Examination of expression and release of Campylobacter concisus zonula occludens toxin

Campylobacter concisus is an oral bacterium linked to inflammatory bowel disease (IBD). This bacterium carries a prophage which encodes the zonula occludens toxin gene (zot), a protein which can compromise intestinal epithelial integrity. In this study, expression and release of Zot when C. concisus is exposed to bile was examined in three strains from IBD patients and reference strain 13826. Additionally, possible release of bacteriophage was investigated. A monoclonal antibody 1-4C381 was produced and verified against zot expressed by Escherichia coli. Using 1-4C381, Zot expressed by C. concisus on horse blood agar and minimal medial MEM-S1 was detected. It was found that C. concisus had clearer expression of Zot when cultured in MEM-S1, yet all strains decreased in CFU. After bile exposure in MEM-S1, expression within C. concisus bacteria was suppressed and Zot was released into the supernatant. From this supernatant, a 20kbp fragment of DNA was visualised and extracted. Using PCR, the C. concisus 16S rRNA gene could not be detected while the prophage-encoded zotwas detected. These findings suggest that C. concisus requires the presence of bile to release Zot which may then damage intestinal epithelial integrity. Furthermore, given zotcould be detected from non-genomic DNA, zotlevels may not correspond with the presence of Zot in the intestines.