Figure 3:

Dose response to intramuscular (IM) vaccination with differing amounts of NA2 VLPs. Groups of BALB/c mice were vaccinated IM in a prime-boost regimen 28 days apart with 1 µg, 5 µg, 10 µg, or 15 µg total protein of NA2 VLP preparation or mock vaccinated with PBS. Mice were then challenged 28 days post-boost vaccination with 5xLD₅₀ mouse adapted A/Hong Kong/1/1968 (H3N2) virus. (A) Total serum IgG responses measured by ELISA at 14 days post-prime vaccination (N=5). (B) Total serum IgG responses measured by ELISA at 14 days post-boost vaccination (N=5) (C) Neuraminidase inhibition (NAI) titers measured 14 days post-boost vaccination (N=5). (D) Body weight changes of mice after challenge with heterologous H3N2 virus (N=5). (E) Mortality of mice after challenge with heterologous H3N2 virus (N=5). (F) Viral titers of lung homogenates harvested at 4 days post infection (N=3). Error bars represent SEM. *= p<0.05; **=p<0.01; ***=p<0.001; ****=p<0.0001.