Characterization of an avian (Gallus gallus domesticus) TCR alpha delta gene locus

Mammalian TCR delta genes are located in the midst of the TCR alpha gene lo cus, In the chicken, one large V delta gene family, two D delta gene segmen ts, two J delta gene segments, and one C delta gene have been identified. T he TCR delta genes were deleted on both alleles in alpha beta T cell lines, thereby indicating conservation of the combined TCR alpha delta locus in b irds. V alpha and V delta gene segments were found to rearrange with one, b oth or neither of the D delta segments and either of the two J delta segmen ts. Exonuclease activity, P-addition, and N-addition during VDJ delta rearr angement contributed to TCR delta repertoire diversification in the first e mbryonic wale of T cells. An unbiased V delta 1 repertoire was observed at all ages, but an acquired J delta 1 usage bias occurred in the TCR delta re pertoire. The unrestricted combinatorial diversity of relatively complex TC R gamma and delta loci may contribute to the remarkable abundance of gamma delta T cells in this avian representative.