Expression of RNA transcripts of potato virus X full-length and subgenomic cDNAs.

Translation of synthetic potato virus X (PVX) RNAs was examined in Krebs II ascite cell extracts and rabbit reticulocyte lysates. Either full-length or subgenomic RNAs produced by in vitro transcription of cDNAs cloned in the T7 promoter vectors were used. Full-length PVX RNA-transcript directed the synthesis of a large polypeptide which was indistinguishable from the translation product (165 kDa) of authentic viral genomic RNA on SDS-PAGE. Translation of the full-length and 3'-truncated RNA species was stimulated by addition of m7GpppG to the T7 transcription system. Subgenomic cDNA transcripts corresponding to the 3'-proximal part of PVX RNA were efficiently translated into the PVX coat protein and 2 as yet unidentified small hydrophobic proteins.