一株鸭源H9亚型禽流感病毒分离株生物学特性研究

对分离到的1株鸭源H9N2亚型禽流感病毒(NJ01株)的生物学特性进行了研究。研究结果显示:其静脉致病指数IVPI为0,脑内致病指数ICPI为0.26,血凝解脱时间NHAT为慢,血凝热稳定时间HOT为30 m in。以108.0ELD50/羽的剂量静脉感染26日龄非免疫鸭,可使40%鸭致死,且从攻毒后存活鸭1 d+2 d喉拭子中100%分离到该病毒;而以相同剂量静脉感染1月龄SPF鸡后不出现死亡,但攻毒后4~6 d的泄殖腔拭子中,均可100%再分离到该病毒。毒株血凝素基因的RT-PCR试验结果显示,与1997年香港3个分离株的同源性为94.8%~96.0%,其HA裂解位点处氨基酸序列为-RSSRG-。研究结果表明该NJ01株为低致病性禽流感病毒,属欧亚大陆分支,在SPF鸡及非免疫鸭体内均能很好地复制。

Biological Characteristic of A Duck-derived H9 Subtype Avian Influenza Virus

The biological characteristic of a strain H9N2 AIV that isolated from duck was investigated in this paper.The results indicated that IVPI was 0,ICPI was 0.26,NHAT was slow,HOT was 30 minutes.The assay of intravenous pathogenicity showed that the mortality of 26-day-old ducks was 40% and the reisolated rate of throat swabs of susceptible ducks was l00% on the 1~2 day after challenging with 108.0 ELD50 NJ01 virus per duck,respectively.In addition,the reisolated rate of cloaca swabs of 30-day-old special free chicks was l00% on the 4~6th day after challenging with the same dose.The Hemagglutinin(HA) gene was amplified by RT-PCR and the sequence analysis results indicated that the homology of HA nucleotide sequence was between 94.8% and 96.0% as compared with three strains isolated from Hongkong,the amino acid sequence of cleavage site region was-RSSRG-.It was concluded that the NJ0I strain was low pathogenic avian influenza virus and belong to Eurasian lineage.It can replicate in SPF chicken and non-immune ducks.