Phages and Genomic Variation in Vibrio Cholerae Evolution

描述(申请人提供)：霍乱弧菌是霍乱的病原体，霍乱是一种威胁生命的急性腹泻疾病。霍乱流行在流行地区，如南亚恒河三角洲地区，有季节性规律发生。2010年在非洲、巴基斯坦和海地发生的霍乱疫情提醒我们，有必要对这种疾病进行进一步调查。霍乱弧菌菌株在人类中引起严重肠道感染的能力取决于它们的毒力基因含量。感染弧菌的细菌病毒(噬弧菌/噬菌体)在不同菌株之间的毒力基因传递中起着关键作用。 霍乱弧菌(例如，霍乱毒素基因通过丝状噬菌体CTXf)。此外，我们在孟加拉国的实地工作提供了直接证据，表明裂解噬菌体似乎通过捕食和影响传染性来结束霍乱流行。这项提议的目的是学习 噬菌体如何通过水平基因转移、捕食和其他影响生物膜形成、传染性和环境持久性等特性的生物相互作用，推动新的霍乱弧菌致病克隆的出现。我们将以六个具体目标来解决这个问题：1)我们将尝试重建在最成功的产毒霍乱弧菌克隆--第7大流行株中发现的丝状前驱体的染色体排列；2)我们将研究编码毒力特性和不同宿主范围的杂交丝状噬菌体的形成；3)我们将利用噬菌体和霍乱弧菌分离株的比较基因组序列分析来推断孟加拉国水环境中噬菌体的抗药性和置换噬菌体的机制；4)我们将利用生物膜降解噬菌体来研究生物膜解离对霍乱弧菌在环境中感染性和持久性的影响；5)我们将测试噬菌体介导毒力基因转移或产生炎症分子、细胞毒素和肠毒素等毒力因子的能力；6)我们将构建适合环境释放和随后在水和患者中进行准确分子跟踪的基因标记噬菌体。

DESCRIPTION (provided by applicant): Vibrio cholerae is the causative agent of cholera, an acute life-threatening diarrhea disease. Cholera epidemics occur with seasonal regularity in endemic areas, such as the Ganges Delta region of South Asia. Cholera epidemics in 2010 in Africa, Pakistan, and Haiti remind us that further investigation of this disease is warranted. The ability of V. cholerae strains to cause severe enteric infection in humans depends on their virulence gene content. Bacterial viruses infecting Vibrio species (vibriophages/phages) are known to play a critical role in the transmission of the virulence genes among different strains of V. cholerae (e.g., cholera toxin genes via the filamentous phage CTXf). Furthermore, our fieldwork in Bangladesh has provided direct evidence that lytic vibriophages seemly end cholera epidemics through predation and influencing infectivity. The objective of this proposal is to learn how vibriophages drive the emergence of new pathogenic clones of V. cholerae through horizontal gene transfer, predation, and other biological interactions that affect properties such as biofilm formation, infectivity and environmental persistence. We will approach this problem with six specific aims 1) we will attempt to reconstruct the chromosomal arrangement of filamentous prophages found in the 7th pandemic strain, the most successful clone of toxigenic V. cholerae; 2) we will study the formation of hybrid filamentous phages encoding virulence properties and different host range; 3) we will use comparative genome sequence analysis of both phages and V. cholerae isolates to deduce the mechanisms of phage- resistance and displacement phages in Bangladesh aquatic environment; 4) we will utilize biofilm-degrading phages to study the effect of biofilm dissociation on V. cholerae infectivity and persistence in th environment; 5) we will test the ability of phages to mediate transfer of virulence genes or to produce virulence factors such as inflammatory molecules, cytotoxins and enterotoxins; 6) we will construct genetically marked phages suitable for environmental release and accurate subsequent molecular tracking in water and patients.