Abstract
The small RNAs of avian reticuloendotheliosis virus (REV) were analyzed by two-dimensional polyacrylamide gel electrophoresis and compared with those of murine leukemia virus and avian sarcoma virus. Although there were some similarities among the three virus types, the patterns of small RNAs were distinct. By characterizing the small RNA which is most tightly associated with REV genome RNA and which can be labeled in limited DNA synthesis reactions, the primer for REV reverse transcription was identified as tRNAPro. This is consistent with previous reports that REV is more closely related to retroviruses of mammalian origin than to other avian viruses. In contrast, REV strong-stop complementary DNA is longer than any previously characterized strong-stop products of avian or mammalian retroviruses. The REV group may, therefore, have been derived from an as yet unidentified mammalian type C virus.