Cooperating events in lymphomagenesis mediated by feline leukemia virus.

Feline leukemia virus (FeLV)-mediated lymphomagenesis in the domestic cat has been examined as a model of lymphoid malignancy in a naturally outbreeding population. The pathogenesis of two distinct, naturally occurring types of FeLV-induced tumors has been investigated: (1) a thymic lymphoma of T-cell origin, typical of FeLV-induced lymphoma, and (2) an extrathymic, extranodal lymphoma of non-B non-T-cell origin. The genetic features of these tumors are clearly distinguishable, and include determinants encoded both by the virus and the host. Virally encoded determinants of pathogenesis include the long terminal repeat (LTR) and the envelope SU protein. Cellular determinants include the involvement of a set of proto-oncogenes, and other factors characteristic of the specific cell type of origin of the tumor. Functional studies are aimed at evaluating the action and interaction of these genetic determinants in the pathogenesis of lymphoma in an animal model system.