Multiplex-PCR assay for detection of some major virulence genes of Salmonella enterica serovars from diverse sources

Abstract

The virulence of Salmonella depends on virulence factors encoded by specific genes. The present study describes the development of a simple and rapid multiplex PCR (m-PCR) assay for simultaneous detection of seven major virulence genes of Salmonella (invA, invH, stn, sopB, sopE, sefC and pefA). Presence of these genes was studied using 17 standard cultures and 76 field isolates from different sources. Seventeen non-Salmonella strains were also tested for specificity of the optimized PCR. A spiked control experiment was done to detect the sensitivity of m-PCR assay. The primer pairs were found to be specific for Salmonella only. The assay detected 250 pg of purified chromosomal DNA, or 12 cfu of Salmonella in crude lysates. All the field isolates and standard strains of Salmonella were found to carry invA, invH, stn and sopB genes, while variability was observed with respect to sopE, sef C and pefA genes. Thus this multiplex PCR assay provides a simple and rapid method for detection of major virulence factors in important clinical serovars of Salmonella.