Figure 6: Effect of heat treatment on the infectivity and haemagglutination activity of viruses.
Aliquots of a virus stock containing 128 HA units were incubated for the times indicated at 50 °C. a, Virus titres in heat-treated samples were determined by plaque assays on MDCK cells. b, Haemagglutination titres in heat-treated samples were determined by using haemagglutination assays with 0.5% TRBCs. Each point represents the mean ± standard deviation from triplicate experiments.