Gallid herpesvirus 2(GaHV-2),commonly known as Marek’s disease virusserotype-1(MDV-1),causes T-cell lymphomas, immunosuppression and neurological disorder inchickens. MDV-1 is classified in the genus Mardivirus of the subfamily Alphaherpesvirinae along withtwo other non-oncogenic poultry viruses,Gallid herpesvirus 3(GaHV-3 or MDV serotype 2)andMelea-grid herpesvirus 1(MeHV-1,MDV serotype 3 or Turkey herpesvirus). This vaccine preventscancer in chickens that become infected with MDV, making it the first vacc...