HIV-1 Cryptic Epitopes: Implications for Vaccine Design

描述（由申请人提供）：HIV-1疫苗学领域主要侧重于鉴定免疫优势反应，以确定可能包含在HIV-1疫苗中的合适免疫原。然而，孤立地关注这种方法有其缺点。主要的问题是HIV-1的巨大序列可变性决定了其他表位的识别。鉴于最近默克疫苗试验或Step研究的失败，这个问题尤其尖锐，因为该疫苗诱导的CD8 T淋巴细胞（CD8- tl）反应的广度有限，可能导致其缺乏疗效。为了确定新的靶点以增加基于CD8-TL的疫苗的广度，目前的建议旨在研究一类独特的表位。隐表位（CE）是从替代阅读框（ARF）翻译而来，而不是用于合成功能蛋白的主阅读框。我们展示的数据表明，CE通常是原发性和慢性HIV-1感染的靶点。这一发现证明了当前提案的目的1，即利用跨越HIV-1蛋白质组ARF的重叠肽全面表征CE。这将产生关于经常被靶向的隐表位以及它们是否与慢性HIV感染（CHI）的病毒控制相关的有价值的信息。当前提案的目标2将确定这些CE反应在原发性HIV感染（PHI）情况下的生物学意义。当变异的病毒传播到非hla - 1匹配的受体时，CE逃避免疫压力并恢复为野生型的倾向将测量这一属性。如果我们的假设被证明是正确的，疫苗领域就可以开始设计诱导CE反应的载体，从而显著增加CD8-TL靶标的数量，而不必增加插入物的大小。最后，在目标3中，我们假设相对低效的蛋白质生产可能因此允许增加CE反应。对正在临床试验中接受两种不同HIV-1疫苗接种者的PBMC样本进行分析，使我们有独特的机会检验该申请中详细说明的这一假设。综上所述，这一建议不仅将确定CE反应的生物学意义，还将确定这些反应是否由目前的重组HIV-1疫苗诱导。这些信息将对未来HIV-1疫苗的设计极有帮助。本研究旨在了解在HIV-1感染和HIV-1疫苗接种过程中可能诱导的细胞毒性T淋巴细胞的全部广度和功能特征。这一信息将与HIV-1疫苗的设计高度相关并直接适用。

DESCRIPTION (provided by applicant): The field of HIV-1 vaccinology has primarily focused on identifying the immunodominant responses to determine suitable immunogens that might be included in an HIV-1 vaccine. However, focusing on this approach in isolation has disadvantages. The main problem is that the enormous sequence variability of HIV-1 dictates that other epitopes be identified. This issue is especially poignant in light of the recent failure of the Merck vaccine trial or Step Study, as the limited breadth of CD8 T lymphocyte (CD8-TL) response induced by this vaccine likely contributed to its lack of efficacy. In an attempt to identify novel targets to increase the breadth of a CD8-TL based vaccine, the current proposal aims to study a unique class of epitopes. Cryptic epitopes (CE) are translated from alternate reading frames (ARF) and not the main reading frame used to synthesize the functional proteins. We show data that CE are commonly targeted in primary and chronic HIV-1 infection. This finding is justification for aim 1 of the current proposal which will characterize CE comprehensively using overlapping peptides spanning the ARF of the HIV-1 proteome. This will yield valuable information about cryptic epitopes that are frequently targeted and whether they correlate with viral control in the setting of chronic HIV infection (CHI). Aim 2 of the current proposal will determine the biological significance of these CE responses in the setting of primary HIV infection (PHI). This attribute will be measured by the propensity of the CE to escape immune pressure and to revert to wild type when the mutated virus is transmitted to a non-HLA-I matched recipient. If our hypothesis were proven to be correct, the vaccine field can begin to design vectors that induce CE responses, thereby significantly increasing the number of CD8-TL targets without necessarily increasing the size of the insert. Lastly, in aim 3 we hypothesize that relatively inefficient protein production may thereby allow for increased CE responses. Analysis of the PBMC samples from recipients of two different HIV-1 vaccines, being tested in clinical trials, allows us the unique opportunity to test this hypothesis as is detailed in the application. Taken together, this proposal will not only determine the biologic significance of CE responses but also determine if these responses are induced using the current recombinant HIV-1 vaccines. Such information will be extremely helpful for future HIV-1 vaccine design. This proposal aims to understand the full breadth and functional features of cytotoxic T lymphocytes that may be induced during both HIV-1 infection and HIV-1 vaccination. This information will be highly relevant and directly applicable to the design of an HIV-1 vaccine.