Vibrio cholerae non-01 and V. mimicus in diarrhoeal disease : a study of virulence factors

Bengü Said
Vibrio cholerae non-01 and V. mimicus, isolated from clinical and environmental sources, were examined for factors related to virulence. The aim was to identify factors which would distinguish pathogenic from non-pathogenic strains and to establish a correlation, if any, with serogroup. The lipopolysaccharide (LPS) of epidemic V. cholerae belonging to serogroups 01 and 0139 are regarded as'virulence factors. In this study certain other serogroups, such as 02,05 and 09 were associated with
more » ... oeal disease. LPS of these organisms may have a role in adhesion. Although 90% of V. cholerae non-01 and V. mimicus colonised tissue culture cells, neither smooth LPS, the presence of flagella nor the possession of the toxin coregulated pilus gene (tcpA) were essential for adhesion. Cholera toxin (CT) is the factor responsible for the dramatic symptoms of epidemic cholera and is produced by V. cholerae serogroups 01 and 0139. However, less than 1% of V. cholerae non-01, non-0139 and V. mimicus possessed the gene for CT. Southern blot analysis of the CT genes revealed that most strains carried one CT gene except for serogroups 023 and 0139 which had two hybridising fragments. The variations in fragment size within the 0139 serogroup suggested that this serogroup was not strictly clonal. In addition to CT both V. cholerae non-01 and V. mimicus expressed several other toxins, often concurrently, which made detection of specific toxins difficult. Over 80% of strains produced haemolysin(s) and cytotoxin(s). The cytotoxic effects on tissue culture cells masked cytotonic effects, such as that caused by CT. V. cholerae and V. mimicus did not produce verocytotoxin (VT) and did not possess the genes for VT. The heat-stable enterotoxin (NAG-ST) gene was found in 3% of V. cholerae non-01 and 12% of V. mimicus strains. All V. cholerae strains belonging to serogroup 014, were NAG-ST positive and Southern blot analysis of the NAG-ST g [...]
doi:10.21954/ fatcat:kmgi6ohd4bgcnczuqtaoprzqcu