Fig 14.

(A) LD₅₀ values of YK455 (VP22LL251AA) and YK456 (VP22LL251AA-repair) in mice following intracerebral inoculation. Three-week-old female mice were inoculated intracerebrally with serial 10-fold dilutions of each virus in groups of 6 per dilution and were monitored for 14 days. LD₅₀ values were determined by the Behrens-Karber method. (B) Virus titers in the brains of mice following intracerebral inoculation. Seventeen 3-week-old female mice were inoculated intracerebrally with 10² PFU of each virus. At 3 days postinfection, the brains of infected mice were harvested, and virus titers were determined by standard plaque assays on Vero cells. The data shown are means and standard errors. A statistically significant difference in virus titer between mice infected with YK455 (VP22LL251AA) and those infected with YK456 (VP22LL251AA-repair) was noted (*, P < 0.005).