FIG. 5.
Mouse neurovirulence assay. A fixed-dose intracerebral challenge with 104 PFU was carried out in 4-week-old ICR mice. (A) YF/JE-S compared with its parental viruses. (B) YF/JE-N compared with its parental viruses. Differences in mortality between YF/JE-S and YF5.2iv were significant (P < .005), based on χ2 analysis of the proportion of survivors.