FIG 2.

Activating FcγRs are not required to control influenza virus in mice treated with polyclonal anti-NA serum. Fifty microliters of heat-inactivated anti-NA sera (circles) or PBS antisera (squares) were passively transferred via the i.p. route into Fcer1g or Fcgr1/Fcgr3 knockout (KO) mice. BALB/c WT mice were included as controls. One day later, the mice were challenged with 1 LD₅₀ of Bel/09 and monitored daily, and any mice that had lost ≥25% of their original body weight were euthanized. Weight loss data represent the mean percentages ± SEM of original body weight over time (n = 8 to 10, pooled from 2 independent experiments). Survival percentages are indicated in the left-hand corner of the graphs where the text color matches colors indicated in the legend for each group (A). In a separate set of experiments, after passive transfer, KO or WT mice were challenged with 0.1 LD₅₀ of Bel/09 and viral titers assessed in lung homogenates on day 3 (B) or day 5 (C) by TCID₅₀. The horizontal lines represent the mean (pooled from 2 independent experiments). The dotted line indicates the detection limit of the TCID₅₀. ns, nonsignificant. *, P < 0.05, **, P < 0.01, and ***, P < 0.001, by one-way ANOVA.