Figure 4.
Maternal antibody protected the newborn mice against EV71 lethal challenge. Female ICR mice (6–8 week) were i.p. injected with different dosage vaccines and PBS at a 3-week interval and allowed to mate at 1 week after the first injection. After 3 weeks, the newborn mice were challenged with 15 LD50 of the EV71 challenge virus. Mortality and clinical disease were monitored and recorded daily after infection. The Mantel-Cox log-rank test was used to compare the survival of pups between each maternal immunization group and the PBS control group at 21 d post-infection.