鳜鱼传染性脾肾坏死病毒的胞嘧啶5-甲基转移酶基因结构及其序列分析

对鳜鱼传染性脾肾坏死病毒（infectious spleen and kidney necrosis virus,ISKNV）的胞嘧啶5－甲基转移酶（MTase）基因的结构及序列进行了分析。序列比较分析表明，ISKNV MTase编码区全长684bp，编码长227个氨基酸的蛋白质，推测分子量为25855D。与一些细菌的MTase比较，ISKNV MTase也含有负责转移甲基的4个保守区，但缺乏识别靶序列的保守区。比较ISKNV与其它6种脊椎动物虹彩病毒的MTase序列并建立系统树，ISKNV显著不同于蛙病毒属和淋巴囊肿病毒属。7种脊椎动物虹彩病毒MTase具有高度保守区，可以此设计引物用PCR方法鉴定脊椎动物虹彩病毒。

Identification and Characterization of the Infectious Spleen and Kidney Necrosis Virus Cytosine DNA Methyltransferase Gene

In the infectious spleen and kidney necrosis virus (ISKNV) genome,an iridovirus,we have identified an open reading frame (ORF) whose deduced amino acid(aa) sequence contains motifs characteristic of cytosine DNA methyltransferases(MTases).The ORF consists of 684bp which codes for a protein of 227 aa with a predicted molecular mass of 25855 Da.Compared with some MTases found in bacteria,ISKNV MTase ORF contains the first four highly conserved motifs of cytosine MTase, but the motif,responsible for DNA binding specificity,is missing.Compared with 6 vertebrate iridoviruses,ISKNV is considered as a new group of Iridoviridae.Partial sequences of 7 vertebrate iridovirus MTases are highly conserved,they can be used to design primers to identify vertebrate iridovirus by PCR method.