title: Comparative genomics of Streptococcus pyogenes M1 isolates differing in virulence and propensity to cause systemic infection in mice.
abstract: Streptococcus pyogenes serotype M1 is a frequent cause of severe infections in humans. Some M1 isolates are pathogenic in mice and used in studies on infection pathogenesis. We observed marked differences in murine infections caused by M1 strain SF370, 5448, 5448AP or AP1 which prompted us to sequence the whole genome of isolates 5448 and AP1 for comparative analysis. Strain 5448 is known to acquire inactivating mutations in the CovRS two-component system during mouse infection, producing hypervirulent progeny such as 5448AP. Isolates AP1 and 5448AP, more than 5448, caused disseminating infections that became systemic and lethal. SF370 was not pathogenic. Phages caused gross genetic differences and increased the gene content of AP1 by 8% as compared to 5448 and SF370. Each of six examined M1 genomes contained two CRISPR-Cas systems. Phage insertion destroyed a type II CRISPR-Cas system in AP1 and other strains of serotypes M1, M3, M6 and M24, but not in M1 strains 5448, SF370, MGAS5005, A20 or M1 476. A resulting impaired defence against invading genetic elements could have led to the wealth of phages in AP1. AP1 lacks genetic features of the MGAS5005-like clonal complex including the streptodornase that drives selection for hypervirulent clones with inactivated CovRS system. Still, inactivating mutations in covS were a common genetic feature of AP1 and the MGAS5005-like isolate 5448AP. Abolished expression of the cysteine proteinase SpeB, due to CovRS inactivation could be a common cause for hypervirulence of the two isolates. Moreover, an additional protein H-coding gene and a mutation in the regulator gene rofA distinguished AP1 form other M1 isolates. In conclusion, hypervirulence of S. pyogenes M1 in mice is not limited to the MGAS5005-like genotype.
authors.affiliation: Infection Immunology Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Fiebig
authors.affiliation: Infection Immunology Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Torsten G
authors.initials: TG
authors.lastname: Loof
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Anshu
authors.initials: A
authors.lastname: Babbar
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Itzek
authors.affiliation: Laboratory of Systems and Synthetic Biology, Wageningen University & Research Centre, Wageningen, the Netherlands.
authors.forename: Jasper J
authors.initials: JJ
authors.lastname: Koehorst
authors.affiliation: Laboratory of Systems and Synthetic Biology, Wageningen University & Research Centre, Wageningen, the Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Schaap
authors.affiliation: Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany. Electronic address: Patric.Nitsche@web.de.
authors.forename: D Patric
authors.initials: DP
authors.lastname: Nitsche-Schmitz
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001435:Bacteriophages / Q000235:genetics; D055028:Comparative Genomic Hybridization / Q000379:methods*; D005098:Exotoxins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D013290:Streptococcal Infections / Q000382:microbiology / Q000473:pathology; D013297:Streptococcus pyogenes / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D005098:Exotoxins
keywords: Bacteremia; Bacteriophage; CRISPR-Cas; Control of virulence; Fibronectin-collagen-T-antigen; Gram-positive; Multiple gene activator; Necrotizing skin and soft tissue infections; Pathogenicity; Sepsis; Whole genome sequencing