Emergence of a new highly successful acapsular group A Streptococcus clade of the genotype emm89 in the United Kingdom
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Group A Streptococcus (GAS) genotype emm89 is increasingly recognized as a leading cause of disease worldwide, yet factors that underlie the success of this emm type are unknown. Surveillance identified a sustained nationwide increase in emm89 invasive GAS disease in the United Kingdom, prompting longitudinal investigation of this genotype. Whole-genome sequencing revealed a recent dramatic shift in the emm89 population with the emergence of a new clade that increased to dominance over previous emm89 variants. Temporal analysis indicated that the clade arose in the early 1990s but abruptly increased in prevalence in 2008, coinciding with an increased incidence of emm89 infections. Although standard variable typing regions (emm subtype, tee type, sof type, and multilocus sequence typing [MLST]) remained unchanged, uniquely the emergent clade had undergone six distinct regions of homologous recombination across the genome compared to the rest of the sequenced emm89 population. Two of these regions affected known virulence factors, the hyaluronic acid capsule and the toxins NADase and streptolysin O. Unexpectedly, and in contrast to the rest of the sequenced emm89 population, the emergent clade-associated strains were genetically acapsular, rendering them unable to produce the hyaluronic acid capsule. The emergent clade-associated strains had also acquired an NADase/streptolysin O locus nearly identical to that found in emm12 and modern emm1 strains but different from the rest of the sequenced emm89 population. The emergent clade-associated strains had enhanced expression of NADase and streptolysin O. The genome remodeling in the new clade variant and the resultant altered phenotype appear to have conferred a selective advantage over other emm89 variants and may explain the changes observed in emm89 GAS epidemiology.
Date Issued
2015-07-14
Date Acceptance
2015-06-15
Citation
mBio, 2015, 6 (4)
ISSN
2161-2129
Publisher
American Society for Microbiology
Journal / Book Title
mBio
Volume
6
Issue
4
Copyright Statement
© 2015 Turner et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license.
License URL
Publication Status
Published
Article Number
e00622-15
Date Publish Online
2015-07-14