The invention concerns an Avipoxvirus comprising in the viral genome a Vaccinia virus host range gene or a homologue of said host range gene. The invention further relates to cells, preferably avian cells, comprising a Vaccinia virus host range gene or a homologue of said host range gene. Moreover the invention concerns the use of a Vaccinia virus host range gene or an homologue thereof to increase the titer of avipoxviruses produced from cells after infection of said cells with the avipoxvirus, wherein the host range gene is expressed in said cells.