Group A streptococcus cell-associated pathogenic proteins as revealed by growth in hyaluronic acid-enriched media.

Group A streptococcus (GAS), also know as Streptococcus pyogenes, is a human pathogen and can cause several fatal invasive diseases such as necrotising fasciitis, the so-called flesh-eating disease, and toxic shock syndrome. The destruction of connective tissue and the hyaluronic acid (HA) therein, is a key element of GAS pathogenesis. We therefore propagated GAS in HA-enriched growth media in an attempt to create a simple biological system that could reflect some elements of GAS pathogenesis. Our results show that several recognised virulence factors were up-regulated in HA-enriched media, including the M1 protein, a collagen-like surface protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, which has been shown to play important roles in streptococcal pathogenesis. Interestingly, two hypothetical proteins of unknown function were also up-regulated and detailed bioinformatics analysis showed that at least one of these hypothetical proteins is likely to be involved in pathogenesis. It was therefore concluded that this simple biological system provided a valuable tool for the identification of potential GAS virulence factors.