The present invention relates to animal viruses such as animal herpesviruses as a vector for diagnostic, therapeutic and prophylactic delivery of foreign genes and nucleic acids to animals, human or primary cells derived thereof, respectively. By using said viruses, the prevention and treatment of infectious, autoimmune and tumor diseases as well as allergies and genetic disorders can be treated. The present invention relates further to procedures to efficiently transduce primary human cells with recombinant animal viruses in vitro and in vivo. The invention further relates to a kit useful (i) for diagnosis and monitoring of innate and adoptive immune responses as well as (ii) for gene therapy and (iii) immunization purposes.