Phylogeny, Structure and Virulence Contributions of NMEC's Virulence Plasmids

描述(申请人提供)：革兰氏阴性新生儿细菌性脑膜炎是全球范围内死亡和发病的主要原因，新生儿脑膜炎大肠杆菌(NMEC)是这些感染的最常见病原体。大多数革兰氏阴性新生儿细菌性脑膜炎的幸存者都有神经后遗症或发育异常，如果不治疗，这种疾病通常是致命的。与其他肠外致病菌大肠杆菌(ExPEC)一样，NMEC具有在肠道外生存并在肠外空间引起疾病的能力。然而，NMEC与其他ExPEC的不同之处在于它们能够达到血液中的高计数并跨越血脑屏障。在这里，我们提出的证据表明，我们对NMEC发病机制的大部分了解都是基于非典型的NMEC菌株，这些菌株缺乏NMEC最常见的特征之一，即它们推测的大毒力质粒。我们对禽类致病大肠杆菌(APEC)中非常相似的质粒的研究以及我们对NMEC的初步研究表明，这是一个重要的疏忽，并导致我们假设NMEC质粒已经进化到提高NMEC的适应性，并通过促进血流生长和血脑屏障穿透而在脑膜炎的发病机制中起关键作用。为了验证这一假设，我们将生成有趣的NMEC质粒序列，将它们与其他质粒进行比较，确定它们的系统发育和进化，并定义它们的核心和泛基因组。此外，我们还将确定与NMEC脑膜炎有关的核心质粒基因及其致病机制。值得注意的是，这种对人类ExPEC质粒的分析在以前还没有报道；因此，我们提出的工作是新颖的。它也是新颖的，因为它寻求洞察NMEC质粒的系统发育和进化，以及它们与NMEC染色体的共同进化。我们相信，这项研究将使未来的许多研究成为可能，以拓宽我们对NMEC的致病性、细菌毒力的进化以及质粒在毒力和宿主适应中的作用的理解，并将导致减少革兰氏阴性新生儿细菌性脑膜炎的发生和减轻影响的新方法。 公共卫生相关性：新生儿脑膜炎引起的大肠杆菌(NMEC)感染导致高发病率和死亡率，幸存者经历长期残疾。 在这里，我们研究了NMEC最被忽视的假定毒力特征之一，即包含大致病性岛的质粒。从这项研究中获得的见解将有助于更好地了解NMEC的发病机制，并可能被用于制定更有效的脑膜炎控制策略。

DESCRIPTION (provided by applicant): Gram-negative neonatal bacterial meningitis is a major cause of mortality and morbidity worldwide with neonatal meningitis Escherichia coli (NMEC) being the most common agent of these infections. Most of the survivors of Gram-negative neonatal bacterial meningitis suffer neurologic sequelae or developmental abnormalities, and if untreated, the disease is usually fatal. Like other extraintestinal pathogeni E. coli (ExPEC), NMEC are well equipped to survive outside the intestine and cause disease in the extraintestinal compartment. However, NMEC are distinguished from other ExPEC by their abilities to reach high counts in the bloodstream and cross the blood-brain barrier. Here, we present evidence that much of what we know about NMEC pathogenesis is based on atypical NMEC strains that lack one of NMEC's most common traits, their large putative virulence plasmids. Our research with very similar plasmids in avian pathogenic E. coli (APEC) and our preliminary studies of NMEC, suggest that this is an important oversight and have led us to hypothesize that NMEC plasmids have evolved to increase NMEC fitness and are critical to the pathogenesis of meningitis by contributing to bloodstream growth and blood-brain barrier traversal. To test this hypothesis, we will generate sequences of interesting NMEC plasmids, compare them to other plasmids, determine their phylogeny and evolution, and define their core and pan-genome. Also, we will identify core plasmid genes contributing to NMEC meningitis and their mechanisms of pathogenicity. Remarkably, such an analysis of human ExPEC plasmids has not previously been reported; thus, the work we propose is novel. It is also novel in that it seeks insight into the phylogeny and evolution of NMEC plasmids and their co-evolution with the NMEC chromosome. We believe that this research will make possible many future studies to broaden our understanding of NMEC pathogenicity, the evolution of bacterial virulence, and the role of plasmids in virulence and host adaptation and will lead to new approaches to decrease the occurrence and mitigate the impact of Gram-negative neonatal bacterial meningitis. PUBLIC HEALTH RELEVANCE: Neonatal meningitis-causing Escherichia coli (NMEC) infections result in high morbidity and mortality with survivors experiencing long-term disability. Here, we study one of NMEC's most overlooked putative virulence traits, large pathogenicity island-containing plasmids. Insights gained from this research will lead to better understanding of NMEC pathogenesis and may be used to create more effective meningitis control strategies.