Figure 4.
Kinetics of antibody responses in the lungs of mice with influenza virus infection. Kinetics of IgA, IgM, IgG, (A) and IgG2a, IgG1 antibody responses and IgG1/IgG2a ratio (B) in the lungs of mice after 5 × 105 p.f.u. A/Beijing/501/2009(H1N1) and A/PR/8/34/(H1N1) viruses infection. Mice were sacrificed at certain time points post infection, and virus-specific antibodies in the lungs were determined by ELISA. Mice without infection were used as the control group. I bars represent standard deviations. The dotted lines were the control level. $ p < 0.05, compared among different time-points within BJ501 viruses infection, # compared among different time-points within PR8 viruses infection, *p < 0.05 and **p < 0.01, compared between BJ501 and PR8 infections at the same time-point.