CHARACTERIZATION AND BIOLOGICAL-ACTIVITY OF DI RNA DIMERS FORMED DURING CUCUMBER NECROSIS VIRUS COINFECTIONS

Coinfections of synthetic transcripts from a cDNA clone of cucumber ne crosis virus (CNV) and cDNA clones of defective interfering (DI) RNAs were previously demonstrated to contain DI-like RNAs approximately twi ce the size of the DI RNA used for cc-inoculation. Analysis of these R NAs revealed that they are head-to-tail repeats of CNV DI RNA sequence (dimers). Sequence analysis of 21 cloned dimer junctions indicated th at approximately half of the junction sequences correspond to precise fusions of monomer units. A cDNA clone corresponding to a dimer of DI RNA 42 was constructed. Synthetic DI RNA 42 dimer transcripts were bio logically active in coinfections, resulting in the accumulation of hig h levels of DI RNA 42 monomers. The possibility that dimers serve as t emplates for the generation of DI RNA monomers is discussed. (C) 1995 Academic Press, Inc.