Induction of Salmonella enterotoxin (stn) gene expression by epithelial cells (IEC-6)

Prevalence of Salmonella enterotoxin (stn) gene among Salmonella enterica and S. bongori was investigated by polymerase chain reaction (PCR) and gene probe and its status of phenotypic expression was examined on chinese hamster ovary cells by cultivating the strains with conventional method for enterotoxin production and by cultivating the organisms in contact with intestinal epithelial cells of rats (IEC-6). All the 19 strains and serovars of S. enterica such as Typhimurium, Enteritidis, Newport, Weltevreden, Indiana, Gallinarum and Kentucky were found to carry stn gene as examined by PCR and gene probe but only a limited number of strains (13 out of 19) expressed phenotypically the enterotoxin when cultured by conventional method. Cultivation of organisms in contact with epithelial cells induced expression of stn gene phenotypically in all the 19 strains. In contrast to S. enterica, strains of S. bongori were found neither genotypically (stn) nor phenotypically (Stn) positive.