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Heuristic Mining of Hierarchical Genotypes and Accessory Genome Loci in Bacterial Populations
Published on: December 7, 2021
Relationships between emm and multilocus sequence types within a global collection of Streptococcus pyogenes
Debra E Bessen1, Karen F McGregor, Adrian M Whatmore
1Department of Microbiology and Immunology, New York Medical College, Valhalla, NY 10595, USA. debra_bessen@nymc.edu
BMC Microbiology
|April 15, 2008
Summary
Streptococcus pyogenes emm type evolution varies by infection site. Throat specialists show stronger selection on emm genes, impacting vaccine strategies against this global pathogen.
Area of Science:
- Microbiology
- Genetics
- Immunology
Background:
- Streptococcus pyogenes is a global pathogen.
- emm gene-encoded M protein antigens are vaccine targets.
- Understanding emm gene evolution is crucial for vaccine development.
Purpose of the Study:
- To investigate the genetic history of emm genes in Streptococcus pyogenes.
- To correlate emm type with bacterial genetic background and host tissue tropism.
- To assess evolutionary pressures on emm genes in different S. pyogenes lineages.
Main Methods:
- Analyzed >500 Streptococcus pyogenes isolates worldwide.
- Utilized multilocus sequence typing to define genetic background.
- Compared emm type distribution and genetic diversity across host-associated groups.
Main Results:
- Categorized isolates into throat, skin, and generalist specialists.
- Found emm type to be a poor marker for bacterial clones.
- Observed higher rates of emm type replacement in throat and skin specialists.
- Noted significantly higher Ka/Ks ratios for throat specialist emm types (4.9) compared to skin (1.5) and generalists (1.3).
Conclusions:
- emm type and genetic background relationships differ across host tissue groups.
- Strongest selection pressures on emm genes are evident in throat specialists.
- Findings have implications for Streptococcus pyogenes vaccine design and deployment strategies.
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