Oral Reovirus-Based Vaccines for Prevention of HIV-1 Disease

描述（由申请方提供）：目前大多数HIV-1候选疫苗都是复制缺陷型，肌内给药，不太可能在粘膜表面诱导免疫应答。拟议研究的目标是开发一种口服的复制能力呼肠孤病毒为基础的HIV-1疫苗，刺激粘膜和全身体液免疫反应，对广泛中和表位的HIV-1。呼肠孤病毒感染肠粘膜以刺激有效的免疫应答，在人体中是天然减毒的，并且可以被操纵以表达疫苗抗原。这些关键特征使呼肠孤病毒成为理想的HIV-1疫苗载体。新的疫苗载体将携带编码HIV-1包膜糖蛋白gp 41的近膜外区（MPER）的HIV-1序列，该序列在gp 41三聚体的基础上形成α-螺旋卷曲螺旋。重要的是，针对MPER的单克隆抗体（MAb）在体外中和HIV-1原代分离株的感染，并在被动免疫的非人灵长类动物中保护免受HIV-1感染。该提议的中心假设是，插入三聚体呼肠孤病毒附着蛋白s1的α-螺旋区的MPER序列将保留天然免疫原性并引发针对HIV-1的中和抗体应答。提出了三个具体的目标，以测试中心假设，并开发呼肠孤病毒为基础的HIV-1疫苗。在特定目标1中，将产生重组呼肠孤病毒，其在呼肠孤病毒s1的表面暴露区域内以天然三聚体构象展示MPER序列。将检测表达MPE的呼肠孤病毒的复制效率、连续传代期间的稳定性以及与MPE特异性mAb的相互作用。第一代呼肠孤病毒载体已被改造，其中MPER序列纳入s1保留天然MPER特异性mAb表位，表明所提出的方法是可行的。在特定目标2中，将检测重组呼肠孤病毒载体接种家兔后诱导的体液免疫应答。将检测免疫家兔血清中是否存在MPR特异性抗体以及中和HIV-1 Env假型病毒和原代分离株感染的能力。将根据初始免疫原性研究的结果设计第二代载体。在特定目标3中，将检测在家兔中诱导最强HIV-1中和体液免疫应答的呼肠孤病毒载体在恒河猴中诱导体液免疫应答的情况。将检测免疫猕猴的血清中的MPER特异性抗体和HIV-1中和能力。这项研究将导致更好地了解疫苗的要求，诱导针对HIV-1的有效粘膜免疫反应，并促进一类新的HIV-1疫苗的开发，靶向粘膜部位。 公共卫生相关性：HIV-1感染是全世界传染病发病率和死亡率的主要原因，并且预防HIV-1感染的疫苗不可用。拟议的研究将开发新的口服呼肠孤病毒为基础的HIV-1疫苗，显示天然构象的中和表位。这项工作将推进关于诱导粘膜免疫的知识，并建立在非人灵长类动物中进行攻毒研究和在人类中进行免疫原性试验的可行性。

DESCRIPTION (provided by applicant): Most current HIV-1 vaccine candidates are replication-defective, administered intramuscularly, and unlikely to induce immune responses at mucosal surfaces. The goal of the proposed research is to develop an orally administered replication-competent reovirus-based HIV-1 vaccine that stimulates mucosal and systemic humoral immune responses against broadly neutralizing epitopes of HIV-1. Reovirus infects intestinal mucosa to stimulate potent immune responses, is naturally attenuated in humans, and can be manipulated to express vaccine antigens. These key features make reovirus an ideal HIV-1 vaccine vector. The new vaccine vector will harbor HIV-1 sequences encoding the membrane-proximal external region (MPER) of HIV-1 envelope glycoprotein gp41, which form a-helical coiled coils at the base of the gp41 trimer. Importantly, monoclonal antibodies (MAbs) directed against MPER neutralize infection by HIV-1 primary isolates in vitro and protect against HIV-1 infection in passively immunized non-human primates. The central hypothesis of this proposal is that MPER sequences inserted into a-helical regions of trimeric reovirus attachment protein s1 will retain native immunogenicity and elicit neutralizing antibody responses against HIV-1. Three specific aims are proposed to test the central hypothesis and develop reovirus-based HIV-1 vaccines. In Specific Aim 1, recombinant reoviruses will be generated that display MPER sequences in native trimeric conformation within surface-exposed regions of reovirus s1. MPER-expressing reoviruses will be tested for replication efficiency, stability during serial passage, and interactions with MPER-specific mAbs. A first-generation reovirus vector has been engineered in which MPER sequences incorporated into s1 retain the native MPER-specific mAb epitope, indicating that the proposed approach is feasible. In Specific Aim 2, recombinant reovirus vectors will be tested for induction of humoral immune responses after inoculation into rabbits. Sera from immunized rabbits will be tested for the presence of MPER-specific antibodies and the capacity to neutralize infection by HIV-1 Env-pseudotyped viruses and primary isolates. Second-generation vectors will be designed based on results of the initial immunogenicity studies. In Specific Aim 3, the reovirus vector that induces the most potent HIV-1 neutralizing humoral immune responses in rabbits will be tested for induction of humoral immune responses in rhesus macaques. Sera from immunized macaques will be tested for MPER-specific antibodies and HIV-1 neutralizing capacity. This research will lead to a better understanding of vaccine requirements for the induction of potent mucosal immune responses against HIV-1 and foster development of a new class of HIV-1 vaccines that target mucosal sites. PUBLIC HEALTH RELEVANCE: HIV-1 infection is a leading cause of infectious disease morbidity and mortality worldwide, and vaccines to prevent HIV-1 infection are not available. The proposed research will develop new orally administered reovirus-based HIV-1 vaccines that display neutralizing epitopes in native conformation. This work will advance knowledge about induction of mucosal immunity and establish the feasibility for challenge studies in non-human primates and immunogenicity trials in humans.