Transcription and in vitro translation of the dsRNA virus isolated from Rhizoctonia solani.

A segmented double-stranded dsRNA virus has been isolated from virulent strains of Rhizoctonia solani. The dsRNA genome has mol. wts. of 1.45 and 1.32 X 10(6). Two full-size transcripts with mol. wts. of 0.74 and 0.66 X 10(6) (2.2 kb and 2 kb, respectively) were synthesized by the virus-associated RNA-dependent RNA polymerase and resolved by denaturing polyacrylamide gel electrophoresis. The transcripts cross-hybridized to the viral dsRNA isolated from a number of strains. The transcripts did not hybridize with the genomic DNA. An unencapsidated species of dsRNA with mol. wt. of 1.6 X 10(6) did not hybridize with the viral transcripts. No cross-hybridization between the two viral dsRNA segments was obtained. The viral-encoded proteins were studied by in vitro translation using the rabbit reticulocyte lysate system. The transcripts served as mRNA for the synthesis of the major capsid protein of 55 kD, and a number of other products. The viral coat protein was immunoprecipitated with antibodies against purified virus particles. Partial proteolysis of the major in vitro product and the authentic capsid protein using Staphylococcus aureus V8 protease produced similar peptide patterns. Denatured viral dsRNA also directed the synthesis of proteins identical to those translated from the transcripts in vitro.