Detection of the induction of Salmonellaenterotoxin gene expression by contact with epithelial cells with RT‐PCR

All strains of Salmonella entericainvestigated were found to carry the Salmonellaenterotoxin gene (stn) as determined by PCR and hybridization studies. However, when using CHO‐K1 cells for testing the toxicity of the strains, not all strains showed a toxic effect (cell elongation) on the cells or did so only at a low level. The cultivation of Salmonellain contact with epithelial cells (IEC‐6) led to an increase in the production of toxin. The stngene expression was detectable with the help of the RT‐PCR after 3 h of incubation. The RNA of the strains was isolated, transcribed into cDNA (with MMLV‐reverse transcriptase) and amplified using PCR. The PCR products were separated electrophoretically using a polyacrylamide gel and detected by silver staining.