齒舌蘭輪斑病毒台灣系統基因序列譯讀與分析

Abstract

齒舌蘭輪斑病毒(Odontoglossum ringspot virus, ORSV)，是感染蘭科植物最重要的病毒之一在分類上屬於菸草嵌紋病毒屬(genus Tobamovirus)，是一種長桿狀顆粒病毒，其顆粒大小約為長度300 nm，寬度18 nm，顆粒中帕可清楚分辨有溝狀構造。在地理的分佈上遍佈溫帶及熱帶地區的非洲、亞洲、澳洲、歐洲、北美及南美洲。本研究完成選殖與譯讀齒舌蘭輪斑病毒台灣系統(ORSV-TW)的全長度核昔酸和肢基酸序列，並與已報告之ORSV-S1（新加坡）、ORSV-Cy1（日本）、ORSV-Cy（韓國）及ORSV-U（美國）等四個系統作全長度核苷酸和肢基酸序列進行比對與分析。ORSV-TW全長度核苷酸序列為6612個核苷酸(accession number AY571290)，其中126/183 kDa RNA-dependent RNA polymerase (RdRp)基因3336/4839個核苷酸，可分別轉譯成1112個胺基酸，分子量為126 kDa。之replicase protein和1612個肢基酸，分子量為183kDa之readthrough protein、movement protein (MP)基因共912個核昔酸，可轉譯成303個胺基酸，分子量為33kDa、coat protein基因（CP）共477個核苷酸，可轉譯成158個胺基酸，分子量為18kDa、5’端非轉譯區63個核苷酸和3’端非轉譯區414個核苷酸。經與國外報告ORSV核苷酸序列相同度及胺基酸序列相似度比對結果顯示，五個系統間各基因的比較結果都達到96％以上，顯示五者具高同源性，種內的遺傳歧異度相當低，為同種病毒之不同系統。 Odontoglossum ringspot virus (ORSV) is a member of Tobamovirus genus in the family of Tobamoviridae. It is an important virus infecting orchid plants and occurring worldwide. The purpose of this study is to sequence the genomic regions of ORSV Taiwan strain (ORSV-TW), and to compare its nucleotide and amino acid sequences with that of four reported ORSV strains of various origins, i.e. ORSVS1 (Singapore), ORSV-Cy1 (Japan), ORSV-Cy (Korea) and ORSV-U (America). The full length genomic RNA of ORSV-TW were 6,612 bp (accession number AY571290 . The length of nucleotide sequences for 126/183 kDa RNA-dependent RNA polymerase (RdRp) genes were 3,336 and 4,839 bp and encoded RdRp replicase and readthrough protein, respectively. Genes of movement protein (MP) and coat protein (CP) consisted of 909 and 474 nucleotides and encoded proteins of MW of 33 and 18 kDa, respectively. The nucleotide sequences of 5' and 3' non-translated regions (NTR) were 63 and 414 bp, respectively. The results of comparison between nucleotide and amino acid sequences of ORSV-TW with that of those reported ORSV strains showed more than 96% identity and similarity indicating that they are different strains of the same virus.