Abstract: Herpesviruses naturally deficient in gD, that is to say not expressing their gD gene in vitro or not possessing this gene, are transformed to express gD in vitro. This transformation by genetic recombination can consist in replacement of the natural promoter by another one or insertion of an expression cassette containing gD and a promoter. The invention also relates to these viruses incorporating a gene coding for an antigen of interest, to the vaccines obtained and to the methods of culture thus improved. The invention relates in particular to avian herpesviruses, especially MDV, and the VZV virus.