Staphylococcus pseudintermedius Sbi paralogs inhibit complement and bind IgM, IgG Fc and Fab

PLoS One. 2019 Jul 23;14(7):e0219817. doi: 10.1371/journal.pone.0219817. eCollection 2019.

Abstract

The success of staphylococci as pathogens has been attributed, in part, to their ability to evade their hosts' immune systems. Although the proteins involved in evasion have been extensively studied in staphylococci affecting humans little characterization has been done with Staphylococcus pseudintermedius, an important cause of pyoderma in dogs. Staphylococcus aureus binder of immunoglobulin (Sbi) interferes with innate immune recognition by interacting with multiple host proteins. In this study, a S. pseudintermedius gene that shares 38% similarity to S. aureus Sbi was cloned from S. pseudintermedius strains representative of major clonal lineages bearing two paralogs of the protein. Binding of immunoglobulins and Fab and Fc fragments as well as interaction with complement was measured. S. pseudintermedius Sbi protein bound IgG from multiple species and canine complement C3, neutralized complement activity and bound to canine IgM and B cells. Evidence from this work suggests Sbi may play an important role in S. pseudintermedius immune evasion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / immunology
  • Carrier Proteins / genetics*
  • Carrier Proteins / immunology
  • Complement System Proteins / immunology*
  • Dogs
  • Immunoglobulin Fab Fragments / immunology*
  • Immunoglobulin Fc Fragments / immunology*
  • Immunoglobulin M / immunology*
  • Sequence Homology, Amino Acid
  • Staphylococcus / genetics
  • Staphylococcus / immunology*

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Immunoglobulin Fab Fragments
  • Immunoglobulin Fc Fragments
  • Immunoglobulin M
  • Sbi protein, Staphylococcus aureus
  • Complement System Proteins

Supplementary concepts

  • Staphylococcus pseudintermedius

Grants and funding

This work was supported by the University of Tennessee Center of Excellence in Livestock Diseases and Human Health (DB, SK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.