Role of specific Nef functions in AIDS pathogenesis

描述（由申请人提供）：我们提出，辅助HIV-1 Nef蛋白不能抑制T细胞活化和凋亡，导致高水平的免疫活化，并加速向AIDS的进展。这一假设是基于我们的发现，即与HIV-1 Nefs形成严格对比的是，HIV-2和大多数SIV Nefs下调TCR/CD 3，并抑制HIV-1感染的原代细胞中的T细胞活化和凋亡。相比之下，其他Nef功能如MHC-II相关不变链（Ii）的上调在大多数或所有灵长类慢病毒中是保守的。本提案的具体目标是：SA 1。阐明Nef介导的li表达上调与AIDS发病机制的相关性。li的稳定表面表达阻止MHC-II肽呈递并可能损害辅助性T细胞应答。我们已经产生了SIVmac Nef变体，从而可以澄清这种Nef功能是否影响SIV/猕猴模型中的辅助性T细胞应答和感染的临床过程。SA 2.阐明各种HIV和SIV Nef如何操纵T细胞和APC的功能。原代T细胞和APC将用共表达GFP和HIV或SIV nef等位基因的前病毒HIV-1或SIV构建体转导，暴露于不同的刺激物，随后评估增殖、病毒扩散、活化标志物的表达和免疫突触的形成。我们希望获得关于HIV和SIV Nefs如何操纵APC和T细胞之间相互作用的新信息。另一个目标是阐明人类、猕猴和Agms的T细胞对激活的反应是否不同。SA 3.了解Nef介导的TCR-CD 3下调在灵长类慢病毒发病机制中的作用。我们将产生表达nef等位基因的SIVmac 239和SIVagm变体，其下调TCR-CD 3的能力不同，并分别在SIV/猕猴和非洲绿色猴中评估其致病性。结果将阐明SIV不能下调TCR-CD 3是否会导致更高水平的T细胞活化和加速的CD 4 + T细胞耗竭。了解低水平免疫激活的潜在机制，从而使自然感染SIV的猴子能够预防疾病进展，可能会导致新的策略，从而延迟甚至预防HIV-1感染者的艾滋病发展。

DESCRIPTION (provided by applicant): We propose that the inability of the accessory HIV-1 Nef protein to inhibit T cell activation and apoptosis contributes to the high levels of immune activation and accelerates progression to AIDS. This hypothesis is based on our findings that - in strict contrast to HIV-1 Nefs - HIV-2 and most SIV Nefs down-regulate TCR/CD3 and inhibit T cell activation and apoptosis in HIV-1-infected primary cells. In contrast, other Nef functions such as up-regulation of the MHC-ll-associated invariant chain (li) are conserved among most or all primate lentiviruses. The specific aims of this proposal are to: SA1. Clarify the relevance of Nef-mediated up-modulation of li expression for AIDS pathogenesis. Stable surface expression of li prevents MHC-II peptide presentation and might impair helper T cell responses. We have generated SIVmac Nef variants allowing to clarify whether this Nef function affects helper T cell responses and the clinical course of infection in the SIV/macaque model. SA2. Elucidate how various HIV and SIV Nefs manipulate the function of T cells and APCs. Primary T cells and APCs will be transduced with proviral HIV-1 or SIV constructs co-expressing GFP and HIV or SIV nef alleles, exposed to different stimuli and subsequently evaluated for proliferation, viral spread, expression of activation markers and formation of the immunological synapse. We want to generate new information on how HIV and SIV Nefs manipulate the interaction between APCs and T cells. Another goal is to elucidate whether T cells form humans, macaques and Agms respond differently to activation. SA3. Understand the role of Nef-mediated down-modulation of TCR-CD3 in the pathogenesis of primate lentiviruses. We will generate SIVmac239 and SIVagm variants expressing nef alleles, which differ in their ability to down-modulate TCR-CD3 and evaluate their pathogenicity in the SIV/macaque and in African green monkeys, rrespectively. The results will clarify whether the inability of SIV to down-modulate TCR-CD3 will result in higher levels of T cell activation and accelerated CD4+ T cell depletion. Understanding the mechanisms underlying the low levels of immune activation and hence what enables naturally SIV-infected monkeys to prevent disease progression might lead to novel strategies allowing to delay or even prevent the development of AIDS in HIV-1-infected individuals.