Efficacy of Strain 68-1 RhCMV Vectors Expressing 5' Leader Polypeptides

 描述（由申请人提供）：开发有效的HIV/AIDS疫苗仍然是国际卫生的一个高度优先事项，因为它是遏制艾滋病流行的最具成本效益的手段。在这个时间点上，很少有一般的HIV/AIDS疫苗策略作为预防性HAV/AIDS疫苗仍然可以用于临床开发-也就是说，在临床前研究中显示出有希望的功效并且在人体临床试验中未被证明无效的疫苗平台。在这些方法中，我们的小组开发了持续巨细胞病毒（CMV）衍生的载体用于引发高频率，无限期持续的HIV/SIV特异性效应记忆T细胞应答的方法。在临床前恒河猴（RM）- SIV模型中，我们已经证明，在粘膜SIV攻击后，>50%的用菌株68-1 RhCMV/SIVgag、/SIVpol、/SIVenv、/SIVrevtatnef载体接种的猴显示出完全的、持久的保护，并通过病毒学和免疫学标准最终清除。保护作用可能是由效应T细胞拦截新生免疫球蛋白的能力决定的。 获得后立即感染HIV/SIV（由于需要记忆扩增和效应子分化，无应答延迟）。如果这一假设是正确的，人们可以推测，如果最早的HIV/SIV免疫原可以在最初感染后数小时内靶向，则可以实现更大的疗效。最近发现了一组新的5'前导序列编码的HIV和SIV多肽，并且这些多肽在HIV/SIV感染的细胞中非常早地表达并且具有高度免疫原性。因此，考虑到每个剪接和未剪接的HIV/SIV mRNA都含有5'前导序列，因此5'前导多肽（5 '-LP）是非常有吸引力的疫苗靶标，并且因此由该区域编码的多肽将在感染后迅速和早期普遍表达。因此，本文提出的研究的主要目标是确定表达SIV 5'前导多肽的RhCMV载体是否可以保护恒河猴免受高致病性SIVmac 239的粘膜攻击，以及这些载体与表达常规SIV开放阅读框的载体组合是否可以增强RhCMV载体疫苗的整体保护功效。（i）鉴定68-1株RhCMV/5 ′-LP载体在恒河猴中的免疫原性，并使用该免疫原性，结合生物化学分析，确定SIV感染的CD 4 + T细胞表达的5 ′-LP表位;（ii）确定菌株68-1 RhCMV/5 '-LP载体疫苗接种对抗限制剂量直肠内SIV攻击的效力;并且如果满足进行/不进行标准，（iii）测定含有菌株68-1 RhCMV/5 ′-LP载体和表达Gag、Rev/Nef/达特、Pol、Env的菌株68-1 RhCMV载体的组合疫苗的免疫原性和效力。

 DESCRIPTION (provided by applicant): The development of an effective HIV/AIDS vaccine remains a high international health priority as the most cost-effective means to stem the AIDS pandemic. At this point in time, there are very few general HIV/AIDS vaccine strategies that remain viable for clinical development as a prophylactic HAV/AIDS vaccine - that is, vaccine platforms that have shown promising efficacy in preclinical studies and not been proved ineffective in human clinical trials. Among these is the approach developed by our group in which persistent Cytomegalovirus (CMV)-derived vectors are used to elicit high-frequency, indefinitely persistent HIV/SIV- specific effector-memory T cell responses. In the preclinical rhesus macaque (RM) - SIV model, we have demonstrated that after mucosal SIV challenge >50% of monkeys vaccinated with strain 68-1 RhCMV/SIVgag, /SIVpol, /SIVenv, /SIVrevtatnef vectors show complete, durable protection and eventual clearance by virologic and immunologic criteria. Protection is likely determined by the ability of effector T cells to intercept a nascent HIV/SIV infection immediately upon acquisition (with no response delay due to requirement for anamnestic expansion and effector differentiation). If this assumption is correct one could speculate that a greater efficacy could be achieved if the earliest HIV/SIV immunogens could be targeted within hours after initial infection. Recently a novel set of 5' leader sequence-encoded HIV and SIV polypeptides was discovered, and these polypeptides are expressed very early in HIV/SIV-infected cells and were highly immunogenic. Therefore, the 5' leader polypeptides (5'-LP) are an extremely attractive vaccine target considering that every spliced and unspliced HIV/SIV mRNA contains the 5' leader sequence, and thus polypeptides encoded from this region will be ubiquitously expressed rapidly and early following infection. Thus, the major objective of the research proposed here will be to determine whether RhCMV vectors expressing SIV 5' leader polypeptides can protect rhesus macaques from mucosal challenge with highly pathogenic SIVmac239, and if these vectors in combination with vectors expressing conventional SIV open reading frames, can enhance the overall protective efficacy of the RhCMV-vectored vaccine. These objectives will be accomplished by experimentally addressing the following Specific Aims: (i) To characterize the immunogenicity of strain 68-1 RhCMV/5'-LP vectors in rhesus macaques and to use this immunogenicity, in combination with biochemical analysis, to define the 5'-LP epitopes expressed by SIV-infected CD4+ T cells; (ii) To determine the efficacy of strain 68-1 RhCMV/5'-LP vector vaccination against limiting-dose, intra-rectal SIV challenge; and if Go/No-Go criteria are met, (iii) To determine the immunogenicity and efficacy of a combination vaccine containing both strain 68-1 RhCMV/5'- LP vectors and strain 68-1 RhCMV vectors expressing Gag, Rev/Nef/Tat, Pol, Env.