Strategies of lentivirus persistence

慢病毒持续进化和逃避免疫控制的能力是慢病毒感染的主要障碍。 开发有效的艾滋病毒疫苗病毒在体内的终身持续性是其能力的函数， 逃避免疫识别和消除以及它的复制能力，即它的复制能力。的 拟议的研究将使用特征良好的马传染性贫血病毒（EIAV）模型来鉴定病毒 在慢病毒进展过程中免疫逃逸变体的进化和选择中重要的因素 疾病将使用在疾病的连续阶段从EIAV感染的马分离的回顾性样品 为了验证病毒变异体成功逃避广泛反应性免疫应答的假设， 在多个遗传区域中的突变，其赋予复制表型的可再现的变化。第一 目的是确定在EIAV疾病的连续阶段占优势的env/rev基因型是否在以下方面不同： 复制表型含有代表性的显性env/rev基因型的重组感染性克隆 将在生长动力学和生长竞争测定中测试疾病的每个阶段的复制能力。 将估计成对变体的相对适合度，并使用标准统计测试来确定何时 适合度差异显着。这些研究将确定复制表型是否有助于变异 疾病进展期间病毒载量的选择和变化。随后的目标将确定 复制差异是免疫逃避的代价，是逃避免疫识别的病毒策略，或者是 两者第二个目标的研究将确定Rev和SU的变化对复制能力的影响 免疫逃避。将Rev的复制表型定量为核输出活性，并使用 基于对CTL杀伤的敏感性来推断免疫逃避表型。SU复制表型将 作为感染性进行测量，通过中和敏感性确定免疫逃避表型 抗体的这些值以及在具体目标1中获得的复制适应度评分将用于 统计学模型，以确定哪种env/rev表型影响病毒载量的变化， 疾病第三个具体目标的实验将确定复制的分子决定因素 在对广泛中和抗体的敏感性方面不同的变体中的表型。EIAV假病毒 将用于定位在传染性和免疫逃逸鉴定中重要的EIAV SU的特异性区域 导致临床疾病复发的SU遗传变化。这种详细的综合分析 将确定关键的病毒决定因素，改变平衡，有利于病毒，或主机， 慢病毒病的进展。设计成功的HIV和其他慢病毒疫苗需要： 我们了解、预测并阻止病毒逃避广泛反应性免疫应答的策略。的 从拟议的研究中获得的信息将确定限制病毒逃逸的新疫苗靶点。 广泛的免疫反应。项目叙述 拟议的研究将确定使慢病毒能够修改其复制的遗传机制 逃避宿主免疫系统的清除这种策略使病毒在体内持续存在， 获得可能增加病毒载量并导致临床疾病进展的新突变。的结果 这项研究将确定新的HIV-1疫苗策略，以抑制病毒逃离病毒的能力。 宿主免疫反应

The ability of lentiviruses to continually evolve and escape immune control is the central impediment in developing an effective vaccine for HIV. The lifelong persistence of virus in vivo is a function of its ability to evade immune recognition and elimination as well as its ability to replicate, i.e. it's replicative capacity. The proposed studies will use the well-characterized equine infectious anemia virus (EIAV) model to identify virus factors important in the evolution and selection of immune escape variants during progression of lentiviral disease. Retrospective samples isolated from EIAV-infected horses at sequential stages of disease will be used to test the hypothesis that virus variants which successfully evade a broadly reactive immune response contain mutations in multiple genetic regions, which confer reproducible changes in replication phenotype. The first aim will determine if env/rev genotypes that predominate at sequential stages of EIAV disease differ in replication phenotype. Recombinant infectious clones containing dominant env/rev genotypes representative of each stage of disease will be tested for replicative capacity in growth kinetic and growth competition assays. The relative fitness of pairs of variants will be estimated, and standard statistical tests used to determine when fitnesses differ significantly. These studies will establish if replication phenotype contributes to variant selection and changes in virus load during progression of disease. Subsequent aims will ascertain whether the replication differences are a cost of immune evasion, a virus strategy to evade immune recognition, or a mix of both. Studies in the second aim will determine the impact of variation in Rev and SU on replicative capacity and immune evasion. The replication phenotype of Rev will be quantified as nuclear export activity, and used to infer an immune evasion phenotype based on sensitivity to CTL killing. The SU replication phenotype will be measured as infectivity, and immune evasion phenotype determined by sensitivity to neutralizing antibody. These values, together with the replication fitness score obtained in Specific Aim 1, will be used in statistical models to determine which env/rev phenotypes affect changes in virus load during progression of disease. Experiments in the third specific aim will identify the molecular determinants of replication phenotype in variants that differ in susceptibility to broadly neutralizing antibody. EIAV-based pseudovirus will be used to map the specific regions of EIAV SU important in infectivity and immune escape identify genetic changes in SU that contribute to recrudescence of clinical disease. This detailed, integrative analyses will identify critical virus determinants that shift the balance in favor of either the virus, or the host, during progression of lentivirus disease. The design of successful vaccines for HIV and other lentiviruses requires that we understand, anticipate, and block viral strategies of evasion from a broadly reactive immune response. The information gained from the proposed studies will identify new vaccine targets that limit virus escape from broadly reactive immune responses. PROJECT NARRATIVE The proposed studies will identify the genetic mechanisms that enable lentiviruses to modify their replication and escape elimination by the host immune system. This strategy allows the virus to persist in vivo, and acquire new mutations that may increase virus load and lead to progression of clinical disease. The results of this study will identify new vaccine strategiesw for HIV-1 that inhibit the viruses ability to escape from the host immune response.