Comparative physical and genetic maps of the virulence plasmids of Salmonella enterica serovars typhimurium, enteritidis, choleraesuis, and dublin

Abstract

Using fragment profiling, PCR, and Southern hybridization, we found that Salmonella enterica serovar Choleraesuis harbored virulence plasmids of various sizes, whereas serovars Typhimurium, Enteritidis, and Dublin carried a plasmid of a unique size. Also, the virulence plasmid of Typhimurium contained genes in the same order detected in the other three plasmids, all of which contained deletions.

FIG. 1

Physical and genetic maps of the virulence plasmids of four Salmonella serovars aligned to pSTV. The vertical line indicates the recognition site of HindIII;the number below the fragment designation is the molecular size (in kilobases) of the fragment. The number listed on the right is the molecular size (in kilobases [the sum of the size of each fragment]) of the virulence plasmid. *, parSB, parS-parB; spvRA, spvR-spvA; pefAC, pefA-pefC. †, the presence of these genes was not checked. , deletion; , heterologous region; █ █ , undetermined deletion region. The size and location of the deletion in the nucleotide sequence are as follows (the arrow indicates the site of deletion): pSEV, in H3, about 22 kb (exact size on H1 of pSTV unknown [25]), and in H7, 7.4 kb (TGGCG↓GTCGCC [this work]); pSCV in H4, 6.8 kb (TGGC↓GGCCGGG; in pefD coordinate, C = 6814 and G = 13627 [6]), and in H3, 35 kb (CATCC↓GGCGG; for their sequences, see reference for traT and reference for sam [this work]). Note that for pSDV, in H4 the site was undetermined.