TISSUE EXPRESSION OF THE SCHISTOSOMA-MANSONI 28-KDA GLUTATHIONE-S-TRANSFERASE

The expression of the Schistosoma mansoni 28 kDa glutathione S-transfe rase (Sm28) was studied using molecular (PCR, in situ hybridization), and immunocytochemical techniques. The presence of Sm28 was demonstrat ed in all developmental stages of the parasite except the intra-uterin e immature egg. In the parenchyma of male and female adult worms the d istribution of Sm28 was limited to a subpopulation of parenchymal cell s and to the dorsal tubercles of the male. The tegument, the muscles, the digestive tract, the neural mass, the vitelline glands, and mature gametes were not immunoreactive. Immature germinal cells in both sexe s, and the ootype in the female genital system, were found to express Sm28. Deposits of immunoreactive material on host skin follow ing cerc arial penetration, exfoliation from the male tubercles, and especially emission of Sm28 from eggs in hepatic granulomas are suspected to be a source of antigen during the parasite infection. The reduction in wo rm fecundity previously observed in immunization experiments may resul t from an antibody response directed against Sm28 present in the ootyp e. There was no cross-reactivity observed, under the experimental cond itions used, between the anti-Sm28 sera and either vertebrate or inver tebrate host tissue.