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

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.