CMV-vectored Vaccine Approaches to Induce Protective Antibodies to HIV-1 Env

项目摘要 用原型疫苗免疫恒河猴巨细胞病毒阳性猕猴 表达Gag、Retanef、Pol和Env的RhCMV 68 -1-载体的猴免疫缺陷病毒（SIV）疫苗， 在大约50%的动物中有效，受保护的动物几乎完全控制了 用致病性SIV粘膜攻击后的系统性SIV感染。然而，疗效发生在 缺乏疫苗诱导的抗体（Ab）反应，而是与非常规抗SIV相关 MHC-II和MHC-E限制性CD 8 T细胞应答。尽管SIV的控制水平是显著的， CMV疫苗平台的开发对于诱导对SIV的体液应答显然是必要的 Env蛋白：许多人认为对有效疫苗至关重要的反应。条件 目前还不清楚诱导这种期望的Ab应答所必需的条件。我们的初步数据显示， 表达SIV Gag的RhCMV能够诱导Gag特异性抗体，但仅在RhCMV阴性RM中。的 相同的RhCMV-Gag疫苗在RhCMV阳性RM中不诱导可比的Ab应答。这一发现 与先前发表的报告一致，显示SIV Env特异性Ab的诱导可忽略不计或没有诱导。 用RhCMV-Env接种的RhCMV阳性RM。这些发现表明，预先存在的RhCMV免疫 可能是一个关键因素，限制抗体诱导疫苗抗原由RhCMV载体提供，使用 基于单独的RhCMV SIV疫苗的方案。原型疫苗抗原表达量 RhCMV疫苗可能是另一个因素，特别是对于RhCMV-Env疫苗， 设计用于“毒性”Env基因的低表达。我们提出，稳健的抗原表达也将是 在用RhCMV-SIV疫苗免疫的RhCMV阳性RM中，抗体诱导至关重要。当前的提议是 i）促进对RhCMV-载体SIV的体液应答的方法的探索性研究 面对预先存在的RhCMV免疫的疫苗，和ii）稳定增加SIV抗原的策略 表情这项研究是基于我们的总体假设，即预先存在的RhCMV免疫和 SIV抗原表达的大小是导致限制性体液应答的关键可变因素 在RhCMV阳性猕猴中观察到。目的1研究SIV特异性抗体在RhCMV阳性细胞中的诱导作用 猕猴通过两种不同的初免-加强方案，利用重组亚单位蛋白（Env和Gag）和 RhCMV-SIV疫苗。将检查免疫动物的循环和粘膜Ab应答、B细胞 以及血液和淋巴结中的T细胞反应。目的2关注候选人RhCMV人的产生 免疫缺陷病毒（HIV）-1 Env疫苗旨在使用新策略增强Env表达 最近描述了一种改良的RhCMV载体埃博拉病毒疫苗。建议的研究将及时提供 为将来研究包括重组的RhCMV-SHIV联合疫苗方案奠定了基础 Env蛋白与RhCMV-Env疫苗一起设计用于改善CMV-HIV疫苗保护效力。

Project Summary Immunization of rhesus cytomegalovirus (RhCMV)-positive rhesus macaques (RM) with the prototype RhCMV68-1-vectored simian immunodeficiency virus (SIV) vaccine expressing Gag, Retanef, Pol and Env is effective in approximately 50% of animals, with protected animals demonstrating almost complete control of systemic SIV infection following mucosal challenge with pathogenic SIV. However, efficacy occurs in the absence of vaccine-induced antibody (Ab) responses, and is instead associated with unconventional anti-SIV MHC-II and MHC-E-restricted CD8 T cell responses. Although this level of SIV control is remarkable, further development of the CMV vaccine platform will clearly be necessary to induce a humoral response to the SIV Env protein: a response considered by many to be essential for an efficacious vaccine. The conditions necessary for induction of such desired Ab responses are currently unclear. Our preliminary data indicate that RhCMV expressing SIV Gag is capable of inducing Gag-specific Ab, but only in RhCMV-negative RM. The same RhCMV-Gag vaccine does not induce comparable Ab responses in RhCMV-positive RM. This finding is consistent with previous published reports showing either negligible or no induction of SIV Env-specific Ab in RhCMV-positive RM vaccinated with RhCMV-Env. These findings suggest that pre-existing RhCMV immunity may be one critical factor that restricts Ab induction to vaccine antigens delivered by RhCMV vectors using protocols based on RhCMV SIV vaccines alone. Magnitude of vaccine antigen expression from prototype RhCMV vaccines may be another factor, particularly for the RhCMV-Env vaccine that was intentionally designed for low expression of the “toxic” Env gene. We propose that robust antigen expression will also be critical for Ab induction in RhCMV-positive RM immunized with RhCMV-SIV vaccines. The current proposal is an exploratory investigation into i) approaches to promote humoral responses to RhCMV-vectored SIV vaccines in the face of pre-existing RhCMV immunity, and ii) strategies to stably increase SIV antigen expression. This investigation is based on our overall hypothesis that pre-existing RhCMV immunity and magnitude of SIV antigen expression are critical modifiable factors contributing to restricted humoral responses observed in RhCMV-positive macaques. Aim 1 will investigate induction of SIV-specific Ab in RhCMV-positive macaques by two distinct prime-boost protocols that utilize recombinant subunit proteins (Env and Gag) and RhCMV-SIV vaccines. Immunized animals will be examined for circulating and mucosal Ab responses, B cell and T cell responses in blood and lymph nodes. Aim 2 focuses on the generation of candidate RhCMV human immunodeficiency virus (HIV)-1 Env vaccines designed to enhance Env expression using a novel strategy recently described for a modified RhCMV-vectored Ebola virus vaccine. Proposed studies will provide a timely foundation for future investigation into combination RhCMV-SHIV vaccine protocols that include recombinant Env proteins together with RhCMV-Env vaccines designed for improved CMV-HIV vaccine protective efficacy.