Antigens of Clonorchis Sinensis in Experimental and Human Infections

An Analysis by Gel-Diffusion Technique

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  • Department of Pathology, University of Hong Kong, Hong Kong
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For a determination of which element of Clonorchis sinensis acts as antigen in mammalian infections, rabbits and guinea pigs were immunized with extracts of whole flukes and of eggs, and with metabolic products of flukes. Reactions of these fractional antigens on gel-diffusion plates against serum from the immunized animals were compared with their reactions against serum from experimentally infected animals and from infected persons. Metabolic products were the effective antigen in acute infections in animals and were most potent in guinea pigs, in which infection caused the greatest biliary obstruction. Eggs were not antigenic in infections. Precipitating antibodies were identified in only 14% of chronic infections in man and virtually only when another liver disease was also present. Since the flukes lie outside the body tissues proper and since antigen was detected in bile in some infections, it is postulated that the metabolic products enter the tissues as antigen and elicit antibody chiefly in circumstances in which bile is resorbed. Experimental infections in animals were not prevented nor reduced by previous immunization; antibodies apparently confer no protection.