immunogenicity of entamoeba histolytica crude and fractionated antigens in animal model

introduction: the immunogenicity of crude amoebic antigen and its fractions preparedfrom entamoeba histolytica (nih:200) was evaluated in experimental animals. material and methods: forty two guinea pigs of either sex free from entamoebainfection and aged around 3 to 4 weeks were randomly divided into 5 groups. the treatedgroups consisted of 8, 10, 6, and 8 animals and 10 animals served as controls. crude amoebicextract and its chromatographed fractions were used to immunize the treated animals. all theanimals were assessed for immunity status, challenged with entamoeba trophozoites andsubsequently examined for lesions of the caecum and liver. results: of the 8 animals immunized with crude antigen, one had liver abscess and 5 hadcaecal lesions. none of the 10 animals immunized with fraction i (fi) had hepatic lesions and one had caecal lesions. both caecal and hepatic lesions were observed in animals immunizedwith fii & fiii. conclusion: results show that vaccination with the f1 fraction of entamoeba histolyticaprovided up to 90% protection against infection. the other fractions and the crude extractprovided less protection.