FIG. 4.

Immunohistochemical analysis of lung sections. Sections from mice 4 days postinoculation with PBS (A and C) or with 300 to 500 CFU of Y. pseudotuberculosis grown at 26°C (B and D) were stained with anti-Y. pseudotuberculosis antibodies. Goat anti-mouse HRP-conjugated antibody was used as a secondary stain. Brown areas represent areas of HRP activity; lighter brown/gray areas are red blood cells. Samples shown are at a magnification of ×10 (A and B) and ×60 (C and D). Arrow (D) indicates an area of colocalization of antibody with bacterial colonies. Boxed sections in panels A and B indicate the areas magnified in panels C and D, respectively.