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Virulent strain of hepatitis E virus genotype 3, Japan

Kazuaki Takahashi1, Hiroaki Okamoto, Natsumi Abe

  • 1Toshiba General Hospital, Tokyo, Japan. kazuaki6.takahashi@po.toshiba.co.jp

Emerging Infectious Diseases
|May 1, 2009
PubMed

Insights

Hepatitis E virus (HEV) genotype 3 caused severe hepatitis in Japan. A unique HEV cluster (JIO) found in patients and swine, featuring a V239A substitution, may explain this increased virulence.

Area of Science:

  • Virology
  • Infectious Diseases
  • Genetics

Background:

  • Hepatitis E virus (HEV) genotype 3 typically causes asymptomatic infections in Japan.
  • Recent cases indicate HEV genotype 3 can induce severe hepatitis, prompting investigation into virulence factors.

Purpose of the Study:

  • To determine the genetic features of HEV associated with increased virulence in severe hepatitis cases.
  • To investigate the phylogenetic relationship and potential zoonotic origin of virulent HEV genotype 3 strains.

Main Methods:

  • Sequencing of complete or near-complete nucleotide genomes of HEV from 8 patients and 5 infected swine.
  • Phylogenetic analysis to identify unique viral clusters and genetic variations.
  • Comparative analysis of amino acid sequences between virulent and non-virulent HEV strains.

Main Results:

  • HEV isolates from patients and swine formed a distinct phylogenetic cluster, designated JIO, separate from other genotype 3 strains.
  • JIO cluster viruses exhibited 18 unique amino acid substitutions compared to other genotype 3 HEV strains.
  • A common V239A substitution in the helicase domain was identified in JIO cluster viruses, potentially linked to increased virulence.

Conclusions:

  • A unique HEV genotype 3 cluster (JIO) associated with severe hepatitis has been identified.
  • The V239A substitution in the helicase domain is a potential marker for increased HEV virulence.
  • The presence of the V239A substitution in both human and swine isolates suggests a zoonotic origin for JIO-related viruses.

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