Nontypeable Pneumococci Can Be Divided into Multiple cps Types, Including One Type Expressing the Novel Gene pspK

Author:

Park In Ho1,Kim Kyung-Hyo2,Andrade Ana Lucia3,Briles David E.4,McDaniel Larry S.5,Nahm Moon H.14

Affiliation:

1. Department of Pathology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA

2. Department of Pediatrics, School of Medicine, Ewha Womans University, Seoul, South Korea

3. Department of Community Health, Federal University of Goias, Goiania, Brazil

4. Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA

5. Department of Microbiology, the University of Mississippi Medical Center, Jackson, Mississippi, USA

Abstract

ABSTRACT Although virulence of Streptococcus pneumoniae is associated with its capsule, some pathogenic S. pneumoniae isolates lack capsules and are serologically nontypeable (NT). We obtained 64 isolates that were identified as NT “pneumococci” (i.e., bacteria satisfying the conventional definition but without the multilocus sequence typing [MLST]-based definition of S. pneumoniae ) by the traditional criteria. All 64 were optochin sensitive and had lytA , and 63 had ply . Twelve isolates had cpsA , suggesting the presence of a conventional but defective capsular polysaccharide synthesis ( cps ) locus. The 52 cpsA- negative isolates could be divided into three null capsule clades (NCC) based on aliC ( aliB- like ORF1), aliD ( aliB- like ORF2), and our newly discovered gene, pspK , in their cps loci. pspK encodes a protein with a long alpha-helical region containing an LPxTG motif and a YPT motif known to bind human pIgR. There were nine isolates in NCC1 ( pspK + but negative for aliC and aliD ), 32 isolates in NCC2 ( aliC + aliD + but negative for pspK ), and 11 in NCC3 ( aliD + but negative for aliC and pspK ). Among 52 cpsA- negative isolates, 41 were identified as S. pneumoniae by MLST analysis. All NCC1 and most NCC2 isolates were S. pneumoniae , whereas all nine NCC3 and two NCC2 isolates were not S. pneumoniae . Several NCC1 and NCC2 isolates from multiple individuals had identical MLST and cps regions, showing that unencapsulated S. pneumoniae can be infectious among humans. Furthermore, NCC1 and NCC2 S. pneumoniae isolates could colonize mice as well as encapsulated S. pneumoniae , although S. pneumoniae with an artificially disrupted cps locus did not. Moreover, an NCC1 isolate with pspK deletion did not colonize mice, suggesting that pspK is critical for colonization. Thus, PspK may provide pneumococci a means of surviving in the nasopharynx without capsule. IMPORTANCE The presence of a capsule is critical for many pathogenic bacteria, including pneumococci. Reflecting the pathogenic importance of the pneumococcal capsule, pneumococcal vaccines are designed to elicit anticapsule antibodies. Additional evidence for the pathogenic importance of the pneumococcal capsule is the fact that in pneumococci all the genes necessary for capsule production are together in one genetic locus, which is called the cps locus. However, there are occasional pathogenic pneumococci without capsules, and how they survive in the host without the capsule is unknown. Here, we show that in these acapsular pneumococci, the cps loci have been replaced with various novel genes and they can colonize mouse nasopharynges as well as capsulated pneumococci. Since the genes that replace the cps loci are likely to be important in host survival, they may show new and/or alternative capsule-independent survival mechanisms used by pneumococci.

Publisher

American Society for Microbiology

Subject

Virology,Microbiology

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3