VIRULENCE AND GENOTYPE/PHENOTYPE OF MYCOBACTERIUM AVIUM

禽类分枝杆菌在健康人中通常是非致病性的。 但会导致艾滋病患者的侵袭性、传播性感染。我们有 发现有三个关键变量会影响互动的结果 与宿主免疫系统的关系：(I)绵羊分枝杆菌菌株； (2)巨噬细胞同时存在艾滋病毒-I型感染；以及 (3)宿主对禽类分枝杆菌和分枝杆菌的免疫状况。 肺结核。定义这些变量在交互中的作用 关于M.avium与宿主的关系，我们建议做以下工作： 我们将使用RNA消减杂交程序来鉴定M。 在宿主细胞生长过程中特异表达的禽类基因(S) 而不是在常规媒体的成长过程中。这些实验将是 使用流行病学相关的临床和环境M。 在基因上难以区分的禽类分离株。基因 鉴定将被克隆，在耻垢分枝杆菌中表达，并检测 用PBMC和巨噬细胞毒力测定的表型效应。 我们将对禽类分支杆菌分离株进行基因和表型鉴定。 关联基因类型(特别是基因的存在)(S) 对PBMC和巨噬细胞的体外毒力和 为了确定禽类分枝杆菌的毒力株是否仅限于 有限的一套遗传谱系。 我们将检查不同的白细胞群的功能和 不同细胞因子在人巨噬细胞耐药中的作用 用强毒和无毒的鸡分支杆菌菌株进行体外感染。我们会 也要确定细胞因子的产生如何与HIV-1合并感染 巨噬细胞和宿主对分枝杆菌的免疫力。 我们将确定是否在体外改变禽类分支杆菌的毒力。 暴露于宿主细胞因子和巨噬细胞中菌株的传代。我们会 还要确定培养环境来源的分布情况 环境中的禽类分枝杆菌毒力菌株和- 致病菌株。 这些研究将使我们能够(I)鉴定和克隆禽类分支杆菌的基因。 与毒力有关；(Ii)确定细胞因子和 宿主对分枝杆菌的防御中的白细胞群；以及(Iii) 确定特定寄主因素是否诱导禽类支原体毒力 菌株。累积起来，来自这些研究的信息将有助于 分枝杆菌合理治疗方法的研究进展 免疫受损宿主的感染。

Mycobacterium avium is generally nonpathogenic in healthy individuals but causes invasive, disseminated infection in AIDS patients. We have found that three critical variables affect the outcome of the interaction of M. avium with the host's immune system: (i) the strain of M. avium; (ii) the presence of concurrent HIV-I infection of the macrophage; and (iii) the immune status of the host with regard to M. avium and M. tuberculosis. To define the role of these variables in the interaction of M. avium with the host we propose the following work: We will use an RNA subtractive hybridization procedure to identify M. avium gene(s) that are specifically expressed during growth in host cells and not during growth in routine media. These experiments will be performed using epidemiologically related clinical and environmental M. avium isolates that are genotypically indistinguishable. The genes identified will be cloned, expressed in M. smegmatis, and examined for phenotypic effects using assays for virulence in PBMCs and Macrophage. We will characterize M. avium isolates genotypically and phenotypically to correlate genotypes (particularly the presence of the gene(s) identified above) with virulence for PBMCs and Macrophage in vitro and to determine if the virulent strains of M. avium are restricted to a limited set of genetic lineages. We will examine the function of different leukocyte populations and of different cytokines in mediating resistance of human Macrophage to infection in vitro with virulent and avirulent M. avium strains. We will also determine how cytokine production varies with HIV-1 coinfection of Macrophage and with the presence of host immunity to mycobacteria. We will determine if the virulence of M. avium is altered in vitro by exposure to host cytokines and passage of strains in Macrophage. We will also culture environmental sources to determine the distribution of virulent strains of M. avium within the environment and the reservoir of- pathogenic strains. These studies will allow us (i) to identify and clone M. avium genes associated with virulence; (ii) to define the role of cytokines and leukocyte populations in the host defense against mycobacteria; and (iii) to determine if specific host factors induce virulence in M. avium strains. Cumulatively, information from these studies will contribute to the development of rational therapeutic modalities for mycobacterial infections in the immunocompromised host.