High sequence conservation among Odotoglossum ringspot virus isolates from orchids

The variability in the nucleotide (nt) and amino acid (aa) sequences of the coat protein (CP) of Odontoglossum ringspot virus (ORSV), which naturally infects orchids worldwide, was investigated. The CP genes of 48 ORSV isolates originating from different locations in Korea were amplified using RT-PCR and sequenced. The encoded CP consists of 158 aa. The CP sequences of the Korean isolates were compared at the nt and aa levels with those of the previously published ORSV isolates originating from different countries. The Korean isolates share 94.8-100% and 92.4-100% CP identity to ORSV isolates from other countries at the nt and aa levels, respectively. No particular region of variability could be found in either sequence of the viruses. In the deduced aa sequence, the N-terminal region was more conserved than the C-terminal region in ORSV. The phylogenetic tree analysis and recombination analysis revealed that there was no distinct grouping between geographic locations and sequence identity, and nor distinct intra-specific recombination events among ORSV isolates.