Oral vaccination with LcrV fromYersinia pestisKIM delivered by live attenuatedSalmonellaentericaserovar Typhimurium elicits a protective immune response against challenge withYersinia pseudotuberculosisandYersinia enterocolitica

The use of live recombinant attenuatedSalmonellavaccines (RASV) synthesizingYersiniaproteins is a promising approach for controlling infection byYersiniaspecies. In this study, we constructed attenuatedSalmonellastrains which synthesize a truncated form of LcrV, LcrV196 and evaluated the immune response and protective efficacy elicited by these strains in mice against two other major species ofYersinia:Yersinia pseudotuberculosisandYersinia enterocolitica. Surprisingly, we found that the RASV strain alone was sufficient to afford nearly full protection against challenge withY. pseudotuberculosis, indicating the likelihood thatSalmonellaproduces immunogenic cross-protective antigens. In contrast,lcrV196expression was required for protection against challenge withY. enterocoliticastrain 8081, but was not sufficient to achieve significant protection against challenge withY. enterocoliticastrain WA, which expressed a divergent form of lcrV. Nevertheless, we are encouraged by these findings to continue pursuing our long-term goal of developing a single vaccine to protect against all three human pathogenic species ofYersinia.