Determinants of retroviral replication in non-native hosts for modeling HIV infection

项目摘要/摘要 由于多种物种特异性宿主因素的限制，HIV-1不会持续感染猕猴 有必要使用SIV/HIV-1嵌合病毒(SHIV)作为替代物来模拟猕猴的HIV-1感染。 用SHIV感染猕猴是疫苗和预防研究中最受欢迎的模型系统 因为SHIV编码HIV-1包膜糖蛋白(Env)--HIV-1中和抗体的关键靶标。 由于疫苗的目标是预防新的感染，因此基于循环、传播的环境形式的SHIV 变种作为挑战病毒是人们所希望的。现有的Shiv/Macaque模型通常使用Shiv编码 HIV-1env来自实验室适应的病毒，其中和敏感性不同于循环中的env变异体。 这大大限制了现有的SIV/猕猴模型预测有效干预的能力(S) 人类。开发编码循环环境变异体的SHIV极具挑战性，主要是 因为这样的病毒在猕猴身上复制得很差，如果真的有的话。为了增加它们的复制和致病性，SHIV 需要在猕猴体内通过连续传代广泛适应。猕猴连续传代的过程 导致Env中自适应突变的积累，从而促进强大的复制。 连续传代通常在感染的头两周内进行，在这段时间里，猕猴 建立强有力的I型干扰素(干扰素)对感染的反应。宿主干扰素反应是一种早期障碍 抗感染是因为IFN的产生上调了几个干扰素刺激基因(ISGs)的表达， 这导致了一种“抗病毒状态”的诱导。由某些ISG编码的蛋白质，称为限制 这些因素是阻止跨物种慢病毒传播的有力屏障。因此，猕猴的限制因素 具有阻断SHV感染的潜力，因为它们可以拮抗HIV-1Env。我们最近发现了猕猴 干扰素诱导的跨膜蛋白(IFITM)作为ISGs选择性限制SHIV复制 对循环中的HIV-1环境变异进行编码。 我们的初步结果表明，在猕猴淋巴细胞中，未传代的SIV可被干扰素有效地抑制。 相反，连续传代的SHIV对干扰素具有抵抗力。我们发现，环境中两个N-连接的糖链的损失 在连续传代时足以增加复制并赋予对干扰素的抵抗力。这项研究建议将： 1)表征了连续传代SHIV的环境适应性变化，增加了复制和干扰素 2)确定N-连接的环境多糖在新城疫病毒感染原代猕猴免疫细胞中的作用 3)评价SHIV在体内的作用。 在5个猕猴IFITM同源物中，受干扰素上调，限制未传代，干扰素敏感 希夫。完成后，这项研究将提供驱动选择的宿主-病毒界面的机械性见解， 湿疹病毒在猕猴体内的适应性和致病性。

PROJECT SUMMARY/ABSTRACT HIV-1 does not persistently infect macaques due to restriction by several species-specific host factors necessitating the use of chimeric SIV/HIV-1 viruses (SHIVs) as surrogates to model HIV-1 infection in macaques. Infection of macaques with SHIVs is the most preferred model system for vaccine and prevention studies because SHIVs encode HIV-1 Envelope glycoprotein (Env) – a key target of HIV-1 neutralizing antibodies. Because the goal of vaccines is to prevent new infection, SHIVs based on circulating, transmitted forms of Env variants are desired as challenge viruses. Existing SHIV/macaque models typically employ SHIVs that encode HIV-1 Env from laboratory-adapted viruses, whose neutralization sensitivities differ from circulating Env variants. This significantly limits the ability of the existing SHIV/macaque models to predict efficacious intervention(s) in humans. Development of SHIVs encoding circulating Env variants has been extremely challenging, mainly because such SHIVs replicate poorly in macaques, if at all. To increase their replication and pathogenicity, SHIVs require extensive adaptation in vivo via serial passage in macaques. The process of serial macaque passage results in accumulation of adaptive mutations in Env that facilitates robust replication. Serial passage is typically performed within the first two weeks of infection, a time during which macaques mount a robust type-I interferon (IFN) response to infection. The host IFN response presents an early barrier against infection because production of IFNs upregulates expression of several IFN-stimulated genes (ISGs), which results in induction of an ‘antiviral state’. Proteins encoded by certain ISGs, referred to as restriction factors, act as potent barriers against cross-species lentiviral transmission. Thus, macaque restriction factors have the potential to block SHIV infection as they can antagonize HIV-1 Env. We recently identified macaque interferon-induced transmembrane proteins (IFITMs) as ISGs that selectively restrict replication of SHIVs encoding circulating HIV-1 Env variants. Our preliminary results suggest that unpassaged SHIV is potently inhibited by IFN in macaque lymphocytes. In contrast, serial passaged SHIVs are resistant to IFN. We found that the loss to two N-linked glycans in Env upon serial passage is sufficient to increase replication and confer resistance to IFN. This research proposal will: 1) characterize the adaptive changes in Env of serial passaged SHIVs that increase replication and IFN resistance; 2) determine the role of N-linked Env glycans in SHIV infection of primary macaque immune cell subsets ex vivo, and mucosal transmission and pathogenicity of SHIVs in vivo; and 3) evaluate the contribution of five macaque IFITM homologs, which are upregulated by IFN, in restriction of unpassaged, IFN-sensitive SHIV. Upon completion, this study will provide mechanistic insights at the host-viral interface that drive selection, adaptation, and pathogenicity of SHIVs in macaques.