VIRULENT TO AVIRULENT CONVERSION OF L. PNEUMOPHILA

嗜肺军团菌从毒力到无毒的转化

• 批准号: 3140274
• 负责人: WILLIAM JOHNSON
• 金额: $ 16.16万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-07-01 至 1992-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3140274
• 关键词: Legionella; antibacterial antibody; bacterial antigens; bacterial proteins; bactericidal immunity; complement pathway; complement receptor; flow cytometry; gene conversion; genetic regulation; genetic strain; growth media; guinea pigs; host organism interaction; immunological substance; legionellosis; lipopolysaccharides; membrane proteins; microorganism culture; microorganism population study; molecular cloning; virulence

Preliminary data from out laboratory have indicated that virulent and avirulent strains of Legionella pneumophila differ in their sensitivity to the bactericidal activity of complement. Virulent strains are not sensitive to the alternative complement pathway and, in the absence of antibody, do not bind C3. In the presence of antibody, virulent strains bind C3 and the terminal complement components are deposited on the surface of the cell. However, the membrane attack complex apparently does not insert into the membrane since there is no reduction in the number of cells in the presence of antibody and complement. In contrast avirulent cells are sensitive to the bactericidal activity of the alternative complement pathway. The addition of antibody results in only slightly increased levels of bactericidal activity. Based on these preliminary data the specific aims of this proposal are to: 1) separate virulent and avirulent cells by use of FACS sorting; 2) determine the stability of pure populations of virulent and avirulent cells and investigate the mechanism of the observed shift; 3) determine the binding site of C3 on avirulent cells It is anticipated that these studies will provide significant information concerning possible virulence factors and may help to elucidate environmental factors that influence the virulence of L. pneumophila.

我们实验室的初步数据表明， 嗜肺军团菌和无毒菌株的不同之处在于， 对补体杀菌活性的敏感性。 毒力 菌株对补体旁路途径不敏感 并且在没有抗体的情况下不结合C3。 存在下 强毒株结合C3和末端补体 组分沉积在电池的表面上。 然而，在这方面， 膜攻击复合物显然不插入到 由于细胞膜中的细胞数量没有减少， 抗体和补体的存在。 相反，无毒细胞 对替代品的杀菌活性敏感 补体途径 抗体的加入只会导致 杀菌活性水平略有增加。 根据这些初步数据， 是：1）通过使用FACS分离毒力和无毒力细胞 筛选; 2）确定毒力纯群体的稳定性 和无毒细胞，并探讨所观察到的机制， 3）确定C3在无毒细胞上的结合位点 预计这些研究将提供重要的 关于可能的毒力因子的信息，可能有助于 阐明了环境因素对L. 嗜肺菌