Avian lymphoid leukosis is correlated with the appearance of discrete new RNAs containing viral and cellular genetic information.

Abstract

Lymphoid leukosis (LL) is a B-cell lymphoma of birds which is caused by a class of RNA tumor viruses called avian leukosis viruses (ALVs). These viruses also occasionally cause other neoplasms such as sarcomas and nephroblastomas. ALVs induce tumors in infected animals only after a latent period of 4–12 months and do not transform cells at detectable frequency in tissue culture (Hanafusa 1977). Despite intensive efforts, no transforming gene has been identified in these viruses. This suggests that the mechanism involved in neoplastic transformation by ALV is fundamentally different from that of the avian acute transforming viruses (sarcoma viruses and acute leukemia viruses). The acute viruses induce tumor formation within about 2 weeks, transform appropriate target cells in tissue culture, and code for transforming proteins (Bister et al. 1979; Erikson 1980; Graf und Beug 1978; Hanafusa 1977; Hanafusa et al. 1980; Hayman et al. 1979; Lee et al. 1980).