Abstract
Schistosomiasis is a parasitic disease causing serious chronic morbidity in tropical countries. Even though an effective treatment exists, it does not prevent re-infection and the development of an effective vaccine still remains the most desirable means of control for this disease. The possible applicability of immunization with a partially purified Soluble Egg Antigen (SEA, 100-137 kDa) for protection against Schistosoma mansoni infection in challenged mice was evaluated by histological and immunohistochemical studying of schistosomula-associated inflammatory reactions and deposition of schistosomal antigens in lung tissues. Schistosomula and inflammatory foci were counted in lung sections by histologic scoring for 25 days Post-Infection (PI). In control non-immunized mice, schistosomula number reached its peak earlier (day 7), decreased rapidly and worms were barely detectable on day 25. In immunized mice, the number reached its peak later (day 9), decreased gradually and many worms were still retained in the lungs until day 25. Mild pulmonary cellular reaction was noticed in control mice while in immunized ones, evident mononuclear cellular infiltration with inflammatory foci appeared earlier (day 7) and significantly increased on subsequent days and was most probably of Delayed Type Hypersensitivity (DTH). Schistosomal antigen deposition in lung tissues was markedly augmented in. immunized mice. The present study indicates that immunization with this SEA caused augmentative pulmonary response against challenge infection, represented by inducing. g anamnestic inflammation in lung tissues with consequent blocking of migration of lung schistosomula and more deposition of schistosomal antigens with more stimulation of the immune response. So, this type of antigen may be useful for the composition of a vaccine against schistosomiasis.