RESUMO
Avian Pasteurella multocida is an agent of fowl cholera. The protective effect achieved through orthodox vaccines is not ideal. The research on novel vaccines against avian Pasteurella multocida is imperative. In this study, the genes encoding outer membrane protein H and A [OmpH and OmpA] were cloned into the eukaryotic expression vector pcDNA3.1[+] and the recombinant plasmids, namely DNA vaccines [pOMPH and pOMPA] were obtained. Five groups of chickens [n=20 per group] were intramuscularly injected with the two recombinant plasmids, attenuated live vaccine, control vector pcDNA[3.1[+]] and PBS, respectively. The immune responses and protective efficacy were evaluated after immunization by serological and challenging. A significant increase in serum antibody levels was observed in chickens vaccinated with the attenuated live vaccine and the two DNA vaccines. Additionally, the lymphocyte proliferation [SI values] were higher in chickens immunized with the attenuated live vaccine and the two DNA vaccines than in those vaccinated with pcDNA[3.1[+]] and PBS [P<0.05]. Furthermore, the two DNA vaccines provided partial protection to the vaccinated chickens; however, the protective efficacy was inferior to that provided by the attenuated live vaccine