Molecular detection of inv A and spv virulence genes in Salmonella typhimurium isolated from human and animals in Iran

Abstract

In the present study, multiplex Polymerase Chain Reaction (m-PCR), simple PCR assay was used to confirm Salmonella typhimurium and detect Salmonella plasmid virulence ( spvA, spvB, spvC ) genes in human, bovine and poultry isolates. Fifty-five S. typhimurium isolates from bovine (n=15), poultry (n=20) and human (n=20) sources were isolated and analyzed with biochemical and serological testes. Firstly, (M-PCR) assay with four sets of primers was selected: ST139 - ST141 (284bp), specific for invA gene of Salmonella spp. the RFbj (663bp), Flic(183bp), Fljb(526 bp) specific for the rfbj, fliC , and fljB genes of S . typhimurium . In the second stage, simple PCR method with one set primer for SpvA (604bp) and another set primer for SpvB (1063bp) were applied to detect spvA and spvB genes. Also an M-PCR assay with two set primers InvA (244bp) and SpvC (571bp) was carried out to simultaneously detect and identify invA and spvC genes in S. typhimurium. Analysis of the samples shows that while the presence of spvA , spvB , and spv C genes in S . typhimurium from bovine source were 100% (15/15), these same genes were present in 65% (13/20), 100% (20/20) and 65%(13/20) of the poultry sources respectively.In addition, twenty (n=20) human isolates of S . typhimurium were obtained from Baghuyatallah University of Medical Science, Tehran, Iran. The study also shows that spvA, spvB and spvC genes were present in 85%, 100% and 85% of human source respectively. The study represents the first report in Iran about the genotypic diversity of spvA, spvB and spvC genes of S . typhimurium .