Monoclonal antibody against l-lectin module of SraP blocks adhesion and protects mice against Staphylococcus aureus challenge

Background/purpose: SraP is a serine-rich repeat protein (SRRP) from Staphylococcus aureus that binds to sialylated receptors to promote bacterial adhesion to and invasion into host epithelial cells, mediated by the L-lectin module of its ligand-binding region.Methods: The sequence encoding the L-lectin module of SraP was inserted into pET28a plasmid, and the recombinant protein was purified by His label affinity chromatography. A monoclonal antibody (mAb) against the L-lectin module was obtained and confirmed by enzyme-linked immunosorbent assay and western blotting. The effect of the mAb on S. aureus adhesion and invasion was assessed in A(549) cells and mice subjected to S. aureus challenge.Results: We successfully obtained a mAb against the L-lectin module of SraP. Pre-incubation with the mAb dramatically inhibited the bacteria's ability to adhere to and invade A(549) cells. Moreover, mice administered mAb through tail vein injection had significantly fewer bacteria in the blood.Conclusion: The anti-SraP(L-Lectin) mAb significantly reduced the adherence and invasion of S. aureus to host cells. This study lays the foundation for the future development of the L-lectin module of SraP as a target for the prevention and treatment of S. aureus infection. Our findings suggest that specific subdomains of SRRPs may represent potential antibacterial drug targets for intervention. Copyright (C) 2019, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC.