Virulence Gene Expression by Bacillus anthracis

描述（由申请人提供）：炭疽芽孢杆菌是一种革兰氏阳性芽孢形成的土壤细菌，是蜡样芽孢杆菌群的成员，以其在哺乳动物（包括人类）中引起致命炭疽疾病的能力而闻名。这种生物特有的公认的毒力因子是炭疽毒素蛋白和聚d -谷氨酸胶囊。许多研究人员的发现已经确定了炭疽毒素和胶囊的结构和功能。我们实验室的工作主要集中在毒素蛋白结构基因表达的遗传基础上，包括pagA、left和cya，以及最近的胶囊生物合成操纵子capBCAD。我们的毒力基因调控模型越来越复杂，包括许多反式调控。最关键和影响深远的调控因子是atxA，一个似乎是炭疽杆菌特有的基因，atxA对所有三种毒素基因的表达都是必不可少的，并有助于控制胶囊操纵子。在这里提出的实验中，我们将通过测试我们目前的毒力调节模型来继续我们对毒力基因表达的研究。我们的总体方法将是确定体外培养的炭疽芽孢杆菌中毒力基因调控因子的功能，并在小鼠炭疽吸入模型中测试其意义。我们还将评估新确定的既定调节靶点的生理作用。最后，我们将探讨-内酰胺酶基因表达差异的分子基础在典型的青霉素敏感和不常见的青霉素耐药炭疽芽孢杆菌之间。炭疽芽孢杆菌是选择药剂清单上的主要细菌。2001年秋天，美国故意释放孢子，导致11例炭疽确诊病例和5人死亡，这戏剧性地说明了这种生物作为生物武器可能对公众健康造成的威胁。正如最近美国的病例所显示的，吸入炭疽芽孢杆菌孢子可导致人类致命的临床结果，只有及时的接触后干预才能限制疾病的程度。我们的总体目标是在小鼠吸入性炭疽模型中识别和表征影响炭疽杆菌感染的炭疽杆菌决定因素。这些决定因素是治疗干预的潜在目标和/或新亚单位疫苗的可能组成部分。

DESCRIPTION (provided by applicant): Bacillus anthracis, a Gram-positive spore-forming soil bacterium and member of the Bacillus cereus group species, is distinguished by its ability to cause lethal anthrax disease in mammals, including humans. Well-established virulence factors unique to this organism are the anthrax toxin proteins and a poly-D-glutamic acid capsule. Findings of numerous investigators have established the structure and function of the anthrax toxins and capsule. Work in our laboratory has focused on the genetic basis for expression of the structural genes for the toxin proteins, pagA, lef, and cya, and more recently, the capsule biosynthesis operon, capBCAD. Our model for virulence gene regulation is of increasing complexity and includes numerous trans-acting regulators. The most critical and far-reaching regulator is atxA, a gene that appears to be unique to B. anthracis, atxA is essential for expression of all three toxin genes and contributes to control of the capsule operon. In experiments proposed here, we will continue our investigations of virulence gene expression by testing our current model for regulation of virulence. Our overall approach will be to determine the function of virulence gene regulators in B. anthracis cultured in vitro and to test for significance in a mouse inhalation model for anthrax. We will also assess the physiological roles of newly identified targets of established regulators. Finally, we will probe the molecular basis for differences in beta-lactamase gene expression between prototypical penicillin-susceptible and less common penicillin-resistant B. anthracis stains. Bacillus anthracis is the lead bacterium on the Select Agent List. The intentional release of spores in the fall of 2001 in the U.S. that resulted in eleven confirmed cases of anthrax and five deaths dramatically illustrated the public health threat this organism can pose when as a bioweapon. As the recent U.S. cases showed, inhalation of B. anthracis spores can result in a fatal clinical outcome in humans and only timely post-exposure intervention can limit the extent of the disease. Our overall objective is to identify and characterize B. anthracis determinants that impact B. anthracis infection in a mouse model for inhalation anthrax. Such determinants are potential targets for therapeutic intervention and/or possible components for new subunit vaccines.