RafE缺失损害棉子糖利用并增加小鼠早期肺炎球菌负荷

文献信息

中文摘要

背景： 肺炎链球菌（肺炎球菌）是儿童中耳感染（中耳炎）最常见的细菌病因之一。这些感染非常普遍，但可能持续存在且难以治疗。肺炎球菌是一种高度遗传多样性的生物，但驱动耳部感染的确切分子因素尚未完全了解。已知细菌代谢能力在感染中起重要作用。方法：在此，我们探索了从患有中耳炎的儿童中耳获得的两株血清型3肺炎链球菌分离株的代谢能力。血清型3是一种临床上令人关注的血清型，尽管已被纳入肺炎球菌结合疫苗，但仍未得到充分控制。我们鉴定出一株无法代谢棉子糖的菌株，并通过结合基因组和表型方法，表明这种代谢缺陷可能是由于编码棉子糖家族寡糖利用系统ABC转运蛋白底物结合蛋白（rafE）的基因中存在提前终止密码子所致。结果：使用肺炎链球菌D39血清型2菌株作为模型，我们表明构建rafE缺失或引入变异基因会导致小鼠耳中肺炎球菌数量增加，提示这可能促进向该部位的转运或在该部位的存活。结论：这项工作进一步证明了肺炎球菌中棉子糖利用位点的变异及其与不同毒力表型的关联。总之，这有助于我们理解这些感染，并可能对设计新疗法和疫苗具有重要意义。重要性：肺炎链球菌是一种生活在健康人鼻腔中的细菌，但可引起肺部、耳部、脑部和血液的一系列感染。在本研究中，我们探索肺炎链球菌如何在身体不同部位获取营养并增殖。我们发现营养摄取途径在不同菌株之间可能存在差异，这改变了它们感染不同部位的方式。我们研究的意义在于理解这些细菌如何在身体不同部位存活，这对于开发预防或治疗疾病的新方法很重要。

英文摘要

Streptococcus pneumoniae (the pneumococcus) is one of the most common bacterial causes of middle ear infections (otitis media) in children. These infections are highly prevalent but can be persistent and challenging to treat. The pneumococcus is a highly genetically diverse organism, but the precise molecular factors that drive infection of the ear are not fully understood. Bacterial metabolic capacity is known to play an important role in infection. Here, we explored the metabolic capacity of two serotype 3 isolates of S. pneumoniae obtained from the middle ear of children with otitis media. Serotype 3 is a clinically relevant serotype of concern due to its inadequate control despite its inclusion in pneumococcal conjugate vaccines. We identified one strain as unable to metabolize raffinose, and by coupling genomic and phenotypic methods, we showed that this metabolic defect was likely due to a premature stop codon in the gene encoding the raffinose-family oligosaccharide utilization system ABC transporter substrate-binding protein (rafE). Using a S. pneumoniae D39 serotype 2 strain as a model, we showed that construction of a rafE deletion or introduction of the variant gene resulted in an increase in the number of pneumococci in the ears of mice, suggesting that this may promote transit to, or survival at, this site. This work provides further evidence of variation at the raffinose utilization locus in pneumococci and an association with distinct virulence phenotypes. Together, this aids our understanding of these infections and may have implications for the design of new therapies and vaccines.IMPORTANCEStreptococcus pneumoniae is a bacterium that lives in the nose of healthy people but can cause a range of infections in the lungs, ears, brain, and blood. In this study, we explore how S. pneumoniae acquires nutrients and proliferates inside different sites of the body. We found that nutrient uptake pathways can differ between strains, and this changes how they infect different sites. The significance of our research is in understanding how these bacteria survive in different parts of the body, which is important for developing new ways of preventing or treating disease.