Characterization of RNA from equine infectious anemia virus

Abstract

The genome of equine infectious anemia virus, a nononcogenic retrovirus, was characterized by velocity sedimentation, electrophoresis in polyacrylamide gels, buoyant density in Cs2SO4 and susceptibility to nuclease digestion. The nucleic acid of purified virus was resolved by sedimentation analysis into a fast-sedimenting genome component, which comprises about 2/3 of the virion RNA, and a slow-sedimenting RNA, which is probably comprised of host-derived tRNA and a trace amount of 5S RNA. The fast-sedimenting RNA had a sedimentation coefficient of 62S and a MW of 5.4 .times. 106 to 5.6 .times. 106, as determined by sedimentation velocity and electrophoretic mobility. Upon heat denaturation, [3H]uridine-labeled 62S RNA dissociated into material comprised of 90-95% single-stranded species, sedimenting predominantly at 34S, with a MW of 2.7 .times. 106 to 2.9 .times. 106 and 5 to 10% 4S RNA. The 62S RNA was predominantly single-stranded but contained double-stranded regions, as indicated by partial resistance to RNase IA and SI nuclease and by a lower buoyant density in Cs2SO4 than that of the single-stranded 34S RNA derived by heat denaturation. The viral genome consisted of two 34S subunits of single-stranded RNA held in a high MW complex with 4S RNA by a mechanism involving a small degree of base pairing. Thus, the structure of equine infectious anemia virus RNA is similar to that of other retroviruses.