VIRULENT TO AVIRULENT CONVERSION OF L. PNEUMOPHILA

来自外部实验室的初步数据表明，致命的 和嗜肺军团菌的无毒菌株不同之处在于 对补体杀菌活性的敏感性。致命的 菌株对替代补体途径不敏感 而且，在没有抗体的情况下，不要结合C3。当着大家的面 在抗体中，强毒株结合C3和末端补体 组件沉积在电池的表面上。然而， 膜攻击复合体显然不会插入到 膜，因为细胞的数量没有减少。 抗体和补体的存在。相比之下，无毒细胞 对替代品的杀菌活性敏感 补体途径。抗体的添加只会导致 杀菌活性略有提高。 根据这些初步数据，这项建议的具体目标 目的是：1)用流式细胞仪分离毒力细胞和无毒细胞 排序；2)确定毒力纯种群的稳定性 和无毒细胞，并探讨观察到的 3)确定C3在无毒细胞上的结合位置 预计这些研究将提供重要的 有关可能的致病因素的信息，并可能有助于 阐明了影响L。 嗜肺症。

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.