Cloning and expression of plasmid DNA sequences involved in Salmonella serotype Typhimurium virulence

Publisher Website
Google Scholar
Abstract
A 22 kb region of the 90kb virulence-associated plasmid, plP1350, of Typhimurium strain C52 was cloned into the mobilizable vector pSUP202, yielding plasmid plP1352. This recombinant plasmid restored full virulence to plasmidless strain C53 in a mouse model. Transposon Tn5 insertion mutagenesis demonstrated the existence of two DNA sequences in plP1352 designated VirA and VirB, both of which are essential for the expression of virulence. A recombinant plasmid containing only the VirA and VirB regions markedly increased the virulence of the plasmidless strain C53, but did not confer full virulence. These results suggested that a third virulence-associated region might be present on plP1352. Eleven proteins encoded by the 22 kb insert sequence of pl P1352 were identified in Escherichia coli SE5000 maxicells. The VirA region encoded at least two proteins with apparent molecular weights of 71000 and 28000 and the VirB region encoded two proteins of 43000 and 38000.