中文摘要：

为了调查毒力的变化和流行的鸭肝炎的外部衣壳蛋白质的关系，( DHAV-1 ) A 病毒类型 1 孤立，毒力，生气中立化试金和 virion 蛋白质的完全的顺序 1 ( VP1 )九剧毒的 DHAV-1 的基因拉紧，它在 20072008 在中国的山东省与临床的症状从感染的小鸭被孤立，被测试。第五个产生鸭胚胎 9 的尿膜的液体孤立为中部的 embryonal 在 12-day-old 鸭胚胎上并且在 7-day-old 小鸭上被测试致命的剂量(ELD50s ) 和中部的致命的剂量(LD50s ) 分别地。结果证明 9 DHAV-1 的胚胎的鸭卵的 ELD50s 孤立在 1.9 之间

英文摘要：

To investigate the relationship of the variation of virulence and the external capsid proteins of the pandemic duck hepatitis A virus type 1 （DHAV-1） isolates, the virulence, cross neutralization assays and the complete sequence of the virion protein 1 （VP1） gene of nine virulent DHAV-1 strains, which were isolated from infected ducklings with clinical symptoms in Shandong province of China in 2007-2008, were tested. The fifth generation duck embryo allantoic liquids of the 9 isolates were tested on 12-day-old duck embryos and on 7-day-old ducklings for the median embryonal lethal doses （ELD50s） and the median lethal doses （LD50s）, respectively. The results showed that the ELD50s of embryonic duck eggs of the 9 DHAV-1 isolates were between 1.9× 10^6/mL to 1.44×10^7/mL, while the LD50s were 2.39 × 10^5/mL to 6.15×10^6/mL. Cross-neutralization tests revealed that the 9 DHAV-1 isolates were completely neutralized by the standard serum and the hyperimmune sera against the 9 DHAV-1 isolates, respectively. Compared with other virulent, moderate virulent, attenuated vaccine and mild strains, the VP1 genes of the 9 strains shared 89.8%-99.7% similarity at the nucleotide level and 92.4%-99.6% at amino acid level with other DHAV-1 strains. There were three hypervariable regions at the C-terminus （aa 158-160, 180-193 and 205-219） and other variable points in VP1 protein, but which didn＇t cause virulence of DHAV-1 change.