Elucidation of colonization and virulence through a novel comparative approach

描述（由申请方提供）：新出现的人类病原体副溶血性弧菌是全球胃肠炎的主要原因。虽然已经确定了一些毒力机制，但这些并不能完全解释这种病原体引起疾病的能力。在这项研究中，我们将阐明机制，有助于殖民和毒力的一种新的比较方法。包括副溶血性弧菌在内的人类致病性弧菌的一个共同特征是它们的许多毒力因子是水平获得的，然而获得的毒力性状必须与其他定殖性状一起沿着协调调节。彻底靶向所有独特序列将是低效的，并且将对连接毒力和定殖的调控网络提供很少的见解。我们建议，这种病原体和相关的细菌，是无法引起疾病，如特征鲜明的光器官共生体费氏弧菌之间的殖民化的比较，将表明殖民化的机制是古老的和保守的属。更重要的是，新的比较将揭示独特的调节转录，特别是有助于副溶血性弧菌的致病生活方式。我们假设，GacA调节的基因在副溶血性弧菌，而不是GacA调节或缺乏的V.fischeri有助于副溶血性弧菌的毒力和定植。我们的假设和预测基于以下事实：1）致病性弧菌中水平获得的毒力因子，包括霍乱毒素，由整个属中保守的调节因子控制，包括共生细菌，费氏弧菌，2）GacA调节费氏弧菌中的共生因子和宿主定植，以及许多病原体中的毒力和定植，包括霍乱弧菌，3）在所有弧菌中不保守的关键共生因子（lux）在费氏弧菌中受GacA调节，表明生活方式特异性性状映射到该调节子。这项研究的具体目标是： * 通过GacA突变产生副溶血性弧菌的全局定殖缺陷型菌株。 * 使用费氏弧菌和副溶血性弧菌中GacA调节子的比较DNA阵列分析来鉴定推定的定殖和毒力性状。 * 确定靶向GacA调节基因在细胞毒性中的作用。 公共卫生相关性：在过去十年中，副溶血性弧菌大流行株的出现，在以前认为没有风险的地区引起疫情，预示着气候变化对人类健康的威胁日益增加。评估感染风险和制定预防方案的一个主要障碍是对副溶血性弧菌的致病性缺乏了解。我们的研究结果将为这种重要的新出现的病原体的毒力机制提供宝贵的见解，揭示宿主的脆弱性，并为预防和治疗感染提供新的机会。

DESCRIPTION (provided by applicant): The emergent human pathogen Vibrio parahaemolyticus is a major cause of gastroenteritis worldwide. Although some virulence mechanisms have been identified, these do not fully explain the ability of this pathogen to cause disease. In this study we will elucidate mechanisms that contribute to colonization and virulence by a novel comparative approach. A common feature of human pathogenic Vibrios, including V. parahaemolyticus, is that many of their virulence factors are horizontally acquired, and yet acquired virulence traits must be coordinately regulated along with other colonization traits. Exhaustively targeting all unique sequences would be inefficient, and would provide little insight into regulatory networks that connect virulence and colonization. We propose that a comparison of colonization between this pathogen and a related bacterium that is incapable of causing disease, such as the well characterized light organ symbiont Vibrio fischeri, will indicate which mechanisms of colonization are ancient and conserved in the genera. More importantly, the novel comparison will reveal uniquely regulated transcripts that contribute specifically to the pathogenic lifestyle of V. parahaemolyticus. We hypothesize that GacA-regulated genes in V. parahaemolyticus that are not GacA-regulated or absent in V. fischeri contribute to the virulence and colonization by V. parahaemolyticus. We base our hypothesis and predictions on the fact that 1) horizontally acquired virulence factors in pathogenic Vibrios including cholera toxin are controlled by regulators conserved throughout the genus including the symbiotic bacterium, Vibrio fischeri, 2) GacA regulates symbiosis factors and host-colonization in V. fischeri and virulence and colonization in many pathogens including Vibrio cholerae, 3) key symbiotic factors that are not conserved in all Vibrios (lux) are regulated by GacA in V. fischeri indicating lifestyle-specific traits map to this regulon. The specific aims of the study are to: * Generate a global colonization-defective strain of V. parahaemolyticus through a mutation in GacA. * Use comparative DNA array analysis of GacA regulons in V. fischeri and V. parahaemolyticus to identify putative colonization and virulence traits. * Determine the role of targeted GacA-regulated genes in cytotoxicity. PUBLIC HEALTH RELEVANCE: The last decade marked the emergence of a pandemic strain of V. parahaemolyticus, which caused outbreaks in regions that were previously not considered to be at risk, foreshadowing the increasing threat to human health due to climate changes. A major obstacle to assessing risk of infection and developing preventative protocols is a lack of understanding of the pathogenicity of V. parahaemolyticus. Our findings will provide invaluable insight into the virulence mechanisms of this important emergent pathogen revealing host vulnerabilities and providing new opportunities to prevent and treat infections.