Oral Presentation 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

Serum antibodies to DRSG protein from Streptococcus dysgalactiae subsp equisimilis increase the risk for chronic kidney diseases: parallels with IgA nephropathy. (#42)

Kadaba (Sri) S Sriprakash 1 , Mohan G Karmarkar 2 , David McMillan 3
  1. Bacterial Pathogenesis Group, QIMR Berghofer MRI, Brisbane, QUEENSLAND, Australia
  2. Microbiology, KEM Hospital, Mumbai, India
  3. University of Sunshine Coast, Maroochydore, Queensland, Australia

Streptococcus dysgalactiae subsp equisimilis (SDSE) is closely related to S. pyogenes. Although SDSE is generally considered as commensal it could cause diseases, and the disease spectrum is similar to that of S. pyogenes. Some isolates of SDSE expresses a secretory protein called DRSG, which is similar to SIC and DRS proteins expressed by some M types of S. pyogenes. SIC, DRS and DRSG proteins are proline-rich and have PXXP motifs. The main role of these protein antigens is to inhibit the function of antimicrobial peptides.

 We earlier showed that antibodies to SIC or DRS are associated with post-streptococcal glomerulonephritis (PSGN). More recently we showed anti-SIC antibodies are also associated with chronic kidney diseases (CKD). Similar studies with DRSG revealed that significantly higher proportion of PSGN and CKD patients had antibodies to DRSG than their corresponding age-matched control subjects. We infer that Infection with DRSG producing SDSE early in life is a risk factor for CKD in later years. We strongly propose sero-surveillance of people who have been infected with SIC, DRS and DRSG producing Streptococci.

 We draw parallels with the most common cause of glomerulonephritis, IgA nephropathy, wherein the patients show elevated levels of antibodies to the proline-rich hinge region of IgA, and the antibody-IgA complex was found in the mesangium.