Synthesis of infectious RNA from full-length cloned cDNA to RNA of cymbidium ringspot tombusvirus.

A full-length DNA copy of cymbidium ringspot virus RNA was cloned downstream of a phage T7 promoter. In vitro transcripts had no extra nucleotides at the 3' terminus, and a 5' end likely to be precisely as in genomic RNA. Transcripts were infective when inoculated into test plants. Northern blots from inoculated plants revealed the presence of genomic and subgenomic RNAs, but not of satellite RNA. Virus particles isolated from infected plants had the same outward aspect and size as those of the wild-type virus and were decorated by an antiserum to CyRSV in immune electron microscopy tests.