Expression of α- and ε-toxin genes in type D vaccine strain in contact with the Caco-2 cell line.

Background: commonly resides in the gastrointestinal tract and can survive in different environmental conditions. This pathogen produces several protein toxins including the potent ε-toxin which is classified as a category B toxin by the Centers for Disease Control and Prevention (CDC). In several studies, the induction of C. perfringens type C or D to produce toxins much more rapidly by close contact of bacteria with Caco-2 cells has been reported.

Aims: The effect of close contact of enterocyte-like Caco-2 cells with type D (vaccine strain) on the production time of ε- and α-toxins was studied.

Methods: During type D contact with Caco-2 cells for 5 h, ε- and α-toxins expressions (at 0, 2, and 5 h) were evaluated by a quantitative real-time PCR assay. Non-contacted bacteria with cells were included as the negative control in this research.

Results: Bacterial contact with the Caco-2 cells induces a significant effect on the mean expression of the ε-toxin gene (etx) (P<0.05). Two h after contact, the highest level of gene expression was detected in the experimental group. Bacterial harvesting time, cell treatment, and their interactions did not affect significantly the mean expression of the α-toxin gene (cpa) (P>0.05).

Conclusion: According to the findings of the present study, 2 h of bacterial contact with Caco-2 cells could stimulate etx gene expression in the type D vaccine strain.