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Streptococcus halichoeri: Comparative Genomics of an Emerging Pathogen
Kirsi Aaltonen1,2, Ravi Kant1,2, Marjut Eklund3
1Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
International Journal of Genomics
|March 10, 2020
Summary
Streptococcus halichoeri, a versatile pathogen, shows adaptability and potential for host switching. Its core genome contains virulence factors, primarily adhesins, suggesting a marine origin and zoonotic risk.
Area of Science:
- Veterinary Microbiology
- Genomics
- Zoonotic Diseases
Background:
- Streptococcus halichoeri is an emerging pathogen with known marine mammal and human isolates.
- Concurrent epidemics in Finnish fur animals (fur animal epidemic necrotic pyoderma) and dogs (ear infections) since 2010 involved S. halichoeri.
Purpose of the Study:
- To investigate a potential common origin for fur animal and dog S. halichoeri isolates.
- To analyze virulence factors and assess the pathogenic potential of S. halichoeri.
Main Methods:
- Whole genome sequencing of 20 S. halichoeri strains (seal, human, dog, fur animal).
- Genome annotation using RAST, core and pangenome analysis, and phylogenetic tree construction.
- Virulence factor assessment using the Virulence Factor Database (VFDB).
Main Results:
- A stable core genome comprising approximately half of the genes was identified, nearly saturated.
- A highly variable pangenome indicates ongoing evolution and adaptability.
- Virulence factors, predominantly adhesins, were concentrated in the core genome, supporting a marine origin.
Conclusions:
- S. halichoeri exhibits significant adaptability, facilitating host and environmental switching.
- The presence of virulence factors in the core genome highlights its pathogenic potential.
- Findings support the marine origin of S. halichoeri and its zoonotic implications.
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