VIRUS-LIKE PARTICLES WITH STABILIZED TRIMERIC ENVELOPE FOR PRIME BOOST IMMUNIZATION

迄今为止，唯一一项显示出对艾滋病毒感染有任何保护作用的疫苗试验（RV 144）是基于 痘病毒引发蛋白加强免疫策略虽然取得的疗效是适度的（~31%）， 这些发现为寻求改进初免-加强免疫方法提供了强有力的理由， 以更好地了解所获得的保护性免疫的性质。在本申请中，我们寻求改进 通过三种独立方法的组合对初次加强免疫的反应：（i）呈现 病毒样颗粒（VLP）上稳定的三聚体Env刺突作为牛痘病毒初免和VLP的免疫原 加强;（ii）掺入来自多种分离物的稳定的三聚体包膜（Env）作为多价VLP免疫原 增加响应的广度;以及（iii）探索可能增加SOSIP数量的方法 VLP上的三聚体尖峰。我们的总体工作假设是， 通过优化免疫原和免疫方案，提高免疫广度 中和和非中和抗体反应的效力， 在人和/或非人灵长类动物模型中的保护作用。具体来说，我们假设，通过呈现 稳定的三聚体Env在痘病毒蛋白质初免加强方案中对VLP的作用，我们将能够增强 中和抗体反应，并通过使用多价Env和增加Env峰的密度 在VLP免疫原上，我们将进一步扩大反应的广度和效力。的 中和和非中和抗体应答的广度和效力增强， 包括V1/V2导向的抗体和介导抗病毒效应子功能的抗体，如ADCC， 将有助于痘病毒-蛋白质初免加强免疫平台的保护效力。 本研究的具体目的是：（1）确定其结构及其抗原性和免疫原性 （2）为了确定来自多种来源的稳定化Env三聚体是否具有稳定化的Env三聚体， 分离物可以掺入VLP上，并且如果这种多价疫苗在用于初免/加强方案时将 增加Nab和非Nab反应的宽度;（3）确定细胞质尾部修饰是否会 增加VLP上稳定的Env尖峰的密度，并且如果增加Env密度将增强宽度和 Env特异性应答的效力;和（4）检查是否从Env特异性应答中向下选择免疫方案， 先前在兔子身上的研究可以应用到猕猴身上。如果成功，从这些研究中获得的见解 将为疫苗和疫苗策略的临床开发提供信息，这些疫苗和疫苗策略可能比 用于RV 144以防止人类感染HIV-1。

To date, the only vaccine trial (RV144) that has shown any protective efficacy against HIV acquisition is based on a poxvirus prime–protein boost immunization strategy. Although the efficacy achieved was modest (~31%), these findings provide a strong rationale to seek improvements for the prime-boost immunization approach and to gain better insight on the nature of the protective immunity achieved. In this application, we seek to improve responses to prime boost immunization by a combination of three independent approaches: (i) to present stabilized trimeric Env spikes on virus-like particles (VLP) as immunogens for vaccinia virus prime and VLP boost; (ii) to incorporate stabilized trimeric envelope (Env) from multiple isolates as polyvalent VLP immunogen to increase the breadth of response; and (iii) to explore approaches that may increase the number of SOSIP trimer spikes on VLP. Our overall working hypothesis is that the protective efficacy of prime-boost immunization can be improved by optimizing immunogen and immunization regimen to enhance the breadth and potency of both neutralizing and non-neutralizing antibody responses that have been associated with protection in human and/or non-human primate models. Specifically, we hypothesize that by presenting stabilized trimeric Env on VLP in the poxvirus-protein prime boost regimen, we will be able to enhance neutralizing antibody responses, and by using polyvalent Env and increasing the density of Env spikes on the VLP immunogens, we will further amplify the breadth and the potency of response. The enhanced breadth and potency of both neutralizing and non-neutralizing antibody responses, including V1/V2-directed antibodies and those that mediate antiviral effector functions, such as ADCC, will contribute to the protective efficacy of the poxvirus-protein prime boost immunization platform. The Specific Aims of this proposal are: (1) To determine the structure and the antigenic and immunogenic profiles of stabilized Env trimers incorporated into VLP; (2) To determine if stabilized Env trimers from multiple isolates can be incorporated on VLP and if such polyvalent vaccines when used in a prime/boost regimen will increase the breadth of Nab and non-Nab responses; (3) To determine if cytoplasmic tail modifications will increase the density of stabilized Env spikes on VLP and if increased Env density will enhance the breadth and potency of Env specific responses; and (4) To examine if immunization regimens down-selected from the preceding studies in rabbits can be translated to macaques. If successful, insights obtained from these studies will inform the clinical development of vaccines and vaccine strategies that may be more effective than those used in RV144 to prevent HIV-1 acquisition in humans.