Marek's Disease Virus, (MDV), is an oncogenic avian doublestranded DNA herpesvirus. It is highly contagious and results in aggressive T-cell lymphomas. Infection of MDV occurs via the respiratory tract, whereits uptake by macrophages and dendritic cells allows it to be transported inthe bloodstream to visceral organs and peripheral nerves, causing death in upto 80 percent of birds. It occurs in two main forms, depending on which partsof the body are affected by the tumours. In the nervous form the nerves,particulary the sciatic nerves, are affected. In the visceral form,greyish-white tumours are found in the ovaries, liver, spleen, kidney, heartand other organs. Suitable for use in ELISA and Western blot. Each laboratory should determine an optimum working titer foruse in its particular application. Other applications have not been tested but use in such assays should not necessarily be excluded.