Survival of mice passively injected with anti-NS1 antisera and challenged with JEV. Groups of four-week-old C3H mice were administered with 100 μl, 30 μl and 10 μl of anti-NS1 mouse antisera, or 100 μl sera from PBS-injected mice (negative control) or 100 μl of anti-SA14-14-2 antisera (anti-JEV), and infected 1 hr later with 20 pfu of JEV SA14. The JEV infected mice were monitored daily for 28 days. The survival curve was constructed using data from one (100 μl anti-JEV, 30 and 10 μl of anti-NS1 antisera), two (sera from PBS-injected mice) or three (100 μl of anti-NS1 antisera) experiments. For 100 μl anti-JEV antisera group, 30 and 10 μl of anti-NS1 antisera groups, sera from PBS-injected mice group, 6 mice were used for each experiments. Six to 12 mice were used for 100 μl anti-NS1 antisera groups of each experiment.