Figure 5. Protection of vaccinated mice against challenge with the influenza A virus.

BALB/c mice (n = 6) were immunized on day 0 and 21 with rNP (10 µg/dose) alone or co-administered with c-di-AMP (10 µg/dose) by intranasal route, whereas control animals received PBS. All groups were challenged on day 60 with a non-lethal dose of the influenza strain A/Puerto Rico/8/34 (H1N1). Animal body weight was then monitored for 14 days. Results are expressed as average percentage of weight loss.