Genetic diversity of the VP1 gene of duck hepatitis virus type I (DHV-I) isolates from southeast Chi
July 3rd, 2008 | by admin |Genetic diversity of the VP1 gene of duck hepatitis virus type I (DHV-I) isolates from southeast China is related to isolate attenuation.
The complete sequence of an isolate (ZJ-V) of Duck hepatitis virus I (DHV-I), originally taken from the field in southeast China was determined. It was 7691 nucleotides long and had 5\’- and 3\’-terminal non-coding regions of 626 and 315 nucleotides, respectively. The poly(A) tail contained at least 22 residues and the single open reading frame encoded a polypeptide of 2249 amino acids. The VP1 gene was also sequenced from nine southeast China field isolates and three attenuated DHV-I vaccine strains. In phylogenetic analysis of the isolates and other published sequences, attenuated and tissue-adapted isolates (including ZJ-V) clustered as genotypes significantly different from the field isolates that had not been passaged in chicken/duck embryos. There were two consistent amino acid substitutions (E(129)–>V(129) and A(142)–>S(142)) between all the field isolates and all the tissue-adapted ones. The carboxyl terminal region was generally the most variable and here the four attenuated Chinese isolates showed six consistent differences from the field isolates (S(181)–>L(181), H(183)K(184)–>R(183)G(1841), N(193)–>D(193), E(205)–>K(205), R(217)–>K(217), N(235)–>D(235)). It seems likely that at least some of these differences result from mutations leading to isolate attenuation.
Liu G, Wang F, Ni Z, Yun T, Yu B, Huang J, Chen J.
Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, People\’s Republic of China.