Macdonald, L. | bioRxiv Science

bioRxiv2023

A monoclonal antibody collection for C. difficile typing

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea and pseudomembranous colitis in adults. Various C. difficile strains circulate currently, associated with different outcomes and antibiotic resistance profiles. However, most studies still focus on the reference strain 630 that does not circulate anymore, partly due to the lack of immunological tools to study current clinically important C. difficile PCR ribotypes. Herein, we immunized mice expressing human variable antibody genes with the Low Molecular Weight (LMW) subunit of the surface layer protein SlpA from various C. difficile strains. Monoclonal antibodies purified from hybridomas bound LMW with high-affinity and whole bacteria from current C. difficile ribotypes with different cross-specificities. This first collection of anti-C. difficile mAbs represent valuable tools for basic and clinical research.

immunology↗

bioRxiv2023

Anti-S-layer monoclonal antibodies impact Clostridioides difficile physiology

Clostridioides difficile (C. difficile), a gram-positive anaerobic and spore-forming bacterium, is the leading cause of nosocomial antibiotic-associated diarrhea in adults and is characterized by high levels of recurrence and mortality. Surface-layer Protein A (SlpA), the most expressed protein on bacterial surface, plays a crucial role in the early stages of infection although its role in C. difficile physiology is yet to be fully understood. Anti-S-layer antibodies have been identified in the sera of convalescent patients and correlate with improved outcome of C. difficile infection (CDI). However, the precise mechanisms of how anti-S-layer antibodies can confer protection to the host remain unknown. In this study, we report the first monoclonal antibodies (mAbs) targeting S-layer of the reference strain 630. Characterization of these mAbs unravels important roles for S-layer protein in growth, toxin secretion, and biofilm formation with, surprisingly, opposite effects of different anti-SlpA mAbs on these functions. One anti-SlpA mAb impaired C. difficile growth and restored sensitivity to lysozyme-induced lysis. These findings suggest that anti-S-layer antibody responses may include protective and detrimental effects for the host and provide important insights for designing adequate S-layer-targeting therapeutics.

microbiology↗