Viral Constraints on SIV Escape from Cytotoxic T Lymphocytes

描述（由申请人提供）：据估计，全球有3900万人感染HIV-1，HIV流行病已成为一个严重的全球健康问题。鉴于40%的受感染者生活在发展中国家，那里的抗逆转录病毒药物并不普遍，因此开发有效的疫苗至关重要。我们的长期目标是阐明病毒进化和免疫相关的保护免受感染的必要先决条件，以发展一个有效的HIV疫苗。细胞毒性T淋巴细胞（CTL）在控制人类免疫缺陷病毒（HIV）感染和恒河猴免疫缺陷病毒（SIV）感染方面发挥着核心作用。然而，HIV/SIV的高突变率允许不断产生病毒变体，这些病毒变体在进化的适应性免疫应答的背景下保持最佳适应性。能够破坏有效的CTL应答的病毒变体已显示导致病毒复制增加和疾病进展。因此，重要的是要定义所使用的策略，病毒分离株突变表位特异性CTL反应，使我们能够预测关键表位的变化，并制定疫苗的方法，以避免选择逃逸变体。我们的初步工作表明，在猴-人免疫缺陷病毒（SHIV）株89.6P中出现的位置2 p11 C，C-M Gag表位取代，允许病毒在感染的Mamu-A*01+恒河猴中逃避CTL识别，与衣壳蛋白中侧翼下游氨基酸取代的出现时间相关。我们的假设是，SHIV-89.6P逃逸高度保守，免疫显性Gag p11 C CTL表位是罕见的，因为需要额外的补偿突变，以促进这种病毒逃逸。在拟议的研究中，我们将使用电子显微镜和X射线结晶检查表位和侧翼突变对病毒核心形成的生物化学，结构和功能相关性。此外，我们将评估逃逸变体SHIV-89.6P在体内的致病性和免疫后果。最终，这些研究将有助于设计新的疫苗接种策略，可以防止病毒逃逸突变的演变。

DESCRIPTION (provided by applicant): With 39 million people estimated to be infected with HIV-1 worldwide, the HIV epidemic has become a serious global health problem. Given that 40% of infected individuals live in developing countries where antiretroviral medications are not widely available, the need to develop an effective vaccine is of paramount importance. Our long-term goal is to elucidate viral evolution and immune correlates of protection against infection as necessary prerequisites to the development of an effecitve HIV vaccine. Cytotoxic T lymphocytes (CTL) play a central role in controlling human immunodeficiency virus (HIV) infection in humans and simian immunodeficiency virus (SIV) in rhesus monkeys. However, the high mutation rate of HIV/SIV allows for the constant generation of viral variants that maintain optimal fitness in the context of an evolving adaptive immune response. Viral variants that are capable of subverting potent CTL responses have been shown to result in increased virus replication and disease progression. Therefore, it is important to define the strategies used by virus isolates to mutate away from epitope-specific CTL responses, so that we can anticipate variations in key epitopes and formulate vaccine approaches to avert selection of escape variants. Our preliminary work showed that the appearance of a position 2 p11C, C-M Gag epitope substitution in a simian-human immunodeficiency virus (SHIV) strain 89.6P that allowed viral escape from CTL recognition in an infected Mamu-A*01+ rhesus monkey is temporally correlated with the emergence of a flanking downstream amino acid substitution in the capsid protein. Our hypothesis is that the SHIV-89.6P escape at the highly conserved, immunodominant Gag p11C CTL epitope is infrequent because additional compensatory mutations are required to facilitate this viral escape. In the proposed studies, we will examine the biochemical, structural, and functional relevance of the epitope and flanking mutations on viral core formation using electron microscopy and x-ray crystallization. In addition, we will evaluate the pathogenicity and immunological consequences of the escape variant SHIV-89.6P in vivo. Ultimately, these studies will facilitate the design of novel vaccination strategies that may prevent the evolution of viral escape mutations.