The fundamental contribution of phages to GAS evolution, genome diversification and strain emergence.
The human bacterial pathogen group A Streptococcus (GAS) causes many different diseases including pharyngitis, tonsillitis, impetigo, scarlet fever, streptococcal toxic shock syndrome, necrotizing fasciitis and myositis, and the post-infection sequelae glomerulonephritis and rheumatic fever. The frequency and severity of GAS infections increased in the 1980s and 1990s, but the cause of this increase is unknown. Recently, genome sequencing of serotype M1, M3 and M18 strains revealed many new proven or putative virulence factors that are encoded by phages or phage-like elements. Importantly, these genetic elements account for an unexpectedly large proportion of the difference in gene content between the three strains. These new genome-sequencing studies have provided evidence that temporally and geographically distinct epidemics, and the complex array of GAS clinical presentations, might be related in part to the acquisition or evolution of phage-encoded virulence factors. We anticipate that new phage-encoded virulence factors will be identified by sequencing the genomes of additional GAS strains, including organisms non-randomly associated with particular clinical syndromes.
Banks
David J
DJ
Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, 903 South 4th Street, Hamilton, MT 59840, USA.
Beres
Stephen B
SB
Musser
James M
JM
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry; D004351:Drug Resistance / Q000235:genetics; D019143:Evolution, Molecular; D015967:Gene Expression Regulation, Viral; D016680:Genome, Bacterial; D008242:Lysogeny; D018942:Macrolides; D017108:Streptococcus Phages / Q000235:genetics* / Q000276:immunology; D013297:Streptococcus pyogenes / Q000235:genetics* / Q000821:virology*; D037521:Virulence Factors / Q000276:immunology
D000900:Anti-Bacterial Agents; D018942:Macrolides; D037521:Virulence Factors