Detection and characterization of defective interfering RNAs associated with the cocksfoot mottle sobemovirus

A new RNA of about 900 nt was found in the virions of cocksfoot mottle virus (CfMV) and in infected plants by RNA hybridization and RT-PCR. Structural features suggested that this RNA is a defective interfering RNA (diRNA). The CfMV diRNA was shown to consist of a 35-nt 5'-terminal genomic region, which formed a hairpin, and a 3'-terminal genomic region, which included the coat protein (CP) gene lacking the first 120 nt. In vitro translation of the diRNA started at the third Met codon to produce truncated CP. The CfMV diRNA was assumed to trans-activate synthesis of the CP subgenomic RNA (sgRNA).