Kilsgård Ola, Karlsson Christofer, Malmström Erik, Malmström Johan
Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, Lund, Sweden; Department of Immunotechnology, Faculty of Engineering Lund, Lund University, Lund, Sweden.
Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
Int J Med Microbiol. 2016 Nov;306(7):504-516. doi: 10.1016/j.ijmm.2016.06.007. Epub 2016 Jun 29.
Streptococcus pyogenes is an important human pathogen responsible for substantial morbidity and mortality worldwide. Although S. pyogenes is a strictly human pathogen with no other known animal reservoir, several murine infection models exist to explore different aspects of the bacterial pathogenesis. Inoculating mice with wild-type S. pyogenes strains can result in the generation of new bacterial phenotypes that are hypervirulent compared to the original inoculum. In this study, we used a serial mass spectrometry based proteomics strategy to investigate if these hypervirulent strains have an altered distribution of virulence proteins across the intracellular, surface associated and secreted bacterial compartments and if any change in compartmentalization can alter the protein-protein interaction network between bacteria and host proteins. Quantitative analysis of the S. pyogenes surface and secreted proteomes revealed that animal passaged strains are associated with significantly higher amount of virulence factors on the bacterial surface and in the media. This altered virulence factor compartmentalization results in increased binding of several mouse plasma proteins to the bacterial surface, a trend that was consistent for mouse plasma from several different mouse strains. In general, both the wild-type strain and animal passaged strain were capable of binding high amounts of human plasma proteins. However, compared to the non-passaged strains, the animal passaged strains displayed an increased ability to bind mouse plasma proteins, in particular for M protein binders, indicating that the increased affinity for mouse blood plasma proteins is a consequence of host adaptation of this pathogen to a new host. In conclusion, plotting the total amount of virulence factors against the total amount of plasma proteins associated to the bacterial surface could clearly separate out animal passaged strains from wild type strains indicating a virulence model that could predict the virulence of a S. pyogenes strain in mice and which could be used to identify key aspects of this bacteria's pathogenesis.
化脓性链球菌是一种重要的人类病原体，在全球范围内导致大量发病和死亡。尽管化脓性链球菌是一种严格的人类病原体，没有其他已知的动物宿主，但仍存在几种小鼠感染模型来探索细菌致病机制的不同方面。用野生型化脓性链球菌菌株接种小鼠会导致产生新的细菌表型，这些表型比原始接种物具有更高的毒力。在本研究中，我们使用基于串联质谱的蛋白质组学策略来研究这些高毒力菌株在细胞内、表面相关和分泌的细菌区室中毒力蛋白的分布是否发生改变，以及区室化的任何变化是否会改变细菌与宿主蛋白之间的蛋白质-蛋白质相互作用网络。对化脓性链球菌表面和分泌蛋白质组的定量分析表明，经动物传代的菌株在细菌表面和培养基中的毒力因子含量显著更高。这种毒力因子区室化的改变导致几种小鼠血浆蛋白与细菌表面的结合增加，这一趋势在来自几种不同小鼠品系的小鼠血浆中是一致的。一般来说，野生型菌株和经动物传代的菌株都能够结合大量的人类血浆蛋白。然而，与未传代的菌株相比，经动物传代的菌株显示出结合小鼠血浆蛋白的能力增强，特别是对于M蛋白结合物，这表明对小鼠血浆蛋白亲和力的增加是该病原体适应新宿主的结果。总之，绘制毒力因子总量与细菌表面相关血浆蛋白总量的关系图，可以清楚地将经动物传代的菌株与野生型菌株区分开来，这表明存在一种毒力模型，该模型可以预测化脓性链球菌菌株在小鼠中的毒力，并可用于识别该细菌致病机制的关键方面。
