Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/21/1998
Publication Date: N/A
Technical Abstract: Rhopalosiphum padi virus (RhPV) is a member of a novel group of insect viruses that includes Drosophila C virus, Plautia stali intestine virus and cricket paralysis virus. Its 10,000 nt RNA genome contains two large open reading frames (ORFs). ORF1 and ORF2 encode the nonstructural and structural polyproteins, respectively. Since no subgenomic RNAs were identified on Northern blots, the 500-800 nt separating the two ORFs were predicted to function as an internal ribosome entry sequence (IRES), similar to the 5-terminal sequences of picornaviruses. In addition, translation of the structural proteins was predicted to occur through a +1 frameshift. To test these hypotheses, cDNA clones including the intergenic region of the RhPV genome were transcribed and translated in vitro and shown to be translated most efficiently under the high-salt conditions used to translate RNAs containing the encephalomyocarditis virus IRES. Detectable amounts of a 100 kDa protein, potentially the product of a frameshift, also were detected under high-salt conditions, indicating that the secondary structure of the RNA may be important for expression of ORF2.