The nucleotide sequence of cymbidium ringspot virus RNA

The complete nuclootidesequence of cymbidium ringspot virus (CyRSV, a tombusvirus) was determined using the dideoxy chain termination method on pUC-cloned cDNA tomplaes or purified RNA. Sequencing strategy of the RNA 3' region is resorted elsevhore. The RNA is 4733 long and contains five open reading frames (ORF) coding for proteins vith Mr 32.885 (33 K), Mr9l.679 (92 K), Mr4O,.34 (41 K), Mr 21,295 (22 K), and Mr1),373 (19 K). The corresponding gene positions are: 161-1048 (33 K); 161-2614 (92 K); 2629-3768 (41 K); 3813-4379 (22 K); 3843- 4360 (19K). The 92 K protein is derived by readthrough of the leaky amber termination codon of the 33K protein. Computer analysis of the sequence encoding the 33 K and the 92K proteins shows extensiVo similaritywith the corresponding region of cucumber necrosis tombusvirus (CNV); this region may therefore code for the viral replicase. The 41 K protein is the virus coat protein. The 22 and 19 K proteins are encoded by two neged ORFs, but only the 22 K product has been detected ia mY and itiila . Expression of the cost protein and 22 K genes requires two specific subgenomic RNAswhich sart at nucleotide position 2118 and 936 from the 3' end, respectively, as shown by primer extension experiments.