FIG 7.

Virulence of A12-LproW105A in infected mice. Six- to 7-week-old female C57BL/6 mice (n = 6/group) were subcutaneously inoculated in the footpad with the indicated doses of A12-WT or A12-LproW105A mutant FMDV. (A) Clinical disease was followed for 7 days after inoculation, and percent survival was calculated as (number of surviving animals/number of animals per group) × 100, daily. (B) Serum samples collected at the indicated times after inoculation were assayed for the presence of virus by plaque assay on BHK-21 cells. (C) FMDV serum neutralizing antibody titers were determined by endpoint dilution and expressed as log TCID₅₀/ml (48). Statistical analysis was performed using Student’s t test. *, P < 0.05; **, P < 0.005.