regulation of gene expression in Mannheimia haemolytica A1.

溶血曼海姆菌 A1 基因表达的调控。

• 批准号: 246-2007
• 负责人: Lo, Reggie
• 金额: $ 3.5万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2009
• 资助国家: 加拿大
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=419216
• 关键词: regulation; gene; expression; Mannheimia; haemolytica

Mannheimia haemolytica A1 (Mh) is an important bacterial pathogen that causes bovine pneumonic pasteurellosis. This respitatory disease results in millions of dollars in economic loss annually to the feedlot cattle industry. Hence, there are continuing interest in understanding the pathogenesis of the bacterium as well as to develop effecive measures to protect animals from the infection. My laboratory has been successful on the characterization of genes that code for many of the virulence factors of the bacterium for more than 20 years. Some of these virulence factors have been produced as recombinant antigens as vaccine components or expressed from transgenic plants in the development of an oral delivery system. On the other hand, the mechanisms that regulate expressin of these virulence genes are not understood. Very little is known about when these virulence genes are expressed during different stages of the infection process. In addition, nothing is known about the enviromental signals that regulate expression of these virulence genes. The objective of this proposal are: i) investigate expression profiles of these genes during an infection in vivo in the animals; and ii) to investigate the mechanisms that regulate expression of the virulence genes. Time course infection experiments will be carried out in which several animals will be infected with Mh and monitored for pneumonic signs. At daily intervals, either nasal samples will be collected or a calf will be sacrificed. Lung washings and lung tissue samples will be collected for extraction of total RNA. The RNA will be used in real-time RT-PCR using Mh specific primers to examine expression of specific genes. It is anticipated that some genes will be expressed early during the infection and some later, depending on the activity of their encoded products in pathogenesis. A second objective is examine the contribution of two-component regulatory systems in regulation of the virulence genes. We have identified several pairs of there systems from the Mh genome sequence. Mutants will be constructed in each of the two cognate proteins to examine the effects on protein expression and the regulatory pathway in response to the two-component system.

溶血性曼氏杆菌A1（Mannheimia haemolytica A1，Mh）是引起牛肺炎的重要病原菌。这种呼吸道疾病每年给饲养场养牛业造成数百万美元的经济损失。因此，人们对了解该细菌的致病机理以及开发有效的措施来保护动物免受感染一直很感兴趣。20多年来，我的实验室一直成功地对编码细菌许多毒力因子的基因进行表征。这些毒力因子中的一些已经作为疫苗组分的重组抗原产生或在口服递送系统的开发中从转基因植物表达。另一方面，调控这些毒力基因表达的机制尚不清楚。关于这些毒力基因在感染过程的不同阶段何时表达，我们知之甚少。此外，对调控这些毒力基因表达的环境信号也一无所知。本提案的目的是：i）研究这些基因在动物体内感染期间的表达谱;和ii）研究调节毒力基因表达的机制。将进行时程感染实验，其中几只动物将感染Mh并监测肺炎体征。每天采集鼻样本或处死一头小牛。将采集肺冲洗液和肺组织样本，用于提取总RNA。RNA将用于使用Mh特异性引物的实时RT-PCR，以检查特定基因的表达。预计一些基因将在感染早期表达，而另一些将在感染后期表达，这取决于其编码产物在发病机制中的活性。第二个目标是研究双组分调控系统在毒力基因调控中的作用。我们已经从Mh基因组序列中鉴定了几对三个系统。将在两种同源蛋白中的每一种中构建突变体，以检查响应于双组分系统对蛋白表达和调节途径的影响。