FIG 4.
FMDV A12-P1 deopt is attenuated in mice. (A and B) Six- to 7-week-old female C57BL/6 mice (n = 6/group) were s.c. inoculated in the footpad with the indicated doses of A12-WT (WT) or A12-P1 deopt mutant (P1deopt) FMDV. 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 (A). Serum samples collected during 7 days after inoculation were assayed for the presence of virus by plaque assay on BHK-21 cells (B). (C and D) Mice that survived the initial inoculation were challenged with 5 × 105 PFU/animal of FMDV A12-WT s.c. in the footpad. Clinical disease was followed for 7 days after inoculation, and percent survival was calculated as described above (C). Serum samples collected during 7 days after inoculation were assayed for the presence of virus by plaque assay on BHK-21 cells (D). A control naive group was included (n = 6). Error bars represent the variation among individual animals within a group.