EL TOR HAEMOLYSIN POTENTIALLY INVOLVED IN THE PATHOGENESIS OF A NON TOXIGENIC VIBRIO CHOLERAE CLINCAL ISOLATE

SAKA, HECTOR A.; ECHENIQUE JOSÉ; BIDINOST ,CARLA; CARRANZA, PABLO; BOCCO, JOSÉ L.

Villa Carlos Paz, provincia de Córdoba

Congreso; XXXVIII Annual Meeting Argentine Society for Biochemistry and Molecular Biology Research - SAIB 2002-; 2002

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Vibrio cholerae non O1 / non O139 (VCN) are natural inhabitants of aquatic environments. Although most  VCN lack cholera toxin (CT) and other virulence determinants implicated in cholera, sporadic cases of gastroenteritis caused by these strains have been described. So far, the factors that contribute to VCN virulence are not clearly understood.  The aim of this study was to investigate putative factors involved in the pathogenesis of a VCN strain isolated from a patient with a diarrheic syndrome clinically indistinguishable from cholera. The presence of several genes related to virulence was studied by PCR. Expected amplimers for toxR and hlyA genes were obtained, but PCR products for ctxA, ace, zot, tcpA and stn were not detected. To investigate the cytotoxigenicity of this strain, sterile culture supernatants were added to COS-7 and VERO cells. Transposon mutagenesis was used to obtain a hlyA null mutant (VCNH-). The parental strain, but not VCNH-, displayed a dramatic cytotoxic effect and vacuolating activity in COS-7 and VERO cells, respectively. Additionally, only the parental strain showed an enterotoxic phenotype in a rabbit ileal loop assay. Although controversial data exists regarding the role of El Tor Haemolysin in CT negative V. cholerae diarrhea, our results suggest that the integrity of hlyA gene is essential for the pathogenesis of this strain.