KIR and MHC Class I Immunogenetics in SIV Infection

描述（由申请人提供）：高度多态性杀伤免疫球蛋白样受体（KIR）及其HLA I类配体在自然杀伤（NK）细胞的调节和HIV-1感染个体控制病毒复制的能力中发挥核心作用。然而，功能性研究，以解决免疫缺陷病毒感染中的KIR-MHC I类相互作用的意义已受到限制，在非人灵长类动物模型中缺乏定义的KIR的MHC I类配体。我们最近鉴定了Mamu-A*02，一种存在于大约20%的印度恒河猴中的MHC I类分子，作为Mamu-KIR 3DL 05（3DL 05）的配体。这种相互作用是肽依赖性的，因为Mamu-A*02四聚体与某些猿免疫缺陷病毒（SIV）肽折叠，而不是其他肽，染色原代NK细胞和表达多个3DL 05等位基因的转染细胞。与抑制性KIR的功能一致，表达Mamu-A*02（A*02）的靶细胞抑制来自3DL 05+猕猴的四聚体阳性NK细胞的脱粒。这些观察结果表明，SIV，也可能是HIV-1，可能获得表位的变化，增加了MHC I类配体对抑制性KIR的亲合力，作为免疫逃避的机制，以防止特定NK细胞亚群的激活。使用KIR和MHC I类定义的恒河猴，我们将专门解决这一假设，以及其他问题的免疫缺陷病毒感染的NK细胞的生物学基础。 本提案的第一个目标（Aim 1）是鉴定Mamu的其他MHC I类配体 - KIR 3DL 01和-KIR 3DL 05;两种KIR通常在恒河猴中表达，并且我们已经鉴定了用于对原代NK细胞上的这些受体进行染色的试剂。这一目标将建立在我们小组最近的工作基础上，为研究KIR-MHC I类相互作用在SIV感染中的作用提供更广泛的基础。我们的第二个目标（Aim 2）是解决病毒肽调节NK细胞活化的功能影响。我们将确定增强或拮抗与3DL 05相互作用的SIV肽的库，并将测试稳定与抑制性KIR相互作用的病毒表位促进病毒表位与3DL 05相互作用的假设。 在携带这些受体的NK细胞的存在下复制。我们的第三个目的（目的3）是比较3DL 05 +/A*02+与3DL 05 +/A*02-动物在SIV感染后3DL 05 + NK细胞的纵向变化。将解决以下问题：A*02结合肽的识别是否刺激或抑制3DL 05 + NK细胞的扩增？A*02+与A*02-动物中3DL 05 + NK细胞是否存在表型/功能差异？3DL 05 + NK细胞向组织的募集是否存在差异？这些前所未有的研究将提供一个更好的了解免疫缺陷病毒感染中KIR-MHC I类相互作用的重要性，特别是病毒肽在调节NK细胞中的作用。 激活作为免疫逃避的机制。

DESCRIPTION (provided by applicant): The highly polymorphic killer immunoglobulin-like receptors (KIRs) and their HLA class I ligands play a central role in the regulation of natural killer (NK) cells, and in the ability of HIV-1 infected individuals to control virus replication. However, functional studies to address the significance of KIR-MHC class I interactions in immunodeficiency virus infection have been limited by the lack of defined MHC class I ligands for KIRs in non-human primate models. We recently identified Mamu-A*02, an MHC class I molecule present in approximately 20% of Indian origin rhesus macaques, as a ligand for Mamu-KIR3DL05 (3DL05). This interaction was peptide-dependent, since Mamu-A*02 tetramers folded with certain simian immunodeficiency virus (SIV) peptides, but not others, stained primary NK cells and transfected cells expressing multiple 3DL05 alleles. Consistent with the function of an inhibitory KIR, target cells expressing Mamu-A*02 (A*02) suppressed the degranulation of tetramer-positive NK cells from 3DL05+ macaques. These observations suggest that SIV, and potentially also HIV-1, may acquire changes in epitopes that increase the avidity of MHC class I ligands for inhibitory KIRs as a mechanism of immune evasion to prevent the activation of specific NK cell subsets. Using KIR- and MHC class I-defined rhesus macaques, we will specifically address this hypothesis, as well as other questions fundamental to the biology of NK cells in immunodeficiency virus infection. The first objective of this proposal (Aim 1) is to identify additional MHC class I ligands for Mamu KIR3DL01 and -KIR3DL05; two KIRs that are commonly expressed in the rhesus macaque and for which we have identified reagents for staining these receptors on primary NK cells. This aim will build on recent work by our group to provide a broader foundation for investigating the role of KIR-MHC class I interactions in SIV infection. Our second objective (Aim 2) is to address the functional implications of viral peptides that modulate NK cell activation. We will determine the repertoire of SIV peptides that enhance or antagonize interactions with 3DL05, and will test the hypothesis that viral epitopes, which stabilize interactions with inhibitory KIRs, facilitate virus replication in the presence of NK cells bearing these receptors. Our third objective (Aim 3) is to compare longitudinal changes in 3DL05+ NK cells following SIV infection of 3DL05+/A*02+ versus 3DL05+/A*02- animals. The following questions will be addressed; Does the recognition of A*02-bound peptides stimulate or suppress the expansion of 3DL05+ NK cells? Are there phenotypic/functional differences in 3DL05+ NK cells in A*02+ versus A*02- animals? Is there a difference in the recruitment of 3DL05+ NK cells to tissues? These unprecedented studies will provide a better understanding of the importance of KIR-MHC class I interactions in immunodeficiency virus infection, and specifically the role of viral peptides in modulating NK cell activation as a mechanism of immune evasion.