Bacterial Iron Acquisition Strategies of Gram-Negative Bacteria from the Pasteurellaceae that Inhabit the Upper Respiratory Tract of Food Production Animals

栖息在食品生产动物上呼吸道的巴斯德氏菌科革兰氏阴性菌的细菌铁获取策略

• 批准号: RGPIN-2016-04555
• 负责人: Schryvers, Anthony
• 金额: $ 2.55万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664537
• 关键词: Bacterial; Iron; Acquisition; Strategies; Gram

My research program involves characterizing iron acquisition systems in important Gram-negative bacterial pathogens of food production animals and developing vaccines for disease prevention. This NSERC application is focused on the pathogens responsible for bovine respiratory disease (BRD) in beef and dairy cattle. The important BRD pathogens (Mannhemia haemolytica, Histophilus somni, Pastuerella multocida) possess surface receptors to extract iron from host transferrin at the bacterial cell surface, providing the ability to proliferate independently from other microbes on the mucosal surface and cause invasive infection. Our vaccine strategy targeting these receptor proteins is based on the premise that we will eliminate the ability of BRD pathogens to proliferate and cause invasive infection but not eliminate related commensal species. However, our current understanding of the prevalence, diversity and exchange of iron acquisition genes amongst the BRD pathogens and related commensal strains is currently inadequate to gauge the reservoir of antigenic variants and the consequence of vaccination on the upper respiratory tract microbiome. Thus the main goals of this program are to determine, (i) the prevalence of iron acquisition genes, (ii) the efficiency of genetic exchange, and (ii) the functional iron acquisition capabilities of pathogenic and commensal strains and species of the Pasteurellacea family that inhabit the bovine upper respiratory tract. We will perform a comprehensive analysis of the presence and diversity of iron acquisition genes present in microbiome samples, in bacteria isolated from microbiome samples and in collections of BRD isolates. In order to evaluate the extent of genetic exchange amongst these related bacterial species we will determine whether the natural transformation systems of the BRD pathogens are functional and then test the efficiency of exchange amongst the BRD pathogens and related commensal bacteria. The ability of the bacteria to use siderophores produced by microbiome constituents or various host iron sources to support growth under iron-limited conditions will be evaluated. Knockouts of the genes will be performed to confirm their role in iron acquisition from different iron sources. This program will provide the foundation for development of rational vaccine strategy and determine what will be required for development of a single vaccine targeting all three BRD pathogens.

我的研究项目包括确定食用动物中重要的革兰氏阴性细菌的铁获取系统的特征，并开发疾病预防疫苗。NSERC的这一应用侧重于肉牛和奶牛中导致牛呼吸道疾病(BRD)的病原体。BRD的重要病原体(溶血性曼氏杆菌、索姆尼氏组织杆菌、多杀性巴氏杆菌)具有表面受体，可从细菌细胞表面的宿主转铁蛋白中提取铁，从而提供独立于粘膜表面其他微生物增殖并导致侵袭性感染的能力。我们针对这些受体蛋白的疫苗策略是基于这样的前提，即我们将消除BRD病原体的增殖和导致侵袭性感染的能力，但不会消除相关的共生物种。然而，我们目前对BRD病原体和相关共生菌株之间铁获取基因的流行率、多样性和交换的了解，目前不足以衡量抗原变异的储存库和疫苗接种对上呼吸道微生物群的影响。因此，该计划的主要目标是确定(I)铁获取基因的流行率，(Ii)遗传交换的效率，以及(Ii)生活在牛上呼吸道的巴氏杆菌科致病和共生菌株和物种的功能性铁获取能力。我们将对微生物样本、微生物样本中分离的细菌和BRD分离株中存在的铁获取基因的存在和多样性进行全面分析。为了评估这些相关细菌物种之间的遗传交换程度，我们将确定BRD病原体的自然转化系统是否起作用，然后测试BRD病原体和相关共生菌之间的交换效率。将评估细菌利用微生物组成分或各种宿主铁源产生的铁载体在铁有限的条件下支持生长的能力。将对这些基因进行敲除，以确认它们在从不同铁源获取铁的作用。该计划将为制定合理的疫苗策略提供基础，并确定开发针对所有三种BRD病原体的单一疫苗所需的条件。