Targeting a bacterial DNABII protein with a chimeric peptide immunogen or humanised monoclonal antibody to prevent or treat recalcitrant biofilm-mediated infections.

Abstract Background: Chronic and recurrent bacterial diseases are recalcitrant to treatment due to the ability of the causative agents to establish biofilms, thus development of means to prevent or resolve these structures are greatly needed. Our approach targets the DNABII family of bacterial DNA-binding proteins, which serve as critical structural components within the extracellular DNA scaffold of biofilms formed by all bacterial species tested to date. DNABII-directed antibodies rapidly disrupt biofilms and release the resident bacteria which promote their subsequent clearance by either host immune effectors or antibiotics that are now effective at a notably reduced concentration. Methods: First, as a therapeutic approach, we used intact IgG or Fab fragments against a chimeric peptide immunogen designed to target protective epitopes within the DNA-binding tip domains of integration host factor to disrupt established biofilms in vitro and to mediate resolution of existing disease in vivo. Second, we performed preventative active immunisation with the chimeric peptide to induce the formation of antibody that blocks biofilm formation and disease development in a model of viral-bacterial superinfection. Further, toward the path for clinical use, we humanised a monoclonal antibody against the chimeric peptide immunogen, then characterised and validated that it maintained therapeutic efficacy. Findings: We demonstrated efficacy of each approach in two well-established pre-clinical models of otitis media induced by the prevalent respiratory tract pathogen nontypeable Haemophilus influenzae, a common biofilm disease. Interpretation: Collectively, our data revealed two approaches with substantive efficacy and potential for broad application to combat diseases with a biofilm component. Funding Supported by R01 DC011818 to LOB and SDG.