Vibrio virulence factors and the quantitative analysis of cytotoxicity elaborated by environmental isolates

Vibrio strains isolated from freshwater environments were screened for the elaboration of haemolysin, cytotoxin and enterotoxins. While characterizing for various toxins, nine strains elaborated 10(3) and more haemolytic units (HU) per ml crude toxin with a maximum of 4.1 x 10(3) HU. About 41.7% of the strains which were tested produced a factor in the culture supernatant which was active in the suckling mouse assay. Cytotoxin studies revealed that all the Vibrio strains did not respond uniformly in the three cell lines tested. The elongation factor of the CHO cell line which was reported to have correlation with the enterotoxic activity, did not with some exceptions correspond to high fluid accumulation ratio in conventional suckling mouse assay. A modified, simple, rapid, sensitive procedure is described to quantify the elaboration of cytotoxic units (CU). When the HeLa cell line was used to estimate the CU production, 29% of the strains produced 10(2) CU with a maximum of 169 CU per 50 microliters of crude toxin.