Antibody responses to Yersinia pestis F1-antigen expressed in Salmonella typhimurium aroA from in vivo-inducible promoters

Attenuated mutants of Salmonella typhimurium are being evaluated as deliver y systems for a variety of heterologous vaccine antigens. Gene promoters wh ich are induced in vivo can direct the stable expression of genes encoding these antigens. We have investigated the utility of the phoP, ompC, pagC an d lacZ gene promoters for expression of the Y, pestis F1-antigen in S. typh imurium SL3261 (aroA). After i.g. (intragastric) dosing the highest level o f spleen colonisation was found with recombinant Salmonella expressing F1-a ntigen from the phoP gene promoter, and this recombinant was most effective in inducing serum and mucosal antibody responses. The use of the pagC gene promoter to direct expression of F1-antigen resulted in the induction of s erum and mucosal antibody responses even though the recombinant Salmonella were unable to colonise spleen tissues suggesting that colonisation of thes e tissues is not essential for the induction of antibody responses. (C) 200 0 Elsevier Science Ltd. All rights reserved.