A novel multivalent, single-domain antibody targeting TcdA and TcdB prevents fulminant Clostridium difficile...

Area of Science:

• Microbiology
• Immunology
• Infectious Diseases

Background:

• Clostridium difficile infection (CDI) incidence and mortality are rising globally.
• Novel therapeutic strategies are urgently needed to combat CDI.

Purpose of the Study:

• To develop and evaluate a novel bispecific antibody (ABA) targeting both Clostridium difficile toxins A (TcdA) and B (TcdB).
• To assess the efficacy of ABA in a murine model of severe CDI.

Main Methods:

• Generation of a tetravalent, bispecific antibody (ABA) with VHH domains targeting TcdA and TcdB.
• In vitro and in vivo neutralization assays using bacterial toxins and a CDI mouse model infected with a C. difficile 027 strain.
• Testing ABA against toxins from various clinical C. difficile isolates.

Main Results:

• ABA demonstrated potent simultaneous binding to both TcdA and TcdB.
• The antibody exhibited significantly enhanced in vitro and in vivo neutralizing activity against C. difficile toxins.
• ABA successfully reversed fulminant CDI in mice after a single dose.
• Broad neutralization of toxins from TcdA(+)TcdB(+) clinical isolates was observed, but not from TcdA(-)TcdB(+) strains.

Conclusions:

• The tetravalent, bispecific antibody ABA is a potent neutralizer of C. difficile toxins A and B.
• ABA shows significant therapeutic potential for treating severe CDI caused by toxin-producing strains.
• Multivalent VHH antibodies targeting both toxins represent a promising approach for broad CDI therapy.