Figure 5.

SCV-CHIK Induces VACV-Specific Antibody Responses and Protects against Lethal Mousepox Challenge

(A) Groups of 6- to 8-week-old female C57BL/6 mice (n = 5 mice per group) were vaccinated i.p. with VACV-CHIK (10⁷ PFUs) or SCV-CHIK (10⁵, 10⁶, and 10⁷ PFUs) and bled at the time points indicated, and VACV-specific IgG levels were determined by endpoint ELISA. (B) At day 30 post-vaccination, serum VACV-specific neutralization activity was determined by PRNT₅₀ assays (n = 3 mice per group). The dotted line indicates the limit of detection (1 in 40 serum dilution). (C) Groups of BALB/c mice (n = 5 per group) were vaccinated with SCV-CHIK or VACV-CHIK or mock vaccinated with PBS. After 4 weeks, mice were challenged with LD₅₀ of ECTV and animal weights were monitored over time. The percentage of weight change post-challenge over time is presented. Statistics by t tests; the PBS mock-vaccinated group was significantly different from all other groups at day 7 post-challenge. (D) Mean clinical scores for animals in (C). Legend as in (C). Statistics by Kolmogorov-Smirnov test; the PBS mock-vaccinated group was significantly different from all other groups at days 6 and 7 post-challenge. (E) Survival post-challenge. Legend as in (C). Statistics by log rank (Mantel-Cox) test.