IMMUNOMODULATORY EFFECTS OF OAT BETA-GLUCAN ADMINISTERED INTRAGASTRICALLY OR PARENTERALLY ON MICE INFECTED WITH EIMERIA-VERMIFORMIS

The immunostimulatory effect of intragastrically or parenterally admin istered beta-(1-->3; 1-->4) glucan, extracted from oats (O beta G), on disease resistance to Eimeria vermiformis was Studied in C57BL/6 mice . Multiple administrations of O beta G by intragastric or subcutaneous routes reduced fecal oocyst shedding compared to the non-treated cont rol group. The administration of O beta G by subcutaneous route result ed in higher levels of total serum immunoglobulins and antigen (sporoz oite and merozoite)-specific immunoglobulins as compared with the non- treated group. To evaluate the effect of a single subcutaneous dose, g roups of mice were treated with O beta G 2 days before E. vermiformis infection, at the time of infection and at 2 or 6 days after infection . From day 11 post-infection the oocyst discharge was significantly di minished (P < 0.05-0.01) in the O beta G-treated groups, except in tho se treated 6 days after infection, as compared to the non-treated cont rol group. The proliferative responses to E. vermiformis sporozoite an tigen of lymphocytes isolated from the spleen were significantly incre ased (P < 0.05) when O beta G was administered 2 days before or at the time off. vermiformis infection. Lymphocyte proliferative responses t o merozoite antigen were not influenced by treatment. In conclusion, O beta G appeared to up-regulate immune mechanisms and provide enhanced resistance against eimerian coccidiosis in mice.