Interferon-γ enzyme-linked immunosorbent spot assay as a tool to study T cell responses to Eimeria tenella infection in chickens.

The enzyme-linked immunosorbent spot (ELISPOT) assay is a sensitive and easy-to-use tool to quantify the number of interferon (IFN)-γ-producing cells and offers a viable alternative for the quantitative measurement of T cell functions in chickens. To study the development of cell-mediated immunity in Eimeria-infected chickens, we measured the number of IFN-γ-producing cells in peripheral blood mononuclear cells by ELISPOT after 3 oral inoculations of Eimeria tenella oocysts at 2-wk intervals. We found that the number of IFN-γ-producing cells was significantly increased at 2 wk after the primary infection compared with the control group. The IFN-γ-producing cells were further increased after repeated infections, and there was a statistically significant increase in the number of IFN-γ-producing cells after the third infection than after the first infection. Our results indicated that the ELISPOT assay can be used to quantitatively measure antigen-specific T cell responses to coccidia or other avian pathogens.