Vgamma9Vdelta2 T cells: Identification in non-primate species and dissection of molecular determinants of antigen-recognition

V γ 9 V δ 2 T细胞是针对病原体和肿瘤的人类免疫应答的效应子。它们的T细胞抗原受体（TCR）识别宿主或微生物类异戊二烯合成的小的焦磷酸化代谢物（磷酸化抗原：PAg）连同细胞表面分子BTN 3A 1。到目前为止，这些细胞只在灵长类动物中发现。就在最近。我们在几种关系相当远的胎盘哺乳动物中发现了V γ 9V δ 2 TCR及其配体BTN 3A 1的基因，其中包括羊驼（Vicugnapacos），这些基因的功能表达在羊驼中得到了直接证实。该项目的主要目的是直接识别和功能表征羊驼作为第一个非灵长类物种中的Vgamma 9Vdelta 2 T细胞。首先，应生成抗Vgamma 9Vdelta 2 TCR和BTN 3A 1的单克隆抗体。这些抗体将用于直接鉴定羊驼外周血中的羊驼V γ 9 V δ 2 T细胞，并研究它们是否可以以PAg和BTN 3A 1依赖性方式活化。如果是的话，羊驼可能是研究自然发生的感染中的Vgamma 9Vdelta 2 T细胞的模型。如果羊驼Vgamma 9Vdelta 2 T细胞缺乏PAg反应性，则将通过尝试重建对PAg的反应来解决这种功能差异的分子基础：通过在羊驼细胞中表达来自灵长类动物的候选分子或在灵长类动物细胞中表达羊驼BTN 3A 1的构建体。利用骆驼科动物的γ-δ T细胞工作的机会也将用于追踪最近发表的羊驼和其他骆驼科动物中γ-δ TCR的体细胞超突变。最后，我们的目标是在其他哺乳动物物种中鉴定V γ 9 V δ 2 T细胞。主要的候选者是九带犰狳（Dasypus novemcinctus），这是特别感兴趣的i）麻风分枝杆菌的天然宿主和ii）作为一个成员的总目的xenarthra，这是分配到一个不同的分支的胎盘哺乳动物比羊驼和人类。总而言之，我们期望通过对这些亲缘关系较远的物种的分析，对γ-δ T细胞的一般生理学有新的认识。

Vgamma9Vdelta2 T cells are effectors of human immune responses against pathogens and tumors. Their T cell antigen receptors (TCR) recognize small pyrophosphorylated metabolites (phosphoantigens: PAg) of host or microbial-isoprenoid-synthesis in conjunction with the cell surface molecule BTN3A1. So far these cells have been found only in primates. Very recently. we found genes for Vgamma9Vdelta2 TCR and its ligand BTN3A1 in several rather distantly related placental mammals, among them alpaca (Vicugna pacos), where functional expression of these genes was directly demonstrated. The major aim of the project is to directly identify and functionally characterize Vgamma9Vdelta2 T cells in alpaca as first non-primate species. At first, monoclonal antibodies against Vgamma9Vdelta2 TCR and BTN3A1 shall be generated. These antibodies will be used to directly identify alpaca Vgamma9Vdelta2 T cells in peripheral blood of alpaca and to investigate whether they can be activated in a PAg and BTN3A1 dependent fashion. If yes, alpaca may represent a model to study Vgamma9Vdelta2 T cells in naturally occurring infections. If alpaca Vgamma9Vdelta2 T cells lack PAg reactivity, the molecular basis of this functional difference will be addressed by trying to reconstitute a response towards PAg: Either by expressing candidate molecules from primates in alpaca cells or constructs of the alpaca BTN3A1 in primate cells. The opportunity to work with camelid gamma-delta T cells shall also be used to track recently published somatic hypermutations of gamma-delta TCRs in alpaca and other camelids. Finally, we are aiming to identify Vgamma9Vdelta2T cells in further mammalian species. The prime candidate would be the nine-banded armadillo (Dasypus novemcinctus) which is of special interest i) as natural host of Mycobacterium leprae and ii) as a member of the superorder xenarthra, which is assigned to a different clade of placental mammals than alpaca and humans. Altogether, we expect from analysis of these rather distantly related species new insights in the general physiology of gamma-delta T cells.