No abstract

Yersinia pestis YadB and YadC are two new outer membrane proteins related with its pathogenicity. Here, codon optimized yadC, yadC810 (aa 32-551) or yadBC antigen genes delivered by live attenuated Salmonella strains are evaluated in mice for induction of protective immune responses against Y. pestis CO92 through subcutaneous (s.c.) or intranasal (i.n.) challenge. Our findings indicate that mice immunized with Salmonella synthesizing YadC, YadC810 or YadBC develop significant serum IgG responses to purified recombinant YadC protein. For s.c. challenge (~230 LD50 of Y. pestis CO92), mice immunized with Salmonella synthesizing YadC or YadC810 are afforded 50% protection but no protection by immunization with the Salmonella strain synthesizing YadBC. None of these antigens provided protection against i.n. challenge (~31 LD50 of Y. pestis CO92). In addition, s.c. immunization with purified YadC810 protein emulsified with Alum adjuvant does not elicit a protective response against Y. pestis administered by either challenge route.