GENE EXPRESSION IN MYCOBACTERIUM TUBERCULOSIS

结核病是人类的一大祸害，是世界范围内死于单一传染病的主要原因。尽管美国的结核病发病率再次开始下降，但结核病在这个国家仍然是一个重要的健康问题，最常影响的是老年人、无家可归者、艾滋病患者和来自结核病流行国家的移民。虽然结核病的病原体结核分枝杆菌早在一个世纪前就被发现了，但关于结核分枝杆菌的基本生理能力、遗传学和致病机制的知识才刚刚开始出现。我们已经鉴定了几个基因，这些基因是结核分枝杆菌H37Rv在培养的人巨噬细胞中生长时表达的，但在实验室肉汤培养时不表达。我们推测，这些基因及其产物可能在巨噬细胞中结核分枝杆菌的生存和生长中起重要作用，并可能与结核杆菌的致病性有关。我们建议(1)通过确定巨噬细胞表达的特定基因产物对巨噬细胞中结核分枝杆菌的生存和生长的贡献，方法是对似乎协同表达的粘粒上的基因进行分子和遗传表征，推测反应调节基因和MCed基因，该基因已被证明可以提高大肠杆菌在培养的巨噬细胞中的存活；以及(2)鉴定和表征结核分枝杆菌在巨噬细胞中吞噬后的早期、晚期和培养中整个生长过程中表达的基因和基因产物。

Tuberculosis, one of the great scourges of humankind, is the leading cause of death worldwide from a single infectious disease. Although the incidence of TB has again begun to decline in the U.S., TB remains a significant health problem in this country, most frequently affecting the elderly, the homeless, individuals with AIDS and immigrants from nations where TB is endemic. Although the causative agent of TB, Mycobacterium tuberculosis, was identified a century ago, knowledge about fundamental physiological capabilities, the genetics and the mechanisms of pathogenicity of M. tuberculosis is only now beginning to emerge. We have identified several genes which are expressed by M. tuberculosis H37Rv when the bacilli are growing in human macrophages in culture, but which are not expressed by the bacilli when they are growing in laboratory broth culture. We hypothesize that these genes and their products may be important in the survival and growth of M. tuberculosis in macrophages and may contribute to the pathogenicity of the tubercle bacilli. We propose to (1) determine the contribution of specific macrophage-expressed gene products to survival and growth of M. tuberculosis in macrophages by molecular and genetic characterization of genes on a cosmid that appear to be coordinately expressed, a putative response regulator gene, and mceD, a gene that has been shown to enhance survival of E. coli in cultured macrophages; and (2) to identify and characterize genes and gene products of M. tuberculosis that are expressed at early times after phagocytosis, at late times, and throughout growth in human macrophages in culture.