Significant mucosal sIgA production after a single oral or parenteral administration using in vivo CD40 targeting in the chicken

- In vivo CD40 targeting established mucosal sIgA responses 7 days post immunization.
- One single administration is sufficient to induce mucosal sIgA, regardless of the route.
- CD40 targeting requires < 1% of the immunogen used in conventional approaches.

Many pathogens enter the host through mucosal surfaces and spread rapidly via the circulation. The most effective way to prevent disease is to establish mucosal and systemic immunity against the pathogen. However, current vaccination programs in poultry industry require repeated administrations of live-attenuated virus or large amounts (10 to 100 μg) of antigen together with adjuvant to induce specific secretory IgA immune responses at the mucosal effector sites. In the present study, we show that a single administration of 0.4 μg of oligopeptide complexed with an agonistic anti-chicken CD40 (chCD40) monoclonal antibody (Mab) effectively targets antigen-presenting cells of the bird's mucosa-associated lymphoid tissue in vivo, and induces peptide-specific secretory IgA (sIgA) in the trachea 7 days post administration. Anti-chCD40 Mab-peptide complex was administered once to four-week old male Leghorns via various mucosal routes (orally, via cloacal drinking, or oculo-nasally) or via subcutaneous (s.c.) immunization. Immunization through any of the three mucosal induction routes induced significant peptide-specific mucosal sIgA responses 7 and 14 days after immunization. Interestingly, s.c. injection of the complex also induced mucosal sIgA. Our data suggest in vivo targeting of CD40 as a potential adjuvant platform, particularly for the purpose of enhancing and speeding up mucosal vaccine responses in chickens, and potentially other food animals. This is the first study able to elicit specific sIgA immune responses in remote mucosal sites with a single administration of only 0.4 μg of antigen.