Schistosoma mansoni: IgG reactivity to soluble adult worm antigen preparation (SWAP) in sera of immunized mice with irradiated attenuated and virulent cercariae.

The aim of this work was to identify the antigens, that elicit a greater or unique immune response in the immunized host against Schistosoma mansoni (Egyptian strain) infection. Moreover the difference in immune response to this antigen between mice immunized with radiation-attenuated cercariae or immunized with virulent cercariae were investigated. Immunobloting technique was used to monitor the fine specificity of host IgG to SDS-PAGE separated SWAP in the sera of different test groups immunized with either radiation-attenuated cercariae or low doses of virulent cercariae compared to non-immunized group. Data from this study showed that groups immunized with virulent and irradiated-attenuated cercariae showed 74.7% and 68.3% reduction in worm burden respectively. Differences of humoral immune response of sera of different tested groups against SWAP proteins were definite. Sera of non-immunized mice precipitated non-immunogenic proteins of 87 and 83 KD. SWAP proteins of 106 and 97 KD were identified only by the sera of vaccinated animals with irradiated attenuated cercariae whether challenged or not. Resistant sera from animals immunized by either irradiated-attenuated cercariae or virulent cercariae recognized low molecular weight antigens that ranged from 34 to 52 KD in addition to 57 KD. This indicated that the 106 and 97KD may be the target antigens for protection by radiation-attenuated larvae, while the marker of resistance induced by attenuated or virulent larvae may be 34-52 and 75 KD antigens.