Effects of cytosine-phosphate-guanosine oligodinucleotides (CpG-ODNs) on oral immunization with protein antigen or replicating parasite

The purpose of this research was to investigate selected methods of mucosal immunization for commercial chickens. Induction of mucosal immunity in commercial chickens through the use of orally administered subunit vaccines or through immunomodulation of the host??s response to live vaccines may be a viable means to control enteric infections in commercial poultry. In the present investigations we evaluated a means for delivering protein antigen in the drinking water and the use of CpG-ODNs, a recently reported mucosal adjuvant, in order to both improve this response and to modulate the host??s immune response when vaccinated with field strains of Eimeria acervulina and Eimeria tenella. In order to evaluate the efficacy of immunizing commercial poultry with subunit vaccines through the drinking water we chose the model antigen Bovine Serum Albumin (BSA). Chicks were administered BSA via intraperitoneal (I.P.) injection, oral crop gavage, or orally through the addition of BSA to the drinking water. These experiments demonstrated the efficacy of drinking water administration to induce antibodyproduction in the serum, intestine, and bile. When BSA was co-administered with CpGODNs we observed a modest increase in this response dependent upon dose. To evaluate the immunomodulation of the host response to live parasite using CpG-ODNs we used three administration models. The first was a single dose of CpGODNs with a trickle immunization regime of Eimeria acervulina. The second was coadministration of CpG-ODNs with a clinical dose of Eimeria acervulina or tenella. The third was pre-administration of CpG-ODNs 24 hours prior to the clinical dose of either species. These studies demonstrate that the first and third models were effective in reducing lesions and improving performance.