Vibrio mimicus and Vibrio cholerae non-01 Isolated from Wild and Hatchery-Reared Fish.

Abstract

In this work, we conducted a phenotypic and serological characterization of a group of Vibrio mimicus and Vibrio cholerae non-01 strains isolated from different fish species in the Chesapeake Bay area (Maryland, USA) in comparison with reference strains. Pathogenicity for fish and mice as well as the biological activities present in their extracellular products (ECP) were also evaluated. The taxonomic analysis revealed that all the strains possessed similar physiological and biochemical profiles with the exception of sucrose fermentation, which is the main differential trait between these two Vibrio species.The isolates showed drug resistance patterns very similar, being all of them sensitive to the majority of the chemotherapeutic agents employed. The serological analysis revealed an antigenic diversity among the strains which was confirmed by the LPS profiles. However, although differences were observed in the profiles of total and outer membrane proteins, the western blot analysis showed that most of these Vibrio isolates shared several immunoreactive bands in the region of 60-70 kDa. Virulence assays demonstrated that although the V. cholerae non-01 and V. mimicus isolates were not pathogenic for the fish tested, all of them proved to be virulent for mice. The extra cellular products (ECP) of all V. cholerae and V.mimicus strains showed high proteolytic and phospholipase activities. Moreover, they exhibited a positive cytotoxic response for all the fish and homoiothermic cell lines tested and produced exotoxins with lethaleffects for fish and mice. The virulence properties for mammals exhibited by all these Vibrio strains is a question of special concern mainly in countries where raw fish or fish products are consumed.