Detection of Vibrio vulnificus and Vibrio cholerae O1 in oyster tissue using immunoelectron microscopy

Rabbit polyclonal antibodies (PAb) against purified cell wall capsular polysaccharide of clinical strains of Vibrio vulnificus and a monoclonal antibody (MAb) against the A antigen of the lipopolysaccharide (LPS) of Vibrio cholerae were evaluated for their usefulness in immunogold electron microscopy of Vibrio spp. in oyster tissues. The PAb to the V. vulnificus clinical strains did not label environmental isolates of this species, nor other Vibrio spp. Likewise MAb to V. cholerae O1 LPS did not cross react with other Vibrio spp., as tested by ELISA and immunogold electron microscopy. Both antibodies labeled pure cultures of the autologous strains and also bound to these phagocytized bacteria in oyster hemocytes. After 24 h exposure to V. cholerae, epithelia of mantle, gill, stomach, and muscle tissue showed low levels of labeling between cells, indicating that LPS material had been deposited there by phagocytic hemocytes involved in diapedesis. Whole cells of V. cholerae and V. vulnificus were only found in intact hemocytes and among stomach contents.