Purified antigen radioimmunoassay in serological diagnosis of Schistosomiasis mansoni

A radioimmunoassay has been developed for detecting human schistosomiasis with high purified Schistosoma mansoni egg antigen labelled with iodine-125. The antigen, major serologic antigen l (M.S.A.1), has striking immunochemical and species specificity and appears to be the principal antigen responsible for the granulmatous response to S.mansoni eggs. This 125I-antigen was tested with 5μl of patient serum as a potential serodiagnostic test for schistosomiasis. 92 control sera from uninfected St. Vincentian patients were seronegative. In studies on 135 lightly infected St. Lucians the 5μl serum 125 I-M.S.A. 1 serodiagnostic test was more sensitive than any test available at the Center for Disease Control, with 64% of infected children, 83% of adolescents, and 98% of adults being positive. 49 heavily infected Kenyans of all age-groups were uniformly (100%) seropositive. Finally a semi-quantitative version of the 125I-M.S.A.1 radioimmunoassay that uses 0.5μl of patient sera demonstrated quantitatively significant differences among age-matched and intensity-matched groups of patients with S.mansoni, S.haematobium, and S.japonicum infections. (author)