Reactogenicity to vaccine in sensitized vs unsensitized guinea pigs.

Images are representative of guinea pigs inoculated i.n. with C. burnetii (C and D) or unsensitized (saline) (A and B), then challenged with a 2 μg intradermal dose of vaccine (Coxevac) at day 42 p.i.. A) Inflammation at day 7 p.c. in unsensitized guinea pig is multifocal (arrows) and limited to the deep dermis. B) Inflammation at day 21 p.c. in unsensitized guinea pig is similar to day 7 (arrow). C) More severe inflammation with extension through the dermis (arrows) at day 7 p.c. in Cb9M-sensitized guinea pig. D) Progression of inflammation in Cb9M-sensitized guinea pig at day 21 p.c. (arrows) with increased frequency of neutrophils and presence of microabscesses (arrowheads).