Evaluation of Protective CMV Vaccines in Rhesus Macaques

描述(由申请人提供)：35年来对一种疫苗的追求仍然没有得到满足，这种疫苗对先天性感染人类巨细胞病毒(HCMV)具有保护效力。人巨细胞病毒自然病史的复杂性、免疫保护相关因素的不完全界定以及设计动力充足的临床试验的财政和后勤因素，都是导致缺乏获得许可的人巨细胞病毒疫苗的原因(S)。目前，在人类和恒河猴(RM)中的研究越来越多地认识到：(1)巨细胞病毒和恒河猴巨细胞病毒(RhCMV)进入内皮细胞和上皮细胞的机制与进入成纤维细胞的机制不同，(2)血清免疫者产生针对介导上皮/内皮细胞趋向性的病毒蛋白的中和抗体。对HCMV的研究表明，UL128、131a、130蛋白与Gh和Gl共同形成一个复合体，该复合体通过内吞途径对上皮/内皮细胞的趋向性是必不可少的，其中任何一种蛋白的缺失都极大地限制了HCMV感染Gb介导的细胞进入细胞，如成纤维细胞。来自自然历史和组织培养研究的证据的优势表明，疫苗策略将需要阻断内胞体(UL128复合体)和成纤维细胞(GB)进入途径，以建立足够的保护性免疫水平，以减少或预防先天性感染。HCMV的数据以及我们在表达rMVA分泌形式的RhCMV UL128作为单个亚基以及表征UL128复合体在RhCMV自然历史中的作用方面的进展导致了这样的假设，即针对UL128复合体的疫苗策略将增强对病毒在体液中脱落的限制。基于这一假设，用UL128复合体免疫RhCMV-NAOVE RM将显著降低系统感染病毒的频率和滴度，导致脱毒病毒水平降低。这一假设将在我们的灵长类动物模型中通过以下目的进行严格的验证：HCMV的持久性和致病机制。(1)UL128复合体表达载体和MVA载体的构建及鉴定(2)优化AIM 1中构建的表达载体在猕猴体内的免疫效果，并对感染RhCMV的猕猴的UL128复合体的外周和粘膜抗体应答进行鉴定。(3)用优化的PRIME/BOOST方案从AIM 2开始免疫RhCMV阴性的RM，然后通过皮下或粘膜途径同时进行成纤维细胞和内吞的RhCMV攻击。

DESCRIPTION (provided by applicant): The 35 year quest for a vaccine that confers protective efficacy against congenital infection with human cytomegalovirus (HCMV) remains unmet. Complexities in HCMV natural history, incompletely defined correlates of immune protection and financial and logistical factors in designing sufficiently powered clinical trials all contribute to the absence of a licensed HCMV vaccine(s). There is now increased recognition from studies in both humans and rhesus macaques (RM) that (1) the mechanism of HCMV and rhesus CMV (RhCMV) entry into cells, such as endothelial and epithelial cells, is distinct from the mechanism of fibroblast entry, and (2) seroimmune individuals develop neutralizing antibodies against the viral proteins mediating epithelial/endothelial cell tropism. Studies with HCMV show that the UL128, 131A, 130 proteins together form a complex with gH and gL that is essential for epithelial/endothelial cell tropism via an endocytic pathway, and the absence of any one of these proteins greatly restricts HCMV infection to gB-mediated entry into cells, such as fibroblasts. The preponderance of evidence from natural history and tissue culture studies evidence indicates that vaccine strategies will need to block both the endocytic (UL128 complex) and fibroblast (gB) entry pathways to establish a sufficient level of protective immunity to reduce or prevent congenital infection. The data with HCMV and our progress in both expressing a secreted form of RhCMV UL128 from rMVA as a single subunit and characterizing the role of the UL128 complex in RhCMV natural history lead to the hypothesis that vaccine strategies targeting the UL128 complex will show enhanced restriction of virus shedding in bodily fluids. Based on this hypothesis, vaccination of RhCMV-naove RM with the UL128 complex will have a significantly reduced frequency and titer of systemic infectious virus, resulting in reduced levels of shed virus. This hypothesis will be rigorously tested in our primate model of HCMV persistence and pathogenesis through the following Aims. (1) Construction and characterization of plasmid expression and MVA vectors for the UL128 complex. (2) Optimization of vaccination in macaques with expression vectors constructed in Aim 1, and characterization of peripheral and mucosal antibody responses to the UL128 complex in RhCMV-infected macaques. (3) Immunization of RhCMV-negative RM by the optimized prime/boost regimen from Aim 2 followed by either a subcutaneous or mucosal route of RhCMV challenge capable of both fibroblast and endocytic entry.