RNA species obtained from clonal lines of avian sarcoma and from avian leukosis virus

Abstract

Gel electrophoresis of the dissociated 60–70 S RNA prepared from cloned avian sarcoma viruses showed a single major peak corresponding to size class a. Class b RNA was not detectable in these preparations. Class a RNA derived from the Schmidt-Ruppin strain of Rous sarcoma virus had a slightly but reproducibly lower electrophoretic mobility than class a RNA of Prague strain Rous sarcoma virus. The presence of avian tumor virus group specific ( gs) antigens in chicken cells before infection did not detectably influence the electropherograms of the dissociated avian sarcoma virus RNA: cloned sarcoma virus from gs positive and gs negative cells showed identical gel patterns. However, two avian sarcoma virus clones derived from a clonal colony of transformed cells contained a new RNA component which migrated slower than class a RNA. This unusual component was found consistently in the original clonal cultures but was not seen if new cells were infected with the same virus, suggesting a cell mediated modification of viral RNA. Additional evidence was obtained for the absence of class a RNA from avian tumor viruses which cannot form foci in fibroblast cultures. Several leukosis and transformation defective viruses which had not been analyzed previously showed class b RNA only. No significant differences between the class b RNA preparations obtained from several independently isolated transformation defective viruses were detected.