ABSTRACT
The present objective was to investigate the possible effect of immunization protocol against Schistosoma mansoni infection using purified lung-stage schistosomulae antigen. Two experimental models [lung and liver] were used, each of 3 groups [Gs]: Immunized G. [10 mice] infected control G. [10 mice] and normal control G. [10 mice]. Hundred micro g of purified schistosomulae antigen followed by two booster doses each of 50 micro g antigen and at one week interval were injected intraperitoneally into Swiss albino mice three days prior to intravenous injection of 3000 viable S. mansoni eggs [lung model] or to exposure to 100 cercariae [hepatic model]. Mice were sacrificed 16 days post-injection [lung model] and 8 weeks post-infection [hepatic model]. Various parasitological parameters, histopathological assessments and immunological parameters were studied. The data revealed that immunization with purified lung-stage schistosomulae antigen induces protective effect against S. mansoni infection. The marked reduction in worm burden, egg load, granuloma diameter and collagen content were accompanied by increased percentage of degenerated ova and amelioration of the associated pathological changes in pulmonary and hepatic tissue. Increased levels of specific immunoglobulins particularly IgG and IgM and decreased ratio of T cell subsets [CD4+/CD8+] in granulomas of both models were also noticed