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Virologica Sinica, 27 (4) : 248-253, 2012
Research Article
Genetic Variation of the VP1 Gene of the Virulent Duck Hepatitis A Virus Type 1 (DHAV-1) Isolates in Shandong Province of China
1. College of Veterinary Medicine, Shandong Agricultural University, Taian 271018, Shandong, China
2. Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Taian 271018, Shandong, China
3. Department of Animal Medicine, Foshan Science and Technology University, Foshan 528231, Guangdong, China
 Correspondence: sjjiang@sdau.edu.cn

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 × 106/mL to 1.44 × 107/mL, while the LD50s were 2.39 × 105/mL to 6.15 × 106/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.

Received: 28 Jun 2012  Accepted: 18 Apr 2012  Published online: 5 Aug 2012
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