Improved Brucella Vaccine Strains

O-多糖既是布鲁氏菌的主要免疫原，也是其主要毒力决定因素。在没有O-多糖的情况下，经典种布鲁氏菌不会引起疾病，并被迅速清除：他是宿主。来自体外模型系统的数据似乎不那么具有决定性。虽然大多数证据表明，粗略突变体对巨噬细胞杀菌机制保持着抵抗力，但一些结果表明，相当大的复制能力可能被对早期杀菌机制的敏感性增加所掩盖。然而，也有一些报道称，粗面突变体感染巨噬细胞可导致细胞毒性细胞死亡。粗面突变体感染巨噬细胞后，伴随肿瘤坏死因子(TNFa)水平的升高，一氧化氮(NO)和巨噬细胞检查显示，暴露于粗面生物的巨噬细胞中核因子-kappaB(NF-kappaB)核募集。越来越多的人达成共识，布鲁氏菌与宿主细胞之间的相互作用可能在一定程度上受到布鲁氏菌表面的脂多糖(LPS)的控制或改变。 我们的长期目标是确定布鲁氏菌细胞内生存所需的基因。他的应用的目的是确定O-多糖通过与巨噬细胞的相互作用在建立成功的感染中的作用。我们的中心假设是O-多糖是布鲁氏菌与宿主巨噬细胞相互作用的重要元素，并通过逃避或改变天然免疫反应来提高存活率。这项拟议研究的基本原理是，了解光滑生物和宿主细胞之间的相互作用以引起适当的摄取和生存将加强对导致持久性和疾病的机制的理解，并为开发改进的疫苗或治疗方法以提高感染的清除提供信息。我们特别好 准备研究这种相互作用是因为我们已经建立了梅菲特布鲁氏菌突变体库和体外和体内感染模型，并有能力使用分子、基因组和生物信息学方法在细胞水平和动物感染模型中检测布鲁氏菌巨噬细胞的相互作用。

O-polysaccharide is both the dominant immunogen and a major virulence determinant of Brucella spp. In the absence of O-polysaccharide classical Brucella species do not cause disease, and are rapidly cleared from :he host. Data from in vitro model systems appears less decisive. Although most evidence suggests rough mutants retain resistance to macrophage microbicidal killing mechanisms, some results suggest considerable replicative ability that may be masked by increased sensitivity to early killing mechanisms. However, there are also reports of cytotoxic cell death (CCD) induced by infection with rough mutants that is specific for "nacrophages. CCD is accompanied by elevated levels of tumor necrosis factor (TNFa), and nitric oxide (NO) and examination of macrophages revealed nuclear recruitment of nuclear factor kappa B (NF-kappaB) in macrophages exposed to rough organisms that remained in the cytoplasm of cells infected with smooth organisms. There is an increasing consensus that interaction between Brucella and the host cell may be in part controlled or altered by lipopolysaccharide (LPS) on the surface of Brucella. Our long-range goal is to identify the genes required for intracellular survival of Brucella. The objectives of !his application are to determine the contribution of O-polysaccharide in establishing a successful infection through its interaction with macrophages. Our central hypothesis is that O-polysaccharide is an essential element in the interaction between Brucella and host macrophages and enhances survival by evading or altering the innate immune response. The rationale for the proposed research is that understanding the interactions between smooth organisms and the host cell to elicit proper uptake and survival will enhance understanding of the mechanisms resulting in persistence and disease and provide information for the development of improved vaccines or treatments to enhance clearance of infections. We are particularly well prepared to study this interaction because we have established a Brucella mefitensis mutant bank and in vitro and in vivo models of infection and have the capacity to examine Brucella macrophage interaction at the cellular level and in animals models of infection using molecular, genomic and bioinformatic approaches.