A novel APOBEC-based vaccine approach for HIV

描述(由申请人提供)：HIV-1的巨大序列多样性仍然是开发有效的预防性疫苗的主要障碍。人APOBEC3G和3F蛋白是Vif缺陷HIV-1的有效抑制剂。HIV-1 Vif通过诱导APOBEC 3G和3F泛素化并随后被蛋白酶体降解来中和它们。APOBEC蛋白酶体加工的增加可能导致APOBEC衍生的多肽表位呈现在HIV-1感染细胞的表面。由于感染HIV的细胞表面可能存在较高水平的APOBEC抗原，因此APOBEC表位可以作为HIV-1感染的替代标志。基于APOBEC表位表达增加的CD8+T细胞靶向HIV-1感染细胞可以绕过HIV-1序列多样性的障碍。我们已经产生了初步数据，表明感染HIV-1的精英控制者对来自APOBEC3G序列的表位产生强烈的T细胞反应。我们还发现，控制SIV感染的精英猕猴会启动APOBEC特异性T细胞反应。基于这些初步观察，我们假设慢病毒感染产生APOBEC特异性CD8+T细胞，能够识别和消除病毒感染的细胞。此外，使用APOBEC序列的疫苗免疫原可以产生APOBEC特异性T细胞，这种T细胞可以识别和杀死感染任何HIV-1变种的细胞。这种新的方法基于感染细胞呈现APOBEC衍生的多肽，而不是HIV-1多肽。我们R21的中心目标是了解APOBEC表位特异性应答对针对HIV-1和SIV的总细胞免疫应答的贡献。这些研究将决定我们是否进入计划的R33阶段。我们对R33有两个目标。我们想知道在逆转录病毒感染过程中产生的APOBEC特异性CD8+T细胞是否能够识别和消除病毒感染的细胞。此外，我们希望确定疫苗诱导的APOBEC特异性细胞免疫反应是否可以控制SIV感染后的病毒复制。我们假设，Vif敏感的APOBEC蛋白的特异性T细胞将在体外和体内抑制病毒复制。该项目将提供APOBEC特异性T细胞专门抑制SIV/HIV-1复制的原则证明数据。因此，这些研究是迈向一种新的疫苗方法的第一步，这种方法通过瞄准艾滋病毒感染的替代标记物来绕过艾滋病毒-1序列多样性的障碍。

DESCRIPTION (provided by applicant): The enormous sequence diversity of HIV-1 remains a major obstacle to the development of an effective prophylactic vaccine. Human APOBEC3G and 3F proteins are potent inhibitors of Vif-deficient HIV-1. HIV-1 Vif counteracts APOBEC 3G and 3F by inducing their ubiquitination and subsequent degradation by the proteasome. Increased proteasomal processing of APOBEC could lead to presentation of APOBEC-derived peptide epitopes on the surface of HIV-1-infected cells. Because higher levels of APOBEC antigens might be present on the surface of HIV-infected cells, APOBEC epitopes could, therefore, serve as a surrogate marker of HIV-1 infection. Targeting CD8+ T cells to HIV-1-infected cells based on increased APOBEC epitope expression could circumvent the obstacle of HIV-1 sequence diversity. We have generated preliminary data that shows HIV-1 infected elite controllers mount strong T cell responses to epitopes derived from the APOBEC3G sequence. We have also discovered that elite-controlling SIV-infected macaques mount APOBEC specific T cell responses. Based upon these initial observations, we hypothesize that lentiviral infection generates APOBEC-specific CD8+ T cells, which are capable of recognizing and eliminating virally infected cells. Further, a vaccine immunogen using APOBEC sequences could generate APOBEC specific T cells, which could recognize and kill a cell infected with any variant of HIV-1. This novel approach targets infected cells based on their presentation of APOBEC derived peptides, not HIV-1 peptides. The central goal of our R21 is to understand the contribution of APOBEC epitope-specific responses to the total cellular immune response directed at HIV-1 and SIV. These studies will dictate whether we proceed to the R33 stage of the plan. We have two goals for the R33. We want to know whether APOBEC-specific CD8+ T cells arising during retroviral infections can recognize and eliminate virally infected cells. Additionally, we want to determine whether vaccine-induced APOBEC-specific cellular immune responses might provide control of viral replication after SIV infection. We hypothesize that T cells specific for Vif-sensitive APOBEC proteins will suppress viral replication both in vitro and in vivo. This project would provide proof-of-principle data that APOBEC-specific T cells specifically suppress replication of SIV/HIV-1. These studies are, therefore, the first steps towards a novel vaccine approach, which circumvents the obstacle of HIV-1 sequence diversity by targeting a surrogate marker of HIV infection.