Cellular immunity after oral administration with V. cholerae.

The mechanisms of oral vaccination have not been clarified yet. In this study, the mechanisms that prevent infection by oral vaccination with Vivrio cholerae (V. cholerae) were investigated. Mice were orally vaccinated with the whole cells, or IF 30 of V. cholerae. The splenic cells or Peyer's patches (PP) cells of these mice were removed and their in vitro antibacterial activity against V. cholerae was determined. The splenic cells of mice orally vaccinated with the whole cells of V. cholerae showed suppression of the bacterium after 6 administrations, but no suppression after a single administration. The PP cells of mice orally vaccinated with the whole cells of V. cholerae showed suppression, irrespective of the number of times of administration. In the groups of mice orally vaccinated with IF30, suppression of V. cholerae was exhibited by the splenic cells of mice after 4 administrations and by the PP cells of mice after a single administration. The above mentioned suppression of V. cholerae was induced by B cells included in the splenic or PP cells of orally vaccinated mice. None of the humoral antibodies of orally vaccinated mice suppressed V. cholerae. Consequently, it is suggested that infection of V. cholerae is prevented locally in the intestine by the primary effect of oral vaccination and then by the splenic cells that recognize the antigen of V. cholerae through consecutive oral administratons.