Identifying, Characterizing and Inducing Effective Anti-HIV T Cell Responses

描述（由申请人提供）： 目前的候选HIV-1疫苗诱导的T细胞（i）具有有限的宽度;即仅识别几个不同的表位;和（ii）主要靶向HIV-1的可变区。此外，在急性HIV-1感染期间，具有靶向可变HIV-1表位的T细胞的个体比具有靶向保守HIV-1表位的T细胞的个体更快地发展为疾病。这些数据支持这样的观点，即有效的基于T细胞的免疫原将仅包含HIV-1的保守区域（保守免疫原方法）。另一种方法（嵌合免疫原方法）是设计包含多种变体的免疫原。这种方法基于这样的理论，即包含多个变体将能够对更广泛的循环变体做出反应，并且可以使免疫系统针对常见的逃逸突变体。该提议试图检验这样的假设，即针对非保守表位的应答的保守性（如通过保守性评分测量的）而不是多样性与疫苗诱导的T细胞应答的有效性相关。该假设将在以下三个具体目的中得到解决：1）评估靶向保守与可变HIV-1表位的T细胞在体外抑制病毒复制的有效性，2）确定使用保守或嵌合免疫原诱导的T细胞是否将在天然HIV-1感染的情况下被激活，并评估它们控制病毒复制的能力;以及3）确定HIV免疫原的片段化是否会通过增加源自缺陷性核糖体产物（DRiP）的表位库来增加诱导的T细胞应答的宽度。该提议将利用一种新的体外引发测定来预测在用候选疫苗接种后将被诱导的T细胞识别的表位特异性。该试验可用作其他基于T细胞的候选免疫原的第一次筛选，仅允许那些显示出最有希望进入更昂贵的人类临床试验的候选物。这些研究对基于T细胞的HIV疫苗的设计具有深远的意义。确定疫苗接种诱导的有效抗病毒T细胞应答是否是由于（i）增加识别的HIV-1变体的数量或（ii）增加特异性，使得仅靶向HIV-1的保守区域（或两者），也将对开发用于具有高突变率的其他感染性生物体（例如丙型肝炎病毒（HCV））的疫苗具有意义。

DESCRIPTION (provided by applicant): Current candidate HIV-1 vaccines induce T cells that (i) possess restricted breadth; i.e. recognize only a few different epitopes; and (ii) predominantly target variable regions of HIV-1. Furthermore, during acute HIV-1 infection individuals who possess T cells targeting variable HIV-1 epitopes progress to disease faster than individuals possessing T cells targeting conserved HIV-1 epitopes. These data support the views that an effective T cell-based immunogen will contain only conserved regions of HIV-1 (the conserved immunogen approach). An alternative approach (the mosaic immunogen approach) has been to design immunogens to include multiple variants. This approach is based upon the theory that inclusion of multiple variants would enable responses to a broader range of circulating variants and could prime the immune system against common escape mutants. This proposal seeks to test the hypothesis that the conservation (as measured by conservation score) rather than the diversity of response against non-conserved epitopes correlates with effectiveness of vaccine-induced T cell responses. This hypothesis will be addressed in the following three Specific Aims: 1) To assess the effectiveness of T cells targeting conserved vs. variable HIV-1 epitopes to suppress viral replication in vitro, 2) To determine if T cells induced using conserved or mosaic immunogens will be activated in the context of natural HIV-1 infection and assess their ability to control viral replication; and 3) To determine if fragmentation of HIV immunogens will increase breadth of induced T cell response by increasing the pool of epitopes derived from defective ribosomal products (DRiPs). This proposal will utilize a novel in vitro priming assay to predict the epitope specificities that will be recognized by induced T cells upon vaccination with candidate vaccines. This assay could be used as a first screen of other candidate T cell based immunogens allowing only those candidates that show the most promise to move forward into more costly human clinical trials. The proposed studies have far reaching implications for design of T cell-based HIV vaccines. Determining whether effective anti-viral T cell responses induced by vaccination are due to (i) increasing the number of HIV-1 variants that are recognized or (ii) increasing specificity such that only conserved regions of HIV-1 are targeted (or both) will also have implications for the development of vaccines for other infectious organisms with high mutation rates e.g. Hepatitis C Virus (HCV).