Elicitation of broad immunity using VLPs with consensus envs

描述(申请人提供)：艾滋病疫苗开发面临的最大挑战之一是不同地理位置的艾滋病毒-1传播人群之间的内在多样性，以及开发能够引起对变异的艾滋病毒-1毒株的持久保护性免疫的疫苗的必要性。虽然在所有病毒蛋白中都观察到了变异，但最大的多样性局限于病毒包膜糖蛋白，这显然反映了这些蛋白在激发宿主免疫识别和反应方面的主导作用，导致包膜蛋白在持续感染过程中的进行性进化。在目前的应用中，我们设计了新型的病毒样颗粒(VLP)免疫原，可以优化粘膜和系统环境特异性免疫反应，以评估通过阴道暴露(全球最常见的HIV-1传播途径)对恒河猴免受异源SIV攻击的保护。我们构建了从SHIV基因序列中表达VLP的DNA载体，其中每个DNA构建体都从一个DNA质粒中表达一个非感染性慢病毒VLP。每个VLP基因插入物表达巨细胞病毒即刻早期启动子通过质粒DNA表达的gag、pol1、env、VPU、Tat和rev基因序列。因此，VLP mRNA的剪接和核输出将受到病毒机制的控制，翻译的蛋白将有效地从转基因细胞中分泌VLP。VLP的主干中已经设计了几个安全突变，以符合美国食品和药物管理局(FDA)关于人类使用HIV-1 DNA疫苗的指南。在这项提议中，表达SHV VLP的基因插入将从DNA中表达。此外，SHIV VLP将从转基因相同DNA质粒的灵长类细胞上清液中提纯。我们建议利用HIV-1的B分支或C分支囊膜糖蛋白构建和鉴定一个SHV VLP-DNA质粒库，每个质粒库包含一个不同的CCR5(RS)。猕猴将以优质/强化免疫方案(DNA优质/粒子强化)接种，以诱导体液和细胞免疫，并将评估对异源B分支Shiv攻击的保护作用。这项建议的目的是评估和比较具有初级包膜的VLP免疫原与具有代表一致包膜序列(分支B或分支C)的包膜的VLP免疫原诱导免疫反应的情况。此外，还将评估SIV-1 VLP对异源SIV挑战的免疫和保护作用。使用共识包膜作为天然寡聚体，可以比较共识包膜与与挑战病毒不匹配的初级寡聚体包膜的混合物所引起的保护性免疫。最后，包含代表分支C(ConC)一致包膜序列的SHIV-1 VLP所激发的免疫应答的广度和保护效果将通过分支B SHIV挑战来评估。

DESCRIPTION (provided by applicant): Among the greatest challenges facing AIDS vaccine development is the intrinsic diversity among circulating populations of HIV-1 in various geographical locations and the need to develop vaccines that can elicit enduring protective immunity to variant HIV-1 strains. While variation is observed in all of the viral proteins, the greatest diversity is localized to the viral envelope glycoproteins, evidently reflecting the predominant role of these proteins in eliciting host immune recognition and response that result in progressive evolution of the envelope proteins during persistent infection. In the current application, we have designed novel virus-like particle (VLP) immunogens that can optimize mucosal and systemic Env-specific immune responses for evaluation against protection from heterologous SHIV challenge in rhesus macaques by vaginal exposure (the most common route of HIV-1 transmission worldwide). We have constructed DNA plasmids to express VLPs from SHIV gene sequences where each DNA construct expresses a non-infectious lentiviral VLP from a single DNA plasmid. Each VLP gene insert expresses the gag, pol, env, vpu, tat, and rev gene sequences that are expressed from a cytomegalovirus immediate-early promoter via plasmid DNA. Thus, VLP mRNA splicing and nuclear export will be controlled by viral mechanisms and translated proteins efficiently secrete VLPs from transfected cells. Several safety mutations have been engineered into the backbone of the VLP to match the U.S. Food and Drug Administration guidelines for the use of HIV-1 DNA vaccines for human use. In this proposal, gene inserts expressing SHIV VLPs will be expressed from DNA. In addition, SHIV VLPs will be purified from the supernatant of primate cells transfected with the same DNA plasmids. We propose to construct and characterize a library of SHIV VLP-DNA plasmids, each containing a different CCR5 (RS)-utilizing clade B or clade C envelope glycoprotein of HIV-1. Rhesus macaques will be vaccinated in a prime/boost regimen (DNA prime/particle boost) for the elicitation of both humoral and cellular immunity, and protection from heterologous clade B SHIV challenge will be evaluated. The goals of this proposal are to assess and compare the induction of immune responses between VLP immunogens with primary envelopes to the elicitation of immunity by VLP immunogens with an envelope representing the consensus envelope sequences (clade B or clade C). SHIV-1 VLPs will also be assessed for elicitation of immunity and protection to a heterologous SHIV challenge. The use of a consensus envelope as a native oligomer allows for the comparison of protective immunity elicited by consensus envelopes to that elicited by a mixture of primary oligomeric envelopes that are mismatched to the challenge virus. Finally, the breadth and protective efficacy of immune responses elicted by a SHIV-1 VLP containing an envelope representing the consensus envelope sequence of clade C (Con C) will be evaluated with a clade B SHIV challenge.