Marek’s disease (MD) is a neoplastic disease of chickens caused by the ubiquitous MD virus (MDV), a lymphotropic alphaherpesvirus. MD is typified by a plethora of clinical signs, among them: neural symptoms, chronic wasting and the pathognomonic development of multiple lymphomas (that manifest as solid tumors in the viscera and musculature). Prevention is achieved by MD vaccines – cell-associated virus or cell-free HVT – administered upon hatching or in ovo (18th embryonic day).