Group B streptococcal serine-rich repeat proteins promote interaction with fibrinogen and vaginal colonization

J Infect Dis. 2014 Sep 15;210(6):982-91. doi: 10.1093/infdis/jiu151. Epub 2014 Mar 11.


Group B streptococcus (GBS) can cause severe disease in susceptible hosts, including newborns, pregnant women, and the elderly. GBS serine-rich repeat (Srr) surface glycoproteins are important adhesins/invasins in multiple host tissues, including the vagina. However, exact molecular mechanisms contributing to their importance in colonization are unknown. We have recently determined that Srr proteins contain a fibrinogen-binding region (BR) and hypothesize that Srr-mediated fibrinogen binding may contribute to GBS cervicovaginal colonization. In this study, we observed that fibrinogen enhanced wild-type GBS attachment to cervical and vaginal epithelium, and that this was dependent on Srr1. Moreover, purified Srr1-BR peptide bound directly to host cells, and peptide administration in vivo reduced GBS recovery from the vaginal tract. Furthermore, a GBS mutant strain lacking only the Srr1 "latching" domain exhibited decreased adherence in vitro and decreased persistence in a mouse model of GBS vaginal colonization, suggesting the importance of Srr-fibrinogen interactions in the female reproductive tract.

Keywords: GBS; Srr1; fibrinogen; vaginal colonization.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Bacterial / physiology*
  • Animals
  • Bacterial Adhesion
  • Cell Line
  • Disease Models, Animal
  • Epithelium / microbiology
  • Female
  • Fibrinogen / metabolism*
  • Membrane Glycoproteins / physiology*
  • Mice
  • Serine
  • Streptococcal Infections / microbiology*
  • Streptococcus agalactiae / pathogenicity*
  • Streptococcus agalactiae / physiology
  • Vagina / microbiology*
  • Vaginal Diseases / microbiology


  • Adhesins, Bacterial
  • Membrane Glycoproteins
  • Serine
  • Fibrinogen