Role of specific Nef functions in AIDS pathogenesis

描述(由申请人提供)：我们认为，辅助HIV-1Nef蛋白无法抑制T细胞的激活和凋亡是导致高水平免疫激活并加速进展为艾滋病的原因之一。这一假说是基于我们的发现--与HIV-1 Nef严格相反--HIV-2和大多数SIV Nef下调TCR/CD3，并抑制HIV-1感染的原代细胞中T细胞的激活和凋亡。相反，其他Nef功能，如上调MHC-11相关的不变链(Li)，在大多数或所有灵长类慢病毒中是保守的。这项提议的具体目标是：SA1。阐明Nef介导的LI表达上调与艾滋病发病机制的相关性。稳定的Li表面表达阻止了MHC-II多肽的呈递，并可能损害辅助T细胞的反应。我们已经产生了SIVmac Nef变体，从而能够澄清这种Nef功能是否影响SIV/猕猴模型中的辅助T细胞反应和临床感染过程。SA2.阐明不同的HIV和SIV Nef如何操纵T细胞和APC的功能。原代T细胞和APC将与共表达GFP和HIV或SIV nef等位基因的前病毒HIV-1或SIV构建体转导，暴露于不同的刺激下，随后评估增殖、病毒传播、激活标记的表达和免疫突触的形成。我们想要产生关于HIV和SIV Nef如何操纵APC和T细胞之间的相互作用的新信息。另一个目标是阐明人类、猕猴和AGM的T细胞对激活的反应是否不同。SA3.了解Nef介导的TCR-CD3下调在灵长类慢病毒发病中的作用。我们将产生表达nef等位基因的SIVmac239和SIVagm变体，它们下调TCR-CD3的能力不同，并分别在SIV/猕猴和非洲绿猴中评估它们的致病性。这一结果将阐明SIV无法下调TCR-CD3是否会导致T细胞激活水平更高，并加速CD4+T细胞的耗尽。了解低水平免疫激活的潜在机制，从而使自然感染SIV的猴子能够防止疾病进展，可能会导致新的策略，从而延迟甚至防止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.