Capsular Polysaccharide Expression in Commensal Streptococcus Species: Genetic and Antigenic Similarities to Streptococcus pneumoniae.
Capsular Polysaccharide Expression in Commensal Streptococcus Species: Genetic and Antigenic Similarities to Streptococcus pneumoniae.
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DOI：
10.1128/mbio.01844-16
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发表时间：
2016-11-15
期刊：
影响因子：
6.4
通讯作者：
Kilian M
中科院分区：
文献类型：
--
作者：
Skov Sørensen UB;Yao K;Yang Y;Tettelin H;Kilian M
荚膜多糖的表达被认为是大多数侵入性细菌的标志，包括肺炎链球菌，其中荚膜是主要毒力因素之一，是成功疫苗的基础。因此，以前的假设是胶囊生产区分肺炎链球菌与密切相关的共生菌群链球菌。通过对187种链球菌（包括90种已确认的肺炎链球菌血清型）的抗原和遗传分析，研究人员证实，在66种链球菌中，74%的链球菌以及几乎所有被测试的口腔链球菌（口腔链球菌亚种、牙链球菌亚种和虎链球菌亚种）和婴儿链球菌中，Wzy/Wzx途径都能产生胶囊。对猪链球菌、副血链球菌、南血链球菌、血链球菌、戈多氏链球菌、血管链球菌、中间链球菌和星状链球菌的基因组分析显示，所有测试菌株都有完整的荚膜生物合成（cps）位点。在3株假肺炎链球菌、26%的密氏链球菌和1株口腔链球菌中检测到截断的cps位点。cps位点基因的序列认同水平证实了肺炎链球菌荚膜多糖的结构多态性是由共生链球菌输入cps片段进化而来的，导致不同来源的基因嵌合体。共生链球菌表达的众多荚膜多糖结构中，至少有8种与已识别的肺炎链球菌血清型具有抗原同一性，这引起了人们对潜在误认的担忧，此外还有关于共生链球菌和病原体的疫苗接种后果和宿主-寄生虫关系的重要问题。荚膜多糖的表达是肺炎链球菌的主要毒力因子之一，是成功的疫苗对抗这种重要病原体引起的感染的基础。与先前的假设相反，本研究表明，通过相同的遗传机制表达荚膜多糖是密切相关的链球菌物种的一般特性，构成了我们共生微生物群的重要组成部分。共生链球菌和肺炎链球菌表达的许多荚膜多糖已被证实具有抗原性，这就对共生菌和病原体的接种后果和宿主-寄生虫关系提出了重要的问题。
Expression of a capsular polysaccharide is considered a hallmark of most invasive species of bacteria, including Streptococcus pneumoniae, in which the capsule is among the principal virulence factors and is the basis for successful vaccines. Consequently, it was previously assumed that capsule production distinguishes S. pneumoniae from closely related commensals of the mitis group streptococci. Based on antigenic and genetic analyses of 187 mitis group streptococci, including 90 recognized serotypes of S. pneumoniae, we demonstrated capsule production by the Wzy/Wzx pathway in 74% of 66 S. mitis strains and in virtually all tested strains of S. oralis (subspecies oralis, dentisani, and tigurinus) and S. infantis. Additional analyses of genomes of S. cristatus, S. parasanguinis, S. australis, S. sanguinis, S. gordonii, S. anginosus, S. intermedius, and S. constellatus revealed complete capsular biosynthesis (cps) loci in all strains tested. Truncated cps loci were detected in three strains of S. pseudopneumoniae, in 26% of S. mitis strains, and in a single S. oralis strain. The level of sequence identities of cps locus genes confirmed that the structural polymorphism of capsular polysaccharides in S. pneumoniae evolved by import of cps fragments from commensal Streptococcus species, resulting in a mosaic of genes of different origins. The demonstrated antigenic identity of at least eight of the numerous capsular polysaccharide structures expressed by commensal streptococci with recognized serotypes of S. pneumoniae raises concerns about potential misidentifications in addition to important questions concerning the consequences for vaccination and host-parasite relationships both for the commensals and for the pathogen. Expression of a capsular polysaccharide is among the principal virulence factors of Streptococcus pneumoniae and is the basis for successful vaccines against infections caused by this important pathogen. Contrasting with previous assumptions, this study showed that expression of capsular polysaccharides by the same genetic mechanisms is a general property of closely related species of streptococci that form a significant part of our commensal microbiota. The demonstrated antigenic identity of many capsular polysaccharides expressed by commensal streptococci and S. pneumoniae raises important questions concerning the consequences for vaccination and host-parasite relationships both for the commensals and the pathogen.