IN-VITRO INTERACTIONS BETWEEN CUCUMOVIRAL SATELLITE RNAS AND RNAS OF HELPER AND NON-HELPER VIRUSES

A model, previously proposed for the interaction of the satellite RNAs with the genomic RNAs of cucumber mosaic virus (CMV), has been evaluated experimentally. This model is based on the ability of the satellite RNA of the Q-strain of CMV to anneal to sequences contained within the coat protein gene of Q-CMV; i.e. to RNA3 and RNA4; an interaction which is suggested to play a role in the regulation of viral functions by satellite RNA. Eight satellite RNAs of cucumoviruses, differing in their effects on symptom production, were annealed to RNAs of various strains of CMV and other helper and non-helper viruses. In addition, truncated transcripts and antisense RNA transcripts of a cloned satellite RNA were annealed to various viral RNAs. Interactions occurred between satellite RNA sequences and most of the helper and non-helper viral RNAs tested, but the nature of the interaction varied with different combinations of satellite RNA and viral RNA. Furthermore, some satellite RNAs annealed with RNAs 1 and 2 as well as with RNAs 3 and 4 of helper viruses. The formation of the hydrogen-bonded satellite RNA: viral RNA complex did not affect the in vitro mRNA activity of these viral RNAs, suggesting that the effects of satellite RNAs are not mediated through the inhibition of the expression of their helper virus genome. © 1993 Academic Press, Inc.