HIV-1 Cryptic Epitopes: Implications for Vaccine Design

描述(申请人提供)：HIV-1疫苗学领域主要集中于确定免疫显性反应，以确定可能包括在HIV-1疫苗中的适当免疫原。然而，孤立地关注这种方法是有缺点的。主要的问题是，HIV-1的巨大序列变异性要求确定其他表位。鉴于最近默克疫苗试验或STEP研究的失败，这个问题尤其令人痛心，因为这种疫苗诱导的CD8 T淋巴细胞(CD8-TL)反应范围有限，可能是导致其无效的原因之一。为了确定新的靶点以增加基于CD8-TL的疫苗的广度，目前的提议旨在研究一类独特的表位。隐蔽表位(CE)是由交替阅读框(ARF)翻译而来的，而不是用于合成功能蛋白的主要阅读框。我们的数据显示，CE通常针对原发和慢性HIV-1感染。这一发现证明了当前提议的目标1的合理性，该目标1将利用跨越HIV-1蛋白质组ARF的重叠多肽来综合描述CE。这将产生关于经常被靶向的隐蔽表位的有价值的信息，以及它们是否与慢性艾滋病毒感染(CHI)的病毒控制相关。当前提案的目标2将确定这些CE反应在原发艾滋病毒感染(PHI)背景下的生物学意义。这一属性将通过CE逃避免疫压力的倾向来衡量，当突变的病毒传播给非HLA-I匹配的接受者时，CE倾向于恢复到野生型。如果我们的假设被证明是正确的，疫苗领域可以开始设计诱导CE反应的载体，从而显著增加CD8-TL靶标的数量，而不一定增加插入片段的大小。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。对正在进行临床试验的两种不同HIV-1疫苗接受者的PBMC样本进行分析，使我们有独特的机会来检验这一假设，正如申请中详细说明的那样。综上所述，这一建议不仅将确定CE反应的生物学意义，而且还将确定这些反应是否是使用当前的重组HIV-1疫苗诱导的。这些信息将对未来的HIV-1疫苗设计非常有帮助。这项建议旨在了解在HIV-1感染和HIV-1疫苗接种期间可能诱导的细胞毒性T淋巴细胞的全部广度和功能特征。这些信息将高度相关，并直接适用于艾滋病毒-1疫苗的设计。

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.