ANALYSIS OF THE SALMONELLA TYPHIMURIUM VIRULENCE PLASMID

鼠伤寒沙门氏菌和其他许多种沙门氏菌是主要的 美国和美国人类发病和死亡的原因 在世界各地。沙门氏菌病主要是通过 摄入受污染的肉类、乳制品和家禽产品。因此，一个 更好地了解沙门氏菌的发病机制将有助于 通过开发疫苗、改进治疗和预防疾病 疾病管理和改进粮食的农业方法 制作。 最近，几个物种的毒力与质粒有关。 沙门氏菌；然而，人们对沙门氏菌的发病机制或遗传学知之甚少 质粒介导的毒力。拟议研究的目标是 因此，要在分子水平上确认(S) 质粒对鼠伤寒沙门氏菌的毒力有贡献。第一个具体 目的是确定由质粒编码的毒力因子和相关基因。 S鼠伤寒沙门氏菌经口小肠外扩散 接种的小鼠。首席调查员已经克隆并突变了 的毒力基因，这些结果是研究 继续使用分子质粒，对质粒进行基因分析-- 中介致死性。未检测到毒力质粒编码的蛋白 S表示，。鼠伤寒沙门氏菌在体外生长，表明毒力 可以对基因进行调控，使其只在动物宿主中表达。 因此，最近分离出了TN5基因。第二个具体目标是 因此，为了阐明质粒编码的毒力基因是如何调控的 通过构建操纵子融合基因和分析基因的表达。毒力 质粒编码蛋白及其在S鼠伤寒杆菌细胞中的位置将是 作为第三个具体目标进行审查。这些研究是自然延伸 努力进一步确定毒力因子及其在 引发保护性免疫。

Salmonella typhimurium and many other species of Salmonella are major causes of morbidity and mortality in humans in the United States and throughout the world. Salmonellosis is acquired primarily through ingestion of contaminated meat, dairy, and poultry products. Thus, a better understanding of pathogenesis of Salmonella should be useful for prevention of disease through vaccine development, improved therapy and management of disease, and improved agricultural methods for food production. Plasmids have recently been associated with virulence of several species of Salmonella; however, little is known about the mechanism or the genetics of plasmid-mediated virulence. The objectives of the proposed research are therefore to identify at the molecular level mechanism(s) by which the plasmid contributes to the virulence of S. typhimurium. The first specific aim is to identify plasmid-encoded virulence factors and genes responsible for the spread S typhimurium beyond the small intestine of orally inoculated mice. The principal investigator has cloned and mutated virulence genes of the plasmid, and these results are the basis for the continued use of molecular plasmid, genetic analysis in dissecting plasmid- mediated virulence. Virulence plasmid-encoded proteins were not detectably expressed by S,. typhimurium growing in vitro, suggesting that virulence genes may be regulated so as to be expressed only in the animal host. Therefore, recently isolated Tn5 genes. The second specific aim is therefore to elucidate how plasmid-encoded virulence genes are regulated through construction of operon fusions and analysis of mRNA. Virulence plasmid-encoded proteins and their locations in S typhimurium cells will be examined as the third specific aim. These studies are a natural extension of efforts to further characterize virulence factors and their roles in eliciting protective immunity.