Schistosoma mansoni antigens applicable to diagnosis of prepatent infections.

Diagnosis of schistosomiasis still depends upon demonstration of eggs in excreta, by which time significant pathology may occur to the human host. This study was undertaken to identify Schistosoma mansoni antigen(s) to be exploited in serodiagnosis of prepatent and/or acute infections. Immunoglobulin G and M responses of inbred and outbed mice to Schistosoma mansoni whole adult worm antigen were monitored in immunoblots using sera obtained at sequential times from mice infected with either 600 or 100 Schistosoma mansoni cercariae each. Regardless of the initial infection dose, immunoblot reactions to two doublets, 31/32 and 34/35 kDa appeared as early as two and three weeks post infection respectively and reactions to 38 and 70 kDa antigens appeared after five weeks infection. Antigens 31/32 and 38 induced both IgG and IgM responses whereas 34/35 and 70 predominantly induced IgG response. Homologues of these four antigens equally reactive with serum of infected mice were also demonstrated in Schistosoma haematobium, worms. Examination of sera from 25 patients suffering from acute Schistosoma mansoni, two suffering from Schistosoma haematobium and 16 patients suffering from infections with other parasite species confirmed the potential of 31/32, 34/35 and 38 kDa antigens in the specific diagnosis of prepatent and acute schistosomal infections but showed cross-reactivity of the 70 kDa antigen.