date:State Univ Ghent, Fac Agr & Appl Biol Sci, Dept Mol Biotechnol, B-9000 Ghent, Belgium; Katholieke Univ Leuven, Fac Agr & Appl Biol Sci, Lab Immunol & Physiol Domest Anim, B-3001 Louvain, Belgium; State Univ Ghent, Fac Vet Med, Lab Vet Immunol, B-9820 Merelbeke, Belgium
Plasmid DNA expressing the major outer membrane protein (MOMP) of an avian Chlamydophila psittaci serovar D strain and recombinant MOMP (rMOMP) with or without the immunomodulating adjuvant I alpha,25-dihydroxyvitamin D-3 have been tested for their ability to elicit an immune response and induce protection in turkeys against challenge with the same serovar. Three vaccination strategies were compared: priming and boosting with either pcDNA1::MOMP or MOMP and priming with pcDNA1::MOMP followed by rMOMP boosting. Turkeys primed with pcDNA1::MOMP showed significant protection against Cp. psittaci challenge, turkeys primed with MOMP did not. The steroid hormone 1 alpha,25-dihydroxyvitamin D3 augmented serum and mucosal antibody titres. However, higher antibody titres were not related to better protection and even had a negative effect on especially bacterial excretion, (c) 2005 Elsevier Ltd. All rights reserved.