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

Group B Streptococcus biofilm regulatory protein A (brpA) contributes to host cell adherence and resistance to innate immune clearance (#113)

Katy Patras 1 , Nichole Adiletta 1 , John Lapek 1 , David Gonzalez 1 , Victor Nizet 1
  1. University of California San Diego, La Jolla, CA, United States

Streptococcus agalactiae (Group B Streptococcus, GBS) colonizes the rectovaginal tract in 20-30% of healthy women; however, during pregnancy GBS can be transmitted to the newborn, potentially causing severe disease including pneumonia, sepsis, and meningitis. We are seeking novel targets for therapeutic interventions that either attenuate GBS virulence or enhance host innate immune function against the pathogen. Here we investigate a GBS surface protein that is a member of LytR-Cps2A-Psr enzyme family with roles in cell wall polymer biosynthesis, shares homology with BrpA from S. mutans, but possesses a unique C-terminal domain. Compared to the wild-type parent strain, GBS ΔbrpA exhibits multiple functional changes to the cell wall including a 10-fold increase in chain length, a biofilm formation defect, increased pigmentation, and decreased adherence to host vaginal and bladder epithelial cells. Furthermore, GBS ΔbrpA demonstrates a 100-fold increased susceptibility to killing by primary human neutrophils while stimulating increased neutrophil reactive oxygen species. In contrast, GBS ΔbrpA was neither more susceptible to endogenous antimicrobials LL-37, lysozyme, nor hydrogen peroxide, in minimum inhibitory concentration assays. Ongoing work seeks to assess the virulence capacity of GBS ΔbrpA using murine in vivo sepsis and colonization models, and to define the morphology, antimicrobial susceptibility, and immune cell interactions controlled by this regulatory factor. We propose that brpA is likely to be an important virulence determinant of GBS, and may be a useful target in design of therapeutic or antibacterial strategies.