The ribonucleic acids of Uukuniemi virus, a noncubical tick-borne arbovirus

Sucrose gradient centrifugation of SDS-treated, purified Uukuniemi virus labeled with 32 P , gave three reproducible peaks of single-stranded RNA, which sedimented at 27–29 S (L), 22 S (M), and 17–19 S (S). In polyacrylamide-agarose gels these RNAs separated into four peaks with apparent molecular weights of about 4.1 × 106 (L), 1.9 × 106 (M), 0.88 × 106 (S1), and 0.78 × 106 (S2), respectively. The major M and L RNAs, which represented about 75% of the total, were found in a constant molar ratio of 1:4.6. Treatment of the RNA species with 1 M formaldehyde or by heating to 100 ° did not result in a degradation of the larger to the smaller RNAs. The base compositions of the RNA species did not differ significantly from each other, but were clearly different from those of the ribosomal 28 S and 18 S RNAs extracted from host chick embryo cells. RNAs with identical sedimentation values and mobilities in gels were found from Uukuniemi virus-infected cells labeled with [ 3 H ]uridine in the presence of actinomycin D.