Biological and biochemical evidence for an interaction between Marek's disease herpesvirus and avian leukosis virus in vivo.

The DNA-containing Epstein-Barr herpesvirus has been implicated in the etiology of Burkitt's lymphoma, a malignant tumor of children in Africa. Recently, however, particles possessing four biochemical characteristics of RNA tumor viruses have also been identified in these tumors. The fact that both types of viruses are found suggests that an interaction between them may be playing a role in the etiology of Burkitt's lymphoma. To explore this possibility with a defined animal model, experiments were performed with the avian Marek's disease, a malignant lymphoproliferative disease associated with a herpesvirus. Controlled contact studies demonstrated that tumorigenesis in a line of isolator-derived, barrier-sustained, specific pathogen-free chickens requires exposure to both the Marek's disease herpesvirus and an avian leukosis virus, Rous-associated virus, type 2. Exposure to either agent alone did not result in tumors. Molecular hybridization experiments to cytoplasmic RNA from similarly contact-exposed conventional Cornell S-line chickens provided further evidence for the occurrence of an interaction between Marek's disease herpesvirus and the avian leukosis virus.