Oral immunization with L-forms of Vibrio cholerae in human volunteers

Oral administration of heat-inactivated lysates of Vibrio cholerae Ogawa L-forms elicited significantly high coproantibody, serum indirect hemagglutinating antibody, and vibriocidal antibody responses in human volunteers, against both homologous and heterologous subtypes of V. cholerae and V. El Tor. Five oral biweekly doses produced an adequate antibody response which persisted for at least 6 weeks after immunization. No untoward side effects were seen.