Phenotypic whole-cell screening identifies a protective carbohydrate epitope on Klebsiella pneumoniae

• Main Authors: Sophia K. Berry (Author), Steven Rust (Author), Carolina Caceres (Author), Lorraine Irving (Author), Josefin Bartholdson Scott (Author), David E. Tabor (Author), Gordon Dougan (Author), Graham Christie (Author), Paul Warrener (Author), Ralph Minter (Author), Andrew J. Grant (Author)
• Format: Book
• Published: Taylor & Francis Group, 2022-12-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1942-0862; 1942-0870; 10.1080/19420862.2021.2006123
• Keywords: phage display; klebsiella pneumoniae; monoclonal antibody; antimicrobial resistance; lipopolysaccharide; Therapeutics. Pharmacology; RM1-950; Immunologic diseases. Allergy; RC581-607
• Source: mAbs, Vol 14, Iss 1 (2022)

The increasing global occurrence of recalcitrant multi-drug resistant Klebsiella pneumoniae infections warrants the investigation of alternative therapy options, such as the use of monoclonal antibodies (mAbs). We used a target-agnostic phage display approach to K. pneumoniae bacteria lacking bulky, highly variable surface polysaccharides in order to isolate antibodies targeting conserved epitopes among clinically relevant strains. One antibody population contained a high proportion of unique carbohydrate binders, and biolayer interferometry revealed these antibodies bound to lipopolysaccharide (LPS). Antibodies that bound to O1 and O1/O2 LPS were identified. Antibodies were found to promote opsonophagocytic killing by human monocyte-derived macrophages and clearance of macrophage-associated bacteria when assessed using high-content imaging. One antibody, B39, was found to protect mice in a lethal model of K. pneumoniae pneumonia against both O1 and O2 strains when dosed therapeutically. High-content imaging, western blotting and fluorescence-activated cell sorting were used to determine binding to a collection of clinical K. pneumoniae O1 and O2 strains. The data suggests B39 binds to D-galactan-I and D-galactan-II of the LPS of O1 and O2 strains. Thus, we have discovered an mAb with novel binding and functional activity properties that is a promising candidate for development as a novel biotherapeutic for the treatment and prevention of K. pneumoniae infections.