Oral Immunotherapy with Human Secretory IgA Improves Survival in the Hamster Model of Clostridioides difficile Infection.

Co-administration of human secretory IgA (sIgA) together with subtherapeutic vancomycin significantly enhanced survival in the Clostridioides difficile infection (CDI) hamster model . Vancomycin (5 or 10 mg/kgx5 days) + healthy donor plasma sIgA/monomeric IgA (TIDx21 days) or hyperimmune sIgA/monomeric IgA (BIDx13 days) enhanced survival of CDI hamsters. Survival curves were significantly improved compared to vancomycin alone (p=0.018 and 0.039 by log-rank (Mantel-Cox) for healthy, and hyperimmune, sIgA, respectively. Passive immunization with sIgA made with recombinant human secretory component and IgA dimer/polymer from pooled human plasma can be administered orally, and prevents lethal infection in a partially treated CDI hamster model.