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

描述（由申请人提供）：目前大多数HIV-1候选疫苗是复制缺陷的，肌肉注射，不太可能在粘膜表面诱导免疫反应。拟议研究的目标是开发一种口服的基于呼肠孤病毒的复制能力强的HIV-1疫苗，该疫苗刺激粘膜和全身体液免疫反应，对抗广泛中和的HIV-1表位。呼肠孤病毒感染肠黏膜以刺激强效免疫反应，在人体内自然减毒，并可通过操纵来表达疫苗抗原。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gp41的膜近端外区（MPER）的HIV-1序列，这些序列在gp41三聚体的基部形成a-螺旋状线圈。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，并保护被动免疫的非人灵长类动物免受HIV-1感染。该建议的中心假设是，插入三聚体呼肠孤病毒附着蛋白s1的a-螺旋区域的MPER序列将保留天然免疫原性，并引发针对HIV-1的中和抗体反应。提出了三个具体目标来验证中心假设和开发基于呼肠孤病毒的HIV-1疫苗。在Specific Aim 1中，将产生重组呼肠孤病毒，在呼肠孤病毒s1的表面暴露区域内以天然三聚体构象显示MPER序列。将测试表达mper的呼肠孤病毒的复制效率、连续传代期间的稳定性以及与mper特异性单克隆抗体的相互作用。已经设计了第一代呼肠孤病毒载体，其中纳入s1的MPER序列保留了天然的MPER特异性mAb表位，表明所提出的方法是可行的。在特异性目标2中，重组呼肠孤病毒载体将在接种家兔后进行诱导体液免疫反应的测试。免疫兔的血清将被检测mper特异性抗体的存在以及中和HIV-1 env假型病毒和原代分离株感染的能力。第二代载体将根据初始免疫原性研究的结果设计。在特异性目标3中，在兔体内诱导最有效的HIV-1中和性体液免疫反应的呼肠孤病毒载体将在恒河猴体内进行诱导体液免疫反应的试验。免疫猕猴的血清将被检测mper特异性抗体和HIV-1中和能力。这项研究将有助于更好地了解诱导针对HIV-1的有效粘膜免疫反应的疫苗需求，并促进开发针对粘膜部位的新型HIV-1疫苗。

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.