Evaluation of Dual Repeated Day-Old Marek’s Vaccine Programs in Future Broiler Breeders

Andrea Delvecchio, Yit Siam Wong, Jean-Claude Gauthier, Isabel Gimeno and Stephane Lemiere


The principle is for future breeder Marek's vaccination program to associate a serotype 3 (SR-3), HVT strain and a serotype 1 (SR-1), Rispens strain. The SR-3 vaccine could be either the native HVT strain vaccine, or the HVT vector of infectious bursal disease protective gene VP2. Some poultry multiplication operations use a dual vaccine application at day-old, SR-3 & SR- 1 injected by sub-cutaneous route, and then another SR-1 using another route, intramuscular for example. Dual vaccine application at day-old was studied in commercial future heavy broiler breeders. SPF chickens were included into the study in order to perform a Marek’s disease challenge. Primary parameter of study monitored throughout the studies was a virus recovery technique, a quantitative polymerase chain reaction (qPCR) performed on feather pulp samples and spleen samples. SR-3 and SR-1-specific qPCRs were used as the techniques for virus recovery. Protection against Marek’s disease challenge used the standard RB1B strain; monitoring of protection against mortality and clinical signs related to Marek's disease throughout the study, as well as tumor formation, as visualized at necropsy was performed. Protection against Marek’s disease challenge was studied in the context of the dual vaccination program. A comparison between dual repeated Marek’s vaccination based on either the native SR-3 HVT vaccine or the vector HVT-IBD VP2 vaccine gave results in favor of the use of such practices in the breeder hatcheries.