The complete nucleotide sequence of the genomic RNA of cymbidium mosaic potexvirus (CymMV) was determined to be 6227 nucleotides in length, excluding the poly (A) tail at the 3' terminus. Similar to other potexviruses, its genome organisation is comprised of five major open reading frames (ORFs 1 to 5), encoding a Mr 160 KDa putative RNA-dependent RNA polymerase (RdRp); a Mr 26KDa/13KDa/10KDa triple-gene-block (TGB) and a Mr 24 KDa coat protein. The CymMV encoded proteins shared a high degree of homology to their corresponding proteins of other members of the potexvirus group. The nucleotide sequence of the 5' noncoding region (NCR) of CymMV and all other potexviruses initiates with GAAAA. CymMV possesses the shortest 5' NCR among all potexviruses. Based on phylogenetic comparisons of RdRp and coat protein, CymMV shares a close relationship to PAMV, NMV, WClMV and SMYEaV. This is believed to be the first record of the complete nucleotide sequence of CymMV.

The nucleotide sequence of the coat protein gene of cymbidium mosaic virus (CyMV) has been determined from a cDNA clone that encompassed the 3'-region of the virus genome. The 0.75 kb coat protein open reading frame (ORF) codes for a 24kD polypeptide. The coat protein coding region was separated from the 3'-poly(A) terminal of the viral genome by an 80 base noncoding region. The derived amino acid sequence of this ORF showed considerable homology with other potexvirus coat protein sequences, notably with narcissus mosaic virus (NMV), potato virus X (PVX), and white clover mosaic virus (WClMV). In vitro expression of the CyMV coat protein gene was carried out by T7 RNA polymerase on the linearized cDNA clone template, followed by in vitro translation of the purified transcript in wheat germ extract. One of the translated products was found to comigrate with the coat protein of the virus at about 24 kD, as determined by NaDodSO4-PAGE. This translated product was also found to crossreact with antibodies raised against CyMV.

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