DEREGULATION OF CELL-GROWTH BY THE K1 GENE OF KAPOSIS SARCOMA-ASSOCIATED HERPESVIRUS

At a position equivalent to the gene encoding the saimiri transforming protein (STP) of herpesvirus saimiri (HVS), Kaposi's sarcoma-associat ed herpesvirus (KSHV) contains a distinct open reading frame called K1 . Although KSHV and HVS are related members of the rhadinovirus subgro up of gamma herpesviruses, K1 and STP exhibit no similarity in amino a cid sequence or in structural organization. Since STP is required for the oncogenic potential of HVS, we investigated the functional consequ ence of K1 expression. Expression of the K1 gene in rodent fibroblasts produced morphologic changes and focus formation indicative of transf ormation. A recombinant herpesvirus in which the STP oncogene of HVS w as replaced with K1, immortalized primary T lymphocytes to IL-2 indepe ndent growth and induced lymphoma in common marmosets. These results d emonstrate the transforming potential of the K1 gene of KSHV.