WO1986001805A1

WO1986001805A1 - Monoclonal antibodies and their use

Info

Publication number: WO1986001805A1
Application number: PCT/GB1985/000407
Authority: WO
Inventors: Bruce William Wright; Peter John Cox; Alice Margaret Noyes; Danny Widdows
Original assignee: Technology Licence Company Limited
Priority date: 1984-09-07
Filing date: 1985-09-09
Publication date: 1986-03-27
Also published as: EP0193576A1; JPS62500172A; GB8422650D0

Abstract

Monoclonal antibodies to the genus Salmonella, the labelled antibodies, compositions and kits containing them, and their use in diagnosis of antigen and treatment.

Description

_MttΛ 86/01805

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MONOCLONAL ANTIBODIES AND THEIR USE This invention relates to monoclonal antibodies and their use.

BACKGROUND OF THE INVENTION Salmonella is described in Zinsser Microbiology (17th ed.) 744-6.

Highly specific divisions have been made among the Salmonella species on the basis of their antigenic structure; the Kauffman-White typing scheme is used herein, whereby Salmonella species are typed according to group antigens. There are the Salmonellae paratyphi A, paratyphi B, enteriditis, london, marseilles, fluntern, hadao and albany, and the invasiveness 1 and 2 antigens, attachment 1 and 3 antigens, and enterotoxins 1 and 2. Salmonellosis probably represents the largest single communicable bacterial disease problem in the United States. Contaminated food and water are the mechanisms of transmission for all Salmonella, including £. typhi. ^In §.• typhi infection (typhoid fever) , the human carrier is the source; man is the only known host. In other salmonelloses, animals are more important. Food-borne salmonellosis is quite common and, for the non-typhoidal types, probably constitutes the major source of infection today. . typhi also can spread via food or water. The actual disease process may be apparent as any of three distinct clinical entities: a gastroenteritis, a septicemia with focal lesions, or an enteric fever such as typhoid fever. Salmonella gastroenteritis, like shigellosis, represents an actual infection of the bowel and usually occurs about 16 hours after ingestion of the organism. The disease is characterised by diarrhea, fever and abdominal pain which is usually self-limiting and lasts for two to five days.

Any species of Salmonella can produce the disease, but the most common cause is S_. enteritidis serotype typhimurium. Salmonella septicemia is prolonged and characterised by fever, chills, anorexia and anaemia. Focal lesions may develop in any tissue, producing osteomyelitis, pneumonia, pulmonary abscesses, meningitis or endocarditis. Gastroenteritis is minor or even absent, and the organism is rarely isolated from the faeces. S_. cholerae-suis is a frequent isolate from this type of disease. Osteomyelitis in persons with sickle cell trait is most frequently caused by S_. cholerae-suis. The prototype and most severe enteric fever is typhoid fever, and the causative agent is S_. typhi. Other Salmonella, particularly serotypes paratyphi A and paratyphi B, also can cause enteric fevers, but the symptoms are milder and the mortality rate is lower. Various vaccines have been tried to control typhoid fever. While some encouraging results have been obtained by use of the K vaccine (containing Vi antigen) in children living in endemic areas, no vaccine has proved to be entirely successful in preventing disease, especially when the number of ingested organisms is large. A more practical approach to prevent spread of typhoid fever is to insure safe drinking water supplies.

As indicated above. Salmonella is known to cause bacterial diarrhea. Bacterial diarrhea is a common and often serious condition manifest as fluid loss from the bowel, leading in many cases to dehydration, and occasionally death.

In addition to diarrhea. Salmonella is known to cause gram-negative sepsis which is a bloodstream infection. It is one of the major infectious disease problems encountered in modern medical centres. While it can be transient and self-limited, severe gram-negative sepsis constitutes a medical emergency.

Present treatment and diagnosis of Salmonella infections vary depending on the locus of the infection. It is estimated that in the United States and Europe many millions of cases of bacterial diarrhea occur annually, of which several million are seen by a physician or admitted to a hospital. Because of the self-limiting nature of the adult disease, most people do not seek treatment. Of the people seeking treatment, bacterial diagnosis of diarrhea is presently made by stool culture techniques. These techniques are generally performed only in hospitals and are slow, requiring one to three days. During this time, the patient is exposed, if treated, to the expense and potential hazard of inappropriate therapy. However, if not treated, the patient is exposed to the hazard of a deteriorating condition pending the test result and initiation of therapy.

At the present time, the test for gram-negative sepsis involves processing blood and urine cultures and other procedures on occasion. In addition to being expensive, blood culture tests are cumbersome. They require a day, and' often several days, to return results. They require expert laboratory skills because of the complex nature of human blood which tends to interact non-specifically with many of the test reagents.

Thus, existing methods of detection of Salmonella with high accuracy in diarrheal or gram-negative sepsis are less than satisfactory in that they consume large amounts of expensive skilled labour and laboratory time, generally taking one and often several days before returning results. The production of monoclonal antibodies is now a well-known procedure first described by Kohler and Milstein, Eur. J. Immunol. 6_ (1975) 292. While the general technique of preparing hybridomas and the resultant monoclonal antibodies is understood, it has been found that preparing a specific monoclonal antibody to a specific antigen is difficult, mainly due to the degree of specificity and variations required in producing a particular hybridoma.

SUMMARY OF THE INVENTION The present invention provides novel monoclonal antibodies for use in accurately and rapidly diagnosing samples for the presence of Salmonella antigens and/or organisms.

Briefly stated, the present invention comprises monoclonal antibodies specific for an antigen of

Salmonella; in particular, the somatic antigens of groups A to Z and 51 to 65, the H (flagellar) antigens A to Z and Zl to Z59; the antigens of Salmonella albany. Salmonella poona and Salmonella brazil; the invasiveness antigens 1 and 2, attachment antigens 1 and 2, and enterotoxins 1 and 2; as well as a monoclonal antibody broadly cross-reactive with an antigen for each species (or substantially-all species) of the genus Salmonella. The invention also comprises labelled monoclonal antibodies for use in diagnosing the presence of the Salmonella antigens, each comprising a monoclonal antibody against one of the above-mentioned antigens to Salmonella or to a particular species thereof and having linked thereto an appropriate label. The label can be, for example, a radioactive isotope, enzyme, fluorescent compound, chemiluminescent compound, bioluminescent compound, ferromagnetic atom or particle.

The invention further comprises the process for diagnosing the presence of Salmonella antigens or organisms in a specimen, comprising contacting said specimen with the labelled monoclonal antibody in an appropriate immunoassay procedure.

Additionally, the invention is also directed to a therapeutic composition comprising a monoclonal antibody for an antigen of Salmonella and a carrier or diluent, as -b-

well as kits containing at least one labelled monoclonal antibody to an antigen of a Salmonella.

DETAILED DESCRIPTION The monoclonal antibodies of the present invention are prepared by fusing spleen cells from a mammal which has been immunised against the particular Salmonella antigen, with an appropriate myeloma cell line, preferably NSO (uncloned) , P3NS1-Ag4/1, or Sp2/0 Agl4. The resultant product is then cultured in a standard HAT (hypoxanthine, aminopterin and thymidine) medium.

Screening tests for the specific monoclonal antibodies are employed utilising immunoassay techniques which will be described below.

The immunised spleen cells may be derived from any mammal, such as primates, humans, rodents (i.e. mice, rats and rabbits) , bovines, ovines and canines, but the present invention will be described in connection with mice. The mouse is first immunised by injection of the particular Salmonella antigen chosen, e.g. for a period of approximately eleven weeks. When the mouse shows sufficient antibody production against the antigen, as determined by conventional assay, it is given a booster injection of the appropriate Salmonella antigen, and then killed so that the immunised spleen may be removed. The fusion can then be carried out utilising immunised spleen cells and an appropriate myeloma cell line.

The fused cells yielding an antibody which gives a positive response to the presence of the particular Salmonella antigen are removed and cloned utilising any of the standard methods. The monoclonal antibodies from the clones are then tested against standard antigens to determine their specificity for the particular Salmonella antigen. The monoclonal antibody selected, which is specific for the particular Salmonella antigen or species, is then bound to an appropriate label. Amounts of antibody sufficient for labelling and subsequent commercial production are produced by the known techniques, such as by batch or continuous tissue culture or culture _in vivo in mammals such as mice. The monoclonal antibodies may be labelled with various labels, as exemplified above. The present invention will be described with reference to the use of an enzyme-labelled monoclonal antibody. Examples of enzymes utilised as labels are alkaline phosphatase, glucose oxidase, galactosidase, peroxidase and urease.

Such linkage with enzymes can be accomplished by any known method, such as the Staphylococcal Protein A method, the glutaraldehyde method, the benzoquinone method, or the periodate method. Once the labelled monoclonal antibody is formed, testing is carried out employing one of a wide variety of conventional immunoassay methods. The particular method chosen will vary according to the monoclonal antibody and the label chosen. At the present time, enzyme immunoassays are preferred owing to their low cost, reagent stability, safety, sensitivity and ease of procedure. One example is the enzyme-linked immunosorbent assay (EIA) . EIA is a solid-phase assay system which is similar in design to the radiometric assay, but which utilises an enzyme in place of a radioactive isotope as the immunoglobin marker.

Fluorescent-immunoassay is based on the labelling of antigen or antibody with fluorescent probes. A non-labelled antigen and a specific antibody are combined with identical fluorescently-labelled antigen. Both labelled and unlabelled antigen compete for antibody binding sites. The amount of labelled antigen bound to the antibody is dependent upon, and therefore a measurement of, the concentration of non-labelled antigen. Examples of this particular type of fluorescent-immunoassay include heterogeneous systems such as Enzyme-Linked Fluorescent Immunoassay, or homogeneous systems such as the Substrate-Labelled Fluorescent Immunoassay. The most suitable fluorescent probe, and the one most widely used, is fluorescein. While fluorescein can be subject to considerable interference from scattering, sensitivity can be increased by the use of a fluorometer optimised for the probe utilised in the particular assay, and in which the effect of scattering can be minimised.

In fluorescence polarisation, a labelled sample is excited with polarised light and the degree of polarisation of the emitted light is measured. As the antigen binds to the antibody, its rotation slows down and the degree of polarisation increases. Fluorescence polarisation is simple, quick and precise. However, at the present time, its sensitivity is limited to the micro ole per litre range^' and upper nanomole per litre range with respect to antigens in biological samples. Luminescence is ^'the emission of light by an atom or molecule as an electron is transferred to the ground state from a higher energy state. In both chemiluminescent and bioluminescent reactions, the free energy of a chemical reaction provides the energy required to produce an intermediate reaction or product in an electronically-excited state. Subsequent decay back to the ground state is accompanied by emission of light. Bioluminescence is the name given to a special form of chemiluminescence found in biological systems, in which a catalytic protein or enzyme, such as luciferase, increases the efficiency of the luminescent reaction. The best known chemiluminescent substance is luminol.

A further aspect of the present invention is a therapeutic composition comprising one or more of the monoclonal antibodies to the particular Salmonella _Λ< _-,__._, PCT/GB85/00407 86/01805 '

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antigen or species, as well as a pharmacologically-acceptable carrier or diluent. Such compositions can be used to treat humans and/or animals afflicted with some form of shigellosis and they are used in amounts effective to cure; the amount may vary widely, depending upon the individual being treated and the severity of the infection.

One or more of the monoclonal antibodies can be assembled into a diagnostic kit for use in diagnosing for the presence of an antigen, antigens or species of

Salmonella in various specimens. It is also possible to use the broadly cross-reactive monoclonal antibody which can identify the genus Salmonella alone or as part of a kit containing antibodies that can identify other bacterial genera or species of Salmonella and/or other bacteria.

In the past, there have been difficulties in developing rapid kits because of undesirable cross-reactions of specimens; e.g. faeces with antiserum. The use of monoclonal antibodies can eliminate these problems and provide highly specific and rapid tests for diagnosis. For example, the incidence of significant diarrhea and diarrheal illness is so high that estimates of market size for such a kit are difficult to make, but a "same day" test could be expected to be used at least as often as stool cultures. Large use of such tests in developing countries might be anticipated because of more frequent and severe diarrhea, and other related illnesses. Additionally, conjugated or labelled monoclonal antibodies for antigens and/or species of Salmonella and other gram-negative bacteria can be utilised in a kit to identify such antigens and organisms in blood samples taken from patients for the diagnosis of possible Salmonella or other gram-negative sepsis. The monoclonal test is an advance over existing procedures in that it is more accurate than existing tests; it gives "same day" results, provides convenience to the patient and improves therapy as a result of early, accurate diagnosis; and it reduces labour costs and laboratory _.time required for administration of the tests.

The kit may be sold individually or included as a component in a comprehensive line of compatible immunoassay reagents sold to reference laboratories to detect the species and serotypes of Salmonella.

One preferred embodiment of the present invention is a diagnostic kit comprising at least one labelled monoclonal antibody against a particular Salmonella antigen or species, as well as any appropriate stains, counterstains or reagents. Further embodiments include kits containing at least one control sample of a Salmonella antigen and/or a cross-reactive labelled monoclonal antibody which would detect the presence of any of the given particular Salmonella organisms in a particular sample.

Monoclonal diagnostics which detect the presence of Salmonella antigens can also be used in periodic testing of water sources, food supplies and food processing operations. Thus, while the present invention describes the use of the labelled monoclonal antibodies to determine the presence of a standard antigen, the invention can have many applications in diagnosing the presence of antigens by determining whether specimens, such as urine, blood, stool, water and milk, contain the particular Salmonella antigen. More particularly, the invention could be utilised as a public health and safety diagnostic aid, whereby specimens such as water or food could be tested for possible contamination.

The invention will be further illustrated in connection with the following Examples which are set forth for purposes of illustration only and not by way of limitation.

The monoclonal antibodies of the present invention were prepared generally according to the method of Kohler and Milstein, supra.

In the Examples:

API = Analytical Profile Index (ref. Ayerst Laboratories)

DMEM = Dulbeccos Modified Eagles Medium FCS = Foetal Calf Serum

% T refers to vaccine concentrations measured in a 1 cm light path

PBS = Phosphate Buffered Saline

TSB = Tryptone Soya Broth CFA = Complete Freunds Adjuvant ip = intraperitoneal iv = intravenous im = intramuscular Example 1 A. Antigen Preparation

Salmonella paratyphi A was obtained from the National Collection of Type Cultures (NCTC accession No. 13) and tested by standard biochemical methods of microbial identification to confirm its identity (using API profiles) . The Salmonella was removed from the lyophile, grown on blood agar, and tested by API to confirm its identity and purity. The bacteria were transferred for growth on to TSB and harvested. The organisms were boiled and washed in for ol saline, and then resuspended in 1% formol saline. B. Animal Immunisation

Six Balb/c mice were injected with the prepared antigen, over five weeks. They were given one ip injection per week for three weeks (0.05 ml 80% T vaccine) of boiled killed Salmonella OAl, followed by a 0.05 ml dose of vaccine iv each week for two weeks. The mice were bled approximately six days after the last injection and the serum tested for antibodies by assay. The conventional assay used for this serum titer testing was the enzyme-linked immunosorbent assay system. When the mice showed antibody production after this regimen, generally a positive titer of at least 10,000, a mouse was selected as a fusion donor and given a booster injection (0.02 ml 80% T vaccine) intravenously, three days prior to splenectomy. C. Cell Fusion

Spleen cells from the immune mice were harvested three days after boosting, by conventional techniques. First, the donor mouse selected was killed and surface-sterilised by immersion in 70% ethyl alcohol.

The spleen was then removed and immersed in approximately 2.5 ml DMEM to which had been added 3% FCS. The spleen was then gently homogenised in a LUX homogenising tube until all cells had been released from the membrane, and the cells were washed in 5 ml 3% FCS-DMEM. The cellular debris was then allowed to settle and the spleen cell suspension placed in a 10 ml centrifuge tube. The debris was then rewashed in 5 ml 3% FCS-DMEM. 50 ml suspension were then made in 3% FCS-DMEM. The myeloma cell line used was NS0 (uncloned) , obtained from the MRC Laboratory of Molecular Biology in Cambridge, England. The myeloma cells were in the log growth phase, and rapidly dividing. Each cell line was washed using, as tissue culture medium, DMEM containing 3% FCS.

The spleen cells were then spun down at the same time that a relevant volume of myeloma cells were spun down (room temperature for 7 minutes at 600 g) , and each resultant pellet was then separately resuspended in 10 ml 3% FCS-DMEM. In order to count the myeloma cells, 0.1 ml O 86/01805 _^_Q_ /

of the suspension was diluted to 1 ml and a haemacytometer with phase microscope was used. In order to count the spleen cells, 0.1 ml of the suspension was diluted to 1 ml with Methyl Violet-citric acid solution, and a haemacytometer and light microscope were used to count the stained nuclei of the cells.

10 8 spleen cells were then mixed with 5 x 107 myeloma cells, the mixture washed in serum-free DMEM high in glucose, and centrifuged, and all the liquid removed. The resultant cell pellet was placed in a 37°C water-bath. ^' 1 ml of a 50 w/v solution of polyethylene glycol 1500 (PEG) in saline Hepes, pH approximately 7.5, was added, and the mixture gently stirred for approximately 1.5 minutes. 10 ml serum-free tissue culture medium DMEM were then slowly added, followed by up to 50 ml of such culture medium, centrif gation and removal .of all the supernatant, and resuspension of the cell pellet in 10 ml of DMEM containing 18% by weight FCS. 10 μl of the mixture were placed in each of 480 wells of standard multiwell tissue culture plates. Each well contains 1.0 ml of the standard HAT medium

(hypoxanthine, aminopterin and thymidine) and a feeder

4 layer of Balb/c macrophages at a concentration of 5 x 10 macrophages/well.

The wells were kept undisturbed and cultured at 37°C in 9% CO_ air at approximately 100% humidity. The wells were analysed for growth, utilising the conventional inverted microscope procedure, after about 5 to 10 days. in those wells in which growth was present in the inhibiting HAT medium, screening tests for the specific monoclonal antibody were made utilising the conventional enzyme immunoassay screening method described below. Somewhere around 10 days to 14 days after fusion, sufficient antibody against the Salmonella paratyphi A antigens was developed in at least one well. D. Cloning

From those wells which yielded antibody aginst the Salmonella paratyphi A antigens, cells were removed and cloned by dilution culture and, as an alternative, by the standard agar method. In the agar method, a freshly-prepared stock solution of sterile 1.2% agar in double distilled water with an equal volume of double-strength DMEM and additives was maintained at 45 C. This solution (10 ml) was then aliquoted into 10 cm Petri dishes, to form a base layer. An overlay of equal volumes of agar and cells in 18% FCS-DMEM was spread evenly over the base. The cells were allowed to multiply for approximately 10 days at 37 C, 7-9% C0₂, 95% RH.

Viable separate colonies were picked off the agar surface and placed into 60 wells of a 96-well microtitre tray in 18% FCS-DMEM. After a further period of growth, the supernatants were assayed for specific antibody by the standard enzyme immunosorbent assay.

In limiting dilution, dilutions of cells suspensions in 18% FCS-DMEM + Balb/c mouse macrophages were made to achieve 1 cell/well and half cell/well in a 96-well microtitre plate. The plates were incubated for 7-14 days at 37 C, 95% RH, 7-9% CO- until semi-confluent. The supernatants were then assayed for specific antibody by the standard enzyme immunosorbent assay.

The clones were assayed by the enzyme immunoassay method to determine antibody production, and a positive clone was recloned using the standard agar method. E. Monoclonal Selection

The monoclonal antibodies from the clones were screened by the standard techniques for binding to Salmonella OAl NCTC 13, prepared as in the immunisation, and for specificity in a test battery of Salmonella -44-

species and related genera bearing different antigens. Specifically, a grid of microtitre plates containing a representative selective of organisms was prepared, boiled, and utilised as a template to define the specificity of the parent group. The EIA immunoassay noted above .may be used.

The monoclonals had the appropriate specificity (to S_. paratyphi A) , and did not react with Shiqella, 12. coli, Pseudomonas, Klebsiella, Serratia or Enterobacter. F. Antibody production and purification

Cells of the monoclonal antibody-producing line specific to the Salmonella paratyphi A antigen were grown in batch tissue culture. DMEM, to which had been added 10% FCS, was used to support growth in mid-log phase, to 1 litre volume. The culture was allowed to overgrow, to allow maximum antibody production. The culture was then centrifuged at 1200 g for approximately 10 minutes. The cell/cell debris was discarded and the antibody-rich supernatant collected. The fluid may then be titrated, as noted above, to establish presence and level of antibody, and purified by a combination of batch ion-exchange chromatography, ammonium sulphate precipitation and column ion-exchange chromatography. To one litre of culture supernatant was added one litre of 0.05M sodium acetate buffer, pH 4.5, and 40 ml of SP-Sephadex, previously equilibrated in 0.1M sodium acetate buffer, pH 5.0. The suspension was stirred at +4 C for one hour. The SP-Sephadex was allowed to settle and the supernatant decanted. The SP-Sephadex was packed in a column, washed with 60 ml of 0.1M acetate buffer, pH 5.0, and eluted with 60 ml of the same buffer plus 1M sodium chloride. The eluate was stirred at +4 C, and an equal volume of saturated ammonium sulphate added slowly. The suspension was stirred for a further 30 minutes, and then the precipitate was harvested by centrifugation at 10,000 g for 10 minutes. The precipitate was dissolved in a minimum volume of cold phosphate/EDTA buffer (20 mM sodium phosphate, 10 mM EDTA pH 7.5 + 0.02% sodium azide) . The dialysed, redissolved precipitate was centrifuged at 30,000 g for 10 minutes and applied to a 10 ml column of DEAE-cellulose, previously equilibrated in phosphate/EDTA buffer. The monoclonal antibody was eluted with phosphate/EDTA buffer. In an alternative procedure, ascites fluid was filtered through glass wool and centrifuged at 30,000 g for 10 minutes. The ascites was then stirred at +4 C and an equal volume of cold, saturated ammonium sulphate added slowly. The mixture was stirred for a further 30 minutes after the addition was complete. The precipitate was harvested by centrifugation at 10,000 g for 10 minutes. The precipitate was dissolved in a minimum volume of cold phosphate/EDTA buffer (20 mM sodium phosphate, 10 mM EDTA, pH 7.5, + 0.02% sodium azide) . The solution was dialysed vs 2 x 1000 ml of the same buffer at +4 C. The dialysed, redissolved precipitate was centrifuged at 30,000 g for 10 minutes and applied to a 10 ml column of DEAE-cellulose, previously equilibrated in phosphate/EDTA buffer. The monoclonal antibody was eluted with phosphate/EDTA buffer. G. Enzyme-Monoclonal Linkage

The monoclonal antibody specific against Salmonella paratyphi A, prepared as above, was linked to an enzyme, viz. highly-purified alkaline phosphatase, using the one-step glutaraldehyde method. Monoclonal antibody was dialysed with alkaline phosphatase (Sigma Type VII-T) , against 2 x 1000 ml of phosphate buffered saline (PBS) , pH 7.4 at +4 C. After dialysis the volume was made up to 2.5 ml with PBS and 25 μl of a 20% glutaraldehyde in PBS solution added. The conjugation mixture was left at room -46-

temperature for 1.5 hours. After this time glutaraldehyde was removed by gel filtration on a Pharmacia PD-10 (Sephadex G-25M) column, previously equilibrated in PBS. The conjugate was eluted with 3.5 ml PBS. The conjugate was then dialysed vs 2 x 2000 ml of TRIS buffer (50 mM TRIS, 1 mM magnesium chloride, pH 8.0 + 0.02% sodium azide) at +4 C. To the dialysed conjugate was added 1/lOth its own volume of 10% BSA in TRIS buffer. The conjugate was then sterile filtered through a 0.22 μm membrane filter into a sterile amber vial and stored at +4 C. H. Monoclonal Antibody Conjugate Testing

The enzyme immunoassay method was used for testing. This method comprises coating the wells of a standard polyvinyl chloride (PVC) microtitre tray with the antigen, followed by addition of monoclonal antibody enzyme conjugate, and finally addition of the enzyme substrate, para-nitrophenyl phosphate.

Monoclonal antibody was produced and found to be specific for the group A antigens of Salmonella. The monoclonal antibody was tested and shown to be of the Class IgG_.

If deemed necessary, the particular epitopic site to which the antibody attaches to the antigen can also be determined. The same enzyme immunoassay method can also be used to determine whether diagnostic specimens such as urine, blood, stool, water or milk contain the antigen. In such cases, the antibody can first be bound to the plate. Examples 2 to 7

The procedure of Example 1 was followed in each of 6 cases, with differences outlined below, to prepare monoclonal antibodies and conjugates for various antigens of the genus Salmonella. In Example 2, the antigen was Salmonella hadar, NCTC 9877; in Example 3, Salmonella albany (formerly K3) NCTC 9869; in Example 4, Salmonella brazil NCTC 8446; in Example 5, Salmonella poona, NCTC 4840; and, in Examples 6 and 7, Salmonella enteriditis, NCTC 5188.

In the antigen preparation step, for Example 6, DMEM was the growth medium, and the organisms were merely washed once in formol saline.

In the animal immunisation step, the sequences of ι~ injections and intervals (given in weeks) were ip-2-ip-2-ip-l-iv-l-iv-l-iv-l-iv-2-iv-2-iv-l-iv in Example 2, ip-l-ip-l-ip-l-iv-l-iv-2-iv-2-iv in Example 3, ip-l-ip-l-ip-l-iv-l-iv-l-iv-l-iv-9-iv in Example 4, ip-l-ip-l-ip-l-iv-2-iv-l-ip-8-iv-2-iv-2-iv-2-iv-2-iv-2- iv-7-iv in Example 5, im (in CFA)-13-iv (in PBS) in Example 6 and ip-l-ip-l-ip-l-iv-l-iv-2-iv-l-iv-9-iv-2- iv-2-iv-2-iv-3-iv₇8-iv in Example 7.

8 In the cell fusion step, 1 x 10 myeloma cells, were used in Example 2, and 6 x 10 in Examples 3, 5 and 6. t^" 1.2 x 10 8 spleen cells were used in Example 2, 1.4 x 108 in Examples 3 and 5.

In the cloning step, the agar method only was used in Examples 2 and 4, and the dilution method only in

Example 5. 5 Additionally in Example 2, and as the antibody production procedure in Examples 3, 4, 5 and 7, Balb/c mice were primed with pristane. for at least 7 days, and

7 injected mtraperitoneally with 10 cells of the monoclonal antibody-producing line. Ascitic fluid was 0 harvested when the mice were swollen with fluid but still alive. The fluid was centrifuged at 1200 g for approximately 10 minutes, the cells discarded, and the antibody-rich ascites collected and stored at -20°C.

Antibody purification for Examples 3 and 4 was by 5 the ammonium sulphate precipitation/DEAE-cellulose 86/01805 ' '

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chromatography method. In Examples 5 and 7, ascites fluid was filtered through glass wool and centrifuged at 30,000 g for 10 minutes. The ascites was then diluted with twice its own volume of cold phosphate buffer (O.l M sodium phosphate, pH 8.2). The diluted ascites was applied to a 2 ml column of Protein A-Sepharose, previously equilibrated with phosphate buffer. The column was washed with 40 ml phosphate buffer. The monoclonal antibody was eluted with citrate buffer (0.1 M sodium citrate, pH 3.5) into sufficient 1 M TRIS buffer, pH 9.0, to raise the pH immediately to about 7.5. The eluate was dialysed in PBS, pH 7.4, at 4 C, and stored at -20 C.

In the antibody conjugation step for Examples 3 and 7, the benzoquinone method was used. 24 mg alkaline phosphatase (Sigma Type VII-T) were dialysed against 2 x 500 ml of 0.25M sodium phosphate buffer, pH 6.0, at +4°C. 18^' mg p-benzoquinone, 18 mg were dissolved in warm AR ethanol and added to the dialysed alkaline phosphatase. The benzoquinone/alkaline phosphatase mixture was left in the dark at room temperature for 1 hour. After this time, unreacted benzoquinone and reaction by-products were removed and the buffer exchanged, by gel filtration on a Pharmacia PD-10 (Sephadex G-25M) column, previously equilibrated in 0.15M sodium chloride. The benzoquinone-activated alkaline phosphatase thus produced was sufficient for six 1.5 mg antibody conjugations. Monoclonal antibody was dialysed against 2 x 500 ml of 0.15M sodium chloride at +4°C. Dialysed antibody was added to 8 mg of benzoquinone-activated alkaline phosphatase, immediately followed by sufficient 1M sodium bicarbonate to give a final concentration of O.lM. The conjugation mixture was left in the dark at +4°C for 48 hours. After this time, sufficient 1M lysine was added to give a final concentration of O.lM. After 2 hours in the dark at room temperature, the conjugate was dialysed against 2 x 1000 ml of PBS + 0.02% sodium azide at +4°C. An equal volume of glycerol was added. The conjugate was sterile-filtered through a 0.22 μm membrane filter into a sterile amber vial and stored at +4°C.

On selection at least, the appropriate specificity was shown for each of Examples 2 to 6. The monoclonal of Example 2 was specific to Salmonella newport and Salmonella hadar. The monoclonal of Example 6 is specific to Salmonella enteriditis which bears the 9,12 antigens representative of Salmonella OD1. The monoclonal antibodies of Examples 2, 3, 4 and 5 are negative to other Salmonella, 33. coli and Shigella, and the monoclonals of Examples 2, 4 and 5 are also negative with respect to Serratia, Enterobacter, Pseudomonas and Klebsiella. The monoclonal of Example 7 cross-reacts with all Salmonella strains tested to date.

The monoclonal antibodies obtained in Examples 2 to 7 are respectively of the Sub-classes IgGl, IgM, IgG2a and IgG3, IgG3, IgM and IgG2a.

Tests using the present invention are superior to existing tests, based on the following advantages: (i) greater accuracy; (ii) same day results, within an hour or two; (iii) reduction in amount of skilled labour required to administer laboratory procedures, resulting in reduced labour costs; (iv) reduction in laboratory time and space used in connection with tests, resulting in reduced overhead expenses; and (v) improved therapy based upon early, precise diagnosis. While the invention has been described in connection with certain preferred embodiments, it is not intended to limit the scope of the invention to the particular form set forth but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Claims

6/01805 * PCT/GB85/00407WHAT IS CLAIMED IS:

1. A monoclonal antibody specific for an antigen or species of Salmonella.

2. The antibody of Claim 1 specific to somatic antigens of Salmonella.

3. The antibody of Claim 1 specific to flagellar antigens of Salmonella .

4. The antibody of Claim 1 specific to the group antigens of Salmonella A •

5. The antibody of Claim 1 specific to the group antigens of Salmonella B .

6. The antibody of Claim 1 specific to the group antigens of Salmonella C .

7. The antibody of Claim 1 specific to the group antigens of Salmonella D .

8. The antibody of Claim 1 specific to the group antigens of Salmonella E .

9. The antibody of Claim 1 specific to the group antigens of Salmonella

10. The antibody of Claim 1 specific to the group antigens of Salmonella G-

( 11. The antibody of Claim 1 specific to the group antigens of Salmonella H to Z.

12. The antibody of Claim 1 specific to the group antigens of Salmonella H group A to .

13. The antibody of Claim 1 specific to antigens of Salmonella H group Zl to Z59.

14. The antibody of Claim 1 specific to the antigen or species of Salmonella albany

15. The antibody of Claim 1 specific to the antigen or species of Salmonella poona.

16. The antibody of Claim 1 specific to the antigen or species of Salmonella brazil

17. The antibody of Claim 1 specific to the invasiveness 1 antigen of Salmonella.

18. The antibody of Claim 1 specific to the invasiveness 2 antigen of Salmonella.

19. The antibody of Claim 1 specific for the enterotoxin 1 of Salmonella..

20. The antibody of Claim 1 specific for the enterotoxin 2 of Salmonella.

21. The antibody of Claim 1 specific for attachment antigen 1 of Salmonella.

22. The antibody of Claim 1 specific for attachment antigen 2 of Salmonella.

23. A monoclonal antibody broadly cross- reactive with an antigen of all species of the genus Salmonella.

24. A labeled monoclonal, antibody consisting essentially of a monoclonal antibody of Claims 1-23 and an appropriate label.

25. The labeled monoclonal antibody of Claim 24, wherein said label is a member of the group selected from a radioactive isotope, enzyme, fluorescent compound, bioluminescent compound, chemiluminescent compound, or ferro¬ magnetic atom, or particle.

26. The labeled monoclonal antibody of Claim 25, wherein said label is an enzyme capable of conjugating with a monoclonal antibody and of being used in an enzyme-linked immunoassay procedure.

27. The labeled mono.clonal antibody of Claim 26, wherein said enzyme is alkaline phos¬ phatase, glucose oxidase, galactosidase, or peroxidase.

28. The labeled monoclonal antibody of Claim 25, wherein said label is a fluorescent compound or probe capable of being used in an immuno-fluorescent or fluorescent immunoassay procedure, enzyme fluorescent immunoassay, or fluorescence polarization immunoassay, photon counting immunoassay, or the like procedure.

29. The labeled monoclonal antibody of Claim 28, wherein said fluorescent compound or probe is fluorescein.

30. The labeled monoclonal antibody of Claim 25, wherein said label is a chemiluminescent compound capable of being used in a luminescent or enzyme-linked luminescent immunoassay.

31. The labeled monoclonal antibody of Claim 30, wherein such chemiluminescent compound is luminol or a luminol derivative.

32. The labeled monoclonal antibody of Claim 25, wherein said label is a bioluminescent compound capable' of being used in an appropriate bioluminescent immunoassay.

33. The labeled monoclonal antibody of Claim 32, wherein such bioluminescent compound is luciferase or a luciferase derivative.

34. A process for diagnosing for the pre¬ sence of an antigen of Salmonella in a specimen comprising contacting at least a portion of said specimen with a labeled monoclonal antibody of Claim 24 in an immunoassay procedure appropri¬ ate for said label.

35. The process of Claim 34, wherein the appropriately labeled immunoassay procedure is selected from immuno-fluorescent or fluorescent immunoassay, immuno-electron microscopy, radio- metric assay systems, enzyme-linked immunoassays, fluorescence polarization, photon-counting bio¬ luminescent, or chemiluminescent immunoassay.

36. The process of Claim 35, wherein said label is an enzyme capable of being used in an enzyme-linked immunoassay procedure.

37. The process of Claim 36, wherein said enzyme is selected from alkaline phosphatase, glucose oxidase, galactosidase, or peroxidase.

38. The process of Claim 35, wherein said label is a fluorescent compound or probe capable of being used in an immuno-fluorescent or fluores¬ cent immunoassay procedure, enzyme fluorescent immunoassay, or fluorescence polarization immuno¬ assay, or photon-counting immunoassay, or the like procedure.

39. The process of Claim 3S, wherein said fluorescent compound or probe is fluorescein.

40. The process of Claim 35, wherein said label is a chemiluminescent compound capable of being used in a luminescent or enzyme-linked luminescent immunoassay.

41. The process of Claim 40, wherein said chemiluminescent compound is luminol or a luminol derivative.^'

42. The process of Claim 35, wherein said label is a bioluminescent compound capable of being used in a bioluminescent or enzyme-linked bioluminescent immunoassay.

43. The process of Claim 42, .wherein said bioluminescent compound is luciferase or a lucif- erase derivative.

44. A therapeutic composition comprising one or more of the monoclonal antibodies of Claims 1-23 and a pharmaceutically acceptable carrier or diluent.

45. A therapeutic composition comprising one or more of the labeled monoclonal antibodies in Claim 24 and a pharmaceutically acceptable carrier or diluent.

46. A method of treating salmonellosis comprising administering an effective amount of a monoclonal antibody of Claims 1-23.

47. A kit for diagnosing for the presence of an antigen or species of Salmonella in a diagnostic specimen comprising at least one monoclonal antibody of Claims 1-23.

48. The kit of Claim 47, wherein said at least one antibody is labeled.

49. The kit of Claim 48, wherein said at least one monoclonal antibody is labeled with a fluorescent compound.

50. The kit as in Claim 48, wherein said at least one monoclonal antibody is labeled with an enzyme.

51. The kit as in Claim 48, wherein said at least one monoclonal antibody is labeled with a member of the group consisting of a radio¬ active isotope, chemiluminescent compound, bio¬ luminescent compound, ferromagnetic atom, or particle.

52. The kit of Claims 48, 49, 50,- and 51 additionally containing at least one known Salmonella antigen as a control.

53. The kit of Claims 48, 49, 50, 51, and 52 containing each known group antigens of Salmonella OA1, OBI, OC1, ^' OD1, OE1, OF1, OG1, OH1, and/or Oil.

54. The kit of Claims 48, 49, 50, 51, and 52 containing the antigens of Salmonella HB, HC1, HC2, HD, and/or HE2.

55. The kit of Claims 48, 49, 50, 51, and 52 containing the antigens of Salmonella albany K3, Salmonella poona K6, and/or Salmonella brazil K7.

56. The kit of Claims 48, 49, 50, 51, and 52 containing invasiveness antigens 1 and 2 of Salmonella.

57. The kit of Claims 48, 49, 50, 51, and 52 containing enterotoxin 1 and 2 of Salmo¬ nella.

58. The kit of Claims 48, 49, 50, 51, and 52 containing attachment antigens 1 and 2 of Salmonella.

59. A kit for diagnosing for the presence of an antigen or species of Salmonella in a diagnostic specimen comprising . at least one monoclonal antibody of Claims 1-23 and a control.

60. The kit of Claim 59, wherein said at least one antigen is labeled and said control is at least one known antigen of Salmonella.

61. A kit for diagnosing for the presence of a gram-negative bacterial infection comprising at least one monoclonal antibody of Claims 1-23.

62. The kit of Claim 61, wherein said at least one monoclonal antibody is labeled.