Abstract
Hepatitis E virus (HEV) is a causative agent of acute viral hepatitis globally. Evolutionary phylogeny classifies the HEV into eight genotypes that correlate with the viral transmission. Only four genotypes have been proven to be responsible for transmission in humans. However, there has been no report on the genomics and genotyping of HEV in Thailand during the past ten years. Here, we identified the genotype distributions of the Thai isolates of HEV and we sequenced two HEV genomes. We screened for 18 Thai isolates of HEV from Siriraj Hospital in Bangkok, from 2014–2016. The HEV genomes were sequenced from the serum and feces of a patient. The results showed that all Thai isolates of HEV were identified as genotype 3 (HEV-3). The ORF2 and genome phylogenies suggested two subgenotypes, called 3.1 and 3.2. The Thai isolates of HEV were frequently found in the subgenotype 3.1. The genome sequences of the two Thai isolates of HEV from the serum and fecal samples of the same patient showed 91% nucleotide similarity with the HEV genotype 3. Comparisons between the HEV genome and the ORF2 phylogenies illustrated that the ORF2 tree can be used to identify HEV genotypes, but it has less phylogenetic power for the HEV evolution. The two new genome sequences of HEV-3 from Thailand could contribute valuable information to the HEV genome study. (226 words)
Highlights
Hepatitis E virus (HEV) or Orthohepevirus A is an emerging viral infection that causes acute hepatitis, which is considered as leading to a low rate of mortality and not developing into chronic hepatitis [1]
The 33 serum samples were collected from 33 patients with hepatitis, who showed an abnormal liver function, based on the enzymes, aspartate aminotransferase (AST) and alanine transaminase (ALT)
All 18 HEV RNA-positive samples were sequenced for partial open reading frame 2 (ORF2) region (919 bp), which encoded a part of viral capsid protein
Summary
Hepatitis E virus (HEV) or Orthohepevirus A is an emerging viral infection that causes acute hepatitis, which is considered as leading to a low rate of mortality and not developing into chronic hepatitis [1]. HEV is classified as a member in the genus Orthohepevirus of the family Hepeviridae. The structure of HEV particle is comprised of a positive, single-stranded RNA genome packed inside the icosahedral capsid proteins [5]. Genome of the virus has ~ 7.2 bases in length, including a 5′-untranslated region (5′-UTR), three open reading frames (ORFs), and a 3′-untranslated region (3′-UTR). The ORF1 contains at least four nonstructural proteins, including a methyltransferase, a cysteine protease, a helicase, and an RNA-dependent RNA polymerase [6]. ORF2 is laid behind the ORF1 and encodes a capsid antigen protein.
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