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Characterization and Sequence Analyses of Duck Hepatitis Viruses Isolated in 200...  

Update Date: [2013-11-14]
No.:44

Reporton.
AHRI report No.44
Topic
Characterization and Sequence Analyses of Duck Hepatitis Viruses Isolated in 2008
Department
Animal Health Research Institute, Council of Agriculture, Executive Yuan
Author
C. H. Tseng*, Y. H. Shih, P. W. Chen, L. Q. Jian, T. S. Huang, C. C. Huang
Summary
Severe outbreaks of duckling and gosling hepatitis, caused by duck hepatitis virus occurring in Taiwan since June 2008 were studied; 21 strains were isolated from specimens. Among them, 18 samples were identified to be duck hepatitis A virus type I (DHAV-1) and 3 samples were identified to contain the Newcastle disease virus (NDV) after sequence analyses and serologic tests. Based on the virus sequence data, the virus causing the outbreaks was confirmed to be DHAV-1. Similarities of VP1 nucleic acids and amino acids of the 18 isolates were 99.2% and 99.6% compared with the DHAV-1 from 2003 and were 92.3% and 95.4% compared with the 5886 vaccine strain. All these DHV isolates could be neutralized by a standard serum against DHAV-1, and the neutralization indices were between 5.33 and 7.67, indicating that all these isolates belonged to DHAV-1 group. In addition, the one-day old ducklings vaccinated with DHAV-1 vaccine by intramuscular route all survived DHV/2008 challenge on the 7th day post vaccination. The protection rates of vaccinated groups of ducklings were 100%, but the mortalities for non-vaccinated control groups of ducklings were 42.9% and 69.2%, respectively. According to the results mentioned above, we suggest that the outbreaks are caused by the DHAV-1, but not by any mutants or other serotypes of DHV.
Keyword
duck hepatitis virus, Newcastle disease virus, phylogenetic analysis