Clostridioides difficile infection (CDI) is a leading cause of antibiotic‑associated diarrhea and colitis, with recurrence rates as high as 35% despite standard antibiotic therapy. Current vaccine efforts have primarily focused on neutralizing toxins; however, toxin‑based vaccine candidates have failed in late‑stage clinical trials and do not prevent bacterial colonization or transmission. There remains a critical unmet need for vaccine strategies that address both disease severity and recurrence by targeting early steps in infection.
Our researchers identified Cell Wall Protein 2 (Cwp2), an abundant and highly immunogenic C. difficile surface protein, as a promising vaccine target. The functional domain of Cwp2 (Cwp2_A) was shown through bioinformatic analysis to be both highly immunogenic and broadly conserved across major toxinotypes and ribotypes, including hypervirulent strains.
In murine models, immunization with recombinant Cwp2_A induced robust anti‑Cwp2 IgG and IgA responses in serum and intestinal samples. Vaccinated mice exhibited significantly improved survival, reduced weight loss and diarrhea, and markedly lower fecal toxin A, toxin B, and spore levels following challenge with a hypervirulent C. difficile strain. Importantly, anti‑Cwp2_A sera inhibited bacterial adhesion to human intestinal epithelial cells in vitro, demonstrating a direct anti‑colonization mechanism. Cellular immune analysis further showed induction of Th1 and Th17 responses, supporting durable and multifunctional immunity.
Figure: Immunization with Cwp2_A Provides Significant Protection Against C. difficile Infection in Mice
Mice immunized with the Cwp2 functional domain (Cwp2_A) were challenged with a hypervirulent Clostridioides difficile R20291 strain. Compared with non‑immunized controls, vaccinated mice showed significantly improved survival, reduced weight loss, and lower incidence of diarrhea, demonstrating strong in vivo protective efficacy of the Cwp2_A vaccine candidate.