Comparative efficacy of biodegradable liposomes and microspheres as carriers for delivery of Vibrio cholerae antigens in the intestine.

The effect of the encapsulated antigens of Vibrio cholerae and their route of administration in induction of immune response was studied in experimental cholera. The antigenic proteins of V. cholerae El Tor strain KB207 were obtained by fractionation of cell-free lysate by high-performance liquid chromatography. The antigenic proteins were pooled and encapsulated in biodegradable liposomes and poly(D,L) lactic co-glycolic acid microspheres. Rabbits were immunized with free as well as encapsulated antigens by different routes. Liposome-encapsulated antigens delivered intraintestinally offered maximum protection. Orally or intraintestinally delivered antigens in microspheres failed to elicit a significant immune response, although as a carrier microspheres were comparable to liposomes when judged by the subcutaneous route. The results suggested that liposomes and microspheres could be used as carriers of protective antigens of V. cholerae for effective immunization.