Phages and Genomic Variation in Vibrio Cholerae Evolution

描述（由申请人提供）：霍乱弧菌是霍乱的病原体，是一种急性危及生命的腹泻疾病。霍乱流行在流行地区，如南亚的恒河三角洲地区，具有季节性规律。2010年在非洲、巴基斯坦和海地发生的霍乱疫情提醒我们，有必要对这一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其毒力基因含量。已知感染弧菌属物种的细菌病毒（弧菌噬菌体/噬菌体）在不同菌株间的毒力基因传播中起关键作用。 诉霍乱（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，表明溶菌噬菌体通过捕食和影响传染性最终结束霍乱疫情。本提案的目的是学习 弧菌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、感染性和环境持久性等特性的生物相互作用来驱动霍乱弧菌新致病性克隆的出现。我们将从以下六个方面着手解决这一问题：1）我们将尝试重建在第7次大流行株中发现的丝状原噬菌体的染色体排列，该株是最成功的产毒霍乱弧菌克隆; 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）我们将利用比较基因组序列分析来推断孟加拉国水环境中霍乱弧菌和霍乱弧菌的噬菌体抗性和置换抗性机制; 4）我们将利用生物膜降解细菌来研究生物膜解离对霍乱弧菌在环境中的感染性和持久性的影响：5）我们将测试细菌介导毒力基因转移或产生毒力因子如炎性分子、细胞毒素和肠毒素的能力; 6）我们将构建适合环境释放的遗传标记的探针，并在水中和患者中进行精确的后续分子追踪。

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.