Genetic identification of avian hepatitis E virus (HEV) from healthy chicken flocks and characterization of the capsid gene of 14 avian HEV isolates from chickens with hepatitis–splenomegaly syndrome in different geographical regions of the United States

Hepatitis–splenomegaly (HS) syndrome is an emerging disease in chickens in North America; the cause of this disease is unknown. In this study, the genetic identification and characterization of a novel virus related to human hepatitis E virus (HEV) isolated from bile samples of chickens with HS syndrome is reported. Based upon the similar genomic organization and significant sequence identity of this virus with HEV, the virus has been tentatively named avian HEV in order to distinguish it from human and swine HEV. Electron microscopy revealed that avian HEV is a non-enveloped virus particle of 30–35 nm in diameter. The sequence of the 3′ half of the viral genome (∼4 kb) was determined. Sequence analyses revealed that this genomic region contains the complete 3′ non-coding region, the complete genes from open reading frames (ORFs) 2 and 3, the complete RNA-dependent RNA polymerase (RdRp) gene and a partial helicase gene from ORF 1. The helicase gene is the most conserved gene between avian HEV and other HEV strains, displaying 58–61% aa and 57–60% nt sequence identities. The RdRp gene of avian HEV shares 47–50% aa and 52–53% nt sequence identities and the putative capsid gene (ORF 2) of avian HEV shares 48–49% aa and 48–51% nt sequence identities with the corresponding regions of other known HEV strains. Phylogenetic analysis indicates that avian HEV is genetically related to, but distinct from, other known HEV strains. This discovery has important implications for HEV animal models, nomenclature and natural history.

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Determination and analysis of the complete genomic sequence of avian hepatitis E virus (avian HEV) and attempts to infect rhesus monkeys with avian HEV

Journal of General Virology ◽

10.1099/vir.0.79841-0 ◽

2004 ◽

Vol 85 (6) ◽

pp. 1609-1618 ◽

Cited By ~ 170

Author(s):

F. F. Huang ◽

Z. F. Sun ◽

S. U. Emerson ◽

R. H. Purcell ◽

H. L. Shivaprasad ◽

...

Keyword(s):

Rhesus Monkeys ◽

Hepatitis E Virus ◽

Genomic Sequence ◽

Hepatitis E ◽

The United States ◽

Open Reading Frames ◽

Coding Region ◽

Virus Shedding ◽

Avian Hepatitis E Virus ◽

Avian Hev

Avian hepatitis E virus (avian HEV), recently identified from a chicken with hepatitis–splenomegaly syndrome in the United States, is genetically and antigenically related to human and swine HEVs. In this study, sequencing of the genome was completed and an attempt was made to infect rhesus monkeys with avian HEV. The full-length genome of avian HEV, excluding the poly(A) tail, is 6654 bp in length, which is about 600 bp shorter than that of human and swine HEVs. Similar to human and swine HEV genomes, the avian HEV genome consists of a short 5′ non-coding region (NCR) followed by three partially overlapping open reading frames (ORFs) and a 3′NCR. Avian HEV shares about 50 % nucleotide sequence identity over the complete genome, 48–51 % identity in ORF1, 46–48 % identity in ORF2 and only 29–34 % identity in ORF3 with human and swine HEV strains. Significant genetic variations such as deletions and insertions, particularly in ORF1 of avian HEV, were observed. However, motifs in the putative functional domains of ORF1, such as the helicase and methyltransferase, were relatively conserved between avian HEV and mammalian HEVs, supporting the conclusion that avian HEV is a member of the genus Hepevirus. Phylogenetic analysis revealed that avian HEV represents a branch distinct from human and swine HEVs. Swine HEV infects non-human primates and possibly humans and thus may be zoonotic. An attempt was made to determine whether avian HEV also infects across species by experimentally inoculating two rhesus monkeys with avian HEV. Evidence of virus infection was not observed in the inoculated monkeys as there was no seroconversion, viraemia, faecal virus shedding or serum liver enzyme elevation. The results from this study confirmed that avian HEV is related to, but distinct from, human and swine HEVs; however, unlike swine HEV, avian HEV is probably not transmissible to non-human primates.

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