Effects of dietary protein types on immune responses and levels of infection with Eimeria vermiformis in mice

The present study reports the dietary effects of bovine a whey fraction, bovine casein and soy protein isolate on the immune responsiveness of C57BL/6J mice infected with Eimeria vermiformis. During the patent period, mice fed a whey fraction had significantly higher blood total white cell, CD4(+) and CD8(+) lymphocyte counts and higher Con A-stimulated IFN-gamma production by spleen cells than those fed other protein sources, but there was no significant difference in output of faecal oocysts. Casein-fed mice had significantly higher levels of Con A-stimulated IFN-gamma production and a lower output of faecal oocysts than soy-fed mice. The study demonstrated that dietary proteins have different impacts on immune responsiveness and level of parasitic infection in the gut; however, the mechanisms affecting level of infection are not clear. These effects appeared not to be solely related to nutritional properties of the diets. Further research into the underlying immune mechanisms and possible direct interactions between bioactive proteins and the parasite E. vermiformis should be fruitful.