Elicitation of broad immunity using VLPs with consensus envs

描述（由申请人提供）：艾滋病疫苗开发面临的最大挑战之一是不同地理位置的HIV-1流行人群的内在多样性，以及开发能够对变异HIV-1毒株产生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变异，但最大的多样性定位于病毒包膜糖蛋白，这显然反映了这些蛋白在引发宿主免疫识别和反应中所起的主导作用，从而导致包膜蛋白在持续感染期间的逐步进化。在目前的应用中，我们设计了新的病毒样颗粒（VLP）免疫原，可以优化粘膜和全身环境特异性免疫反应，以评估恒河猴阴道暴露（世界上最常见的HIV-1传播途径）对异源SHIV攻击的保护作用。我们构建了从SHIV基因序列中表达vllp的DNA质粒，其中每个DNA质粒表达来自单个DNA质粒的非传染性慢病毒VLP。每个VLP基因插入表达gag、pol、env、vpu、tat和rev基因序列，这些基因序列是由巨细胞病毒立即早期启动子通过质粒DNA表达的。因此，VLP mRNA剪接和核输出将受到病毒机制的控制，翻译蛋白可以有效地从转染细胞中分泌VLP。为了符合美国食品和药物管理局关于人类使用HIV-1 DNA疫苗的指导方针，已经在VLP的骨干中设计了几个安全突变。在这个提议中，表达SHIV VLPs的基因插入将从DNA中表达。此外，SHIV VLPs将从转染相同DNA质粒的灵长类细胞上清中纯化。我们建议构建并表征SHIV VLP-DNA质粒库，每个质粒含有不同的CCR5 (RS)-利用HIV-1进化支B或进化支C包膜糖蛋白。将对恒河猴接种一种初始/增强方案（DNA初始/颗粒增强），以激发体液和细胞免疫，并评估对异源B支SHIV攻击的保护作用。本提案的目的是评估和比较具有初级包膜的VLP免疫原与具有代表共识包膜序列（分支B或分支C）的包膜的VLP免疫原之间的免疫应答诱导。还将评估SHIV-1 VLPs对异源SHIV攻击的免疫激发和保护作用。使用共识包膜作为天然寡聚物，可以将共识包膜引起的保护性免疫与与攻毒病毒不匹配的初级寡聚包膜混合物引起的保护性免疫进行比较。最后，将用B支系SHIV攻击来评估含有代表C支系一致包膜序列的SHIV-1 VLP引发的免疫应答的广度和保护功效。

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.