Boosting cell-intrinsic innate immune recognition of HIV-1 by dendritic cells

描述（由申请人提供）：2011 年有 250 万人感染了 HIV-1。显然，需要一种预防 HIV-1 感染的疫苗。然而，针对 HIV-1 的免疫反应与天花等其他病毒的免疫反应有根本不同，天花已针对这些病毒开发出有效的疫苗。面对已记录的 HIV-1 特异性体液和细胞免疫反应，HIV-1 感染者会发展为艾滋病，甚至可能继发感染 HIV-1。如果不基于对抗 HIV-1 免疫力的了解对疫苗设计进行重大修改，即使是活疫苗也无法预防 HIV-1 感染。记忆性抗病毒反应，包括细胞毒性 T 淋巴细胞和中和抗体，需要 DC 启动幼稚的抗原特异性 T 细胞，这些 DC 已充分成熟以产生一系列信号和因子，包括 IL-12。当模式识别受体 (PRR) 在呈递病毒抗原的同一 DC 内被激活时（内在检测），这种成熟对于引发抗病毒反应是最佳的。 HIV-1 进入常规抗原呈递 DC 的主要途径允许有效的 HIV-1 抗原呈递，但妨碍成熟：不发生逆转录，PRR 不被激活，并且不产生 1 型干扰素。在 DC 不成熟的情况下 T 细胞的启动为众所周知的无效抗 HIV-1 免疫反应提供了解释。为了最大化 DC 成熟并改善 HIV-1 特异性 T 细胞启动的结果，本文提出的实验将增加呈递 HIV-1 抗原的相同 DC 内 PRR 对 HIV-1 的内在识别。这将通过使用 VSV 糖蛋白进行假分型并利用有关 DC 内 HIV-1 先天免疫感应的最新发现，将 HIV-1 重定向至生产性 DC 进入途径来完成：TRIM5 介导的 NF-κB 和 c-Jun 信号传导将通过 HIV-1 衣壳的工程修饰在 DC 中激活；通过阻断三磷酸水解酶 SAMHD1，将允许新生 HIV-1 在 DC 中逆转录； DC 核酸酶 TREX1 和 RNASEH2 的破坏将允许 HIV-1 逆转录物积累到激活 1 型 IFN 的水平； PRR（例如 cGAS）将由 HIV-1 本身传递，以放大先天免疫信号。这些干预措施的组合可以使树突状细胞成熟，以最佳方式引发抗 HIV-1 特异性 CD4 和 CD8 T 细胞反应，这些条件将用于免疫最先进的人源化小鼠，我们已经在其中检测到了 HIV-1 毒株特异性中和抗体。这些实验将确定树突状细胞对 HIV-1 的内在感知是否会改善对 HIV-1 的获得性免疫反应，如果确实如此，将为开发人类有效的抗 HIV-1 疫苗提供路线图。

DESCRIPTION (provided by applicant): 2.5 million people became infected with HIV-1 in 2011. Clearly, a vaccine that prevents HIV-1 infection is needed. The immune response to HIV-1, though, differs fundamentally from that of other viruses such as smallpox for which effective vaccines have been developed. In the face of documented HIV-1-specific humoral and cellular immune responses, HIV-1-infected people progress to AIDS and can even be secondarily infected with HIV-1. Without critical modifications to vaccine design based on understanding of anti-HIV-1 immunity, even a live-vaccine would not prevent HIV-1 infection. Anamnestic, antiviral responses, including cytotoxic T lymphocytes and neutralizing antibodies, require priming of naïve, antigen-specific T cells by DCs that have matured sufficiently to produce an array of signals and factors, including IL-12. Such maturation is optimal for priming antiviral responses when pattern recognition receptors (PRRs) are activated within the same DCs that present viral antigen (intrinsic detection). The dominant pathway by which HIV-1 enters conventional, antigen-presenting DCs permits efficient HIV-1 antigen presentation but precludes maturation: reverse transcription does not occur, PRRs are not activated, and type 1 interferon is not produced. T cell priming in the absence of DC maturation provides an explanation for well-described, ineffective anti-HIV-1 immune responses. To maximize DC maturation and improve the outcome of HIV-1-specific T cell priming, the experiments proposed here will increase intrinsic recognition of HIV-1 by PRRs within the same DCs that present HIV-1 antigen. This will be done by redirecting HIV-1 to a productive DC-entry pathway by pseudo-typing with VSV Glycoprotein and exploiting recent discoveries concerning innate immune sensing of HIV-1 within DCs: TRIM5-mediated NF-κB and c-Jun signaling will be activated in DCs by engineered modifications in the HIV-1 capsid; nascent HIV-1 reverse transcription in DCs will be permitted by blocking the triphosphohydrolase SAMHD1; disruption of DC nucleases TREX1 and RNASEH2 will permit HIV-1 reverse transcripts to accumulate to levels that activate type 1 IFN; PRRs such as cGAS will be delivered by HIV-1 itself in order to amplify innate immune signaling. The combination of these interventions that matures DCs to optimally prime anti-HIV-1-specific CD4+ and CD8+ T cell responses will be identified and these conditions will be used to immunize state-of-the-art, humanized mice, in which we have already detected HIV-1 strain-specific neutralizing antibodies. These experiments will determine if intrinsic sensing of HIV-1 by DCs improves acquired immune responses to HIV-1 and, if it does, offer a roadmap for the development of potent, anti-HIV-1 vaccines in people.