Marek's disease: an update on oncogenic mechanisms and control

Marek's disease (MD) is a common lymphoproliferative disease of poultry cau sed by a highly contagious and oncogenic herpesvirus. In spite of the wides pread use of highly effective MD vaccines, recently there have been worryin g trends in the evolution of MD virus pathotypes towards greater virulence. In the last few years, there has been significant progress in determining the molecular structure of MD virus and several genes that map within the: repeat regions of the virus, such as BamHI-H family, ICP4, meq and pp38, wh ich are potentially associated with the latency and transformation have bee n identified. The functions of some of these genes have provided insights i nto the mechanisms of MD virus-induced oncogenesis. This review summarises some of these oncogenic mechanisms and the progress in the control of MD. ( C) 2000 Harcourt Publishers Ltd.