Inter-species gene flow drives ongoing evolution of Streptococcus pyogenes and Streptococcus dysgalactiae subsp....

Area of Science:

• Microbiology
• Genomics
• Infectious Diseases

Background:

• Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an emerging pathogen causing invasive infections.
• SDSE shares clinical and epidemiological similarities with Streptococcus pyogenes.

Purpose of the Study:

• To investigate the genomic relationship between SDSE and S. pyogenes.
• To assess the potential for cross-protection and vaccine evasion between these species.

Main Methods:

• Systematic genomic analysis of 501 disseminated SDSE strains.
• Comparative genomic analysis with S. pyogenes.
• Identification of shared genes, mobile genetic elements, and recombination events.

Main Results:

• Extensive genomic overlap observed between SDSE and S. pyogenes, with over 75% of core genes shared.
• Evidence of cross-species recombination in one-third of shared genes.
• Significant sharing of mobile genetic elements and insertion regions between the species.
• 12 out of 34 S. pyogenes vaccine antigen genes are present in >99% of both SDSE and S. pyogenes isolates.
• Six vaccine candidate genes showed evidence of inter-species recombination.

Conclusions:

• SDSE and S. pyogenes exhibit substantial genomic overlap, challenging distinct pathogen classification.
• Shared genetic elements and recombination impact streptococcal pathobiology and host-pathogen interactions.
• Findings have significant implications for streptococcal disease surveillance and the development of broad-spectrum vaccines.