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Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
Published on: September 11, 2020
Genetic basis for the new pneumococcal serotype, 6C
In Ho Park1, Saeyoung Park, Susan K Hollingshead
1Department of Pathology, University of Alabama at Birmingham, 845 19th Street South, BBRB 614, Birmingham, AL 35294, USA.
Infection and Immunity
|June 20, 2007
Summary
A new pneumococcal serotype, 6C, originated from a single recombination event in the 6A serotype's capsule gene locus. This event, occurring over 27 years ago, involved the replacement of the wciN region, creating the distinct 6C serotype.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- A novel pneumococcal serotype, 6C, has been identified and is closely related to serotype 6A.
- Understanding the genetic underpinnings of serotype variation is crucial for vaccine development and epidemiology.
Purpose of the Study:
- To investigate the genetic basis for the emergence of pneumococcal serotype 6C.
- To identify the specific genetic alterations responsible for differentiating serotype 6C from serotype 6A.
Main Methods:
- Analysis of the capsule gene loci (wciN region) from 14 diverse 6C isolates.
- DNA sequencing of the entire capsule gene locus from a representative 6C isolate.
- Functional analysis through gene transfer experiments.
Main Results:
- All 6C isolates share a unique 1,029-bp wciN region sequence, distinct from the 1,222-bp sequence in 6A.
- A recombination event in the wciN region created a novel open reading frame encoding a putative glycosyl transferase.
- Transfer of the 6C wciN region into a 6A locus successfully converted it to 6C.
- The 6C capsule gene locus is highly homologous to 6A, differing primarily in the wciN region.
Conclusions:
- Pneumococcal serotype 6C arose from a single recombination event within the 6A capsule gene locus.
- This event, predating the study by at least 27 years, involved the replacement of the native 6A wciN gene with a sequence of unknown origin.
- The genetic plasticity of the pneumococcal capsule locus facilitates the emergence of new serotypes.
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