A complete genomic DNA sequence of Marek's disease virus type 2, strain HPRS24

Marek’s disease (MD) is a contagious lymphoproliferative disorder of chickens, and has been a major cause of poultry mortality in many countries since the 1960s. The causative agent of MD, a highly cell-associated herpesvirus called Marek’s disease virus (MDV), was isolated (Bankowski et al. 1969; Churchill and Biggs 1967,Churchill and Biggs 1968; Nazerian et al. 1968; Solomon et al. 1968; Witter et al. 1969) and live vaccines were developed by serial passages in cultured cells (Churchill et al. 1969a,Churchill et al.1969b) or by use of apathogenic herpesvirus isolated from turkeys (Kawamura et al. 1969; Okazaki et al. 1970; Witter et al. 1970). At present, vaccines derived from all three serotypes offer different levels of protection against the disease, either alone or in bivalent and trivalent combinations (Calnek and Witter 1997).