FIG. 2.

Postexposure passive serotherapy protects wild-type and μMT mice from lethal intranasal Y. pestis infection. (A) C57BL/6 mice were intranasally infected with 2 × 10⁵ CFU Y. pestis KIM D27. At 18 h postinfection, the indicated dose of convalescent-phase sera was administered. Compared with mice that received no serotherapy, a 10-μl dose of postexposure serotherapy significantly protected C57BL/6 mice against mortality (n = 5 per group; P < 0.02). (B) B-cell-deficient μMT mice were intranasally infected with 2 × 10⁵ CFU Y. pestis KIM D27 (Yp) or were left uninfected. At 18 h later, some animals received 10 μl of convalescent-phase sera, as indicated. Compared with mice that received no serotherapy, the postexposure serotherapy significantly protected μMT mice (n = 8 per group; P < 0.001).