中文摘要：

为评估H5N1亚型禽流感病毒（AIV）在实验室环境下对鸭的致病力,本研究以无特殊病原（SPF）鸭为模型,对我国近年分离的7株病毒进行了致病力分析。结果发现其中4株病毒对鸭致死率为100%,2株病毒对鸭的致死率分别为60%和80%,另外1株病毒,A/goose/Hubei/51/05（GS/HB/51/05）,对鸭无致病力。本研究还发现,与高致病力毒株一样,GS/HB/51/05也可在鸭体内呈全身性复制,并且可通过喉头和泻殖腔向外排泄。我们推测GS/HB/51/05可能是中国南方出现的其他对鸭呈高致病力的H5N1病毒的祖先,对这些病毒的系统研究,可揭示H5N1亚型AIV对鸭的致病力遗传机制。

英文摘要：

Ducks are regarded as the natural reservoir of influenza viruses,and previous studies indicated that the avian influenza viruses could replicate in the digestive tract of ducks and shed through cloaca without causing any clinic signs in these animals. However,H5N1 influenza viruses have caused multiple disease outbreaks in ducks in recent years. To evaluate the virulence of the H5N1 influenza viruses in the experimental set,we tested 7 H5N1 influenza viruses in special pathogen free（SPF） ducks. We found 4 out of the 7 viruses are highly pathogenic for ducks,and these viruses killed 100 % of the inoculated ducks within 7 days. Two viruses killed partial of the inoculated ducks,while one virus,A/goose/Hubei/51/05（GS/HB/51/05） ,did not induce any cliuic signs or kill any of the ducks inoculated. We further found that,though it is non-pathogenic to ducks,the GS/HB/51/05 replicates systemically in ducks,and the inoculated ducks also shed the virus through both larynx and cloaca. Our data suggested that the GS/HB/51/05 may be a close ancestor of those duck-lethal H5N1 influenza viruses found in southern China,and detailed studies of these viruses will provide an insight on the genetic basis of the virulence of H5N1 influenza viruses in ducks.