Sequence analysis and comparison of avian hepatitis E viruses from Australia and Europe indicate the existence of different genotypes

Abstract

Avian hepevirus infections were detected in chickens suffering from big liver and spleen disease or hepatitis–splenomegaly syndrome in Australia, the USA and Europe. Available data indicate their genetic relationship to mammalian hepatitis E virus (HEV). In the present study, the near-complete genomic sequences of an Australian and a European isolate of avian hepatitis E virus (avian HEV) are reported for the first time. Furthermore, the phylogenetic relationship to other avian HEVs is determined. Sequence analyses of these isolates identified major genetic differences among avian HEVs. Most of them are located within the open reading frame (ORF)1 region, although only a few lie within conserved motifs of predicted domains. Non-silent mutations in the ORF2 region suggest the presence of potentially different epitopes among avian HEV isolates. Finally, phylogenetic analysis confirmed the distant relationship to mammalian HEV and additionally suggested that the avian HEVs can be separated into three different genotypes: 1 (Australia), 2 (USA) and 3 (Europe), indicating a geographical distribution pattern.

Consensus proposals for classification of the family Hepeviridae

“…Although four genotypes of Orthohepevirus B have been proposed (Bilic et al, 2009;Hsu & Tsai, 2014;Huang et al, 2004), these are much less diverse than the genotypes of Orthohepesvirus A. For example there is ,6 % divergence in Orthohepevirus B complete genome amino acid sequences (Figs 1 and 3), which is less than the divergence observed within HEV-3 (,9 %) and HEV-4 (,7 %).…”

“…HEV was first recognized in the 1980s and its nucleotide sequence published in the 1990s (Huang et al, 1992;Reyes et al, 1990; although the underlying criteria are controversial (Okamoto, 2007;Smith et al, 2013). A more distantly related virus detected in chickens also has been divided into genotypes (Bilic et al, 2009;Hsu & Tsai, 2014;Huang et al, 2004).…”

A PSAP motif in the ORF3 protein of hepatitis E virus is necessary for virion release from infected cells

“…Genotypes 1 and 2 have caused outbreaks of hepatitis E as water-borne epidemics, while genotypes 3 and 4 have been found in sporadic cases of acute hepatitis E that were most likely zoonotic in origin because genotypes 3 and 4 HEVs infect not only humans, but also swine, and rarely, other non-primate mammals (Meng, 2010;Okamoto, 2007). At least three genotypes of avian HEV have been identified from chickens worldwide, but these genotypes only share approximately 50 % nucleotide sequence identity with mammalian HEVs (Meng, 2010;Bilic et al, 2009).…”

Construction of an infectious cDNA clone of genotype 1 avian hepatitis E virus: characterization of its pathogenicity in broiler breeders and demonstration of its utility in studying the role of the hypervariable region in virus replication

“…Avian HEV has been identified from mostly broiler breeders and layers in many countries (Bilic et al, 2009;Shivaprasad & Woolcock, 1995;Troxler et al, 2014). The pathogenicity of avian HEV remains largely uncharacterized.…”

“…At least four different genotypes of avian HEV have been identified from chickens worldwide: genotype 1 from chickens in Australia, genotype 2 from chickens in the USA, genotype 3 from chickens in Europe and China, and genotype 4 from chickens in Hungary and Taiwan (Bányai et al, 2012;Bilic et al, 2009;Haqshenas et al, 2001;Hsu & Tsai, 2014;Huang et al, 2004;Marek et al, 2010;Zhao et al, 2010). The status of avian HEV infection in chickens in Asia is largely unknown since there was only one report of avian HEV detection from China before the virus was identified recently in Korea and Taiwan (Hsu & Tsai, 2014; Kwon et al, 2012;Zhao et al, 2010).…”