ArticleBMC genomics2014
Non-typeable pneumococci circulating in Portugal are of cps type NCC2 and have genomic features typical of encapsulated isolates.
Article in BMC genomics, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 12 papers.
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Who cites it
12 citing papers in PubMed.
- Prevalence, Antimicrobial Resistance, and Genetic Diversity of Non-TypeableHealth science reports · 2026Review
- Storage stability of non-encapsulated pneumococci in saliva is dependent on null-capsule clade, with strains carryingMicrobiology (Reading, England) · 2025Article
- High Levels of Detection of Nonpneumococcal Species of Streptococcus in Saliva from Adults in the United States.Microbiology spectrum · 2023Article
- Persistence of Pneumococcal Carriage among Older Adults in the Community despite COVID-19 Mitigation Measures.Microbiology spectrum · 2023Article
- Impact of Temporary Storage Conditions on the Viability of Streptococcus pneumoniae in Saliva.mSphere · 2022Article
- Identification of Streptococcus pneumoniae by a real-time PCR assay targeting SP2020.Scientific reports · 2019Article
- Streptococcus pneumoniae PspC Subgroup Prevalence in Invasive Disease and Differences in Contribution to Complement Evasion.Infection and immunity · 2018Article
- Article
- Sequencing of the variable region ofOpen biology · 2017Article
- Polyamine transporter potABCD is required for virulence of encapsulated but not nonencapsulated Streptococcus pneumoniae.PloS one · 2017Article
- Review
- Immunization with Pneumococcal Surface Protein K of Nonencapsulated Streptococcus pneumoniae Provides Protection in a Mouse Model of Colonization.Clinical and vaccine immunology : CVI · 2015Article
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Authors and funding
6 authors.
Funding
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Abstract
backgroundPneumococcus is a major human pathogen and the polysaccharide capsule is considered its main virulence factor. Nevertheless, strains lacking a capsule, named non-typeable pneumococcus (NT), are maintained in nature and frequently colonise the human nasopharynx. Interest in these strains, not targeted by any of the currently available pneumococcal vaccines, has been rising as they seem to play an important role in the evolution of the species. Currently, there is a paucity of data regarding this group of pneumococci. Also, questions have been raised on whether they are true pneumococci. We aimed to obtain insights in the genetic content of NT and the mechanisms leading to non-typeability and to genetic diversity.
resultsA collection of 52 NT isolates representative of the lineages circulating in Portugal between 1997 and 2007, as determined by pulsed-field gel electrophoresis and multilocus sequence typing, was analysed. The capsular region was sequenced and comparative genomic hybridisation (CGH) using a microarray covering the genome of 10 pneumococcal strains was carried out. The presence of mobile elements was investigated as source of intraclonal variation. NT circulating in Portugal were found to have similar capsular regions, of cps type NCC2, i.e., having aliB-like ORF1 and aliB-like ORF2 genes. The core genome of NT was essentially similar to that of encapsulated strains. Also, competence genes and most virulence genes were present. The few virulence genes absent in all NT were the capsular genes, type-I and type-II pili, choline-binding protein A (cbpA/pspC), and pneumococcal surface protein A (pspA). Intraclonal variation could not be entirely explained by the presence of prophages and other mobile elements.
conclusionsNT circulating in Portugal are a homogeneous group belonging to cps type NCC2. Our observations support the theory that they are bona-fide pneumococcal isolates that do not express the capsule but are otherwise essentially similar to encapsulated pneumococci. Thus we propose that NT should be routinely identified and reported in surveillance studies.
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