SURFACE CHANGE AND VIRULENCE IN COXIELLA BURNETII

伯内特柯克斯体的表面变化和毒力

• 批准号: 3129690
• 负责人: LOUIS P MALLAVIA
• 金额: $ 14.98万
• 依托单位: WASHINGTON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-07-01 至 1991-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3129690
• 关键词: Escherichia coli; Q fever; bacterial genetics; genetic manipulation; genetic strain; immunogenetics; macrophage; microorganism antigen; microorganism immunology; phagocytosis; plasmids; tissue /cell culture; virulence

The rickettsial agent of Q fever, Coxiella burnetii is an obligate intracellular parasite which replicates within the cellular phagolysosome. Classical genetic methods to define functional characteristics are not available and as a result, the physiology and genetic capabilities of C. burnetii are poorly understood. Although the mechanisms of virulence of C. burnetii is not known, a distinct antigenic phase variation has been associated with a reduction in virulence. The antigenic shift occurs when organisms isolated from infected animals (phase I) are repeatedly passed in eggs (phase II). As the organisms undergo an antigenic change to phase II, there is a concomitant decrease in virulence. In order to develop an understanding of the nature of the genes involved in virulence, we will examine a recently isolated plasmid and chromosomal DNA for genes relating to phase variation and virulence. We will first use the plasmid isolated from the Nine Mile, phase I strain (labeled by nick translation) to determine how widely plasmid sequences are distributed in other strains of C. burnetii (Southern blotting, hybridization). We will also attempt to cure C. burnetii of its plasmid. These studies will allow us to see if a correlation exists between virulence and the plasmid. Next recombinant DNA techniques will be used to place plasmid and chromosomal genes in E. coli. Those genes coding for phase specific and other surface antigens will be identified by specific antisera. Other bacteria which share properties with C. burnetii will be examined for the presence of DNA sequences related to those of the plasmid. In addition, possible metabolic functions will be examined using recombinant DNA techniques to place plasmid sequences into defined E. coli auxotrophs and look for growth due to complementation. These studies will provide the first analysis of the genetic capabilities of a rickettsial agent, and are part of the long range objectives of our laboratory in understanding the biochemical basis of the hostparasite relationship.

Q发烧的立克人Coxiella burnetii是一种义务 细胞内寄生虫在细胞吞噬体内复制。 定义功能特征的经典遗传方法不是 可用，因此，C。 伯内蒂（Burnetii）了解不足。 虽然C.的毒力机制 Burnetii尚不清楚，独特的抗原相变为 与毒力降低有关。 抗原转移发生 从感染动物中分离出的生物（I期）反复传递 鸡蛋（II期）。 随着生物发生的抗原变化， 毒力伴随着降低。 为了发展一个 了解毒力涉及的基因的性质，我们将 检查最近分离的质粒和染色体DNA的基因 相位变异和毒力。 我们将首先使用分离的质粒 从九英里，I期应变（由昵称标记）到 确定如何在其他菌株中分布广泛的质粒序列 C. burnetii（南部印迹，杂交）。 我们还将尝试 治愈其质粒的burnetii。 这些研究将使我们能够查看是否 毒力与质粒之间存在相关性。 下一个重组DNA 技术将用于将质粒和染色体基因放在大肠杆菌中。 那些编码相特异性和其他表面抗原的基因将是 通过特定的抗血清确定。 共享特性的其他细菌 将检查C. burnetii是否存在与DNA序列相关的存在 到质粒的人。 另外，可能的代谢功能将是 使用重组DNA技术检查将质粒序列放入 定义的大肠杆菌相互营养素，并因互补而寻找生长。 这些研究将对遗传能力进行首次分析 立克代理人的属于我们的远程目标的一部分 实验室了解宿主星座的生化基础 关系。