Figure 6

Survival of 1-day-old SPF chicks inoculated intracerebrally with rescued wt and HN-mutated viruses at 106 EID50/chick. Ten chicks were allocated to each group.
Survival of 1-day-old SPF chicks inoculated intracerebrally with rescued wt and HN-mutated viruses at 106 EID50/chick. Ten chicks were allocated to each group.