THE SITES OF ANTIGEN FORMATION IN DIFFERENT DEVELOPMENTAL STAGES OF CLONORCHIS SINENSIS

Abstract

Indirect fluorescent antibody tests were used to localize effective antigens at the sites of their formation in adult flukes, metacercariae and eggs of Clonorchis sinensis. Sera from rabbits experimentally immunized against various elements of the flukes and from experimentally infected rabbits as well as sera from human cases of clonorchiasis were used. Specific fluorescence was demonstrated in the cuticle, oral and ventral sucker, pharynx, digestive caecum and its contents, testes, seminal receptacle and ovary of the adult fluke. Weak specific fluorescence was found in metacercariae and in the walls of their cysts. Clonorchis eggs showed no reaction. No cross reactions were detected with sera from human cases of schistosomiasis, ascariasis, trichuriasis, hook-worm disease or syphilis. It is concluded that the adult fluke of Clonorchis is the main source of antigens that effectively stimulate antibody production in the definitive host, and that the maturing metacercariae are responsible for the initial antigenic stimulation during the first few weeks.