Development and evaluation of subunit vaccine CmeC against Campylobacter jejuni

描述（由申请人提供）：空肠弯曲杆菌（Campylobacter jejuni）， NIAID B类优先病原体，是美国人类肠炎的主要细菌原因，对公众健康构成重大威胁。在过去十年中，弯曲杆菌对临床抗生素的耐药性不断增加，迫切需要制定替代干预策略，如疫苗接种，以预防和控制弯曲杆菌感染。尽管近年来在阐明空肠梭菌的免疫原性和保护性抗原方面取得了进展，但动物对空肠梭菌定植的免疫接种仅取得了部分成功，具有显著保护作用的免疫原性抗原仍有待确定。本R21应用的主要目的是开发和评价一种针对空肠梭菌的新型亚单位疫苗CmeC。空肠梭菌的外膜蛋白（OMPs）被认为是病原体-宿主相互作用的主要介质，因此是设计保护性疫苗的有希望的候选者。最近，我们在弯曲杆菌中发现了一种独特的OMP CmeC。作为多药外排系统CmeABC的关键组成部分，CmeC有助于弯曲杆菌对广谱抗菌素产生耐药性，并且通过介导胆汁耐药对弯曲杆菌在动物肠道中的定殖至关重要。CmeC是一种体内免疫原性OMP，在各种弯曲杆菌菌株中广泛分布并组成性表达。特别是，CmeC的表达被肠内存在的胆盐显著诱导。基于这些观察结果，我们假设CmeC是一种新的亚单位疫苗候选物，用于免疫干预弯曲杆菌感染。为了验证我们的假设，我们计划i)检测弯曲杆菌原代分离株CmeC的序列多态性、抗原同源性和体外免疫保护作用；ii)评价新型亚单位CmeC疫苗在鸡空肠梭菌感染模型中的免疫原性和保护效果；iii)确定CmeC疫苗在增强临床抗生素疗效方面的作用。一旦拟议的研究完成，我们期望获得关于靶向CmeC对人类弯曲杆菌感染的免疫保护可行性的关键信息。CmeC在肠道定植和抗生素耐药性方面独特的双重功能极大地提高了其应用的创新性和意义。相关性：空肠弯曲杆菌是美国引起人类肠胃炎的最常见的食源性细菌病原体，拟议的研究将为开发有效的空肠弯曲杆菌疫苗提供新的信息，以保护公众健康。

DESCRIPTION (provided by applicant): Campylobacter jejuni, a NIAID Category B Priority Pathogen, is the leading bacterial cause of human enteritis in the United States and presents a major threat to public health. Increasing resistance of Campylobacter to clinical antibiotics in the past decade raised an urgent demand for the development of alternative intervention strategies, such as vaccination, to prevent and control Campylobacter infections. Despite recent progress on the elucidation of immunogenic and protective antigens in C. jejuni, vaccination of animals against C. jejuni colonization had only partial success and the immunogenic antigens with significant protective effect remain to be determined. The main goal of this R21 application is to develop and evaluate a novel subunit vaccine CmeC against C. jejuni. Outer membrane proteins (OMPs) of C. jejuni are considered the major mediators of the pathogen-host interaction, as a consequence, the promising candidates for the design of protective vaccines. Recently, we have characterized a unique OMP CmeC in Campylobacter. As a key component in multidrug efflux system CmeABC, CmeC contributes Campylobacter resistance to a broad spectrum of antimicrobials and is also essential for Campylobacter colonization in animal intestine by mediating bile resistance. As an immunogenic OMP in vivo, CmeC is widely distributed and constitutively expressed among various Campylobacter strains. Particularly, expression of CmeC is dramatically induced by bile salts present in intestine. Based on these observations, we hypothesize that CmeC is a novel subunit vaccine candidate for immune intervention against Campylobacter infections. To test our hypothesis, we plan to i) examine sequence polymorphism, antigenic homology, and in vitro immune protection of CmeC in primary Campylobacter isolates; ii) evaluate the immunogenicity and protective efficacy of a novel subunit CmeC vaccine in a chicken model of C. jejuni infection; and iii) determine the role of CmeC vaccine in potentiating the efficacy of clinical antibiotics. Once the proposed studies are completed, we expect to obtain critical information on the feasibility of targeting CmeC for immune protection against Campylobacter infections in humans. The unique dual functions of CmeC in intestinal colonization and antibiotic resistance greatly improve innovative aspect and significance of this application. Relevance: Campylobacter jejuni is the most prevalent foodborne bacterial pathogen causing human gastroenteritis in the U.S. The proposed research will provide novel information on the development of effective vaccine against C. jejuni to protect public health.