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Updated: Mar 19, 2026
Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
Genomic Investigation Reveals Highly Conserved, Mosaic, Recombination Events Associated with Capsular Switching among
Mustapha M Mustapha1, Jane W Marsh2, Mary G Krauland3
1Infectious Diseases Epidemiology Research Unit, University of Pittsburgh mmm147@pitt.edu.
Abstract:
Neisseria meningitidis is an important cause of meningococcal disease globally. Sequence type (ST)-11 clonal complex (cc11) is a hypervirulent meningococcal lineage historically associated with serogroup C capsule and is believed to have acquired the W capsule through a C to W capsular switching event. We studied the sequence of capsule gene cluster (cps) and adjoining genomic regions of 524 invasive W cc11 strains isolated globally. We identified recombination breakpoints corresponding to two distinct recombination events within W cc11: A 8.4-kb recombinant region likely acquired from W cc22 including the sialic acid/glycosyl-transferase gene, csw resulted in a C→W change in capsular phenotype and a 13.7-kb recombinant segment likely acquired from Y cc23 lineage includes 4.5 kb of cps genes and 8.2 kb downstream of the cps cluster resulting in allelic changes in capsule translocation genes. A vast majority of W cc11 strains (497/524, 94.8%) retain both recombination events as evidenced by sharing identical or very closely related capsular allelic profiles. These data suggest that the W cc11 capsular switch involved two separate recombination events and that current global W cc11 meningococcal disease is caused by strains bearing this mosaic capsular switch.
Insights
The global spread of meningococcal disease is linked to Neisseria meningitidis sequence type 11 (ST-11) strains. These hypervirulent strains acquired a W capsule through two recombination events, leading to current global W ST-11 meningococcal disease.
Area of Science:
- Microbiology
- Genomics
- Epidemiology
Background:
- Neisseria meningitidis ST-11 is a hypervirulent lineage historically linked to serogroup C.
- This lineage is believed to have acquired the W capsule via a capsular switching event.
- The study investigates the genomic basis of this capsular switch in invasive W ST-11 strains.
Discussion:
- Analysis of 524 invasive W ST-11 strains revealed two distinct recombination events.
- A 8.4-kb region, likely from W ST-22, facilitated the C-to-W capsular switch.
- A 13.7-kb segment, likely from Y ST-23, altered capsule translocation genes.
Key Insights:
- The W capsular switch in ST-11 involved two separate recombination events.
- The majority of global W ST-11 strains (94.8%) harbor both recombination events.
- This mosaic capsular switch is responsible for current global W ST-11 meningococcal disease.
Outlook:
- Understanding these recombination events is crucial for tracking meningococcal disease evolution.
- Genomic surveillance of Neisseria meningitidis can identify emerging hypervirulent strains.
- Further research may elucidate the evolutionary advantages conferred by these genetic alterations.
