The role of T cells in the protection against epithelial infections in chickens

T cells represent a major lymphocyte population in chickens and share many features with their mammalian counterparts including subsets expressing the αβ or γδ T cell receptors. In contrast to mice and humans the frequency of γδ T cells in chickens can be as high as 50% of the peripheral lymphoid cells. Primary infection with Eimeria leads to the development of a strong immunity in chickens and vaccinated animals clear the parasite within 48 to 72h; however, the underlying immune mechanisms remain widely unknown. T cell mediated immune response are thought to be essential for the elimination of the parasite. Intraepithelial lymphocytes are the most common lymphoid cells in the gut and most of them express T cell specific antigens. While T cells are essential for the control of infection, nothing is known about the T cell subpopulations that contribute to this immune response in chickens. In order to dissect the T cell mediated immune response in chickens we generated γδ T cell knockout chickens and will generate and characterize αβ T cell knockout chickens. In addition, we will cross αβ and γδ T cell knockout chickens to obtain birds with a complete T cell knockout. With the help of rapid NGS-based MHC genotyping we will identify animals suitable for adoptive transfer studies in order to transfer defined T cell populations prior to pathogen challenge. Using Eimeria challenge studies in the different T cell knockout chicken lines, we will define the role of T cell subsets in the context of infection. Furthermore, the fate of transferred cell populations will be followed by FACS, Immunohistochemistry as well as single-cell sequencing analyses. The individual research projects within FOR5130 benefit from the collaborations among each other and provide a better insight into the immune system of chickens in relation to important pathogens.