Duck hepatitis virus type I: studies with inactivated vaccines in breeder ducks.
Inactivated type I duck hepatitis virus (DHV) vaccines were evaluated under field and laboratory conditions in breeder ducks which had been primed with modified (attenuated) live virus (MLV) vaccine. A single booster dose of inactivated DHV vaccine was as efficacious as the present method of periodic booster doses of MLV based on antibody levels in the breeder ducks and resistance of progeny ducklings to challenge with virulent DHV. Ducklings primed with MLV vaccine at 12 weeks of age and boosted with inactivated DHV at 18 weeks developed antibody titres 16-fold higher than those in ducks that received only the MLV priming. In ducks not primed with MLV the immunogenicity of inactivated DHV was found to be limited.
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Duck Research Laboratory, Department of Avian and Aquatic Animal Medicine, New York State College of Veterinary Medicine, Cornell University, Eastport, New York, USA.