Apobec3 and the Neutralizing Antibody Response Against Pathogenic Retroviruses

摘要 尽管经过几十年的研究，保护人类免受HIV-1感染的免疫学相关性， SIV在非人灵长类动物中的感染仍然知之甚少。相反，关于Friend逆转录病毒（FV）的研究 小鼠感染强调了中和抗体应答在疾病恢复中的重要性， 疫苗保护，这一反应被广泛认为是成功的HIV-1疫苗的关键。有趣的是 FV感染中的中和抗体应答受关键宿主基因Rfv3的显著影响。我们最近 Rfv3被鉴定为Apobec3，一种有效的先天性限制因子，可以抵抗广泛的逆转录病毒 包括HIV-1（圣地亚哥ML等人，2008年）。Science 321：1343 - 6）。这一发现揭示了一个意想不到的联系 在免疫反应的先天和体液之间，这可能对HIV-1有重要意义。 疫苗研发。我们在这个提案中的总体目标是探索Apobec 3之间的迷人联系 活性和针对病原性逆转录病毒感染的中和抗体应答：小鼠， 猴子和人类在特异性目的1中，Apobec3/Rfv3表型的潜在机制将是 在FV鼠模型中解剖。这将涉及对病毒动力学、干扰素调节 野生型与Apobec3缺陷型小鼠的病理学，以及中和抗体的详细表征。 针对FV包膜蛋白的抗体。由于猿和人类的Apobec3同源物被阻止， 通过慢病毒Vif蛋白，我们假设减弱Vif功能可以拯救Apobec 3， 改善中和抗体反应。在特异性目的2中，野生型和Vif减毒SIV和SHIV 菌株将用于感染恒河猴。Apobec3功能和中和抗体动力学，效价， 从连续的血液样品中监测宽度和表位特异性。最后，Apobec3函数具有 它与HIV-1耐药性有关，但它对HIV-1抗体反应的影响仍然未知。近期 因此，从HIV-1感染的最早阶段获得样本， 将先天Apobec3功能与中和抗体产生联系起来的机会。在具体目标3中， 我们建议检查Vif功能多样性、Apobec3诱导、干扰素 调节，以及HIV-1感染中的免疫导向抗体发展。我们已经召集了一个 具有Apobec 3/Vif生物学、鼠逆转录病毒免疫学、SIV 和SHIV猕猴模型系统，以及HIV-1的发病机制。我们假设理解 Apobec3介导的先天免疫可能会产生有希望的和"盒子外"的见解，用于增强 抗HIV-1感染的中和抗体反应。

ABSTRACT Despite decades of research, the immunological correlates of protection against HIV-1 infection in humans or SIV infection in nonhuman primates remain poorly understood. In contrast, studies on Friend retrovirus (FV) infection in mice highlighted the importance of the neutralizing antibody response in disease recovery and vaccine protection, a response widely considered as critical for a successful HIV-1 vaccine. Interestingly, the neutralizing antibody response in FV infection is significantly influenced by a key host gene, Rfv3. We recently identified Rfv3 as Apobec3, a potent innate restriction factor that counteracts a broad range of retroviruses including HIV-1 (Santiago ML et al. 2008. Science 321: 1343-6). This discovery revealed an unexpected link between the innate and humoral arms of the immune response that may have important implications for HIV-1 vaccine development. Our overall objective in this proposal is to probe the fascinating link between Apobec3 activity and the neutralizing antibody response against pathogenic retroviral infections in three species: mice, monkeys and humans. In Specific Aim 1, the underlying mechanism of the Apobec3/Rfv3 phenotype will be dissected in the FV murine model. This will involve in-depth studies on virus dynamics, interferon regulation and pathology in wild type versus Apobec3-deficient mice, and a detailed characterization of neutralizing antibodies against the FV envelope protein. Since the simian and human homologues of Apobec3 are thwarted by the lentiviral Vif protein, we hypothesize that attenuating Vif function may rescue Apobec3 and improve neutralizing antibody responses. In Specific Aim 2, wild type and Vif-attenuated SIV and SHIV strains will be used to infect rhesus macaques. Apobec3 function and neutralizing antibody kinetics, potency, breadth and epitope specificity will be monitored from sequential blood samples. Finally, Apobec3 function has been linked to HIV-1 resistance, but its impact on HIV-1 antibody responses remains unknown. The recent acquisition of samples from the earliest stages of HIV-1 infection therefore opens an unprecedented opportunity to link innate Apobec3 function and neutralizing antibody development. Thus, in Specific Aim 3, we propose to examine the relationship between Vif functional diversity, Apobec3 inducibility, interferon regulation, and envelope-directed antibody development in HIV-1 infection. We have assembled a highly qualified team of investigators with expertise in Apobec3/Vif biology, murine retrovirus immunology, the SIV and SHIV macaque model systems, and HIV-1 pathogenesis for this project. We postulate that understanding Apobec3-mediated innate immunity may yield promising and "outside the box" insights for augmenting neutralizing antibody responses against HIV-1 infection.