Homologous DNA sequences on the virulence plasmids of pathogenic Yersinia and Salmonella dublin Lane

Abstract

Yersinia and Salmonella harbour plasmids that encode traits important for virulence, enabling both pathogenic genera to survive and growth in cells of the reticulo-endothelial organs during systemic infections. We have detected DNA homology between the Salmonella dublin virulence plasmid pSDL2 and the plasmids of the pathogenic Yersinia species pestis, pseudotuberculosis, and enterocolitica. Three regions of pSDL2 were found to share homology with the virulence plasmid plB1 of Yersinia pseudotuberculosis. Two separate hybridizing segments mapped within the previously characterized 6.4kb vir region of pSDL2 in the Sal/l B fragment. The third homologous region involved the replicon of plB1, which hybridized to the Sal/l C2 fragment of pSDL2. The virulence plasmid pCD1 from Y. pestis showed similar homology with the three regions of pSDL2. Homologies to the vir and Sall C2 regions of pSDL2 were also found on plasmids from Yersinia enterocolitica serotypes 0:9, 0:3 and 0:5, 27. The discovery of separate homologous regions on the virulence plasmids of Salmonella and Yersinia suggests a distant evolutionary relationship.