombinant human lactoferrin, human serum albumin and human Protein C in the milk of lactating females or human serum albumin in the liver of the transgenic animal.
  • transgenic non-human mammals of the invention are produced by introducing a "transgene" into an embryonal target cell of the animal of choice.
  • a transgene is a DNA sequence which is capable of producing a desirable phenotype when contained in the genome of cells of a transgenic non-human mammal.
  • the transgene comprises a "recombinant DNA sequence" encoding a "recombinant polypeptide”. In such cases, the transgene is capable of being expressed to produce the recombinant polypeptide.
  • a "recombinant polypeptide” (or the recombinant DNA sequence encoding the same) is either a “heterologous polypeptide” or a “homologous polypeptide".
  • Heterologous polypeptides are polypeptides which are not normally produced by the transgenic animal. Examples of heterologous polypeptides include human milk proteins such as lactoferrin, lysozyme, secreted immunoglobulins, lactalbumin, bile salt-stimulated lipase, etc., human serum proteins such as albumin, immunoglobulins, Factor VIII, Factor IX, protein C, etc.
  • the recombinant DNA sequences include genomic and cDNA sequences encoding the recombinant polypeptide.
  • the transgene may be integrated in a random manner into the genome of the species used for transgenesis.
  • transgenes encoding human lactoferrin, human serum albumin and human Protein C in conjunction with a ⁇ S1 casein secretory signal sequence under control of ⁇ S1 casein expression regulation sequences are designed to produce and secrete these heterologous polypeptides from the mammary gland of a lactating transgenic mammal into its milk.
  • a homologous polypeptide is one which is endogenous to the particular transgenic species.
  • endogenous polypeptides from bovine species include bovine milk proteins such as ⁇ S1, ⁇ S2, ⁇ - and «-casein, ⁇ -lactoglobulin lactoferrin, lysozyme, cholesterol hydrolase, serum proteins such as serum albumin and proteinaceous hormones such as growth hormones.
  • the transgene is preferably integrated in a random manner into the genome of the species used for transgenesis.
  • transgenic animal which contains not only the transgene encoding the endogenous polypeptide but also the corresponding endogenous genomic DNA sequence. Accordingly, such transgenic non-human mammals are readily characterized by an increase in the copy number of genes encoding the endogenous polypeptide. Further, the transgene will generally be located at a position which is different from the endogenous gene.
  • the transgenic animal When DNA encoding a homologous polypeptide is expressed, for example, in bovine species, the transgenic animal is characterized by an increase in the amount of the homologous polypeptide in either the endogenous tissue or fluid in which it is normally found and/or by its presence in a tissue and/or body fluid which either does not normally contain the homologous polypeptide or produces it at significantly lower levels.
  • bovine cholesterol hydrolase is normally present in the colostrum for about the first 15-20 days of lactation.
  • This naturally occurring endogenous polypeptide increases calf weight.
  • This protein is also a homologous polypeptide when, for example, its expression in mammary secretory cells is placed under the control of expression regulation sequences, such as those obtained from bovine casein genes, which facilitate the expression of the homologous polypeptide beyond the lactation period that it is normally present.
  • bovine cholesterol hydrolase expression is maintained in transgenic bovine milk by placing the expression of cholesterol hydrolase recombinant DNA (either cDNA or genomic) under the control of bovine ⁇ S1 casein expression regulation sequences.
  • a genomic recombinant DNA When a genomic recombinant DNA is used, it is engineered such that it has appropriate restriction sites (e.g. ClaI and SalI) at the 5' and 3' end of the structural gene such that it is capable of being inserted into an appropriate transgene genomic cassette (e.g. p-16 kb, CS which is described in Example 15).
  • an appropriate transgene genomic cassette e.g. p-16 kb, CS which is described in Example 15.
  • a recombinant DNA encoding bovine cholesterol hydrolase derived from cDNA may be placed under control of bovine ⁇ S1 casein expression regulation sequence by substituting the human lactoferrin sequences in a plasmid such as p16, 8HLF3 (containing a hybrid intervening sequence) or p16, 8HLF4 (containing a homologous ⁇ S1 casein intervening sequence).
  • the cDNA clone is engineered such that it has appropriate ClaI and SalI restriction sites at the ends of the recombinant DNA.
  • bovine lactoferrin is normally present in only trace amounts in cow's milk. When, however, bovine lactoferrin is expressed under control of other regulatory sequences, for example, obtained from an ⁇ S1 casein gene, higher amounts of lactoferrin in the milk of transgenic bovine species are obtained.
  • a transgene comprising DNA encoding homologous bovine growth hormone is incorporated into the bovine genome to confer superior growth characteristics to the transgenic animal.
  • homologous polypeptides include, for example, a polypeptide which normally is maintained intracellularly in a particular species but which is secreted into the milk or other extracellular compartment of the transgenic species, such as the circulatory system.
  • heterologous or homologous polypeptides are characterized by specific amino acid and nucleic acid sequences. It is to be understood, however, that such sequences include naturally occurring allelic variations thereof and variants produced by recombinant methods wherein such nucleic acid and polypeptide sequences have been modified by the substitution, insertion and/or deletion of one or more nucleotides in such nucleic acids to cause the substitution, insertion or deletion of one ore more amino acid residues in the recombinant polypeptide.
  • the transgene When expression of the DNA of the transgene is necessary to generate a desired phenotype, e.g. to produce a recombinant polypeptide, the transgene typically includes at least a 5' and preferably additional 3' "expression regulation sequences" each operably linked to a recombinant or secretory-recombinant DNA as defined hereinafter.
  • expression regulation sequences in addition to controlling transcription also contribute to RNA stability and processing, at least to the extent they are also transcribed.
  • Such expression regulation sequences are chosen to produce tissue-specific or cell type-specific expression of the recombinant or secretory-recombinant DNA. Once a tissue or cell type is chosen for expression, 5' and optional 3' expression regulation sequences are chosen. Generally, such expression regulation sequences are derived from genes that are expressed primarily in the tissue or cell type chosen. Preferably, the genes from which these expression regulation sequences are obtained are expressed substantially only in the tissue or cell type chosen, although secondary expression in other tissue and/or cell types is acceptable if expression of the recombinant DNA in the transgene in such tissue or cell type is not detrimental to the transgenic animal. Particularly preferred expression regulation sequences are those endogenous to the species of animal to be manipulated.
  • expression regulation sequences from other species such as those from human genes may also be used.
  • Particularly preferred expression regulation sequences from human genes are human lactoferrin (hLF) sequences.
  • the expression regulation sequences and the recombinant DNA sequences are from the same species, e.g., each from bovine species or from a human source. In such cases, the expression regulation sequence and the recombinant DNA sequence are homologous to each other.
  • the expression regulation sequences and recombinant DNA sequences are obtained from different species, e.g., an expression regulation sequence from bovine species and a recombinant DNA sequence from a human source) . In such cases, the expression regulation and recombinant DNA sequence are heterologous to each other.
  • the following defines expression regulation sequences from endogenous genes. Such definitions are also applicable to expression regulation sequences from non-endogenous, heterologous genes.
  • the 5' expression regulation sequence includes the transcribed portion of the endogenous gene upstream from the translation initiation sequence (the 5' untranslated region or 5' UTR) and those flanking sequences upstream therefrom which comprise a functional promoter.
  • a "functional promoter” includes those necessary untranscribed DNA sequences which direct the binding of RNA polymerase to the endogenous gene to promote transcription.
  • Such sequences typically comprise a TATA sequence or box located generally about 25 to 30 nucleotides from the transcription initiation site.
  • the TATA box is also sometimes referred to the proximal signal.
  • the promoter further comprises one or more distal signals located upstream from the proximal signal (TATA box) which are necessary to initiate transcription.
  • Such promoter sequences are generally contained within the first 100 to 200 nucleotides located upstream from the transcription initiation site, but may extend up to 500 to 600 nucleotides from the transcription initiation site. Such sequences are either readily apparent to those skilled in the art or readily identifiable by standard methods. Such promoter sequences alone or in combination with the 5' untranslated region are referred to herein as "proximal 5' expression regulation sequences". In addition to such proximal 5' expression regulation sequences, it is preferred that additional 5' flanking sequences (referred to herein as “distal 5' expression regulation sequences”) also be included in the transgene.
  • distal 5' expression regulation sequences are believed to contain one or more enhancer and/or other sequences which facilitate expression of the endogenous gene and as a consequence facilitate the expression of the recombinant or secretory-recombinant DNA sequence operably linked to the distal and proximal 5' expression regulation sequences.
  • the amount of distal 5' expression regulation sequence depends upon the endogenous gene from which the expression regulation sequences are derived. In general, however, such sequences comprise 5' flanking regions of approximately 1 kb, more preferably 16 kb and most preferably about 30 kb of 5' flanking sequence.
  • distal 5' expression regulation sequence used from any particular endogenous gene is readily determined by varying the amount of distal 5' expression regulation sequence to obtain maximal expression.
  • the distal 5' expression regulation sequence will not be so large as to extend into an adjacent gene and will not include DNA sequences which adversely effect the level of transgene expression.
  • 3' expression regulation sequences also be included to supplement tissue or cell-type specific expression.
  • Such 3' expression regulation sequences include 3' proximal and 3' distal expression regulation sequences from an appropriate endogenous gene.
  • the 3' proximal expression regulation sequences include transcribed but untranslated DNA positioned downstream from the translation stop signal in the recombinant DNA sequence (also referred to as the 3' untranslated region or 3' UTR).
  • Such sequences generally terminate at a polyadenylation sequence (either from the endogenous gene or from other sources such as SV40) and sequences that may affect RNA stability.
  • 3' UTR's comprise about 100 to 500 nucleotides downstream from the translation stop signal in the gene from which the 3' regulation sequence is derived.
  • Distal 3' expression regulation sequences include flanking DNA sequences downstream from the proximal 3' expression regulation sequence. Some of these distal sequences are transcribed, but do not form part of the mRNA while other sequences in this distal 3' expression regulation sequence are not transcribed at all.
  • Such distal 3' expression regulation sequences are believed to contain enhancer and/or other sequences which enhance expression.
  • Such sequences are believed to be necessary for efficient polydenylation and contain transcription termination sequences
  • such sequences comprise about 2 kb, more preferably 8 kb and most preferably about 15 kb of 3' flanking sequence.
  • a preferred 3' flanking sequence is the 3' flanking sequence of the human lactoferrin (hLF) gene.
  • hLF human lactoferrin
  • Transgenic animals containing transgenes that include about 9 kb of hLF 3' flanking sequences show enhanced expression of recombinant polypeptides in milk compared to animals containing transgenes that include 1 kb or less of hLF 3' flanking sequence, due to an enhancer or other enhancing sequence located in this region.
  • the human lactoferrin 3' flanking sequence will be at least 1 kb in length up to about 9 kb in length or longer, typically 3 to 7 kb, more typically 4 to 5 kb.
  • enhancers or enhancing sequences can be isolated and used in combination with various amounts of homologous or heterologous sequences.
  • the enhancing sequences can range in length from about 50 basepairs to aL ut 2 kb, more typically from about 100 basepairs to about 500 basepairs.
  • transgene having a 5' expression regulation sequence and a 3' flanking sequence that originate from the same gene.
  • the 5' expression regulation sequence and 3' flanking sequence are from the bovine ⁇ S1-casein gene.
  • a genomic sequence such as a human genomic clone or clones, can be introduced into an animal to produce a transgenic animal containing a transgene that has the sequence of the human gene, including all or part of the 5' expression regulation sequences, coding sequences, introns, and 3' untranslated and flanking sequences.
  • the human lactoferrin genomic sequence is used in its entirety, but various components can be substituted with components from other mammary gland specific genes.
  • the use of both 5' and 3' expression regulation sequences are preferred, in some embodiments of the invention, endogenous 3' regulation sequences are not used.
  • the 3' proximal expression regulation sequences normally associated with the genomic DNA encoded by the recombinant DNA sequence are used to direct polyadenylation.
  • distal 3' regulation sequences from the genomic DNA encoding the recombinant polypeptide may also be employed preferably in the same amounts as set forth for endogenous 3' expression regulation sequences.
  • the recombinant polypeptide encoded by the transgene may comprise either genomic DNA or a double stranded DNA derived from cDNA.
  • the optimal amount of 3' expression regulation sequence may be readily determined by varying the amount of 3' flanking sequence to obtain maximal expression of the recombinant polypeptide.
  • the distal 3' regulation sequence be it from an endogenous gene or a heterologous gene, will not extend into the adjacent gene from which is derived and will exclude any sequences which adversely effect the level of transgene expression.
  • the transgenes of the invention preferably also comprise a "recombinant intervening sequence" which interrupts the transcribed but untranslated 5' region of the transgene.
  • intervening sequences can be derived, for example, from bovine ⁇ S1 casein and from human lactoferrin.
  • sequences as used herein are "homologous recombinant intervening sequences" in that the 5' and 3' RNA splice signals in such recombinant intervening sequences are those normally found in an intervening sequence from an endogenous or heterologous gene.
  • Recombinant intervening sequences may, however, also comprise a "hybrid intervening sequence".
  • hybrid intervening sequences comprise a 5' RNA splice signal and 3' RNA splice signal from intervening sequences from different sources.
  • hybrid intervening sequences comprise at least one "permissive RNA splice sequence".
  • a permissive RNA splice siqnal is an RNA splice signal sequence, preferably a 3' RNA splice signal, from an intron contained within a repertoire of germ line DNA segments which undergo rearrangement during cell differentiation.
  • Such gene repertoires include the immunoglobulin super gene family, including the immunoglobulins and T-cell antigen receptors as well as the repertoire of the major histocompatibility complex (MHC) genes and others.
  • Particularly preferred permissive splice sequences are those obtained from the immunoglobulin repertoire, preferably of the IgG class, and more preferably those 3' splice signal sequences associated with the J-C segment rearrangement of the Ig heavy and light chain, most preferably the heavy chain.
  • a particularly preferred permissive splice sequence comprises that portion of the sequence as shown downstream of the HindIII site in Fig. 11.
  • a particularly preferred hybrid intervening sequence comprises the entire sequence shown in Fig.
  • hybrid intervening sequences containing permissive RNA splice signals are preferably used when the recombinant DNA corresponds to a cDNA sequence.
  • a transgenic mouse was obtained which produced approximately 1330 ⁇ g/ml of hLF in the transgenic milk.
  • This amount of recombinant polypeptide far exceeds the previously reported amounts for production of various protein in transgenic mouse milk of generally less than 10 ⁇ g/ml and in one case approximately 50 ⁇ g/ml. It also exceeds the maximum of 8 ⁇ g/ml of hLF produced herein when the same transgene was used that contained a homologous bovine intervening sequence rather than the hybrid intervening sequence.
  • hybrid intervening sequences are not limited to transgenes utilizing cDNA sequence. Rather, hybrid intervening sequences are also useful when the recombinant polypeptide is encoded by a genomic sequence. Based on the results obtained with the cDNA recombinant DNA and the general expectation that genomic DNA sequences express at higher levels than sequences derived from cDNA, it is expected that such hybrid intervening sequences used in conjunction with genomic recombinant DNA will further enhance expression levels above that which would otherwise be obtained with genomic sequence alone.
  • transgenes include large amounts of 5' and 3' expression regulation sequences.
  • the recombinant DNA is preferably derived from genomic clones which may be tens to hundreds of kilobases in length. Based on the present technology for cloning and manipulating DNA, the construction and microinjection of transgenes is practically limited to linearized DNA having a length not greater than about 50 kb. However, the transgenes of the invention, especially those having a length greater than about 50 kb, may be readily generated by introducing two or more overlapping fragments of the desired transgene into an embryonal target cell.
  • the overlapping fragments undergo homologous recombination which results in integration of the fully reconstituted transgene in the genome of the target cell.
  • it is preferred that such overlapping transgene fragments have 100% homology in those regions which overlap.
  • lower sequence homology may be tolerated provided efficient homologous recombination occurs.
  • the non-homology does exist between the homologous sequence portions, it is preferred that the non-homology not be spread throughout the homologous sequence portion but rather be located in discrete areas. Although as few as 14 base pairs at 100% homology are sufficient for homologous recombination in mammalian cells (Rubnitz, J. and Subramani, S. (1984) Mol. Cell. Biol. 4: 2253-2258), longer homologous sequence portions are preferred, e.g. 500bp, more preferably 1000bp, next most preferably 2000bp and most preferabl greater than 2000bp for each homologous sequence portion.
  • transgene so generated has a unit length of 38 kb, there is no known practical limit to the size of the transgene which may be formed using larger and/or greater numbers of overlapping transgene fragments. In particular, it is expected that transgenes may be formed by this approach having lengths between about 50 to 1000 kb and more preferably between 50 and 500 kb.
  • transgenic bovine species containing transgenes incorporating recombinant DNA comprising genomic DNA which otherwise could not be incorporated into a pronucleus to form a transgenic animal.
  • genomic transgenes are expected to produce higher expression levels in transgenic cows as compared to that which is produced by transgenes encoding recombinant cDNA.
  • a "secretory DNA sequence" encoding a functional secretion signal peptide is also operably linked within the transgene to direct secretion of the recombinant polypeptide from one or more cell types within the transgenic animal.
  • Secretory DNA sequences in general are derived from genes encoding secreted proteins of the same species of the transgenic animal. Such secretory DNA sequences are preferably derived from genes encoding polypeptides secreted from the cell type targeted for tissue-specific expression, e.g. secreted milk proteins for expression in and secretion from mammary secretory cells. Secretory DNA sequences, however, are not limited to such sequences.
  • Secretory DNA sequences from proteins secreted from other cell types within the species of transgenic animal may also be used, e.g., the native signal sequence of a homologous gene encoding a protein secreted other than in the mammary glands.
  • heterologous secretory DNA sequences which encode signal secretion peptides from species other than the transgenic animals my also be used e.g., human t-PA, human serum albumin human lactoferrin and human lactalbumin and secretion signals from microbial genes encoding secreted polypeptides such as from yeast, filamentous fungi, and bacteria.
  • a secretory DNA sequence may be defined functionally as any DNA sequence which when operably linked to a recombinant DNA sequence encodes a signal peptide which is capable of causing the secretion of the recombinant polypeptide.
  • a secretory DNA sequence encoding a secretory signal sequence functional in the mammary secretory cells of bovine species is used to cause secretion of recombinant polypeptide from bovine mammary secretory cells.
  • the secretory DNA sequence is operably linked to the recombinant DNA sequence. Examples of such secretory DNA sequences include DNA sequences encoding signal secretion sequences for bovine ⁇ S1 casein, murine lactoferrin and human transferrin.
  • the preferred secretory DNA sequence is that encoding the secretory sequence of ⁇ S1 casein from bovine species. The use of this secretory DNA sequence is described in more detail in the Examples.
  • “Operably linked" in the context of linking a secretory DNA sequence to a recombinant DNA sequence means that the secretory DNA sequence (comprising codons encoding the secretory signal peptide sequence) is covalently coupled to the recombinant DNA sequence so that the resultant secretory-recombinant DNA sequence encodes 5' to 3' for the secretory signal sequence and recombinant polypeptide. Accordingly, the reading frame for the secretory sequence and the recombinant DNA sequence must be covalently combined such that an open reading frame exists from the 5' end of the mRNA sequence formed after transcription and processing of the primary RNA transcript.
  • This open reading frame in the RNA contains a 5' sequence portion encoding the secretory signal peptide and a 3' sequence portion encoding the recombinant polypeptide.
  • the recombinant polypeptide produced upon expression of the secretory-recombinant DNA sequence is of a form which is capable of being secreted from targeted cells which express the DNA sequence.
  • the signal peptide generally is removed in vivo during secretion to produce an extracellular form of the recombinant polypeptide.
  • a secretory-recombinant DNA sequence is expressed predominantly in the mammary secretory cells of transgenic bovine species.
  • tissue-specific expression is obtained by operably linking mammary specific expression regulation DNA sequences to the above secretory-recombinant DNA sequence.
  • mammary specific regulation sequences include the aforementioned regulation sequences contained in various bovine genes preferentially expressed in the mammary secretory cells of the species.
  • mammary specific genes include ⁇ S1 casein; ⁇ S2-casein; ⁇ -casein; K-casein; ⁇ -lactalbumin; and ⁇ -lactoglobulin.
  • Preferred expression regulation sequences are derived from ⁇ S1 casein as described more in detail in the Examples.
  • the transgenes of the invention that are designed to secrete the recombinant polypeptide into transgenic bovine milk are capable of causing such secretion at levels significantly higher than that previously reported for transgenic mice and sheep.
  • the recombinant polypeptide is encoded by a recombinant DNA corresponding to, or derived from, cDNA
  • the molar concentration of the recombinant polypeptide is preferably greater than about 1.0 ⁇ M, more preferably greater than about 100 ⁇ M, and most preferably greater than 100 ⁇ M.
  • the amount of recombinant polypeptide is preferably greater than 50 ⁇ g/ml, more preferably greater than about 500 ⁇ g/ml and most preferably greater than about 1000 ⁇ g/ml (1mg/ml).
  • the transgene of the invention encodes a recombinant polypeptide that is encoded by recombinant DNA derived from or corresponding to genomic DNA (or comprised substantially of such genomic sequences, e.g. greater than about 50%, more preferably greater than about 75%, most preferably greater than 90% of the codons encoding the recombinant polypeptide are from genomic seguences)
  • the molar concentrations and protein levels in bovine transgenic milk are the same as for cDNA or higher.
  • the molar concentration of the recombinant polypeptide in such transgenic milk is preferably greater than about 50 ⁇ M, more preferably greater than about 150 ⁇ M, most preferably greater than about 500 ⁇ M.
  • the levels are preferably greater than about 10 mg/ml, more preferably greater than about 2.5 mg/ml, most preferably greater than 5 mg/ml.
  • the foregoing molar concentration and protein levels in bovine transgenic milk will vary depending upon the molecular weight of the particular recombinant polypeptide.
  • a particular advantage of producing a recombinant polypeptide in bovine transgenic milk is that relatively large molecular weight polypeptides may be so produced which are otherwise difficult to produce in large quantities in other systems such as prokaryotic expression systems.
  • any recombinant polypeptide may be produced in bovine transgenic milk according to the invention, it is generally preferred that such recombinant polypeptides have a molecular weight greater than about 10,000 Daltons.
  • other recombinant polypeptides having molecular weights of greater than 15,000, greater than 20,000 and greater than 60,000 Daltons may also be expressed in transgenic bovine milk.
  • human lysozyme having a molecular weight of 17,000 Daltons and lactoferrin having a molecular weight of 79,000 Daltons may be readily produced in the transgenic milk of bovine species according to the disclosure of the invention.
  • the recombinant polypeptides of the invention have a wide range of molecular weights.
  • the foregoing preferred molar concentrations of recombinant polypeptides are adjusted when higher molecular weight recombinant polypeptides are produced. Such adjustment is made by converting the molar concentration to the amount of protein produced and adjusting the molar concentrations so that the recombinant protein level is within the following preferred concentrations.
  • transgenic mice Most of the previous reports relating to the production of polypeptides in transgenic milk involve transgenic mice. The mouse, however, normally produces between 55 to 80 milligrams of protein per ml of milk. A cow, on the other hand, normally produces between 30 to 34 milligrams of protein per ml.
  • the recombinant polypeptide concentration be between about 3 and 50% of the normal bovine milk protein concentration (i.e., between about 1 and 17 milligrams of recombinant polypeptide per ml of transgenic milk), more preferably between 10 to 20% (i.e., between 3 to about 7 milligrams per ml) and most preferably between 10 and 15% (i.e., between about 3 and 5 milligrams per ml) of the normal amount of protein produced in bovine milk.
  • Such preferred ranges also provide a preferred maximum limit to the aforementioned levels of protein produced in transgenic bovine milk.
  • transgene of the invention are performed by standard methods known to those skilled in the art or as described herein. Once the transgene or overlapping homologous fragments encoding the transgene are constructed as described they are used to make transgenic non-human animals.
  • Methods of introducing transgenes or overlapping transgene fragments into embryonal target cells include microinjection of the transgene into the pronuclei of fertilized oocytes or nuclei of ES cells of the nonhuman animal. Such methods for murine species are well known to those skilled in the art.
  • the transgene may be introduced into an animal by infection of zygotes with a retrovirus containing the transgene (Jaenisch, R. (1976) Proc. Natl. Acad. Sci. USA 73:1260-1264).
  • the preferred method is microinjection of the fertilized oocyte.
  • the fertilized oocytes are first microinjected by standard techniques.
  • pre-implantation embryos preferably contain approximately 16 to 150 cells.
  • the 16 to 32 cell stage of an embryo is commonly referred to as a morula.
  • blastocysts Those pre-implantation embryos containing more than 32 cells are commonly referred to as blastocysts. They are generally characterized as demonstrating the development of a blastocoel cavity typically at the 64 cell stage.
  • Methods for culturing fertilized oocytes to the pre- implantation stage include those described by Gordon, et al. (1984) Methods in Enzymology 101 : 414; Hogan, et al.
  • transgene integration in the pre-implantation embryo is highly desirable.
  • methods are provided for identifying embryos wherein transgenesis has occurred and which permit implantation of transgenic embryos to form transgenic animals.
  • one or more cells are removed from the pre-implantation embryo.
  • the embryo is preferably not cultivated past the morula stage (32 cells). Division of the pre-implantation embryo (reviewed by Williams et al.
  • the hemi-embryo which is not analyzed as described herein, if shown to be transgenic, is used to generate a clonal population of transgenic non-human animals.
  • One of each of the hemi-embryos formed by division of pre-implantation embryos is analyzed to determine if the transgene has been integrated into the genome of the organism.
  • Each of the other hemi-embryos is maintained for subsequent implantation into a recipient female of the species.
  • a preferred method for detecting transgenesis at this early stage in the embryo's development uses these hemi-embryos in connection with a unique property of the restriction endonuclease Dpn I .
  • This enzyme recognizes the sequence GATC in double-stranded DNA but only when the adenine in each strand within this sequence is methylated at N-6.
  • the transgene containing the sequence GATC is methylated prior to microinjection either by transferring the transgene on an appropriate plasmid through a DAM + strain of microorganisms such as E. coli MM294 or by directly methylating the transgene with dam methylase.
  • the methylated transgene (preferably without any exogenous sequences such as plasmid vector) is then microinjected into fertilized oocytes (approximately 10 to 500 copies per pronucleus, more preferably 50 to 100 copies per pronucleus).
  • the fertilized oocytes so obtained are cultured in vitro to the pre-implantation stage. During this early growth and cell division phase, the genomic DNA is replicated. Accordingly, those copies of the methylated transgene integrated into the genome of the fertilized oocyte are unmethylated after replication whereas any non-integrated transgenes which may still exist after replication will remain methylated. (Lacks, S., et al. (1977) J. Mol. Biol. 114 : 153.) This differential methylation pattern for integrated versus non-integrated transgene permits the identification of which fertilized oocytes have integrated the transgene into the genome.
  • the identification of the pre-implantation embryos containing the integrated transgene is achieved by analyzing the DNA from each of the hemi-embryos. Such DNA is typically obtained by lysing the hemi-embryo and analyzing the thus released DNA after treatment as described by Ninomiy, T. et al. (1989) Molecular Reproduction and Development 1 : 242-248. Each of the DNA samples is treated with Dpn I. Thereafter, a polymerase chain reaction (Saiki, et al. (1985) Science 230:1350-1354) is preformed to amplify all or part of the transgene.
  • extension primers each complimentary to opposite strands at opposing ends of the transgene are used for amplification.
  • extension primers are chosen such that the amplified gene product spans the Dpn I site in the transgene. If Dpn I cleavage has not occurred, PCR amplification results in amplified sequences having a predetermined size whereas primer extension for those transgenes which have been cleaved will not result in exponential amplification.
  • the Dpn I/PCR amplified DNA from the hemi-embryo is subjected to electrophoresis followed by hybridization with labeled probe complimentary to the region of the transgene between the two extension primers.
  • This facilities the determination of the size of the amplified DNA sequences, if any, and provides an indication of whether the transgene has been integrated into the pre-implantation embryo from which the hemi- embryo was obtained (now called a "transgenic hemi-embryo"). If it has, the remaining untreated transgenic hemi-embryo is transplanted into a recipient parent.
  • the transgenic non-human animal having the desired phenotype conferred by the integrated transgene is identified by an appropriate method in utero or after birth.
  • restriction endonucleases capable of cleaving a methylated DNA sequence but incapable of cleaving the unmethylated form of a recognition sequence may be used in the aforementioned method.
  • the above described methods for the detection of transgenesis in pre-implantation embryos provide economical and time saving method for generating transgenic non-human animals since they significantly decrease the number of pregnancies required to produce a transgenic animal and substantially increase the likelihood that an implanted embryo will produce a transgenic non-human animal. Such methods are especially important for those animals for which very low or non-existent frequencies of transgenesis have been obtained, e.g. bovine species.
  • the above described method for detecting transgenesis in pre-implantation embryos is combined with embryonic cloning steps to generate a clonal population of transgenic embryos which may thereafter be implanted into recipient females to produce a clonal population of transgenic non-human animals also having the same genotype.
  • transgenic embryos and/or non-human transgenic animals having the same "genotype” means that the genomic DNA is substantially identical between the individuals of the embryo and/or transgenic animal population. It is to be understood, however, that during mitosis various somatic mutations may occur which may produce variations in the genotype of one or more cells and/or animals. Thus, a population having the same genotype may demonstrate individual or subpopulation variations.
  • transgenic hemi-embryo After a hemi-embryo is identified as a transgenic hemi-embryo, it is cloned. Such embryo cloning may be performed by several different approaches. In one cloning method, the transgenic hemi-embryo is cultured in the same or in a similar media as used to culture individual oocytes to the pre-implantation stage. The "transgenic embryo” so formed (preferably a transgenic morula) is then divided into "transgenic hemi-embryos" which can then be implanted into a recipient female to form a clonal population of two transgenic non-human animals.
  • the two transgenic hemi-embryos obtained may be again cultivated to the pre-implantation stage, divided, and recultivated to the transgenic embryo stage. This procedure is repeated until the desired number of clonal transgenic embryos having the same genotype are obtained. Such transgenic embryos may then be implanted into recipient females to produce a clonal population of transgenic non-human animals.
  • the transgenic embryo is cloned by nuclear transfer according to the techniques of Prather, etal. (1988) Biol. Reprod. 37:59-86; Roble, et al. (1987) J. Anim. Sci. 64: 642-664.
  • nuclei of the transgenic embryo are transplanted into enucleated oocytes, each of which is thereafter cultured to the blastocyst stage.
  • the transgenic embryos may be resubjected to another round of cloning by nuclear transplantation or may be transferred to a recipient parent for production of transgenic offspring having the same genotype.
  • transgenesis in addition to the foregoing methods for detecting early transgenesis, other methods may be used to detect transgenesis. Such methods include in utero and post partum analysis of tissue. In utero analysis is performed by several techniques. In one, transvaginal puncture of the amniotic cavity is performed under echoscopic guidance (Bowgso, et al. (1975) Bet. Res. 96: 124-127; Rumsey, et al. (1974) J. Anim. Sci. 39:386-391). This involves recovering about 15 to 20 milliliters of amniotic fluid between about day 35 and day 100 of gestation.
  • This volume of amniotic fluid contains about 1000 to 12,000 cells per ml originating from the urogenital tract, the skin and possibly the lungs of the developing embryo. Most of these cells are dead. Such cells, however, contain genomic DNA which is subjected to PCR analysis for the transgene as an indication of a successful transgenesis. Alternatively, fetal cells may be recovered by chorion puncture. This method also may be performed transvaginally and under echoscopic guidance. In this method, a needle is used to puncture the recipient animal's placenta, particularly the placentonal structures, which are fixed against the vaginal wall. Such sampling may be performed around day 60 of gestation in bovine species. Chorion cells, if necessary, are separated from maternal tissue and subjected to PCR analysis for the transgene as an indication of successful transgenesis.
  • Transgenesis may also be detected after birth.
  • transgene integration can be detected by taking an appropriate tissue biopsy such as from the ear or tail of the putative transgenic animal. About one to two centimeters of tail or about five to ten square millimeters of ear are obtained followed by southern blotting with a probe for the transgene according to the method of Hogan, et al. (1986) Manipulating the Mouse Embryo, Cold Spring Harbor Laboratory.
  • Transgenesis can also be determined by using the southern blot technique with DNA obtained from other tissues.
  • semen from a recombinant bull will be useful for identifying transgenic animals.
  • Transgenesis may also by detected by assaying for expression of the recombinant polypeptide in a tissue, secretion (e.g., saliva), or other body fluid.
  • a tissue secretion (e.g., saliva)
  • saliva secretion
  • the goal is expression of a recombinant polypeptide in milk of cows it will be especially useful to assay the saliva of bulls for expression levels. This is because some mammary specific promoters may also cause salivary gland expression, albeit at low levels. See, e.g., Archibald et al. (1990) Proc. Nat. Acad. Sci. USA 87Z:5178-5182.
  • the transgenic milk so obtained may be either used as is or further treated to purify the recombinant polypeptide. This depends, in part, on the recombinant polypeptide contained in the transgenic milk and the ultimate use for that protein. Thus, when the recombinant polypeptide is secreted into transgenic milk to increase the nutritional value of the bovine milk, no further purification is generally necessary.
  • An example of such a situation involves one of the preferred embodiments wherein human lactoferrin is produced in the milk of bovine species as a supplement to control intestinal tract infections in newborn human infants and to improve iron absorption.
  • human lactoferrin produced in transgenic bovine milk may be partially purified by acidifying the milk to about pH 4-5 to precipitate caseins.
  • the soluble fraction (the whey) contains the human lactoferrin which is partially purified.
  • the recombinant polypeptide contained in bovine transgenic milk may also be used in food formulations.
  • a particularly useful food formulation comprises an infant formula containing one or more recombinant polypeptides from transgenic bovine milk which have either nutritional or other beneficial value.
  • an infant formula containing human lactoferrin from transgenic bovine milk made according to the present invention provides a bacteriostatic effect which aids in controlling diarrhea in newborn.
  • recombinant polypeptides such as human casein and human lysozyme may also be generated in transgenic bovine milk to provide nutritional value.
  • Table 2 sets forth the constituents of a typical infant formula. As indicated therein, the protein content varies between about 1.8 and 4.5 grams of protein per 100 kilocalories of formula.
  • the total protein including recombinant polypeptide should lie between the values at least based on regulatory requirements in the United States from which the formulation in Table 2 is based.
  • the amount of total protein including recombinant polypeptide may vary from the foregoing depending upon the local regulations where the particular formula is intended to be used.
  • the source of protein shall be at least nutritionally equivalent to casein.
  • recombinant protein according to the invention or recombinant proteins and other proteins.
  • other food formulations may also be supplemented with recombinant polypeptides from transgenic bovine milk.
  • recombinant polypeptides may be used to supplement common diet formulations.
  • purification methods consistent with such an application are called for. Such purification methods will depend on the particular recombinant polypeptide to be purified and are generally known to those skilled in the art. Such methods typically include a partial purification by casein fractionation followed by chromotography of the appropriate fraction containing the recombinant polypeptide. Such chromotography includes affinity chromotography, ion exchange chromotography, gel filtration and HPLC.
  • transgenes are provided for producing human lactoferrin in the milk of transgenic bovine species.
  • Human lactoferrin (HLF) is a single chain glycoprotein which binds two ferric ions. Secreted by exocrine glands (Mason, et al. (1978) J. Clin. Path. 31:316-327; Tenovuo, et al. (1986) Infect. Immun. 51:49-53) and polymorphonuclear neutrophil granulocytes (Mason, et al. (1969) J. Exp. Med. 130: 643-658), this protein functions as part of a host non-specific defense system by inhibiting the growth of a diverse spectrum of bacteria.
  • HLF exhibits a bacteriostatic effect by chelation of the available iron in the media, making this essential metal inaccessible to the invading microorganisms (Bullen, et al. (1972) Br. Med. J. 1:69-75: Griffiths, et al. (1977) Infect. Immun. 15:396-401; Spik, et al. (1978) Immunology 8:663-671; Stuart, et al. (1984) Int. J. Biochem. 16:1043-1947). This effect is blocked if the protein is saturated with ferric ions.
  • HLF displays a direct bacteriocidal effect on certain microorganisms (Arnold, et al. (1980) Infect. Immun.
  • Lactoferrin is the major iron binding protein in human milk (present at a concentration of about 1.5-1.7 mg/ml) and may play a role in the absorption of iron by the small intestine. All of the iron present in breast milk is thought to be bound to hLF and is taken up at very high efficiencies compared to formula (Hide, D.W., et al. (1981) Arch. Pis. Child. 56:172). It has been postulated that the high uptake of the hLF bound iron is due to a receptor in the jejunum and data has been presented suggesting existence of receptors in Rhesus monkeys (Cox, et al. (1979) BBA 588 : 120; Davidson, L.A., et al. (1985) Fed.
  • human lactoferrin in the milk of transgenic bovine species provides a source of human lactoferrin.
  • Such lactoferrin may be purified from the transgenic milk for formulation purposes.
  • the whole transgenic milk may be used, preferably after pasteurization, in either liquid or dried form.
  • the beneficial action of human lactoferrin may be potentiated by combining the human lactoferrin or the transgenic milk containing it with human lysozyme.
  • the human lysozyme may be simultaneously produced in the transgenic cow by introducing a second transgene simultaneously with the HLF transgene to produce a transgenic cow capable of producing more than one recombinant polypeptide in the transgenic milk.
  • the transgenes may be sequentially introduced into bovine species.
  • a transgenic bovine species is obtained containing one of the transgenes.
  • embryonic cells, such as eggs are obtained from the transgenic female and treated so as to incorporate the second transgene encoding the second polypeptide.
  • the egg is fertilized, followed by microinjection of the pronucleus of the zygote so obtained.
  • the invention contemplates the production of transgenic bovine species and transgenic milk wherein more than one recombinant polypeptide is produced by such a transgenic animal in the transgenic milk.
  • the complete amino acid sequence of HLF has been determined (Metz-Boutigue et al. (1984) Eur. J. Biochem. 1451 : 659-676).
  • HLF comprises two domains, each containing one iron-binding site and one N-linked glycosylation site. These domains show homology between each other, indicative of an ancestral gene duplication and fusion event.
  • HLF shares extensive homology with other members of the transferrin family (Metz-Boutigue, supra; Pentecost, etal. (1987) J. Biol. Chem.
  • human lactoferrin comprises a polypeptide having the amino acid sequence substantially as described by Metz-Boutigue, et al. (1984) Eur. J. Biochem. 1451:659-676 and as set forth in Fig. 2. It is noted, however, that an earlier partial sequence of the human lactoferrin sequence disclosed a number of discrepancies between the published sequence and that obtained herein. Specifically, the following discrepancies exist (amino acid numbering is from the sequence in Figure 1 with DNA position in parenthesis) : Amino Acid Pos ition In Metz -Boutigue
  • human lactoferrin is also defined by the sequence shown in Figure 1 which combines the sequence differences obtained herein with the published sequence.
  • the term human lactoferrin also includes allelic variations of either of these sequences or recombinant human lactoferrin variants wherein one or more amino acids have been modified by the substitution, insertion or deletion of one or more amino acid residues.
  • human lactoferrin may be produced in milk with all or part of a secretory signal sequence covalently attached thereto.
  • a "human lactoferrin DNA sequence” is a DNA sequence which encodes human lactoferrin as defined above. Such a human lactoferrin DNA sequence may be obtained from a human mammary gland cDNA library or may be derived from the human genome.
  • Example 2 herein describes the cloning and nucleotide sequence of human lactoferrin derived from a human mammary gland cDNA library. The DNA sequence of this human lactoferrin is shown in Fig. 1 and Fig. 2 and is substantially the same as that described by Rado, et al.
  • plasmids containing an expressible transgene encoding hLF is described in the examples.
  • One of these plasmids is cGPlHLF also sometimes referred to as 16,8HLF3) contains a transgene designed for tissue-specific expression in bovine mammary secretory cells.
  • transgenes are provided for producing human serum albumin in the milk of transgenic bovine species.
  • Human serum albumin is a serum protein which contains 584 amino acid residues (Minghetti, et al. (1986) J. Biol. Chem. 261:6747). It is the most abundant protein in human serum and performs two very important physiological functions. Serum albumin is responsible for about 80% of the total osmolarity of blood and it transports fatty acids between adipose tissues.
  • Human serum albumin is used primarily to expand plasma volume by restoring osmotic pressure in the circulatory system .
  • a heat treated serum derived hSA fraction is infused in most shock and trauma victims, including most of the patients undergoing extensive surgery.
  • HSA is presently derived from human blood plasma as a by-product from blood fractionation processes to obtain rare blood proteins such as factor VIII and IX.
  • the recently developed technology of producing such factors by biotechnological means threatens the source of human serum albumin.
  • human serum albumin comprises a polypeptide having the amino acid sequence substantially as that described by Minghetti, et al., ibid; Lawn, et al. (1981) Nucl. Acids Res. 9:6103. Also included are variations thereof including recombinant human serum albumin variants wherein one or more amino acids have been modified by the substitution, insertion or deletion of one or more amino acid residues (Minghetti, et al. (1986) J. Biol. Chem. 261:6747-6757). In some instances, human serum albumin may be produced in milk by expressing a transgene which contains DNA encoding the secretory signal sequence of hSA.
  • human serum albumin may be produced in and secreted from liver cells of a transgenic animal utilizing a completely heterologous transgene comprising human genomic DNA encoding 5' expression regulation sequences, the human serum albumin secretion signal and structural gene and 3' expression regulation sequences.
  • transgenes containing this heterologous sequence were formed by in vivo homologous recombination of overlapping transgene fragments to reconstitute the hSA gene in the transgenic animal. The so formed transgenic animal produced human serum albumin in its circulatory system.
  • a "human serum albumin DNA sequence” is a DNA sequence which encodes human serum albumin as defined above.
  • Such a human serum albumin DNA sequence may be obtained from ⁇ HAL-HAI, XHAL-3W and XHAL-HI4 as described by Urano, et al. (1986) J. Biol. Chem. 261:3244-3251 and Urano, et al. (1984) Gene 32:255-261 and in the Examples herein.
  • the human serum albumin DNA sequence was cloned as described in Example 10 herein and subsequently manipulated to substitute for the human lactoferrin gene encoded in plasmid cGPlHLF (also referred to as p16,8HLF4). From this plasmid a transgene is obtained containing 16 kb of the 5' expression regulation sequence of the bovine ⁇ S1 casein gene, human serum albumin DNA sequence and approximately 8 kb of the 3'-flanking region of the ⁇ S1 casein bovine gene. This transgene is used to microinject fertilized oocytes from bovine species.
  • blastocysts containing the hSA transgene are implanted into a recipient female bovine species and brought to term.
  • the following is presented by way of example and is not to be construed as any limitation on the scope of the invention.
  • Placental tissue was obtained from the slaughterhouse. Surrounding connective tissue was removed and pieces of about 30 grams were quickly frozen in liquid N 2 . Chromosomal DNA was isolated as follows: 30 grams of tissue was homogenized (on ice) with 35 ml of Buffer 1 containing 300 mM Sucrose; 60 mM KCl; 15 mM NaCl; 60 mM Tris. HCI pH 8.2; 0.5 mM spermidine; 0.15 mM spermine; 2 mM EDTA; 0.5 mM EGTA. 65 ml of icecold buffer 1 containing 1% NP40 was added and the mixture was incubated for five minutes on ice.
  • RNAse A and T1 were added to final concentrations of 0.4 mg/ml and 6 u/ml respectively. After incubation at 37°C for three hours, Proteinase K was added to a final concentration of 0.1 mg/ml. This mixture was incubated for 15 hours at 37°C. The mixture was then carefully extracted with phenol.
  • the aqueous phase was isolated and 1/30 volume of 3M NaOAc pH 5.2 and one volume of isopropylalcohol was added.
  • the precipitate (DNA) was rinsed with 70% ethanol and slowly dissolved in 0.5 ml of 10 mM Tris.HCl pH 8.0; 1 mM EDTA, at 4°C.
  • Primer 1 was located at position-681 relative to the major transcription initiation site and had the following sequence:
  • Primer #2 was located at position +164 relative to the major transcription initiation site and had the following sequence: 5'-TGA AGC TTG CTA ACA GTA TAT CAT AGG-3' (Seq. ID. No.: 6).
  • the first eight nucleotides of this primer are not encoded by the bovine genome, but contain a HindIII restriction site to facilitate subsequent cloning steps. These primers were annealed to the chromosomal DNA and extended in the presence of deoxynucleotides by TAQ-polymerase.
  • the other primer was located at position 1070 of the cDNA sequence and had the following sequence: 5'-GCA
  • the bacteriophage particle titre was determined on Escherichia coli MB406 a permissive host strain (Stratagene Inc.). For this, several dilutions of the phage stock were made in SM buffer (50 mM Tris. HCI pH 7.5, 100 mM NaCl, 10 mM MgSO4, 0.01% gelatin) and mixed with 200 ⁇ l MB406 (O.D.
  • 550 0.9; after 20 minutes at 37°C, 3 ml top agarose (Luria-Bertani medium, 0.8% agarose, 10 mM MgCl 2 ) was added and this was plated on LB plates and incubated overnight at 37°C.
  • 3 ml top agarose Lia-Bertani medium, 0.8% agarose, 10 mM MgCl 2
  • Approximately 600,000 phages were then plated by adding the required amount of phage stock to 400 ⁇ l MB406. The subsequent plating was as described as above.
  • the next step was transfer of the phage to nitrocellulose filters. Plates were placed at 4°C for one hour. Nitrocellulose filters (S&S) were placed on the top agarose layer and exact position was marked. After lifting, the filters were soaked for (1) 30 minutes in denaturation buffer (1.5M NaCl, 0.5M NaOH); (2) 5 minutes in neutralizing buffer (1.5MNaCl, 0.5M Tris. HCI pH 8.0). After rinsing with 2xSSPE (360 mM NaCl, 20 mM NaH 2 PO 4 , 2 mM EDTA), the filters were baked under vacuum at 80°C for two hours.
  • denaturation buffer 1.5M NaCl, 0.5M NaOH
  • neutralizing buffer 1.5MNaCl, 0.5M Tris. HCI pH 8.0
  • Prehybridization of the filters was performed in a buffer containing 50% formamide, 5x Denhardt's solution (0.1% Ficoll, 0.1% polyvinylpydrolidone, 0.1% bovine serum albumin), SxSSPE, 0.1% SDS and 100 ⁇ g/ml denatured salmon sperm DNA at 42°C for two hours. Hybridization was performed in same buffer at 42°C overnight in a shaking waterbath. The probe, generated as previously described, was labelled using the Random Primed labelling kit from Boehringer Mannheim. After overnight hybridization the filters were washed three times with 2xSSC, 0.1% SDS at room temperature.
  • phage DNA was prepared with one volume isopropanol. Phage DNA was washed once with 70% ethanol and dissolved in 50 ml Tris.HCl pH 7.5, 1 mM EDTA buffer. Restriction enzyme analysis, agarose gel electrophoresis, transfer of DNA from gel to nitrocellulose filter and Southern blotting were all done according to standard procedures (Maniatis (1982), Molecular Cloning: A Laboratory Manual). Hybridization with probes (described hereinafter) was performed according to the same procedure as the screening conditions described above.
  • Duplicate nitrocellulose filters from the initial phage plating used for isolating 5' clones were screened with the 3' ⁇ S1-casein probe using the same hybridization conditions previously described. Eight positive clones were identified after two rounds of screening. Phage DNA was prepared as described. Subsequent restriction digests with SaII, EcoRI, and Sal/EcoRI and Southern hybridization with the 3' ⁇ S1 probe showed identical inserts in seven of the eight clones. One clone containing an 18.5 kb EcoRI insert was further analyzed with the restriction enzymes BsteII and BamHI. A restriction map of that clone is shown in Fig. 4.
  • T4 ligase and T7 polynucleotide kinase were obtained from Boehringer-Mannheim, New England Biolabs, or Bethesda Research Laboratories. Radio-isotopes were purchased from Amersham.
  • a human mammary gland cDNA library in bacteriophage ⁇ gt11 was obtained from Clontech, Inc., Palo Alto, Calif.
  • the human mammary gland library was screened by standard plaque hybridization technique (Maniatis, et al. (1982) Molecular Cloning: A Laboratory Manual) with three synthetic oligomers. Two of the oligomers were 30-mers corresponding to the cDNA sequence of Rado et al., supra, at amino acid positions 436-445 and 682-691. The third was a 21-mer "best guess" probe based on human codon bias and coding for amino acid sequence of HLF between amino acid residues 18 and 24. Respectively, they were:
  • DNA fragments were isolated by use of low-melting agarose (Crouse et al, supra) and subcloned into bacteriophase M13mpl8 or M13mp19 (Messing et al. (1983) Methods Enzymol. 101, 20-78).
  • the sequence was determined using the Sequenase enzyme (modified T7 DNA polymerase) (Tabor et al. (1987) Proc. Natl. Acad. Sci. USA 84, 4767-4771). All reactions were carried out according to the manufacturer's specifications (US Biochemicals). The sequence is shown in Fig. 1.
  • the hLF sequence was digested with HindIII and EcoRI (present in the surrounding phage sequences) and subcloned into the HindIII and EcoRI site of pUC19 to form pUS119 Lacto 4.1. This clone contained the entire coding sequence of the mature form of hLF, but lacked the complete signal sequence.
  • CAT chloramphenicol Acetyl transferase gene
  • the CAT gene is useful to detect the expression level for a heterologous gene construct since it is not normally present in mammalian cells and confers a readily detectable enzymatic activity (see Gorman, C.N., et al. (1983), Mol. Cell. Biol., 2 , 1044-1051) which can be quantified in the cells or animals containing an expressible gene.
  • fragment 2 Approximately 1.6 kb (fragment 2, Fig. 5A) of ⁇ S1-casein 3'-flanking sequence was isolated by PCR amplification from a bovine 3'-flanking genomic clone from Example 1. This region contained the previously described splice within the 3' untranslated region of ⁇ S1-casein gene. Fragment 2 was subcloned into the SmaI site of pUC19. The primer sequences consisted of: 5'-GAGGGACTCCACAGTTATGG-3'
  • a polyadenylation sequence was obtained from SV40 virus as a BamHI-DraI fragment (fragment 3 in Fig. 5A) isolated from pRSVcat (Gorman, CM., et al. (1982), Proc. Natl. Acad. Sci., 79, 6777-6781).
  • a bacterial CAT coding sequence was subcloned into pUC19 as a PstI-BamHI fragment.
  • Fragment 1 of ⁇ S1-casein promoter was subcloned into pMH-1 (Fig. 6) between the Ncol and HindIII sites to form pMHS15' flank.
  • the SV40 polyadenylation sequence (fragment 3) was subcloned as a BamHI-DraI fragment into pUC19 immediately 3' to the 3' ⁇ S1-casein flanking sequence (fragment 2) to form pUC19 3' UTR/SV40. This allowed for the removal of a continuous EcoRI-SalI fragment (containing the 3'-flanking sequence and poly (A) sequence) that was subcloned into pMH-1 to derive pMHS13'UTR (Fig.
  • CAT fragment fragment 4 in Fig. 5B, PstI-BamHI
  • SV40 polyadenylation fragment fragment 3 in Fig. 5A, BamHI-DraI
  • Each of these CAT plasmids were transfected into human 293S cells (Graham, F.L., et al. (1977), J. Gen. Virol., 36, 59-72) by the calcium phosphate co-precipitation method (Gorman, CM., et al. (1983), Science, 221, 551; Graham, F.L., et al. (1973), Virology, 52, 456-467). Cells were harvested 44 hours after transfection and cell extracts were assayed for CAT activity (Gorman, CM., et al. (1982), Mol. Cell. Biol., 2 , 1011; deCrombrugghe, B., et al.
  • a control plasmid expressing CAT driven by the Cytomegalovirus Immediate early promoter (Boshart, M., et al. (1985), Cell, 41. 521) was transfected into human 293 S cells to assay for transfected efficiency.
  • pS13'5'CAT was expressed in these cells at a level which was approximately 30-100 fold lower than the control plasmid, but significantly higher than background. Primer extension analysis indicated that transcription had initiated predominantly in the expected region.
  • Bovine ⁇ S1-casein 5'-flanking sequence from Example 1 was isolated from the bovine genomic library (phage GP1) as a SalI-BglII fragment.
  • the BglII site lies at the junction of the first intron and second exon of the ⁇ S1-casein gene.
  • Bovine ⁇ S1-casein signal sequence (Stewart et al. (1984) Nucl. Acids Res. 12, 3895) was prepared from synthetic DNA synthesized on a Cylone Plus ® DNA Synthesizer (Millgen/Biosearch I) and contained the entire signal sequence plus XhoI and Cla I sites attached to the 5'-end, and NaeI to the 3'-end (fragment 8, Fig. 7B).
  • the hLF 3'-linker (fragment 7, Tig. 7C) was subcloned into the EcoRI-KpnI sites of pMH3'UTR (Fig. 7A) to produce pMH3 ' UTRhLF2 linker (Fig. 7A) .
  • the two hLF coding fragments (fragments 5 and 6 in Fig. 7C) were subcloned into the NaeI and EcoRI sites of pS13'hLF1/2L (Fig. 7B) to make pS13'UTRhLF (Fig. 7C).
  • the large ⁇ S1-casein 3' UTR fragment from pMH3'E10 (Fig. 7A) was isolated as a BstEII-Sa1I fragment and subcloned into the same sites of pS13'UTRhLF to form phLF3' 10 kb (Fig. 7D).
  • Cosmid cGP1HLF was prepared from a 3-way ligation (Fig. 7F) :
  • Fragments from (a), (b), and (c) were ligated together and transfected into bacteria using commercial lambda packaging extracts (Stratagene, Inc.) to produce cGPlHLF.
  • Bovine ⁇ S1-casein/hLF expression plasmids Bovine ⁇ S1-casein/hLF expression plasmids.
  • the HindIII-SalI fragment of pS13'UTRhLF was subcloned into the same sites in pMHS15' flank to form pS13'5'hLF (Fig. 7E).
  • This plasmid contains 681 bp of bovine ⁇ S1-casein promoter sequence, the ⁇ S1-casein/IgG hybrid intron, the ⁇ S1-casein signal sequence, the hLF coding region, approximately 1.6 kb of ⁇ S1-casein 3'-flanking sequence, and the SV40 late region polyadenylation sequence.
  • Plasmid pS13'5'hLF (Fig. 7E) was cut with Kpnl and BamHI which border the ⁇ S1-casein 1.6 kb 3'-flanking sequence. The larger vector fragment was purified, made blunt ended with Klenow, and self-ligated to form pS15'hLF.
  • the Sepharose beads were suspended (2 mg/ml) in phosphate-buffered saline (PBS; 10 mM sodium phosphate, 0.14 M NaCl containing 10 mM EDTA, 0.1% ( w /v) Polylorene and 0.02% ( w /v) NaN 3 , pH 7.4.
  • PBS phosphate-buffered saline
  • Sepharose suspensions (0.3 ml) were incubated for five hours at room temperature by head-over-head rotation with samples (usually 50 ⁇ l) in 2-ml polystyrene tubes. Sepharose beads were then washed with saline (five times with 1.5 ml) and incubated for 16 hours at room temperature with 50 ⁇ l (1kBq) of 125 I-labeled-affinity-purified polyclonal rabbit anti human lactoferrin antibodies, together with 0.5 ml of PBS, 0.1% ( w /v) Tween-20. Thereafter the Sepharose was washed again with saline (four times with 1.5 ml) and bound radio activity was measured. Results were expressed as percent binding of the labelled antibodies added.
  • lactoferrin levels were expressed in nanomolar, using purified human milk lactoferrin as a standard (serial dilutions in PBS, 10 mM EDTA, 0.1% ( w /v) Tween-20.
  • 293S cells were transfected with the above hLF plasmids as described (1 ⁇ g of a CMV-CAT plasmid was co-transfected as control for transfection efficiency).
  • the proteins behave, identical to hLF in a human milk sample in a dose response assay measuring the amount of 125 I- anti-lactofernn bound as a function of the amount of sample used.
  • the protein has about the same size (-80kD) as in a human milk sample as judged by Western blotting.
  • the hLF RNA produced in the cells has the correct size and its level is similar for both plasmids as judged by Northern - blotting.
  • Immature oocytes are obtained in large quantity (400-600/day) by aspirating follicles of ovaries obtained at abbatoirs. Immature oocytes are cultured for a period in vitro before they are competent to be fertilized. Once "matured", oocytes are fertilized with sperm which has also been matured, or "capacitated” in vitro. The pronuclei of the fertilized oocyte is then injected with the transgene encoding for the expression and secretion of human lactoferrin.
  • Zygotes resulting from this in vitro fertilization and microinjection are then cultured to the late morula or blastocyst stage (5-6 days) in medium prepared, or "conditioned" by oviductal tissue. Blastocysts are then transferred non-surgically to recipient cattle for the balance of gestation or analyzed for integration of the transgene as described herein.
  • IMM In vitro maturation
  • Ovaries are obtained immediately after slaughter at local abbatoirs and oocytes are recovered.
  • oocytes are obtained from living cattle by surgical, endoscopic, or transvaginal ultrasonic approaches. In all cases, oocytes are aspirated from ovarian follicles (2-10 mm diameter). After washing, oocytes are placed in a maturation medium consisting of M199 supplemented with 10% fetal calf serum, and incubated for 24 hours at 39°C Sirard et al. (1988) Biol. Reprod. 39, 546-552.
  • IVF In vitro fertilization
  • Matured oocytes are fertilized with either fresh or thawed sperm.
  • Sperm are prepared for fertilization by first obtaining a population of sperm enriched for motility by a "swim-up" separation technique (Parrish et al. (1986) Theriogenology 25, 591-600).
  • Motil sperm are then added to a fertilization media, consisting of a modified Tyrode's solution (Parrish et al. (1986) supra.) supplemented with heparin to induce sperm capacitation (Parrish et al. (1988) Biol. Reprod. 38, 1171-1180).
  • IVF In vitro culture
  • Conventional culture systems which support development of murine, rabbit, or human ova, do not support development of bovine embryos past the 8-16 cell stage. This problem has been overcome by pre-conditioning culture media with oviductal tissue. Oviduct-conditioned medium will support bovine embryos past the 8-16 cell stage to the blastocyst stage in vitro (Eyestone and First (1989) J. Reprod. Fert. 85,
  • Bovine embryos have proved refractory to in vitro culture. This in part stems from the existence of a "block" to cleavage in vitro at the 8-16 cell stage. This block may be alleviated by culturing embryos in the oviducts of rabbits (reviewed by Boland (1984) Theriogenology 21, 126-137) or sheep (Willadeen (1982) in: Mammalian Egg Transfer, (E. Adams, ed., pp. 185-210)); Eyestone et al. (1987) Theriogenology 28, 1-7).
  • Bovine embryos did not yield to attempts to culture them in vitro past the 8-16 cell "block” until Camous et al. (1984) J. Reprod. Fert. 72, 479-485 demonstrated cleavage to 216 cells when embryos were co-cultured with trophoblastic tissue.
  • Blastocysts have been produced in this system after superovulation and artificial insemination, or by in vitro maturation (IVM), and fertilization (IVF) of immature oocytes. Blastocysts produced in this fashion resulted in pregnancies and live calves after transfer to recipient animals. The results obtained were as follows:
  • Tissue suspension can be used for embryo-co- culture.
  • media may be conditioned for 48h; after centrifuging the suspension, the supernatant may be used as embryo culture medium.
  • Conditioned medium may be stored at -70°C, if desired.
  • Conditioned medium should be used at full strength for embryo culture (no dilution) (Eyestone (1989) ibid).
  • the DNA fragment containing the hLF expression unit is excised from the vector by digestion with the appropriate restriction enzyme(ss) and separated on agarose gels.
  • the fragment is purified by electroelution, phenol and chloroform extraction and ethanol precipitation (Maniatis et al.).
  • the DNA fragment is dissolved in and dialyzed in 10 mM tris, 0.1 mM EDTA pH 7.2 at a concentration of 1 to 2 ⁇ g/ml. Microinjection needles are filled with the dialyzed DNA solution.
  • cumulus cells are removed from the egg by either vortexing at maximal speed for 2 minutes or pipetting the eggs up and down several times in a standard micropipet.
  • Bovine pronuclei are injected in principle as murine pronuclei (Hogan, B. et al. (1986) in: Manipulating the mouse embryo, Cold Spring Harbor Laboratory) with an additional centrifugation step in order to visualize the pronuclei.
  • the injection takes place 18-24 hours after fertilization. The time varies depending on the bull used as a source of semen. Different batches of semen cause the nuclei to become visible at different times.
  • Bovine oocytes matured and fertilized in vitro, are spun in an eppendorf tube in 1 ml of tyrodes-hepes solution (Parrish (1987)) at 14500 g for eight minutes (Wall et al. (1985) Biol. Reprod. 32, 645-651). The embryos are transferred to a drop of tyrodes-hepes solution on a microscope slide covered with paraffin oil. Using a hydraulic system the oocytes are fixed to the egg holder in such a way that both the pronuclei are visible (using interference-contrast or phase contrast optics). If necessary, the oocytes are rolled to change their position on the egg holder to visualize the pronuclei.
  • the injection needle is brought into the same sharp focus of one of the pronuclei.
  • the needle is then advanced through the zona pellucida, cytoplasm into the pronucleus.
  • a small volume of 1-3 pl is injected (containing 20-100 DNA copies) into the pronucleus either by using a constant flow or a pulse flow (using a switch) of DNA solution out of the needle.
  • two cell stage embryos are spun as described and the nuclei of both blastomers are injected as described.
  • the injected embryos are then transferred to a drop of co-culture medium as described in Example 6 in order to develop to the morula or blastocyst stage.
  • PCR is performed as described previously (Ninomiy, T. et al. (1979) Molecular Reprod. and Devel. 1, 242-248) with sets of two primers, one in ⁇ S1 and the other in hLF cDNA sequence. For example, in a PCR where the forward primer (30mer) ⁇ S1 sequence is ATG AAA CTT ATC CTC ACC TGT CTT GTG
  • Bovine morula developed from microinjected oocytes are split according to the method of Donahue (Donahue, S. (1986) Genetic Engineering of Animals, ed. J. Warren Evans et al., Plenum).
  • One half of the morula is kept in culture to develop into blastocysts.
  • the other half is subjected to the DNA analysis as described in Example 8.
  • the morula kept in culture are developed into a blastocyst or as a source for nuclear transfer into enucleated zygotes.
  • Blastocyst transfer into synchronized cows is performed according to the method of Betteridge (Betteridge, K.J. (1977) in: Embryo transfer in farm animals: a review of techniques and applications).
  • hLF is detected in the milk of lactating transgenic offspring using the RIA of Example 5.
  • ⁇ HAL-HA1, XHAL-3W and ⁇ HAL-H14 Three overlapping phage clones that contain the complete hSA gene are used to construct an expression vector for hSA. They are designated ⁇ HAL-HA1, XHAL-3W and ⁇ HAL-H14. They are described in Urano, et al. (1986), J. Biol. Chem., 261, 3244-3251; and Urano, et al. (1984), Gene, 32, 255-261. The sequence of the gene plus some surrounding regions is published in Minghetti, et al. (1986), J. Biol. Chem., 261, 6747-6757. A single phage containing the complete hSA gene is constructed as fol lows :
  • Clone HA-1 is cut with BstEII and AhaII.
  • the ⁇ 1400 bp fragment running from position 1784 (in the first exon, just downstream of the ATG) to 3181 is isolated and a synthetic linker is attached to the BstEII site at the 5' end containing the first few amino acids that are cut off with BstEII as well as the sequence surrounding the ATG as well as a few convenient restriction sites. This fragment is called fragment #1.
  • Clone 3W is cut with AhaII and SacI the ⁇ 13.1 kb fragment running from position 3181 to 16322 is isolated and a synthetic linker is attached to the SacI site to facilitate cloning in phage EMBL3. This fragment is called fragment #2.
  • this new clone yields a fragment containing the complete hSA gene with about 2.5 kb 3'-flanking sequence.
  • cosmid cGPlHLF is partially digested with Clal and BamHI. This removes the signal sequence, the coding sequence of hLF, the 3'-UTR and poly (A) addition region of ⁇ S1-casein as well as a small region 3' of the casein gene.
  • the expression vector so formed contains, (1) 16 kb of promoter sequences derived from the ⁇ S1-casein gene, (2) the first exon and intervening sequence of this gene both present in GP1, (3) the signal sequence of the hSA gene the complete genomic gene coding for hSA including 2.5 kb downstream of that gene, and (4) ⁇ 8 kb of 3'-flanking sequence derived from the ⁇ S1-casein gene.
  • This transgene is used to produce transgenic bovine species producing hSA in their milk in a manner analogous to that used to produce hLF in the milk of bovine species.
  • heterologous proteins from milk is facilitated by the fact that, following casein precipitation, those proteins, for the most part, are found in the whey fraction which is less contaminated than the production media used in microbial or cell-based systems.
  • Chromatographic techniques are preferred for the purification of hSA from cow milk. This approach produces a better recovery and higher albumin purity as well as a lower content of albumin polymers as compared with ethanol fractionation (Curling (1980) in: “Methods of Plasma Protein Fractionation", Curling, ed., Academic Press London, UK; Curling et al. (1982) J. Parenteral Sci. Technol. 36, 59; Berglof et al. and Martinache et al. (1982) Joint Meeting IHS-ISBT, Budapest). The specific transport role of hSA as well as its major role in maintaining intravascular osmotic pressure may also be better preserved upon chromatographic purification (Steinbruch (1982), Joint Meeting ISH-ISBT, Budapest). The following steps are used to recover hSA produced in the milk of transgenic cows:
  • steps 3-6 are essentially identical to the method described by Curling and others (Curling (1980) op. cit.; Curling et al. (1982) op. cit.; Berglöf et al. (1982) op. cit.) for the purification of hSA from plasma.
  • ⁇ HAL-HA1, XHAL-H14 and XHAL-3W Three overlapping genomic hSA clones were used to generate the hSA gene in transgenic mice, ⁇ HAL-HA1, XHAL-H14 and XHAL-3W, are shown in Figure 8 as reported by Urano, et al. (1984), Gene, 32, 255-261 and Urano, et al. (1986), J. Biol. Chem., 261 3244-3251. Briefly, a genomic library was constructed from a partial EcoRI digest of human fibroblast DNA.
  • this library was screened with 32 P-labeled human albumin genomic clones by hybridization in 1 M NaCl, 50 mM Tris-HCl (pH 8.0), 10 mM EDTA, 0.1% SDS, 100 ug/ml of sheared salmon sperm DNA and lOx Denhardt's solution at 65° C overnight after prehybridization in 3x SSC and 10x Denhardt's solution.
  • the fragments were treated with klenow DNA polymerase and dNTP's to fill in overhanging sticky ends.
  • the blunt ended fragments were then treated with bacterial alkaline phosphatase to remove the 5' phosphate groups from each fragment.
  • the overlapping DNA fragments were next concentrated then coinjected into the male pronuclei of fertilized mouse eggs according to published methods (Hogan, et al. (1986) in "Manipulating the Mouse Embryo: A Laboratory Manual", Cold Spring Harbor Laboratory). While the number of molecules injected varied from ⁇ 25 to ⁇ 100 per egg cell, the ratio of the individual fragments was approximately 1:1:1.
  • Embryos were implanted into the uteri of pseudo pregnant female mice according to the methods of Hogan, et al., supra.
  • genomic DNA from the newborn pups was subject to the following specific digestions followed by Southern hybridization with HSA cDNA probes:
  • Bst EII cuts outside the HSA gene region and yields an 18 kb band if correct recombination occurred
  • Nco I cuts outside the overlapping regions and yields bands of 8.0 and 9.3 kb if correct recombination occurred;
  • Hinc II cuts in the overlapping regions, yielding several bands indicative of correct arrangement in these regions.
  • 22 had correctly recombined all three fragments. From 20 out of those 22 animals blood was collected and assayed for the presence of hSA protein using a radio immuno assay. 15 out of those 20 animals showed hSA expression at levels between 0.5 and 5 ⁇ g/mL. None of the animals that had no recombination or that were not transgenic showed any expression.
  • RNA blots only two (the two with the highest protein level) showed a band.
  • mRNA i.e., poly(A)+ RNA
  • reverse transcriptase to synthesize cDNA, followed by PCR, we have observed a perfect relationship between the presence of RNA and protein. However, in this experiment we could not determine the size(s) of the RNA.
  • This example describes the construction of two hLF transgenes wherein the first contains approximately 16 kb of ⁇ S1 casein 5' expression regulation sequence (pGP1hLF (16 kb) also referred to as p16,8HLF4) and the second contains approximately 7.9 kb of ⁇ S1 casein 5' expression regulation sequence (pGP1hLF (8 kb) also referred to as p8.8HLF4).
  • pGP1hLF 16 kb
  • p8HLF4 7.9 kb of ⁇ S1 casein 5' expression regulation sequence
  • a 1.8 kb EcoRI-BglII fragment (fragment C in Fig. 9) was isolated from phage clone GP1. This fragment runs from position -100 of the transcription start site into the second exon of the ⁇ S1 casein gene.
  • the BglII site lies at the junction of the first entron and second exon of the ⁇ S1 casein gene.
  • the 3' end containing the BglII site was ligated to a synthetic BglII-ClaI linker and subcloned into the plasmid pUC19.
  • the resulting plasmid is designated pEBS. Fragment B in Fig.
  • Fragment B includes sequences from position -7500 to position -100 of the transcription start site in the ⁇ S1 casein gene.
  • the plasmid so formed is designated pEB3S and contains the combination of fragments B and C is the 8.9 kb EcoRI-ClaI fragment running from position -7500 to position +1400 of the transcription start site.
  • the insert from pNE was isolated as a NotI-EcoRI fragment and together with the EcoRI-ClaI insert from pNE3BS was ligated into the cloning vector pKUN2.
  • the resulting plasmid pGP1 ( ⁇ 2ex) contains 16 kb of ⁇ S1 casein promoter plus the 5' end of the gene to the BglII site at the border of the second exon.
  • the final plasmid (16,8HLF4) containing the transgene was assembled using the NotI-ClaI fragment from clone pGPI ( ⁇ 2ex) and the Xho-NotI fragment from clone pHLF 3' 10 kb.
  • the structure of this transgene is the same as previously described herein.
  • CATGGCAGCTGT-5' (sEQ. id nO.: 19)
  • the hLF sequence is now surrounded by two unique restriction sites (ClaI and SalI) and can be replaced by any recombinant ANA sequence that has a ClaI-site at the 5'- end and a SalI-site at the 3'- end.
  • Another transgene was constructed that is identical to the foregoing except that it contains only about 8 kb of 5' ⁇ S1 casein expression regulation sequence. It was constructed by taking the NotI-ClaI fragment from pNE3BS and fusing it directly into Xho-otI fragment from clone pHLF 3' 10 kb. The resulting plasmid was designated pGPlhLF (7 kb) (also referred to as p8.8HLF4).
  • Plasmid 16,8hLF4 was modified to contain a hybrid splice signal ( ⁇ S1 casein-IgG) described in examples 3 and 5.
  • the resulting plasmid was designated 16,8hLF3 and is identical to 16,8hLF4 except for the presence of a hybrid intron versus a "natural" casein intron in the 5'-UTR.
  • the hLF signal sequence can also be used in all of the cDNA constructs disclosed herein instead of the casein signal sequence. This can be done in the following way: A synthetic oligo was made that contains the complete hLF signal sequence (see Fig. 2) plus a ClaI restriction site at the 5 ' -end and an EagI restriction site at the 3'-end. These restriction sites also border the casein- signal sequence in the other plasmids (e.g., p16,8hLF4). A fragment containing the hLF-cDNA surrounded by ClaI and SalI sites was cloned in pGEM7 (Stratagene, Inc.) containing a ClaI and SalI site.
  • pGEM7 Stratagene, Inc.
  • the resulting plasmid was digested with ClaI and EagI and used as a vector to accommodate the ClaI-Eagl fragment containing the hLF sequence.
  • the cDNA with its own sequence, was excised as a ClaI-SalI fragment and inserted in ClaI-SalI digested p16,8hLF4 to generate p16,8hLF5.
  • this Cla-Sal fragment containing the hLF-cDNA plus hLF signal sequence can be inserted in any hLF cDNA vector.
  • Transgenic mice were generated utilizing several of the transgenes identified in the examples herein.
  • the transgenes used are identified in Tables 3 and 4.
  • the 5' and 3' expression regulation sequences were from the bovine ⁇ S1 casein gene
  • the RNA splice signal in the 5' untranslated region was either homologous from the ⁇ S1 casein gene or a hybrid casein-IgG intervening sequence.
  • the recombinant DNA in each case was derived from cDNA clones.
  • the transgene containing 26 kb of 5' ⁇ S1 casein expression regulation sequence was generated by in vivo homologous recombination of overlapping fragments.
  • a phage clone containing an approximately 14 kb SalI insert was identified. This insert contains about 11.5 kb of sequence upstream from the 5' casein sequence contained in 16,3hLF4 and about 2.5 kb of overlapping sequence.
  • the NotI insert from 16,3hLF4 and the SalI phage insert were coinjected to produce the 26.8hLF4 mice.
  • the number in the plasmid designations before the comma represents the approximate length in kbp in the 5' sequence from the bovine ⁇ Sl casein promoter/flanking region while the number after the comma represents the approximate length in kbp in the 3' flanking sequence of the ⁇ Sl gene. Note the actual number of bases for the 8 kb and 16 kb promoter (5' flanking region) is 6.2 and 14.5 kbp, respectively.
  • 16,8hLF4 is expressed at high level (in same range as 16,8hLF3). However, (in mice) this only occurs in a small number of cases and 1/16 when 8,8hLF4 and 26,8hLF4 are included). Similar results were obtained using a hSA cDNA.
  • the 16,8hSA4 transgene was constructed by digesting p16,8hLF4 with ClaI and SalI to remove the hLF cDNA sequence.
  • hSA cDNA was excised from a clone with EcoRI.
  • a ClaI synthetic linker was added to the 5' (upstream) end and a SalI linker to the 3' (downstream) end.
  • 16,8hSA4 was formed from which the NotI insert was excised and used for microinjection.
  • the 16,8hSA4 construct yield 9 lines. One of the 9 lines gave high level expression (100 ⁇ g/ml)), while the remaining 8 of 9 gave low expression (0.01-0.05 ⁇ g/ml). This indicates that the level and the frequency of hLF expression in the mouse mammary gland are not determined by the particular cDNA used, but are an inherent characteristic or the 16,8X4 construct (i.e., the 16 kb 5' and 8 kb 3' flanking regions of the ⁇ -S1 casein gene combined with the heterologous IVS).
  • RNA analysis has shown that expression of the cDNA constructs is tissue-specific and stage-specific (i.e., expression is only observed in the lactating mammary gland) , that the transcripts are correctly sized and that RNA and protein levels correlate.
  • Bovine oocytes were collected by aspiration of follicles present on ovaries obtained from slaughterhouses and transported in an insulated container at 30-32°C Oocytes, together with follicular fluid, were aspirated from 2-8 mm diameter follicles and pooled into 50 ml conical tubes. Cumulus-oocyte complexes (COC) were allowed to settle into a pellet, after which the supernatant was discarded and the pellet washed in 50 ml TL-Hepes (Vander Shaws, et al. (1991) Theriogenology 35 , 288 (Abstr.).
  • COC Cumulus-oocyte complexes
  • COC containing several intact, unexpanded cumulus cell layers, were selected and isolated under a dissecting microscope at 15 x magnification, washed four times in 10 ml TL-Hepes, once in 2-3 ml TCM199+10% fetal calf serum (M199) and then paraffin oil (20 COC/droplet). COC were incubated for 23 h in a humidified atmosphere of 5% CO 2 in air at 39°C
  • oocytes A total of about 2500 oocytes were used. On average, two aspiration sessions occurred per week. The yield of aspirated oocytes was highly variable from day to day, with a mean daily number of about 150. Maturation and fertilization were analyzed by cytological analysis. Maturation was defined as the breakdown of the nuclear membrane, the appearance of the first polar body and a metaphase plate. Oocytes were fertilized in vitro with frozen thawed-sperm obtained from three different bulls with excellent characteristics with respect to genetic background, field performance and ease of calving. Sperm capacitation was facilitated with heparin. Parrish, J. et al. (1986) Theriogenology 25: 591-600.
  • sperm preparations were enriched for live, motile sperm by a "swim-up" procedure (Parrish, J. et al.
  • sperm were centrifuged through a percoll gradient. After isolation of the motile portion, sperm were counted on a hemocytometer, diluted to an appropriate concentration to yield a 25-fold concentrated stock.
  • the fertilization medium consisted of TALP medium (Banister, Bethal Biol. Reprod. 28: 235-247) supplemented with 2.0-10.0 mg/ml heparin (from porcine intestinal mucosa, 177 IU/mg; Sigma) and if the cumulus was removed prior to fertilization, 1mM hypotaurine, 10mM penicillamine, 20mM epinephrine and 2mM sodium metabisulfite.
  • Matured COC were selected on the basis of expanded cumulus masses for fertilization, washed once in 10 ml fertilization medium, and either added directly to fertilization droplets, or first stripped of their cumulus investment by gentle pipetting through a small-bore, fire-polished pipet and then added to the droplets. Finally, sperm cells were added to a final concentration of 1 ⁇ 10 6 -2.0 ⁇ 10 6 /ml. After 16-24 h, presumptive zygotes were removed from fertilization droplets.
  • Microinjection The 26 kbp casein-hLF transgene (from p 16,8hLF4) used for microinjection was released by NotI digestion and purified by agarose gel electrophoresis and electroelution. The final DNA concentration was adjusted to 2.5 ⁇ g/ml. Batches of 50 cumulus-intact fertilized oocytes were stripped either as described above or by vortexing 2 minutes in 2ml TL-hepes medium in a 10ml conical tube. In order to visualize the pronuclei, cumulus free oocytes were centrifuged in 1ml TL-hepes medium 8 minutes at 14,500 x g in an Eppendorf centrifuge. Wall, R. et al. Biol. Reprod. 32 : 645-651. Microinjection was performed essentially as described by Hogan B. et al. (1985) Manipulating the Mouse Embryo: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y..
  • Embryo culture Embryos were cultured from the zygote to the compact morula or blastocyst stage in oviductal- tissue conditioned medium. Eyestone et al., (1991) J. Reprod. Fert. 92:59-64. Oviducts were obtained at slaughter and transported at ambient temperature. Luminal tissue from 2-4 oviducts (1-2 cows) was harvested by gently scraping intact oviducts on the outside with a glass slide. The extruded material was washed 5 times in 10 ml TALP-Hepes and diluted in M199 to a tissue:media ratio of 1:50. Media were conditioned in 50 ml "T" flacks containing five ml of oviduct tissue suspension.
  • the synchronization schedule was set up so that recipients started estrous on the same day at which oocytes were aspirated from slaughterhouse ovaries (i.e., start of maturation is day 1).
  • Estrous in recipient cattle was synchronized with a 9-day Norgestamet (Intervert, Boxmeer, The Netherlands) treatment (administered in an ear implant according to the manufacturer), and a 500 ⁇ g dose of cloprostanol given on day 7 of the Norgestamet treatment.
  • Estrous occurred within 2-3 days after implant removal.
  • Embryos were transferred non-surgically to recipient heifers 5-7 days after estrous (1-2 embryos/uterine horn).
  • Pregnancy was determined by rectal palpation at 45 to 60 days of gestation. A total of 21 pregnancies were established (confirmed by rectal palpation 45-460 days after transfer). During pregnancy, 2 fetuses were lost. One recipient aborted spontaneously for unknown reasons at 7.5 months of gestation. The second fetus, collected at slaughter of the recipient at 3 weeks after the calculated day of parturition, was a full grown dead calf having an abnormal embryonic development called 'schistosoma reflexum'. In both cases, no intact DNA could be isolated for analysis. Nineteen calves were born after normal pregnancies. One of these calves died during parturition, and a second, 24 hours after birth, because of pneumonia following accidental inhalation of milk.
  • hLF human lactoferrin
  • Fig. 12A the coding sequence of the hLF cDNA is depicted by a hatched box. The position of the translational start and stop codon is indicated. The 5' and 3' untranslated regions are encoded by ⁇ S1 casein exons (open boxes). Intervening sequences interrupting these exons are represented by a single line. The expression unit is surrounded by flanking sequences derived from the bovine ⁇ S1 casein gene (indicated by a double line). Positions of restriction enzyme sites are indicated by the following symbols: R, EcoRI; A, Asp718; N, NotI.
  • the NotI sites are not present at the indicated positions in the bovine ⁇ S1 casein gene itself, but were introduced by synthetic linkers.
  • the black bar represents the position of the probe used to detect the presence of the transgene. Sizes of the fragments (in kbp) obtained after digestion with EcoRI or Asp718 are shown at the bottom.
  • DNA analysis DNA was isolated from placenta, blood and ear tissue from all calves. A Southern blot analysis of the extracted DNA is shown in Fig. 12B. Ten ⁇ g of DNA was loaded per lane. Fragment size markers are in kbp (HindIII digest of lamda DNA) are indicated on the left.
  • Lane 1 EcoRI digested human DNA (isolated from blood), lane 2, Eco RI digested DNA from calf #4 isolated from blood; lane 3, Asp718 digested DNA from calf #4 isolated from blood; lane 4, EcoRI digested placental DNA from calf #4; lane 5, Asp718 digested placental DNA from calf #4; lane 6, EcoRI digested DNA from calf #15 isolated from blood; lane 7, Asp718 digested DNA from calf #15 isolated from blood; lane 8, EcoRI digested DNA from calf #15 isolated from ear tissue; lane 9, Asp718 digested DNA from calf #15 isolated from ear tissue; lane 10, EcoRI digested placental DNA from calf #15; lane 11, Asp718 digested placental DNA from calf #15; lane 12, EcoRI digested DNA isolated from the tail of a transgenic mouse harboring the same construct.
  • DNA extraction, Southern blot analysis and hybridization were performed according to standard procedures.
  • the probe used in the Southern blotting experiment was a 758 bp EcoRV-EcoRI fragment covering the 3' part of the hLF cDNA of Figure 2.
  • Southern blot analysis using hLF cDNA as a probe indicated that in tissues of two calves (#4 and #15) transgene sequences had been integrated into the host genome. Calf #15 (a female) was mosaic for integration of the transgene. Placental tissue was positive, whereas in blood and ear tissue no hLF sequences could be detected. The copy number in tne placenta was 1-2.
  • the restriction enzyme map of the transgene was different from that expected based on the map of the casein-hLF plasmid (FIG. 12A) and based on the pattern obtained in many individual transgenic mice (data not shown). Hence, a rearrangement had occurred involving a deletion of part of the DNA construct. It is not clear whether this rearrangement event is related to the fact that the transgene could not be detected in all tissues. In mice, it has been shown that over 30% of all transgenic animals born are mosaic.
  • Calf #4 (a male) showed, in all three tissues, the same hybridization pattern that was identical to the expected one. Restriction digestions with different enzymes indicated that head-to-tail concatamers of intact copies had integrated and there was no indication of rearrangements. Copy numbers were estimated by comparing the intensities of the transgenic band with bands resulting from hybridization of the hLF probe to human DNA (FIG. 12B) . In calf #4, between 5 and 10 copies of the transgene had integrated in all three tissues examined.
  • expression cassettes where the flanking regions including the transcription initiation site of the ⁇ S1 casein gene are operably linked to the untranslated regions of the gene to be expressed.
  • Such an expression cassette is p-16 kb,CS and was constructed as follows: plasmid pS1 3'5'hLF was used as a template in a PCR experiment. This plasmid contains 680 bp of promoter sequence of the ⁇ S1 casein gene as well as its first exon.
  • the upstream primer was located just upstream of the insert in the plasmid moiety (just upstream of a NotI restriction site). Its sequence is: 5'-CGA CGT TGT AAA ACG ACGG-3'.
  • the downstream primer was located in exon 1. Its sequence matches the first 19 bp of the exon exactly and also has a non-hydridizing region of 17 bp containing a ClaI and a SalI site. It has the following sequence:
  • the amplified fragment was digested with NotI and SalI and ligated into pKUN2 (see Example 13).
  • the resulting plasmid (p-680CS) therefore harbors a proximal promoter fragment from -680 to + 19, plus two restriction sites just downstream of those 19 bp.
  • This plasmid was digested with NotI (just upstream of -680) and NsiI (at-280) and used as a vector to ligate to a fragment running from a NotI site (just upstream of -16 kb) to NsiI (-280) isolated from p16,8hLF4 (Example 13).
  • This plasmid (p-16 kb,CS) therefore harbors a promoter fragment from ⁇ -16,000 to +19. It can be used to insert genomic genes that carry their own UTR's and poly (A)-signal. After insertion of the genomic gene as a ClaI-SalI fragment, the ⁇ S1 casein 3'-flanking region can be inserted as a SalI-fragment.
  • a human genomic library in EMBL-3 (Clonotech) is probed with a sequence specific for protein C.
  • a purified phage DNA prep containing the complete Protein C gene is isolated.
  • the phage is isolated from an ⁇ . coli strain having the Dam phenotype, such a strain GM113. This results in cloned DNA which is not methylated and as such all ClaI restriction sites can be cleaved.
  • a ClaI Nhel fragment running from positions +1333 to 11483 is isolated. This is designated fragment I.
  • pGEM7 (Stratogene, Inc.) is digested with SphI and SmaI.
  • Primer GP125 has the following sequence:
  • Primer GP 126 has the following sequence: 5' - GGG ATC GAT CAG ATT CTG TCC CCC AT - 3'
  • Primer GP125 has an overlap with exon 0 (position 654 to 675 of the Protein C gene) and introduces a ClaI site in the 5' untranslated region. Exon 0 is the exon not identified by Foster, et al. Primer GP126 overlaps the region from 1344 to 1315 in the Protein C gene. This region contains a ClaI site.
  • the region between position 654 and 1344 is amplified using either human DNA or phage DNA as a template.
  • the so amplified material is digested with ClaI and cloned in vector pGEN7a to form pPCCC
  • This vector is propagated in a dam negative strain such as GM113 and partially cut with ClaI (only the plasmids that are cut once with ClaI at position 1340 are of interest) and completely with Xbal.
  • the ClaI NheI fragment (fragment 1) is cloned into this vector.
  • the resultant plasmid is designated pPC Its structure is shown in Fig. 10.
  • the Protein C transgene is isolated as a ClaI-SalI fragment and ligated into p16 kb, CS (See Example 15) to generate a transgene capable of expressing Protein C in bovine milk, this plasmid is designated p16 kb,CS,PC
  • transgenic bovine species capable of producing protein C in their milk.
  • hLF genomic cosmid libraries were screened using an hLF cDNA clone described herein as a probe.
  • 2 clones designated 13.1 and 13.2; one from each human cosmid library
  • the insert sizes of these hLF genomic clones was 42 kbp for clone 13.1 and 43 kbp for clone 13.2.
  • Clones 13.1 and 13.2 contain 5 kbp and 13 kbp of 5' flanking sequences, respectively.
  • the 3' flanking region of clone 13.2 is between 1 kbp and 3 kbp; clone 13.1 contains 7 kbp of additional 3' flanking sequence.
  • hLF clones The identity of the hLF clones was confirmed by sequencing several exons (incl. first and last) and comparing these sequences and the promoter region to the hLF cDNA sequence shown in Fig. 2. In addition, the clones were transfected into human kidney 293 cells and hLF expression was detected, indicating that both clones were functional.
  • Figs. 13-16 illustrate the overall procedure for generating the ⁇ S1 casein/genomic hLF transgene.
  • the most 5' ApaI site in the structural hLF gene is located in exon I, in the hLF signal sequence.
  • the 400 bp region immediately 5' of exon I was sequenced. This region contains the transcription initiation site of the hLF gene and a TATA-box. This region also includes a BamHI restriction site.
  • the 8 kbp or 16 kbp ⁇ S1 5' casein promoter and flanking sequence was fused to 9 kb of the 5' region of the structural hLF gene (Fig. 15A) and this fragment was coinjected with an overlapping hLF fragment containing about 33 to 34 kbp of the 3' sequence of generic hLF clone 13.1 obtained by ClaI digestion. See Figs. 13 and 16.
  • the BamHI fragment (containing exon I) from clone 13.2 was subcloned into the plasmid pUC19 (Fig. 14). From this clone, a 8.9 kbp ApaI-SalI fragment was isolated by ApaI (partial digest) and SalI digestion. This fragment lacks most of the hLF signal sequence and all of the hLF 5' UTR. A synthetic sequence (Fig. 15B) representing this missing region was obtained by synthesizing 2 complementary DNA strands (a 68-mer and a 62-mer) which runs from the 5' ApaI site into the downstream region from the hLF TATA-box.
  • the diagnostic 7.8 kb band was detected in all 8 transgenic mouse lines, indicating that each transgenic mouse contained recombined fragments.
  • milk was collected from lactating females (founder and/or offspring) and assayed for hLF protein expression.
  • the data on 7 mouse lines is shown below.
  • mouse 983 is classified as a high level expressor.
  • tissue-specificity of hLF expression was determined by isolating total RNA from a large number of tissues and analyzing for the presence and levels of transgene derived mRNA. Based on this analysis, hLF mRNA only occurs in the lactating mammary gland and expression is tissue- and stage-specific.
  • RNA levels were below the threshold of detection in lines 950 and 951, but were high in high expressing lines and correlated with bovine ⁇ S1 casein expression levels. This was determined by Northern blot analysis of both bovine lactating mammary gland RNA and mammary gland RNA from lactating transgenic mice. A 24 bp synthetic oligomer which hybridizes to exactly the same sequence in the 5' UTR of bovine ⁇ S1 casein RNA and in the transgene RNA was used as a probe. Expression levels were compared directly by quantification of the amount of labelled probe hybridized to the transgene-and ⁇ S1 RNA.
  • the ratio of mRNA to protein was in the same range for bovine ⁇ S1 casein and hLF. This indicates that translation and secretion of the transgene derived hLF is not impaired.
  • the length of the hLF mRNA was as expected (about 2.5 kb) but in mouse line 937 a longer band (3-3.5 kb) of slightly less intensity was also observed. The occurrence of this band may be related to the homologous recombination process. It remains to be determined if this RNA translates into bona fine hHL.
  • casein promoters are less favorable for obtaining high level expression than other milk specific promoters.
  • present data show that this is not the case.
  • the transgenes containing ⁇ S1 casein sequences perform better than any other mammary gland specific transgene reported.
  • hLF genomic transgenes have also been generated by conventional ligations in cosmids.
  • the first construct ShLFgen is similar to the transgene generated by coinjection, but contains the 3' ClaI fragment from hLF clone 13.2. The size of this fragment is about 26-27 kb.
  • the second construct 16hLFgen is identical to ShLFgen, but contains a larger stretch of ⁇ S1 casein promoter sequences.
  • Fig. ISA (referred to as 8hLFgen9k) was used to prepare the ShLFgen construct.
  • This NotI-MluI fragment contains the synthetic ClaI-ApaI fragment depicted in Fig. 15B.
  • This synthetic sequence contains 24 bp of the hLF 5'-UTR and encodes for most of the hLF signal sequence (see Fig. 15C).
  • This NotI-MluI was ligated with the 3' MluI-ClaI fragment from clone 13.2 and a ClaI-NotI linker as shown in Fig. 17.
  • the cloning vector was cosmid pWE15 cut with NotI, from which tne internal ClaI and SalI sites had been deleted.
  • the first intron of the hLF gene is located 4 bp downstream of the ApaI site in the signal sequence.
  • the DNA sequence encoding the 19 aa signal sequence is partly located in exon 1 (43 bp, encoding 14 aa and 1 codon partially) and in exon 2 (the first 14 bp, encoding 4 aa and 1 codon partially).
  • the exact position of hLF intron 1 was determined by DNA sequencing and comparing the genomic sequence to the hLF cDNA sequence.
  • the sequence upstream of the translation initiation site (355 bp, containing the hLF 5' UTR and 5' flanking region) was also sequenced.
  • the hLF transcription initiation site was not included in the genomic hLF constructs as shown.
  • the cDNA contains a Thr codon (ACA) at aa position 130 (see Fig. 2).
  • ACA Thr codon
  • genomic hLF clones 13.1 and 13.2 (exon 4, plus parts of intron 3 and 4) have been sequenced. These clones contain the sequence ATA, which encodes isoleucine.
  • the cDNA also contains a Cys codon (TGC) at position 404 (see Fig. 2). In hLF clones 13.1 and 13.2 this is a GGC, encoding glycine.
  • the 5' NotI-MluI fragment from the construct depicted in Fig. 15A was ligated to the 3' MluI-ClaI fragment from clone 13.1, combined with a ClaI-NotI linker (compare Fig. 17: read 13.1 instead of 13.2).
  • the cloning vector was cosmid pWE15, from which the internal ClaI and SalI sites had been deleted, cut with NotI. Prior to microinjection, vector sequences were removed via NotI digestion. All constructs were cut from tne vector using NotI, and microinjected.
  • mice containing ShLFgen and 5 mice containing 16hLFgen were generated.
  • Preliminary expression date in milk are as follows:
  • the bovine ⁇ LG-promoter (beta-lactoglobulin) was used to construct a transgene encoding for the expression of hLF. Briefly, the ⁇ S1 promoter in the genomic hLF constructs ShLFgen and 8hLFgen37 were replaced with the bovine ⁇ LG-promoter . The resulting constructs are referred to as 0LG-hLFgen and 0LG-hLFgen37. The overall strategy for these constructions are depicted in Figs. 18-20.
  • the charon 28 phage clone ⁇ LG-13 described by Silva et al., (1990) Nucl. Acids Res. 18:3051, was obtained from Dr. Carl A. Batt.
  • This clone was isolated from a bovine genomic library by screening with a ⁇ LG cDNA probe. It contains the structural ⁇ LG gene and about 8 kb of 5' flanking region. From this clone, a 4.3 kb EcoRI fragment was isolated and subcloned into plasmid pKUN5 using standard procedures (see Fig. 18). From this plasmid, a 3.2 kb NotI-SacI fragment was isolated. The NotI site was derived from the polylinker of the cloning vector.
  • the SacI site lies 15 bp downstream of the BLG transcription initiation site.
  • a PvuII site is located five bp upstream of the translation initiation site.
  • a fragment representing the region between the SacI and PvuII sites (including these sites) was generated by synthesizing and annealing the 30-mer and 37-mer DNA oligomers depicted in Fig. 18. This fragment also contains a ClaI and a SalI site directly downstream of the PvuII site (Fig. 18).
  • the 8.9 ClaI-SalI fragment from construct 8hLFgen9k (Example 15A) was isolated and cloned into p ⁇ LG3.2 after cutting this vector with ClaI and SalI. This ligation resulted in construct p0LGhLFgen9k (Fig. 19). From this construct the 9.4 kb NotI-MluI fragment was isolated and, together with the 23-24 kb MluI-NotI fragment isolated from ShLFgen, ligated into a NotI cut pWE15 cosmid, resulting in p ⁇ LG-hLFgen (Fig. 19). The 34 kb NotI insert was isolated from the cosmid by NotI digestion and microinjected following standard procedures.
  • the ⁇ LG-hLFgen insert was isolated and microinjected following standard procedure.
  • ⁇ LG-hLFgen (the shorter of the 2 constructs) was injected and 7 independent mouse lines were produced.
  • Expression data for hLF product in milk is available for the following lines:
  • the hLF Promoter HLF is normally expressed at relatively high levels (1-2 mg/ml) in human milk.
  • the intact hLF gene under control of its own promoter was microinjected using standard procedures.
  • cosmid vector C2RB (Fig. 13) containing the genomic hLF clones does not contain unique restriction sites flanking the hLF insert, the intact insert could not be isolated directly from this cosmid. It was desirable to include all 5' and 3' flanking sequences present in hLF clones 13.1 and 13.2 into the transgene.
  • clone 13.2 (Fig. 13) contains the most 5' flanking sequences (13 kb) and clone 13.1 the most 3' flanking sequences (7 kb more than 13.2), the 5' part of 13.2 was combined with the 3' part of 13.1.
  • the cosmid 13.2 was linearized at the Pvul site 0.5 to 0.8 kb upstream of the 5' region of the hLF insert (Fig. 20) and subsequently treated with the exonuclease Bal31, thereby removing approximately 1 kb of cosmid and 0.2 to 0.5 of 5' hLF sequence. Subsequently, the DNA was treated with T4 polymerase to create blunt ends and cut with MluI.
  • This plasmid contains a NotI site directly 5' of the SmaI site. From this plasmid, the 19 kb NotI-MluI fragment was isolated and ligated with the 30 kb MluI-NotI 3' fragment from construct 8hLFgen37 into a NotI cut pWE15 cosmid, resulting in p5'hLFgen37 (Fig. 20).
  • the 49 kb NotI insert was isolated and microinjected following standard procedures.
  • the structure and sequence of the human lysozyme gene has been described (Peters, et al. (1989) Eur. J. Biochem iH: 507-516).
  • the structural hLZ gene contains 4 exons and is 5.3 kb in size.
  • clone ⁇ 7.2.1 contains 14 kb insert comprising 8.7 kb of 5' flanking sequences and 5.3 kb of the genomic hLZ gene.
  • Exon 4 is only partly included: clone ⁇ 7.2.1 stops at one of the Sau3A sites at position 5333 and 5350 (numbering according to Peters, et al., op. cit.). The region downstream of position 5333/5350 (532 or 549 bp of exon 4 sequences) is missing. These sequences are non-coding and represent part of the 3' UTR of the hLZ gene. All hLZ coding sequences are present in ⁇ 7.2.1.
  • the 5' flanking region (including the promoter) of the hLZ gene was removed and replaced with the bovine ⁇ S1 casein gene promoter by subcloning into the plasmid p-16kbCS which is described in Example 16.
  • the fusion site is located in the 5' UTR of the hLZ gene (exon 1), such that in addition to 23 bp of casein 5' UTR most of the hLZ 5' UTR is present. All coding sequences in this construct, including the signal sequence, are derived from hLZ clone ⁇ 7.2.1 (Fig. 23A).
  • the 3' UTR of the hLZ gene in clone ⁇ 7.2.1 was fused to the 3' UTR + flanking region of the bovine ⁇ S1 casein gene described previously.
  • the resulting 3'UTR of construct 16,8hLZ is therefore derived partly from the hLZ gene (exon 4, running from bp 4761 to bp 5333/5350) and partly (including par of exon 8 and all of exon 9) from the bovine ⁇ S1 casein gene.
  • the 3' flanking region (8 kb) is derived entirely from the bovine ⁇ S1 casein gene. Construction details for 16,8hLZ:
  • the 6 bp directly 5' to the AUG codon in hLZ exon 1 constitute a Hindi site.
  • a SalI phage polylinker site is located directly 3' of the ⁇ 7.2.1 insert. These sites were used to isolate a 5.3 kb HincII-SalI insert (Fig. 23).
  • the resulting synthetic DNA fragment has artificial 5' KpnI-HincII fragment and the 5.3 kb HincII-SalI fragment were subcloned into a KpnI-SalI cut pKUN-1 plasmid (Fig. 23A). From the resulting 9.3 kb plasmid (pKHLys3'5.3) the 5.3 kb ClaI-SalI fragment was isolated and subcloned into a Cla-SalI cut p-0.7kbCS plasmid (the equivalent of p-16CS but containing less 5' flanking sequences), resulting in pKhLZ0.7.
  • expression vector 16,8hLZ3, shown in Fig. 22, is as follows.
  • Previously described expression vector 16,8hLF3 was used in the construction of 16,8hLZ3.
  • the vector 16,8hLZ3 contains not only the bovine ⁇ S1 casein gene promoter, but also the complete first exon and part of the first intron of the bovine ⁇ S1 gene. In addition, it contains part of the first intron plus the splice acceptor site of an immunoglobulin gene.
  • the signal sequence and part of the 3' UTR and the complete 3' flanking region are also derived from the bovine ⁇ S1 casein gene.
  • the hLF cDNA and the ⁇ S1 casein signal sequence are excised from this vector by ClaI-SalI double digestion.
  • the ClaI site is located 5 bp 5' to the translation initiation codon.
  • mice Seven transgenic mice were generated for construct 16,8hLZ. Expression data are available for 6 independent mouse lines (data from lactating offspring, using our standard hLZ assay on milk samples).
  • hLZ expresses at relatively nign levels.
  • hLZ levels are only 50 ⁇ g/ ⁇ i (max). Since hLZ is a 15 kD protein, a level of 0.26 mg/ml hLZ compares to - 1.3 mg/ml of hLF (hLF is 80 kD).
  • mice Four independent transgenic mice were generated for covalent 16,8hLZ3. The following expression data are available from mouse lines 905 and 907.
  • 16,8hLZ3 can be expressed at relatively high levels (0.36 mg/ml compares to - 1.8 mg/ml hLF). However, as also shown, 16,8hLZ3 does not always express at high levels. Although the number of mice analyzed is very low, constructs 16,8hLZ and 16,8hLZ3 seem to behave more or less similar with regard to frequency of expression and expression levels. It should be noted, however, that another 7 lines of mice transgenic for 16,8hLZ also contain the 16,8hLF3 construct. (See below.) None of these lines expressed as high as 0.36 mg/ml. Therefore, 16,8hLZ3 appears to be a more efficient construct then 16,8hLZ. This could be caused by the heterologous splice site (which does enhance hLF cDNA expression levels).
  • 16.8hLZ The hLZ expression level of mouse line 649, coinjected with the 16,8hLF3 and 16,8hLZ expression cassettes is comparable to that of line 661 injected only with 16,8hLZ. In most cases, high level expression of hLZ is not obtained upon coinjection (1/7: high expression (line 649); 2/7 (650 and 660): intermediate-low expression; 4/7: low expression). Upon injection of single hLZ transgene, similar data are obtained (1/4: high expression (line 661); 1/4: intermediate; 2/4: low expression). Therefore, behavior of the 16,8hLZ transgene is not measurably influenced by the presence of the 16,8hLF3 transgene.
  • these constructs can be expressed at relatively high levels (0.2-0.5 mg/ml range) with approximately 20-25 % of the resulting transgenic mice expressing at these high levels (3/13; 7 coinjections + 6 single inj.). Also coinjection with 16,8hLF3 does not appear to influence expression of 16,8hLZ.
  • the low expressors which produced levels are from 0.1 to 5 ⁇ g/ml (8/13) and
  • mice having the coinjected fragments express at high levels. This is similar to the frequency of high level expression observed upon injection of one fragment (5/13).
  • both 16, 8hLF3/16, 8hLZ mice lines (649 and 660) express hLF at much higher levels than observed previously. This indicates that the presence of the hLZ construct stimulates expression of the 16,8hLF3 construct.
  • the high hLF levels are accompanied by high hLZ levels.
  • RNA analysis reveals that the 16,8hLZ transgene in line 660 is transcriptionally at least as active as the hLF transgene.
  • genomic hLZ constructs are transcribed at much higher levels than the hLF cDNA constructs, and expressed in the same range as the genomic hLF transgenes.
  • hLZ transgenes expressing at 0.25 mg/ml is comparable to a protein level of 5 mg/ml, a level of 50 ⁇ g/ml equivalent to 1 mg/ml.
  • mouse line 649 hLZ mRNA levels exceeded bovine ⁇ S1 mRNA levels - which had been 10-fold diluted - several fold. Since bovine ⁇ S -casein is expressed at - 12 mg/ml (and is of similar size as hLZ), these hLZ RNA levels would be equivalent to an expression level of several mg/ml.
  • Construct 16,8 A hLZ3 is a derivative of 16,8 hLZ3.
  • 16.8 A hLZ3 the hLZ 5' UTR sequences and the hLZ signal sequence have been replaced with the corresponding sequences from the bovine ⁇ S1-casein gene.
  • a hLZ3 is a derivative of 16,8
  • a hLZ3 the bovine ⁇ S1-casein gene 3' UTR and flanking sequences have been replaced with the hLZ3' UTR and 4.5 kb of hLZ3" flanking sequences.
  • Vector p07.8hLZ (Fig. 23B) was digested with Cla1 and Sal1.
  • the 4.7 kb fragment (comprising 0.7 kb of the ⁇ S1-casein 5' flanking sequences and the plasmid vector) was isolated and ligated to linker GP 278/279 (Fig. 25).
  • This DNA sequence comprises part of the bovine ⁇ S1-casein 5' UTR, the complete bovine ⁇ S1-casein signal sequence and 25 bp of hLZ sequence, encoding the N-terminal region of adult hLZ.
  • the ligation product was isolated and ligated to a 5.3 kb Bal1-Sal1 fragment from pKHLys3'5.3 (which is depicted in Fig.
  • the resulting constructs is pO.7AhLZ ⁇ 3'. From this construct the 5.3 kb Cla1-Sal1 fragment was isolated and inserted into a Cla1-Sal1 vector, derived from p16,8hLF3 (also used in construction of 16,8 hLZ3). The resulting construct is designated p16,8A hLZ3 (Fig. 26).
  • a hLZ3 the vector pO.7AhLZ ⁇ 3' was digested with Xba1 and Sal1, and a Xba1-Not1-Sal1 linker was inserted (Fig. 27).
  • This vector was linearized with Xba1, and the 6.5 kb Xba1 fragment from ⁇ HLYS1 (described by Peters et al., Eur. J. Biochem. 182, 507-516, 1989) was inserted in the sense orientation. This resulted in vector pO.7AhLZ.
  • transgene without plasmid sequences was isolated as a Notl fragment (16,8A hLZ3; 27.8 kb; 16,AhLZ3; 24.3 kb), purified and microinjected into fertilized mouse oocytes following standard procedures.
  • construct 16 A hLZ3 yields much higher expression levels than any other hLZ construct tested.
  • transgenic embryos Of the six transgenic embryos, five were male and one was female according to a PCR-analysis with primers specific for a bovine Y-chromosome repeat. These data demonstrate that the transgene can be transmitted to both males and females and has not integrated in the Y-chromosome.
  • sequences of the Y-chromosome specific primers are:
  • animal sample 1 (ng/ml) sample 2 (ng/ml) 9772 25 18
  • the amount detected was 2 ng/ml.
  • Example 15 Of the 21 animals born in the experiment described in Example 15, one animal (male) was judged to be mosaic based on the tact that it was immunotolerant for hLF. This animal showed an hLF expression in saliva of 100 ng/ml .
  • transgenes used are capable of expressing hLF (and hLZ) in bovines.

Abstract

Un transgène de production de polypeptides recombinés dans le lait d'une espèce bovine transgénique comprend au moins une séquence de régulation d'expression, une séquence d'ADN sécrétoire codant une séquence de signaux sécrétoires, laquelle est fonctionnelle dans des cellules sécrétoires mammaires de l'espèce bovine, ainsi qu'une séquence d'ADN recombiné codant le polypeptide recombiné. L'invention concerne également des procédés de production d'espèces bovines transgéniques. Le procédé consiste à introduire le transgène précité dans une cellule cible embryonnaire d'une espèce bovine, à transplanter la cellule cible embryonnaire trangénique ainsi formée dans un parent bovin receveur et à identifier au moins un petit femelle capable de produire le polypeptide recombiné dans son lait. L'invention concerne aussi des espèces bovines transgéniques ainsi que le lait produit par ces dernières. On a également mis au point des procédés de production de mammifères non humains transgéniques présentant un phénotype recherché. Le procédé consiste premièrement à méthyler un transgène puis à l'introduire dans des oocytes fécondés. Les oocytes sont ensuite mis en culture pour former des embryons de préimplantation. Alors, on retire au moins une cellule de chacun des embryons de préimplantation et l'ADN digéré au moyen d'une endonucléase de restriction capable de cliver le transgène méthylé mais incapable de cliver la forme non méthylée du transgène.
PCT/US1993/005724 1989-12-01 1993-06-15 Production de polypeptides recombines par des especes bovines et des procedes transgeniques WO1993025567A1 (fr)

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AU45373/93A AU4537393A (en) 1992-06-15 1993-06-15 Production of recombinant polypeptides by bovine species and transgenic methods
US10/170,221 US20030192068A1 (en) 1989-12-01 2002-06-11 Production of recombinant polypeptides by bovine species and transgenic methods
US10/987,587 US20050198698A1 (en) 1989-12-01 2004-11-12 Production of recombinant polypeptides by bovine species and transgenic methods

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US5856178A (en) * 1993-08-30 1999-01-05 Utah State University DNA cassettes for expression of lytic peptides in mammalian cells and transgenic organisms containing same
WO1995018224A1 (fr) * 1993-12-29 1995-07-06 Gene Pharming Europe Bv Production recombinee de proteines modifiees manquant de certains acides amines
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