MOLECULAR PATHOGENESIS OF MAREKS-DISEASE - RECENT DEVELOPMENTS

Marek's disease (MD) is a lymphoproliferative disorder induced by a he rpesvirus in chickens, its natural host. After an early cytolytic infe ction, the virus induces lymphomas in T-cells. These cells are latentl y infected with the virus, but very few viral transcripts or proteins are detectable. Although there are indications that some of these viru s-encoded transcripts may be involved in tumourigenesis, the exact nat ure of the virus-cell interaction contributing towards the transformed phenotype is not completely understood. Among the transcripts the meg protein with basic leucine zipper (bZIP) characteristic of the fos/ju n family of transcriptional activators is thought to play a major role in MDV-induced oncogenesis. Similarly the MDV-encoded immediate early transcripts, ICP4, also seems to play an important role in latency an d transformation. Apart from the virally-encoded factors, various host cell factors may be involved in the induction of rumours. Although no t much work has been done in elucidating these factors, the possible r ole of tumour suppressor genes like p53, proto-oncogenes like Bcl-2 ca pable of blocking apoptosis, and telomerases in the induction of lymph omas are discussed. Some of the recent findings concerning the molecul ar mechanisms of interactions between MD virus and retroviruses are al so presented.