Identification of Vibrio cholerae pathogenicity island (ctxA, OmpW and tcpA) in non - O139 and non - O1 V. cholerae strains isolated from Karun River in Ahvaz, Iran

Abstract

Vibrio cholerae is a usual inhabitant of the marine environment and causes severe diarrheal disease contaminating thousands of people each year in developing countries. The virulence of Vibrio spp. is regulated by the ctxAB and tcpA genes. These genes are supposed to be exclusively associated with clinical strains of O1 and O139 serogroups. In the present study, we examined the presence of virulence genes that contains OmpW, ctxA and tcpA of V. cholerae classical and Eltor variants in environmental strains of non-O1 and non O139 V. cholerae that were cultured seasonally from four sampling stations of the Karun River in Ahwaz. One hundred water samples were collected from four stations of Ahvaz Karun River. The colonies that were grown on TCBS confirmed to be Vibrio spp. by biochemical, serological and molecular methods. After DNA extraction, a polymeras chian reaction (PCR) assay was performed for detection of ctxA and tcpA (both Classical and ElT or variants) and OmpW was in the strain that was recognized as V. cholerae non-O139 and non-O1. Among 100 environmental samples of fresh water in this study, 27 isolate confirmed as V. cholerae spp. by PCR assay with ompW gene. Of among them, 4 isolate that were confirmed V. cholerae non O1-non O139 had gene for toxin coregulated pilli (Classical and Eltor). V. cholerae is one of the major causes of morbidity and mortality in the developing countries. The studies that were performed on V. cholera nonO1, nonO139 strains that usually do not carry the ctx genes coding for cholera toxin (CT) or toxin-co regulated pilus which are the most important virulence characteristics of the cholera causing strains.