title: Phylogenetic relationship and virulence inference of Streptococcus Anginosus Group: curated annotation and whole-genome comparative analysis support distinct species designation.
abstract: BACKGROUND
  The Streptococcus Anginosus Group (SAG) represents three closely related species of the viridans group streptococci recognized as commensal bacteria of the oral, gastrointestinal and urogenital tracts. The SAG also cause severe invasive infections, and are pathogens during cystic fibrosis (CF) pulmonary exacerbation. Little genomic information or description of virulence mechanisms is currently available for SAG. We conducted intra and inter species whole-genome comparative analyses with 59 publically available Streptococcus genomes and seven in-house closed high quality finished SAG genomes; S. constellatus (3), S. intermedius (2), and S. anginosus (2). For each SAG species, we sequenced at least one numerically dominant strain from CF airways recovered during acute exacerbation and an invasive, non-lung isolate. We also evaluated microevolution that occurred within two isolates that were cultured from one individual one year apart.
  
  
  RESULTS
  The SAG genomes were most closely related to S. gordonii and S. sanguinis, based on shared orthologs and harbor a similar number of proteins within each COG category as other Streptococcus species. Numerous characterized streptococcus virulence factor homologs were identified within the SAG genomes including; adherence, invasion, spreading factors, LPxTG cell wall proteins, and two component histidine kinases known to be involved in virulence gene regulation. Mobile elements, primarily integrative conjugative elements and bacteriophage, account for greater than 10% of the SAG genomes. S. anginosus was the most variable species sequenced in this study, yielding both the smallest and the largest SAG genomes containing multiple genomic rearrangements, insertions and deletions. In contrast, within the S. constellatus and S. intermedius species, there was extensive continuous synteny, with only slight differences in genome size between strains. Within S. constellatus we were able to determine important SNPs and changes in VNTR numbers that occurred over the course of one year.
  
  
  CONCLUSIONS
  The comparative genomic analysis of the SAG clarifies the phylogenetics of these bacteria and supports the distinct species classification. Numerous potential virulence determinants were identified and provide a foundation for further studies into SAG pathogenesis. Furthermore, the data may be used to enable the development of rapid diagnostic assays and therapeutics for these pathogens.
authors.forename: Adam B
authors.initials: AB
authors.lastname: Olson
authors.forename: Heather
authors.initials: H
authors.lastname: Kent
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Sibley
authors.forename: Margot E
authors.initials: ME
authors.lastname: Grinwis
authors.forename: Philip
authors.initials: P
authors.lastname: Mabon
authors.forename: Claude
authors.initials: C
authors.lastname: Ouellette
authors.forename: Shari
authors.initials: S
authors.lastname: Tyson
authors.forename: Morag
authors.initials: M
authors.lastname: Graham
authors.forename: Shaun D
authors.initials: SD
authors.lastname: Tyler
authors.forename: Gary
authors.initials: G
authors.lastname: Van Domselaar
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada. surette@mcmaster.ca.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Surette
authors.forename: Cindi R
authors.initials: CR
authors.lastname: Corbett
mesh_terms: D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D023061:Gene Order; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D056426:Genetic Loci; D016680:Genome, Bacterial; D023281:Genomics; D000071677:Histidine Kinase; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide; D011494:Protein Kinases / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D034366:Streptococcus anginosus / Q000145:classification* / Q000235:genetics* / Q000472:pathogenicity; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors; D011494:Protein Kinases; D000071677:Histidine Kinase