Meeting Abstract

P3-118   -   Comparison of Sphenodon punctatus and Tiliqua rugosa genomes reveals genomic basis of loss of γδ T cells in Squamates Morrissey, KA*; Samson, J; Rivera, M; Bu, L; Hansen, VL; Gemmell, NJ; Gardner, MG; Bertozzi, T; Miller, RD; University of New Mexico; University of New Mexico; University of New Mexico; University of New Mexico; University of Rochester; University of Otago; University of Otago; University of Otago; University of New Mexico kmorrissey@unm.edu

T cells are a critical component to the adaptive immune response of all jawed vertebrates. Two ancient T cell lineages, the αβ and γδ T cells, are present in all major gnathostome lineages. However, the squamate reptiles appear unique by lacking the γδ T cells. Here we investigate the basis of the loss of the γδ T cells in squamates. The genome and transcriptome of a skink, Tiliqua rugosa, was compared with that of the tuatara, Sphenodon punctatus, the nearest relative to squamates that has γδ T cells. We demonstrate that there are relatively large deletions in the T. rugosa genome in the regions where the genes encoding the TCRγ and TCRδ chains of the γδ T cell receptor (TCR) would be expected to be located. We also confirm that the genes encoding the chains of the TCR of αβ T cells do not appear to have increased in complexity in the squamates to compensate for the loss of γδ T cells. Squamates are a lineage of vertebrates noticeably lacking in studies of their immune system. Here we show that they are a natural model of the effects of γδ T cell knockout.