Unraveling new characteristics of γδT cells using scRNA-seq in TCR KO chicken

The characterization of T cells in chickens has proven to be challenging, primarily due to the lack of specific markers to differentiate classical Th1, Th2, and Th17 subsets. Furthermore, chickens possess a notably high proportion of {gamma}{delta} T cells, making them a unique model for investigating the poorly understood role of these cells not only in chickens but also in mammals. To gain deeper insights into the functions and characteristics of the {beta} and {gamma}{delta} T cell subsets in chickens, whole transcriptome analysis (WTA) on CD3+ single cells isolated from wild type (WT), TCR C{beta} knockout (KO) and TCR C{gamma} KO chickens at embryonic day (ED) 18, day (d) 3, and d14 post-hatch was conducted. The results indicate that {gamma}{delta} T cells exhibit cytolytic activity in both TCR C{beta} KO and WT chickens. A distinct cluster of {gamma}{delta} T cells expressing genes associated with the interferon pathway was revealed in TCR C{beta} KO chickens, which may contribute to the severe phenotype in these chickens, which is characterized by severe inflammation of spleen, gut and stomach. Additionally, novel gene markers were identified that precisely define the {beta} and {gamma}{delta} T cell subsets. These findings provide new insights into chicken T cell biology and contribute to a better understanding of the mechanisms underlying the severe phenotype observed in TCR C{beta} KO chickens.