Amino acid prototrophy as a positive selective marker in Francisella

描述（由申请方提供）：在自然界中，土拉热弗朗西丝菌引起人畜共患病土拉菌病。F.土拉热因其高度传染性和通过雾化传播的潜在容易性而被列为A类选择病原体。世界范围内的恐怖活动导致人们越来越关注F的潜在用途。作为回应，国家过敏和传染病研究所扩大了其生物防御研究计划，努力开发新的F。土拉热病治疗剂和疫苗。这项研究的长期目标是为兔热病疫苗和治疗方法的开发确定新的靶点。然而，目前的遗传研究是有限的，由于缺乏可用于强毒力的F。土拉菌菌株在本研究中，我们将开发基于氨基酸原养型的非抗生素标记，作为F.土拉热。我们将使用遗传学方法来鉴定与F互补的异源基因。土拉热菌菌株Schu S4在缺乏必需氨基酸的确定成分培养基上生长。所得到的基因将用于产生几个新的F。tularensis穿梭载体。这项工作的结果将提供急需的遗传工具，这将有助于药物发现，疫苗开发，细胞生物学实验，以及用强毒F.土拉菌菌株

DESCRIPTION (provided by applicant): In nature, Francisella tularensis causes the zoonotic disease tularemia. F. tularensis is a category A select agent because of its highly infectious nature and the potential ease of its dissemination by aerosolization. Worldwide terrorist activities have resulted in growing concerns about the potential use of F. tularensis as a bioterrorist weapon; in response, the National Institute of Allergy and Infectious Diseases has expanded its biodefense research program in an effort to develop new F. tularensis therapeutics and vaccines. The long term goal of the proposed research is to identify novel targets for the development of tularemia vaccines and therapeutics. However, current genetic research is limited due to a shortage of selectable genetic markers for use in virulent F. tularensis strains. In this proposal we will develop non-antibiotic markers based on amino acid prototrophy for use as positive selective genetic markers in F. tularensis. We will use a genetic approach to identify heterologous genes that complement F. tularensis strain Schu S4 for growth on defined media lacking essential amino acids. The resulting genes will be used to generate several new F. tularensis shuttle vectors. The results of the proposed work will provide much needed genetic tools which will facilitate drug discovery, vaccine development, cell biology experiments, and microbiological experiments with virulent F. tularensis strains.