CIBTech Journal of Microbiology ISSN: 2319-3867 (Online) An Open Access, Online International Journal Available at http://www.cibtech.org/cjm.htm 2014 Vol. 3 (1) January-March, pp.11-14/Muthu et al. Research Article © Copyright 2014 | Centre for Info Bio Technology (CIBTech) 11 DETECTION OF VIRULENCE GENES FROM SALMONELLA SPECIES IN CHENNAI, INDIA G. Muthu 1 , A. Suresh 5 , D.VishnuPrabu 3 , A.K. Munirajan 3 , S. Esther Mary 4 , E. Sathishkumar 2 , P. Gopinath 2 and *S. Srivani 2 1 Central Research Laboratory, SMV Medical College and Hospital, Pondicherry University, Puducherry 2 Departments of Microbiology, Dr. ALM PG IBMS, University of Madras, Chennai-113 3 Departments of Genetics, Dr. ALM PG IBMS, University of Madras, Chennai-113 4 Department of Microbiology, ESIC Hospital, Chennai- 600 078 5 Centre for Drug Discovery and Development, Sathyabama University, Chennai-600 119 *Author for Correspondence ABSTRACT The present study was undertaken to detect the two genes, namely, Salmonella enterotoxin (stn) and plasmid encoded fimbrial (pef) genes, among clinical isolates of three Salmonella species from humans. A total of 176 isolate belonging to Salmonella enterica serovar Typhi (133), Salmonella enterica serovar paratyphi A (41) and Salmonella enterica serovar Typhimurium (2) serovars were analyzed by Polymerase Chain Reaction (PCR) using their specific primers for the detection of stn, and pef genes. Varying pattern of stn, and pef genes were observed amongst the isolates. While, stn was found in 140/176 (79.5%) Salmonella strains, the pef gene was not found in any of the tested strains. PCR findings indicated that the stn gene is widely distributed among Salmonella irrespective of the serovars and source of isolation. Keywords: Salmonella, Enterotoxin gene, Polymerase Chain Reaction (PCR) INTRODUCTION Salmonella is a facultative intracellular pathogen that causes a variety of infectious diseases like typhoid, septicemia and gastroenteritis owing to bacterial multiplication in intestinal submucosa and production of enterotoxins which elicits the inflammatory response of the host (Salyers and Whitt, 1994). Virulence factors responsible for pathogenicity in enteric bacteria are often plasmid encoded, as in Escherichia coli, Yersinia spp. and Shigella spp. In Salmonella, the existence of plasmid-borne virulence genes was first suggested in 1982, but current evidence suggests that the contribution of virulence plasmids to pathogenesis in Salmonella is less important than in the above mentioned bacteria. Virulence plasmids have been found only in a few serovars of Salmonella (Guiney et al., 1994, Bäumler et al., 1998). Epidemiology and pathogenic process in salmonellosis are dictated by an array of factors that act in tandem and ultimately manifest in the typical symptoms of salmonellosis. Virulence genes encode products that assist the organisms in expressing its virulence in the host cells. Some genes are known to be involved in adhesion and invasion viz., sef, pef, spv or inv; (Clouthier et al., 1993, Bäumler et al., 1996, Krause et al., 1992, Galán et al., 1992) others are associated with the survival in the host system- mgtC (Blanc-Potard and Groisman, 1997)or in the actual manifestation of pathogenic processes viz., sop, stn, pip A, B, D (Wallis and Galyov, 2000, Chopra et al., 1994, Wood et al., 1998). Nucleic acid based diagnostic techniques are being employed for the detection of various gene -encoded virulence factors viz., Salmonella enterotoxin (stn), (Prager et al., 1995, Rahman, 1999) Salmonella Enteritidis fimbriae (sef) and plasmid encoded fimbriae (pef) genes (Rahman et al., 2000). However, the distribution of these genes among the various isolates obtained from biological source is yet to be elucidated. The present study reports that the distribution of stn, and pef genes among the Salmonella strains isolated from clinical cases of infections in human.