The replication of Semliki Forest virus.

Abstract

SUMMARY Using polyacrylamide gel electrophoresis, column chromatography on CF11 cellulose and salt precipitation, together with ribonuclease treatment, we have identified, in chick cells infected with Semliki Forest virus, four species of virus-specified single-stranded RNA, three species of double-stranded RNA and a multi-stranded RNA species. The mol. wt. of the four single-stranded RNA species were 4.0 × 106, 3.1 × 106, 2.3 × 106 and 1.8 × 106. The kinetics of virus-specified RNA synthesis were studied in virus-infected cells, both early in infection and when virus-specified RNA synthesis was at the maximum rate. The first species of virus RNA detected were the multi-stranded and double-stranded species of RNA. The first single-stranded species detected was the 42S virus particle RNA, at 1.5 h after infection. The average time taken to synthesize a molecule of virus-specified RNA was between 1 and 1.5 min. Multi-stranded and double-stranded RNA both had the properties expected of an intermediate in RNA synthesis, and the number of single-stranded equivalents in the multi-stranded species was 4.3. The data show that synthesis of virus RNA is mainly semi-conservative and that the virus messenger RNA is of the same polarity as the genome.