IMMUNIZATION WITH LIVE RECOMBINANT SALMONELLA-TYPHIMURIUM AROA PRODUCING F1 ANTIGEN PROTECTS AGAINST PLAGUE

An attenuated Salmonella typhimurium strain which expressed the Fl cap sular antigen of Yersinia pestis was constructed by transformation of S. typhimurium SL3261 with plasmid pFGAL2a, a derivative of pUC18 whic h contained the caf1 gene without the leader sequence. The recombinant was used to vaccinate mice intragastrically end intravenously. The im munity induced was able to protect mice against challenge with a virul ent strain of plague. Protection correlated with the induction of high titers of immunoglobulin G in serum samples and a specific T-cell res ponse.