Activating KIR Copy Number Variation Is Associated with Granzyme B Release by NK Cells during Primary Simian Immunodeficiency Virus Infection in Rhesus Monkeys

Abstract

Here we show that the number of activating killer cell immunoglobulin-like receptor (KIR) copies in rhesus monkeys is associated with the extent of release of cytotoxic granules by cytolytic NK cells during primary simian immunodeficiency virus SIVmac251 infection. These findings suggest that NK cells expressing high levels of activating KIRs efficiently kill SIVmac251-infected cells, and this efficient killing contributes to the NK cell-mediated control of replication of this virus during early infection. While it is well established that NK cells play a central role in the early control of a number of viral infections (11,18,22,23), their role in containing HIV-1 replication is only now being clarified. Studies have shown that activating killer cell immunoglobulin-like receptors (KIRs) that are expressed on NK cells are involved in controlling HIV-1 replication and slowing HIV-1 disease progression (1,2,15,17). While there is reason to suppose that NK cells affect HIV-1 replication early following infection, these cells are difficult to study during primary infection because it is difficult to obtain early blood samples from infected individuals. The simian immunodeficiency virus (SIV)-infected rhesus monkey provides an important nonhuman primate animal model for studying NK cell biology during a primary AIDS virus infection. We have recently demonstrated an association between specific NK cell subpopulations and the early containment of SIV replication in rhesus monkeys and a contribution of activating KIRs in stimulating NK cells to control the spread of SIV (8). In that study, we evaluated copy number variation (CNV) of KIR3DH, which represents an activating KIR receptor family in rhesus monkeys (4, 9), and showed that KIR3DH copy numbers were negatively associated with SIV replication at the time of the early peak of viral replication in Mamu-A*01 Ϫ rhesus monkeys that express restrictive TRIM5 alleles. This observation implicated NK cells that express activating KIRs in controlling viral replication during early SIV infection. However, the mechanism underlying this phenomenon remains unclear.The present study was initiated to determine how activating KIRs might affect SIV replication during primary infection. One important function of NK cells is to kill virus-infected target cells, and the present study assessed whether the cytolytic activity of NK cells is affected by KIR3DH CNV. In this study, the cytotoxicity of peripheral blood NK cells of Mamu-A*01 Ϫ rhesus monkeys was evaluated by measuring intracellular granzyme B and perforin levels and assessing CD107a surface expression on NK cells following in vitro stimulation with K562 cells, a cell line that does not express major histocompatibility complex (MHC) class I molecules (3,13,14). Peripheral blood mononuclear cells (PBMCs) were isolated from EDTA-anticoagulated whole blood by Ficoll-Paque (GE Healthcare, Piscataway, NJ) gradient separation and either stained immediately or cryopreserved in liquid nitrogen. After thawing, cryopreserved cells were ...

Co‐evolution of the MHC class I and KIR gene families in rhesus macaques: ancestry and plasticity

“…It has been long established that particular macaque MHC class I alleles are associated with differential outcomes in experimental disease settings , but it is only in recent years that KIR has been studied in this context. On a modest scale compared with human studies in terms of numbers of subjects tested, similar sorts of KIR associations have been made in the simian immunodeficiency virus (SIV) model in rhesus macaques , which is studied in the context of AIDS vaccine research. In essence, these studies have demonstrated that NK cells play an important role in the containment of SIV infection but also that particular KIR‐MHC combinations determine either a poor or a good prognosis, as is reflected by a high or low viral load, respectively.…”

Novel KIR genotypes and gene copy number variations in northeastern Thais

“…Seventy‐three individuals were characterized for KIR copy number profiles. Thirty‐six copy number profiles were found; (a) usual KIR copy number, (b) expanded copy number profiles, (c) contracted copy number profiles . [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…Seventy-three individuals were characterized for KIR copy number profiles. Thirty-six copy number profiles were found; (a) usual KIR copy number, (b) expanded copy number profiles, 26,40 (c) contracted copy number profiles. 26 KIR3DP1 and 2DL4, that typically present with two copies, were found at one, three or four copies in 1Á4-5Á5% of NETs.…”

“…KIR genes are highly homologous and are closely arranged head‐to‐tail, facilitating unequal crossing over during meiosis and generation of novel KIR haplotypes, including gene duplications and hybrid genes . Several studies have linked genetic associations of diseases to KIR copy number …”

“…22,23 Several studies have linked genetic associations of diseases to KIR copy number. [24][25][26][27] Recently, genetic variation of KIR and their HLA ligands in northeastern Thais (NETs) was reported, [28][29][30][31] by conventional methods [sequence-specific priming-PCR (PCR-SSP) typing]. However, gene copy number variations of KIR have not previously been reported in Thais.…”