Development of a vaccine for immunization against classical as well as variant strains of infectious bursal disease virus using reverse genetics

Available IBDV vaccines based on classical IBDV strains do not induce full protection in the presence of maternally derived antibodies (MDA) against variant strains. The aim of this study was the generation of an IBDV chimera between both classical and variant strains. Characterization of the generated chimeric IBDV (D78-Chim) was performed in both cell culture and susceptible chickens using the classical vaccine strain D78 for comparison. Growth kinetics on cell culture showed that the D78-Chim replicates comparable to the live vaccine strain D78. Administration of the D78-Chim to SPF chickens resulted in equally high virus neutralizing antibodies titres against both, classical and variant IBDV strains. In vivo experiments in commercial chickens revealed that D78-Chim and D78 induced comparable bursal damage in presence of maternally derived antibodies. Both D78-Chim and D78 viruses were able to breakthrough a similar level of MDA