Immune Mechansims of Rotavirus Protection & Clearance

轮状病毒是全球幼儿严重胃肠炎的主要原因。一种预防轮状病毒感染的疫苗将在发展中国家每年防止50多万人死亡，并每年为美国节省超过10亿美元的医疗费用，但最近，唯一获得许可的疫苗因相关副作用而被撤回。预防轮状病毒感染和由此引起的疾病取决于免疫反应的启动和维持。这项应用的目的是了解和比较轮状病毒活感染和非复制亚单位疫苗(VLP)诱导的保护性免疫反应的差异。对活轮状病毒感染和VLP疫苗的免疫应答将由许多因素来区分，包括应答时间、控制应答的细胞类型以及免疫记忆的建立。在小鼠中，轮状病毒感染和VLP疫苗接种可诱导无菌免疫。轮状病毒和VLP诱导小鼠产生不育性免疫的确切机制尚未引起。我假设(I)原发轮状病毒感染建立的清除和灭菌免疫主要是由于T细胞非依赖性B淋巴细胞激活的结果，以及(Ii)VLP疫苗接种将通过T细胞依赖性B淋巴细胞激活而引起灭菌免疫。为了验证这一假设，将使用流式细胞术来识别、定量和功能表征在清除原发轮状病毒感染期间、接种VLP疫苗后以及在先前感染或VLP接种的小鼠的轮状病毒攻击之后激活的淋巴细胞亚群。这将是第一次系统地识别和比较活体感染动物和VLP疫苗接种动物中激活的淋巴细胞亚群，并将这些反应与免受感染的保护相关联的研究。了解轮状病毒和VLP疫苗如何激活免疫系统以诱导灭菌免疫的机制将有助于更好的疫苗设计，并可能确定测试人类潜在疫苗有效性的基准。

Rotavirus is the leading cause of severe gastroenteritis in young children worldwide. A vaccine to prevent a rotavirus infection would prevent over 500,000 deaths/year in developing countries and save the United States over $1 billion a year in health care costs, but recently, the only licensed vaccine was withdrawn due to associated side effects. Protection from rotavirus infection and resulting disease is dependent on the initiation and maintenance of an immunological response. The goal of this application is to understand and compare the difference in protective immunological responses induced by a live rotavirus infection and by a non-replicating subunit vaccine (VLPs). The immunological response to both live rotavirus infection and a VLP vaccine will be differentiated by many factors including the time of response, the type of cells that control the response, and establishment of immunological memory. In mice, rotavirus infection and VLP vaccination can induce sterilizing immunity. The exact mechanisms through which rotavirus and VLPs induce sterilizing immunity in the mouse have not been elicited. I hypothesize that (i) clearance of and sterilizing immunity established by a primary rotavirus infection occurs predominately as a result of T cell independent B lymphocyte activation, and (ii) VLP vaccination will cause sterilizing immunity through T cell dependent B lymphocyte activation. To test this hypothesis, flow cytometry will be used to identify, quantitate, and functionally characterize activated lymphocyte subsets during clearance of a primary rotavirus infection, after vaccination with VLPs, and after a rotavirus challenge of previously infected or VLP vaccinated mice. These will be the first studies to systematically identify and compare subsets of activated lymphocytes between a live infected and VLP vaccinated animal and correlating these responses with protection from infection. Understanding the mechanisms of how rotavirus and vaccination with VLPs activate the immune system to induce sterilizing immunity will aid in better vaccine design and may identify benchmarks for testing potential vaccine effectiveness in humans.