Desiccation resistance in Coxiella burnetii

伯内氏立克次体的干燥抗性

• 批准号: 8700034
• 负责人: HOWARD A SHUMAN
• 金额: $ 19.19万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-05 至 2016-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8700034
• 关键词: Abattoirs; Acute; Aerosols; Agriculture; Alleles; Animal Housing; Antibiotic Therapy; Antimicrobial Resistance; Bacteria; Betaine; Biological Products; Biology; Birth; Breathing; Cattle; Cell physiology; Cells; Cellular biology; Centers for Disease Control and Prevention (U.S.); Chronic; Collection; Contracts; Coxiella; Coxiella burnetii; DNA; Deinococcus radiodurans; Desiccation; Development; Disease; Disease Outbreaks; Dose; Doxycycline; Endocarditis; Environment; Epidemic; Epithelial Cells; Farming environment; Gene Expression Profile; Genes; Genetic; Genetic Techniques; Goat; Growth; Human; Human Volunteers; Individual; Infection; Life; Livestock; Measurement; Meat; Metabolism; Methods; Military Personnel; Milk; Molecular; Molecular Weight; Mutate; Netherlands; Organism; Osmolar Concentration; Oxygen; Phagolysosome; Physiology; Plants; Prevalence; Proline; Property; Proteins; Q Fever; Radiation; Reporting; Research; Resistance; Sampling; Sheep; Stress; Time; Trehalose; Vaccines; Vacuole; Work; antimicrobial; axenic culture; base; cell type; design; flu; macrophage; mutant; oxidative damage; pathogen; preconditioning; programs; public health relevance; radiation resistance; research study; resistance mechanism; response; screening; solute; tissue culture; trafficking; trait; transmission process

DESCRIPTION (provided by applicant): Coxiella burnetii is a gram-negative g-proteobacterial species that causes Q fever, an acute debilitating flu-like illness. People contract Q fever from contaminated material from farm animals or from material in slaughterhouses and meat packing plants. It is estimated that as many as 1010 organisms can be shed at parturition. Although Q fever is self-limiting in most cases, a chronic, difficult to treat endocarditis - associated form f the disease can develop in a small percentage of recovered individuals. A large outbreak of Q fever continues in a small heavily agricultural region in the Netherlands, where more than 4,000 individuals have contracted the disease since 2007. C. burnetii is extremely stable in the environment as it is extremely resistant to desiccation. In addition, when C. burnetii infects host cells, it resides in an intracellular vacuole that has many properties of phagolysosomes. Indeed, the organism is only metabolically active at the intravacuolar pH of 4.5 and is resistant to the antimicrobial defenses usually found in mature phagolysosomes. The molecular mechanisms of resistance to environmental stresses are poorly understood. Recent advances in axenic culture of C. burnetii and emerging genetic techniques make it now possible to pursue experimental approaches that were not possible up until now. The work described in this proposal is aimed at finding out the molecular basis of the extreme desiccation resistance of C. burnetii. In order to do this three specific aims are proposed. The first specific aim is to identify small molecular weight osmo-protectant compatible solutes that should be produced or accumulated upon osmotic stress. Upon desiccation, the bacteria must first adapt to increased osmolarity usually by synthesis or accumulation of solutes such as trehalose, glycine betaine or proline. This phenomenon has not been explored for C. burnetii. We will expose C. burnetii to hyperosmotic conditions, isolate low molecular weight solutes and examine the contents of the extracts by 13C-NMR. The second specific aim is to identify C. burnetii genes that are regulated by hyperosmotic conditions, oxidative damage, and by desiccation. Usually even if bacteria are tolerant of hyperosmotic conditions, they remain sensitive to desiccation. Desiccation sensitivity is thought to be due to oxidative damage to proteins and DNA from high intracellular concentrations of Fe. Transcriptome analysis by RNAseq will be used to identify C. burnetii genes that are upregulated by exposure of C. burnetii to all three stresses. Finally the third aim is to use genetic approaches to identify genes required for desiccation resistance in C. burnetii. This will be accomplished by screening for transposon-induced mutants that have lost the ability to tolerate desiccation. The proposed work will provide the first set of information about how C. burnetii resists osmotic stress and desiccation.

描述（由申请人提供）：伯氏杆菌是一种革兰氏阴性g-变形菌，可引起Q热，这是一种急性使人衰弱的流感样疾病。人们从农场动物或屠宰场和肉类包装厂的污染材料中感染Q热。据估计，分娩时可脱落多达1010种微生物。虽然Q热在大多数情况下是自我限制的，但在一小部分康复的个体中，可能会出现一种慢性的、难以治疗的心内膜炎相关的疾病。在荷兰的一个小农业区，Q热的大规模爆发仍在继续，自2007年以来，已有4000多人感染了这种疾病。伯氏梭菌在环境中非常稳定，因为它对干燥有极强的抵抗力。此外，当伯氏梭菌感染宿主时