ABSTRACT
The finding that Fab fragments of the anti-E1 Tor haemagglutinin were able to afford protection in vivo (low but significant), as well as a significant reduction in Vibrio cholerae adherence to isolated intestinal epithelial cells in-vitro, implicate that masking of these cell-bound haemagglutinin sites per se, would be sufficient to confer protection in E1 Tor cholera infection. Subsequently, the related working hypothesis that the E1 Tor cell-bound haemagglutinin is playing an adhesive role is validated. In natural immunity, it could be envisaged that antiserum to this cell-bound haemagglutinin of V. cholerae E1 Tor would be highly protective due to the synergistic effects of the dual protective mechanisms in operation at the intestinal sites viz. a masking and agglutinating phenomenon.