Figure 4
The negative effect of the HA A180V mutation on viral release. A Virus elution from chicken erythrocytes. Twofold dilutions of F/98 and rF/HAA180V viruses were incubated with equal volumes of chicken erythrocytes at 4 ℃ for 30 min, and the HA titres at 37 ℃ representing the virus elution from chicken erythrocytes were monitored for 6 h. The result was presented as the percentage of the initial HA titre at 4 ℃. B, C Virus release assay. A180V HA mutation does not affect viral infection (B) and significantly prevents virus release from the MDCK cell surface (C). The results are displayed as the mean ± SD of three independent experiments, and the comparisons were performed with a t test. **Indicates a significant difference between groups (P < 0.01).