IgY-mediated protection against Vibrio cholerae infection: Efficacy of avian antibodies targeting a chimeric recombinant protein.

Introduction: Vibrio cholerae, the etiologic pathogen of diarrheal disease, prevails mainly in developing countries, transmitted through contaminated water or food. The unique genetic makeup and remarkable competency has prompted intensive research to unravel the bacterium virulence properties. Egg yolk immunoglobulins (IgY) have emerged as innovative biotherapeutics for both passive immunotherapy and prophylactic strategies.

Methods: In the present study, we generated avian antibodies against a chimeric recombinant protein comprising OmpW-TcpA-CtxB (OTC) antigens from V. cholerae, and examined its efficacy against bacterial toxins and infection. The chimeric protein was expressed in E. coli BL21 (DE3) and purified using Ni-NTA affinity chromatography. Leghorn chickens were intramuscularly immunized with the recombinant protein and the purity of extracted IgYs was assessed through SDS-PAGE analysis. The immunoreactivity and specificity of anti-OTC-IgYs were evaluated through protein and whole-cell ELISA, and their ability to neutralize cholera toxin (CT) of V. cholerae was evaluated in Y1 cell line. Finally, the protective efficacy of orally administered anti-OTC-IgY was investigated in V. cholerae-infected infant mice.

Results: Anti-OTC-IgY successfully neutralized the cytotoxic effects of CT at a concentration of 250 µg/mL. Oral administration of two 100 µg doses of anti-OTC-IgY and resulted in 60% and 20% survival rates in suckling mice infected with LD and 10 LD of V. cholerae, respectively.

Conclusion: The anti-OTC-IgY antibodies exhibited significant immunoreactivity, toxin-neutralizing potency, and protective effects, establishing their potential as promising antimicrobials against the bacterial pathogenicity through passive immunotherapy.