KIR and MHC Class I Immunogenetics in SIV Infection

描述(申请人提供)：高度多态的杀伤免疫球蛋白样受体(KIRS)及其HLAI类配体在自然杀伤(NK)细胞的调节和HIV-1感染者控制病毒复制的能力中发挥核心作用。然而，由于在非人类灵长类动物模型中缺乏明确的KIR的MHC I类配体，因此解决KIR-MHC I类相互作用在免疫缺陷病毒感染中的重要性的功能研究一直受到限制。我们最近确定了MAMU-A*02，一种存在于大约20%的印度猕猴体内的MHC I类分子，作为MAMU-KIR3DL05(3DL05)的配体。这种相互作用是肽依赖的，因为MAMU-A*02四聚体与某些猴免疫缺陷病毒(SIV)肽折叠，而不是其他四聚体，染色的原代NK细胞和表达多个3DL05等位基因的细胞。表达MAMU-A*02(A*02)的靶细胞可抑制3DL05+猕猴四聚体阳性NK细胞的脱颗粒，这与抑制性KIR的功能一致。这些观察结果表明，SIV和潜在的HIV-1可能获得了表位的变化，这些表位增加了MHC-I类配体对抑制性KIR的亲和力，作为一种免疫逃避机制，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，我们将具体解决这一假说，以及免疫缺陷病毒感染中NK细胞生物学的其他基本问题。 这项提议的第一个目标(目标1)是为MAMU确定更多的MHC I类配体 KIR3DL01和-KIR3DL05；KIR3DL01和-KIR3DL05；这两个KIR在恒河猴中普遍表达，我们已经确定了这些受体在原代NK细胞上染色的试剂。这一目标将建立在我们团队最近的工作基础上，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(目标2)是研究调节NK细胞激活的病毒多肽的功能含义。我们将确定增强或拮抗与3DL05相互作用的SIV多肽的谱系，并将测试病毒表位，它稳定了与抑制性KIR的相互作用，促进了病毒 在带有这些受体的NK细胞存在的情况下进行复制。我们的第三个目标(目标3)是比较SIV感染3DL05+/A*02+和3DL05+/A*02-动物后3DL05+NK细胞的纵向变化。将解决以下问题：A*02结合肽的识别是刺激还是抑制3DL05+NK细胞的扩张？A*02+与A*02-动物的3DL05+NK细胞是否存在表型/功能差异？3DL05+NK细胞向组织的募集有差异吗？这些史无前例的研究将使我们更好地了解KIR-MHC I类相互作用在免疫缺陷病毒感染中的重要性，特别是病毒多肽在调节NK细胞中的作用。 激活作为一种免疫逃避机制。

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.