Streptococcus pneumoniae (pneumococcus) is a major human pathogen producing structurally diverse capsular polysaccharides. Widespread use of highly successful pneumococcal conjugate vaccines (PCVs) targeting pneumococcal capsules has greatly reduced infections by the vaccine types but increased infections by nonvaccine serotypes. Herein, we report a new and the 100th capsule type, named serotype 10D, by determining its unique chemical structure and biosynthetic roles of all capsule synthesis locus (cps) genes. The name 10D reflects its serologic cross-reaction with serotype 10A and appearance of cross-opsonic antibodies in response to immunization with 10A polysaccharide in a 23-valent pneumococcal vaccine. Genetic analysis showed that 10D cps has three large regions syntenic to and highly homologous with cps loci from serotype 6C, serotype 39, and an oral streptococcus strain (S. mitis SK145). The 10D cps region syntenic to SK145 is about 6 kb and has a short gene fragment of wciNα at the 5′ end. The presence of this nonfunctional wciNα fragment provides compelling evidence for a recent interspecies genetic transfer from oral streptococcus to pneumococcus. Since oral streptococci have a large repertoire of cps loci, widespread PCV usage could facilitate the appearance of novel serotypes through interspecies recombination.

中文翻译：

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一种新的肺炎球菌胶囊类型10D，是第100种血清型，具有来自口腔链球菌的大cps片段。

肺炎链球菌（肺炎球菌）是一种主要的人类病原体，可产生结构多样的荚膜多糖。针对肺炎球菌胶囊的高度成功的肺炎球菌结合疫苗（PCV）的广泛使用已大大减少了疫苗类型的感染，但增加了非疫苗血清型的感染。在这里，我们通过确定其独特的化学结构和所有胶囊合成位点（cps）基因的生物合成作用，报告了一种新的第100个胶囊类型，称为血清型10D 。名称10D反映了它与血清型10A的血清学交叉反应，以及在23价肺炎球菌疫苗中用10A多糖免疫后产生的交叉调理抗体。遗传分析表明10D cps具有与血清型6C，血清型39和口腔链球菌菌株（链霉菌SK145）的cps基因座同位并高度同源的三个大区域。与SK145同源的10D cps区域约为6 kb，在5'端具有wciNα短基因片段。这种无功能的wciNα片段的存在为最近种间从口腔链球菌向肺炎球菌的遗传转移提供了令人信服的证据。由于口服链球菌具有大量的cps基因座，因此广泛使用PCV可以通过种间重组促进新型血清型的出现。