CHEETAH Center for the Structural Biology of HIV Infection, Restriction, and Viral Dynamics

项目总结 尽管未经治疗的艾滋病毒/艾滋病感染是致命的，但人类仍有一系列强大的先天抗病毒反应 这有助于抑制复制，并在传播和病毒反弹期间对病毒施加强大的选择性压力 在艺术中断之后。这些观察表明，先天性免疫反应可能具有治疗价值，如果我们 可以更好地理解它们，并找到加强它们的方法。要感染细胞，HIV-1必须经受这种先天的挑战 免疫传感器和限制。项目2中的研究，针对艾滋病毒的细胞防御，将重建和描述 在病毒生命周期的前半部分，细胞先天免疫感知和限制HIV-1的机制。 目标1(SERINC结构、机制和抗病毒活性)的研究将建立在我们最新的低温EM结构的基础上 HSERINC3，以及我们发现限制SERINC是非特异性磷脂扰乱酶，以及丢失 磷脂酰丝氨酸(PS)的不对称性可引起抗病毒作用。我们假设SERINC通过改变SERINC的 病毒粒子脂双层的天然不对称性。我们建议确定SERINC如何翻转血脂，并测试 SERINC通过改变PS的分布和破坏Env构象发挥其抗病毒活性。 目标2(HIV-1识别和先天信号)的研究将利用我们重建cGAs先天免疫的能力 体外复制HIV核心的检测和我们发现HIV-1衣壳抑制物可以促进先天信号转导 被感染的髓系细胞。我们现在建议确定：1)病毒核心结构和稳定性如何影响cGAS介导的 反转录的检测，2)衣壳结合因子如PQBP1如何在髓系cGAS传感中起作用 细胞，3)CA抑制剂是否以及如何促进HIV-1的cGAS检测，4)细胞特异性因子如何调节cGAS 活动，以及5)由此产生的下游反应如何限制HIV-1感染。 目标3(TRIM限制)的研究将根据我们的观察得出TRIM5蛋白在周围形成六角形笼子 即将到来的HIV-1衣壳。这一目标的实验旨在填补我们对病毒理解的根本空白。 在最初的TRIM5识别步骤之后的抑制和信号传递过程，并发现宿主如何协同因子 促进或调节TRIM5限制。 AIM 4(重建其他限制)的研究将建立在我们重建SAMHD1和APOBEC3G的能力的基础上 限制在体外复制HIV-1核心，我们现在建议重建MXB限制。这些重组的 反应将被用来填补我们对限制机制、辅助因素和调节的理解的空白，并检查 衣壳蛋白抑制剂如何增强MXB活性。

PROJECT SUMMARY Although untreated HIV/AIDS infections are fatal, humans nevertheless have an array of powerful innate antiviral responses that help suppress replication and exert strong selective pressures on the virus during transmission and during viral rebound following ART interruption. These observations suggest that innate immune responses could be of therapeutic value if we can understand them better and discover ways to strengthen them. To infect a cell, HIV-1 must run a gauntlet of such innate immune sensors and restrictions. Studies in Project 2, Cellular Defenses Against HIV, will reconstitute and characterize the mechanisms of cellular innate immune sensing and restriction of HIV-1 that occur during the first half of the viral life cycle. Studies in Aim 1 (SERINC Structure, Mechanism, and Antiviral Activity) will build on our recent cryoEM structure of hSERINC3, and our discoveries that restricting SERINCs are nonspecific phospholipid scramblases and that loss of phosphatidyl serine (PS) asymmetry elicits antiviral effects. We hypothesize that SERINCs inhibit HIV-1 entry by altering the natural asymmetry of the virion lipid bilayer. We propose to determine how SERINCs flip lipids, and to test whether SERINCs exert their antiviral activities by altering PS distribution and disrupting Env conformations. Studies in Aim 2 (HIV-1 Recognition and Innate Signaling) will leverage our ability to reconstitute cGAS innate immune sensing of replicating HIV cores in vitro and our discovery that HIV-1 capsid inhibitors can promote innate signaling in infected myeloid cells. We now propose to determine: 1) how viral core structure and stability affect cGAS-mediated detection of reverse transcription, 2) how capsid-binding factors such as PQBP1 contribute to cGAS sensing in myeloid cells, 3) whether and how CA inhibitors can promote cGAS detection of HIV-1, 4) how cell-specific factors regulate cGAS activity, and 5) how the resulting downstream responses restrict HIV-1 infection. Studies in Aim 3 (TRIM Restrictions) will follow from our observation that TRIM5 proteins form hexagonal cages around incoming HIV-1 capsids. Experiments in this Aim are designed to fill fundamental gaps in our understanding of the viral inhibition and signaling processes that follow this initial TRIM5 recognition step, and to discover how host cofactors facilitate or modulate TRIM5 restriction. Studies in Aim 4 (Reconstitution of Other Restrictions) will build on our ability to reconstitute SAMHD1 and APOBEC3G restriction of replicating HIV-1 cores in vitro, and we now propose to reconstitute MxB restriction. These reconstituted reactions will be used to fill gaps in our understanding of restriction mechanisms, cofactors, and regulation, and to examine how capsid inhibitors can enhance MxB activity.