Induction of a protective immune response against Chlamydophila psittaci in SPF chicken following vaccination with OMP-1 DNA and CPG oligonucleotides as an adjuvant

In the present study we determined whether CpG motifs could be used as an immune adjuvant for the Omp-1 DNA vaccine against Chlamydophila psittaci, based on the major outer membrane protein (MOMP), to induce the protection in specific pathogen free chickens against an intranasal challenge. Six sequences of phosphorothioate-CpG oligodeoxynucleotides (CpG ODNs) with strong immunostimulatory activity were designed to be examined. The CpG ODN with three GTCGTT repeats significantly promoted splenic lymphocyte proliferation and increased macrophage nitric oxide in a in vitro study. Birds vaccinated with CpG ODN and pcDNA3.1:MOMP induced moderate antibody response and higher lymphoproliferative stimulation while chickens primed-boosted with DNA alone did not. Furthermore, DNA vaccine plus CpG ODN accelerated chlamydial clearance in the spleen and lungs, and decreased inflammatory cellular infiltration. All above evidences show that CpG ODN can be used as an effective adjuvant with a DNA vaccine and this immunisation protocol resulted in an enhanced clearance of Chlamydophila psittaci.