EFFECT OF CHOLERA-TOXIN ON VACCINE-INDUCED IMMUNITY AND INFECTION IN MURINE SCHISTOSOMIASIS-MANSONI

Intradermal vaccination of mice with soluble adult worm antigen (SWAP) in combination with Mycobacterium bovis BCG (Swedish strain) induced significant protection against subsequent infection with Schistosoma m ansoni cercariae. When cholera toxin (CT) was used as an adjuvant in c ombination with SWAP or fraction A, no significant protection was obse rved. However, intradermal vaccination in combination with CT triggere d a strong anti-SWA.P antibody response and induced a strong delayed-t ype hypersensitivity response to schistosome antigens (SWAP or fractio n A), one significantly higher than that in the SWAP-BCC group. In add ition, vaccinating mice intranasally with SWAP or cercarial antigen to gether with CT as adjuvant failed to induce any significant protection . Surprisingly, mice given CT alone intranasally revealed a significan tly enhanced worm burden. These findings suggest that mucosal applicat ion of CT may modulate the host-parasite relationship in favor of para site survival.