H7N2禽流感病毒CK/HB/1/02株NA全基因序列分析

Sequencing analysis of NA gene of H7N2 AIV CK/HB/1/02 strain

采用RT—PCR扩增了国内H7N2禽流感病毒（AIV）CK／HB／1／02分离株的完整神经氨酸酶（NA）基因节段，测定了其核苷酸序列，并与GenBank中AIVNA基因序列进行了同源性比较和氨基酸编码分析，绘制了NA基因的系统发育进化树。结果表明，AIVCK／HB／1／02分离株NA基因的完整序列长度为1467bp，包括5’-末端和3’-末端的非编码区，其最大阅读框（ORF）编码469个氨基酸，第61～65位氨基酸序列为-NITGI-。不同于国内H9N2AIV的特殊遗传标记。谊病毒NA基因的核苷酸序列与GenBank中人类流感病毒A／Leningrad／134／57（H2N2）的NA基因同源性最高，为93．3％；其次为香港的鸭源、人源、猪源H3N2病毒（89％～93％）；而与我国北京、广东、香港和韩国的H9N2AIV以及芙国的H7N2AIV的同源性较低（85％～88％）。在N2基因系统发育进化树中。CK／HB／1／02分离株处于欧亚分支内，与H2N2人流感病毒的亲缘关系较近；与北美HTN2AIV处在不同分支，遗传距离较远。

The whole NA eDNA fragment of HTN2 AIV CK/HB/1/02 isolate was amplified by reverse transcription polymerasc chain reaction（RT-PCR） with primers specific to the NA gene. The DNA fragment was sequenced and compared to the GenBank data. The 1 467 bp nueleotide sequence of NA gene was obtained,coding all the 469 amino acids of NA protein. The 61-65 amino acids of NA were -NITGI-,different from the special genetic marker of the Chinese HgN2 strains. NA gene of the isolate exhibits 93.3% homology with human influenza virus A/Leningrad/134/57（H2N2） ,89%-93% identity to Hong Kong H9N2 strains from duck,human and swine,85%- 88% to HTN2 virus from U.S. and HgN2 virus from Beijing,Guangdong of China and South Korea. The isolate is situated in the Euro-Asia branch of the N2 phylogenetic tree and close to human H2N2 virus,and is less related with HTN2 isolates from North America which is in a different branch.