Construction of recombinant Marek's disease virus (MDV) lacking the meq oncogene and co-expressing AIV-H9N2 HA and NA genes under control of exogenous promoters.

•The MDV–BAC genetics system is highly flexible and facilitates the engineering of recombinant multivalent vaccine.•The rescue of rMDV as an ideal viral vector carries exogenous genes and lacks the meq oncogene.•The rMDV may be a useful tool not only to screen for a herpes and AIV-H9N2 multivalent vaccine, but also for fundamental research on the biology of the recombinant virus.•We were able to combine Red/ET with FLP/FRT screening system to mediate two steps of recombination.