Application of an immunosuppressed Microtus fortis animal model to study the infection of Schistosoma japonicum.

Objective To establish an immunosuppressed Microtus fortis(Mf) animal model,and to evaluate the role of T and B lymphocytes in the natural resistance against Schistosoma japonicum using this model.Methods 40 adult healthy Mf were divided into four groups:treatment with immunosuppressive drugs and S.japonicum infection(group A),immunosuppressive drugs only(group B),S.japonicum infection only(group C) and the control animals(group D).To establish the immunosuppression model,the animals were then injected with inmunosuppresive drugs three times per week for 6 weeks.The state of immunosuppression was confirmed with the lymphocyte proliferation and ELISA assays.Animals were anaethesized and executed on day-42 post-infection.Perfusion method was used to collect adult worms from the mesenteric veins.Eggs in the liver were observed under microscope.Results In the immunosuppressed animals,lymphocytes proliferation was significantly suppressed and the level of IgG antibody against schistosoma was lower than the other groups.Adult worms and eggs were not found in both of immunosuppressed and non-suppressed animals.Conclusion T and B-cell do play a direct role in the resistance of S.japonicum infection in M.fortis.