Targeting 5' leader-encoded defective ribosomal products for HIV T cell vaccines

 描述（由申请方提供）：最近在非人灵长类动物中进行的疫苗研究已经证明了病毒特异性CD 8 T细胞应答抑制或根除SIV感染的潜力。恒河猴CMV（RhCMV）和其他持续和非持续复制载体对这些目标有很大贡献，但即使是目前最好的免疫原也会使大约50%的动物不受保护。实现T细胞疫苗的全部潜力， 需要开发新的免疫原，其引发足够大小、宽度、功能和组织分布的T细胞应答， 最好在感染的最初几小时和几天开始。我们在这里提出了一个新的疫苗概念，建立在最近的临床前疫苗试验的成功。这种新策略是基于我们实验室最近的意外发现，即从HIV-1和广泛不同的SIV株mac 251/239、E660、SL 92 b和FTq的5' RNA前导序列（以前称为5'“非翻译”区）表达一组新的进化上保守的多肽，并且这些肽在体内具有高度免疫原性。HIV和SIV 5'前导编码的多肽代表了一类新的缺陷核糖体产物（DRiP），其在其他病毒感染中构成抗原呈递肽的重要来源，并充当病原体入侵的早期哨兵。由于5' RNA前导序列是每个剪接和未剪接的HIV-1和SIV RNA信息的一部分，因此它是每个生产性感染细胞中最早和最丰富的vRNA种类，使得由该区域编码的肽作为潜在的疫苗靶点具有吸引力。目前的拨款提案将通过测试以下假设来探索这种潜力：由HIV-1和SIV的5' RNA前导序列编码的新型多肽通常在自然感染中表达并具有免疫原性，并且当由RhCMV载体疫苗表达时，将引发T细胞应答，从而在印度恒河猴-SIVmac 239感染模型中提供保护。具体目标是：（i）确定HIV-1和SIV感染中T细胞对5'前导肽应答的普遍性、广度和动力学;（ii）研究5'前导肽在感染细胞上的表达和呈递的动力学以及T细胞识别和病毒控制的效率;（iii）探索5'前导编码的T细胞表位的保守性和与病毒逃逸相关的适应性成本;和（iv）评价5 ′前导序列编码的多肽作为疫苗的免疫原性和保护效力。这些研究的意义超出了HIV/AIDS疫苗研究：通过证明一类新的5' RNA前导编码的DRiP的表达和免疫识别，我们发现了与HIV-1免疫发病机制、潜伏期和根除研究相关的慢病毒基因表达的新范式。

 DESCRIPTION (provided by applicant): Recent vaccine studies in nonhuman primates have demonstrated the potential for virus-specific CD8 T cell responses to constrain or eradicate SIV infection. Rhesus CMV (RhCMV) and other persistently and non- persistently replicating vectors have contributed substantially toward these goals, but even the best current immunogens leave approximately 50% of animals unprotected. Realization of the full potential of T cell vaccines will require the development of novel immunogens that elicit T cell responses of sufficient magnitude, breadth, functionality and tissue distribution that virus replication can be effectively contained, preferably beginning in the initial hours and days of infection. We propose here a novel vaccine concept that builds upon the successes of recent preclinical vaccine trials. This new strategy is based on our laboratories' very recent and unexpected discovery that a novel set of evolutionarily conserved polypeptides is expressed from the 5' RNA leader sequence - previously termed the 5' "untranslated" region - of HIV-1 and the widely divergent SIV strains mac251/239, E660, SL92b and FTq, and that these peptides are highly immunogenic in vivo. HIV and SIV 5' leader-encoded polypeptides represent a new class of defective ribosomal products (DRiPs), which in other viral infections constitute an important source of peptides for antigen presentation and act as early sentinels of pathogen invasion. Because the 5' RNA leader sequence is part of every spliced and unspliced HIV-1 and SIV RNA message, it is the earliest and most abundant vRNA species in every productively infected cell, making peptides encoded by this region attractive as potential vaccine targets. The current grant proposal will explore this potential by testing the following hypothesis: Novel polypeptides encoded by 5' RNA leader sequences of HIV-1 and SIV are commonly expressed and are immunogenic in natural infection, and when expressed by a RhCMV vectored vaccine, will elicit T cell responses that confer protection in the Indian rhesus macaque - SIVmac239 infection model. Specific aims are: (i) To determine the prevalence, breadth and dynamics of T cell responses to 5' leader peptides in HIV-1 and SIV infection; (ii) To investigate the kinetics of expression and presentation of 5' leader peptides on infected cells and the efficiency of T cell recognition and virus control; (iii) To explore the conservation of 5' leader-encoded T cell epitopes and fitness costs associated with virus escape; and (iv) To evaluate the immunogenicity and protective efficacy of 5' leader-encoded polypeptides as vaccines. The implications of these studies extend beyond HIV/AIDS vaccine research: by demonstrating the expression and immunological recognition of a new class of 5' RNA leader-encoded DRiPs, we have uncovered a new paradigm of lentiviral gene expression relevant to studies of HIV-1 immunopathogenesis, latency and eradication.