Second Generation Rabies Vaccines

描述(申请人提供)：狂犬病是一个主要的全球健康问题，每年导致约40,000至70,000人死亡，1000多万人在接触潜在感染的动物后接受暴露后预防(PEP)。成本和合规问题极大地阻碍了当前疫苗的有效性。为了解决这个问题，目前的疫苗在预防几种新发现的狂犬病相关病毒方面并不有效。此外，最近在许多本应含有灭活狂犬病病毒的疫苗中发现了活病毒。综上所述，开发新的暴露前和暴露后疫苗对于应对这一全球健康问题是必要的。由于暴露前疫苗接种仅限于实验室工作人员和兽医等高危人群，因此PEP是预防人类狂犬病的世界标准。因此，开发替代的PEP是本应用的目标。目前的PEP包括一剂被动免疫(狂犬病免疫球蛋白)和五种狂犬病疫苗主动免疫。我们假设复制缺陷的RV将成为优秀的狂犬病PEP。它们能够诱导强大的先天和获得性免疫反应，本质上是安全的，可以培养到高水平。提出了两个具体的目标：第一，将构建P或M基因缺失的基于复制缺陷的RV载体。还将构建表达两个完全相同的RV G拷贝的P或M缺失RV，从而诱导细胞凋亡并增强抗RV免疫应答。我们将在体外对这些新病毒载体的遗传稳定性、生长动力学和转基因表达进行表征。第二，轮状病毒感染使PEP可行的一个标志是在外围部位暴露的时间和轮状病毒感染中枢神经系统的时间之间的相对较长的时间。因此，快速的体液反应绝对是成功的PEP所必需的。我们将研究使用这些新载体在小鼠体内诱导免疫反应的动力学。RV G蛋白的ELISA、病毒中和试验和流式细胞仪分析将用于研究诱导的体液反应。T辅助反应对强烈的B细胞反应是重要的，将通过针对RV G和N的增殖试验来评估。最有希望的载体将在明确定义的叙利亚仓鼠模型中进行测试，以确定在感染致病RV毒株后是否提供保护。这些反应将与获得许可的灭活狂犬病疫苗进行比较。这一应用程序的目标是开发安全有效的替代品，以取代目前的人类暴露后狂犬病预防措施。发展只需一至两剂疫苗而不是六剂疫苗的治疗方法，将大大提高狂犬病病毒的预防效果。

DESCRIPTION (provided by applicant): Rabies is a major global health issue that kills approximately 40,000 to 70,000 people per year and over 10 million people receive post-exposure prophylaxis (PEP) after exposure to potentially infected animals. Cost and compliance issues have greatly hampered the effectiveness of current vaccines. To confound this issue, current vaccines are not effective at preventing disease from several newly identified rabies related viruses. In addition, live virus was recently discovered in a lot of vaccine that was supposed to contain inactivated rabies virus. Taken together, the development of novel pre- and post-exposure vaccines is necessary to combat this global health issue. Since pre-exposure vaccination is reserved only for those at-risk populations, such as laboratory workers and veterinarians, PEP is the world-wide standard for human rabies prevention. As such, the development of alternative PEPs is the goal of this application. Current PEPs are comprised of one dose of passive immunization (rabies immune globulin) along with five active immunizations with rabies vaccines. We hypothesize that replication-deficient RVs will make excellent rabies PEPs. They are able to induce potent innate and adaptive immune responses, are intrinsically safe and can be grown to high liters. Two specific Aims are proposed: First, replication-deficient RV-based vectors will be constructed that have either P or M genes deleted. P- or M-deleted RVs that express two identical copies of RV G will also be constructed, which induces apoptosis and enhances anti-RV immune responses. We will characterize the genetic stability, growth kinetics, and transgene expression of these new viral vectors in vitro. Second, a hallmark of RV infection that makes PEP feasible is the relatively long period between the time of exposure at the peripheral site and the time when RV infects the central nervous system. As such, a rapid humoral response is absolutely required for a successful PEP. We will investigate the kinetics of the induced immune response in mice using these new vectors. RV G protein ELISAs, virus neutralization assays, and flow cytometry analysis will be used to study the induced humoral response. T-helper responses, which are important for strong B-cell responses, will be evaluated by proliferation assays against RV G and N. The most promising vectors will be tested in a well-defined Syrian hamster model to determine whether protection is provided after infection with a pathogenic RV strain. The responses will be compared with a licensed inactivated rabies vaccine. The goal of this application is to develop safe and effective alternatives to the current human rabies post- exposure prophylaxis. The development of treatment that relies on only one to two doses of vaccine instead of six inoculations will greatly enhance the effectiveness of rabies virus prevention.