Characterization of Full Genome of Rat Hepatitis E Virus Strain from Vietnam

Tian-Cheng Li

, Yasushi Ami, Yuriko Suzaki, Shumpei P. Yasuda, Kumiko Yoshimatsu, Jiro Arikawa, Naokazu Takeda, and Wakita Takaji

Author affiliations: Author affiliations: National Institute of Infectious Diseases, Tokyo, Japan (T.-C. Li, Y. Ami, Y. Suzaki, W. Takaji); Graduate School of Medicine, Hokkaido University, Sapporo, Japan (S.P. Yasuda, K. Yoshimatsu, J. Arikawa); Osaka University, Osaka, Japan (N. Takeda)

Abstract

We amplified the complete genome of the rat hepatitis E virus (HEV) Vietnam strain (V-105) and analyzed the nucleotide and amino acid sequences. The entire genome of V-105 shared only 76.8%–76.9% nucleotide sequence identities with rat HEV strains from Germany, which suggests that V-105 is a new genotype of rat HEV.

Hepatitis E virus (HEV) is a positive-sense single-stranded RNA virus (1), classified as the sole member of the genus Hepevirus in the family Hepeviridae (2). Hepatitis E, caused by HEV infection, is a serious public health concern in developing countries and is recognized as sporadic and endemic acute hepatitis (3). To date, at least 4 genotypes of HEV have been isolated from humans (4). In addition, HEV has been isolated from other mammals, including pigs, wild boars, wild deer, rabbits, ferrets, bats, chickens, and wild rats (5–9). Much direct evidence indicates that HEV is transmitted from pigs or wild boars to humans, and therefore hepatitis E caused by genotypes 3 and 4 is recognized as a zoonotic disease (6,8,10).
Rat HEV was first isolated from Norway rats in Germany (7,11). Since then, rat HEV strains have been isolated from wild rats in other areas of Germany and detected in wild rats in the United States and Vietnam (12–14). Those results suggest that rat HEV infection is not restricted to Germany but is broadly distributed in wild rats throughout the world. The nucleotide sequences of the rat HEV isolated in Germany and the United States are similar; however, the partial sequences of the Vietnam rat HEV strain (V-105, JN040433) have been found to have 78.18%–79.43% identities with isolates from Germany, R63 and R68 (14). To confirm whether new genotypes of rat HEV exist, we amplified the entire genome of the rat HEV V-105 strain and analyzed the sequences. We confirmed that the rat HEV strain isolated in Vietnam belongs to a new genotype of rat HEV.