Hepatic Histopathological and Histochemical Changes in Mice Infected with Schistosoma Mansoni After Vaccination with Gamma Radiation - Attenuated Schistosomules

Current strategies for the control of schistosomiasis are based primarily on chemotherapy but successful vaccination against infection has been also demonstrated in several host parasitic models. The present study was designed to assess the effect of vaccination with schistosomulae atte nuated by different doses of γ-radiation in mice challenged with S. mansoni cercariae regarding hepatic histopathological changes using Haematoxylin and Eosin (H &E) stain, and hepatic histochemical changes using periodic acid Schiff's (PAS), and bromophenol blue (BPB) to examine the polysaccharides and proteins contents. Sixty mice were used in four groups, the first group served as control normal group I (10 mice), the second group was infected by subcutaneous (S.C.) injection with 100 S. mansoni cercariae/mouse as infected control group II (10 mice). Groups III and IV (20 mice each) were subdivided equally into two subgroups A and B where subgroups IIIA and IVA were vaccinated by (S.C.) injection with 500 schistosomulae irradiated with 15 Krad and 20 Krad gamma-radiation. Meanwhile, subgroups IIIB and IVB were vaccinated by (S.C.) injection with the same doses of irradiated schistosomulae and then challenged after 4 weeks by S.C. injection with 100 S. mansoni cercariae. Hepatocytes, in the acute infected mice (group II) showed marked histopathological and histochemical changes with marked decrease in PAS +ve materials and total proteins, whereas moderate changes were observed in the liver of vaccinated un challenged subgroups IIIA and IVA (15 and 20 Krad respectively) and slight changes were detected in the livers of the mice vaccinated and challenged subgroups IIIB and IVB . It has been showen that schistosomules irradiated at 20 Krad induced marked amelioration in both histopathological and histochemical changes that did schistosomules irradiated at 15 Krad. It could be concluded that gamma radiation is a good tool for vaccination against schistosomiasis mansoni and 20 Krad is most effective dose.