Immune response to Yersinia outer proteins and other Yersinia pestis antigens after experimental plague infection in mice

There is limited information concerning the nature and extent of the immune response to the virulence determinants of Yersinia pestis during the cours e of plague infection. In this study, we evaluated the humoral immune respo nse of mice that survived lethal Y. pestis aerosol challenge after antibiot ic treatment. Such a model may replicate the clinical situation in humans a nd indicate which virulence determinants are expressed in vivo. Immunoglobu lin G enzyme-linked immunosorbent assay and immunoblotting were performed b y using purified, recombinant antigens including F1, V antigen, YpkA, YopH, YopM, YopB, YopD, YopN, YopE, YopK, plasminogen activator protease (Pla), and pH 6 antigen as well as purified lipopolysaccharide. The major antigens recognized by murine convalescent sera were F1, V antigen, YopH, YopM, Yop D, and Pla. Early treatment with antibiotics tended to reduce the immune re sponse and differences between antibiotic treatment regimens were noted. Th ese results may indicate that only some virulence factors are expressed and /or immunogenic during infection. This information mag prove useful for sel ecting potential vaccine candidates and for developing improved serologic d iagnostic assays.