Phylogenetic analysis of avian hepatitis E virus samples from European and Australian chicken flocks supports the existence of a different genus within the Hepeviridae comprising at least three different genotypes

Using PCRs that amplify regions of helicase and capsid genes, the presence of avian hepatitis E virus (avian HEV) was determined in samples from European and Australian chicken flocks (collected from 2005 to 2007 and 1986 to 1995, respectively). A total of 27 virus samples from 9 countries were analysed to determine the phylogenetic relationship following PCRs and nucleic acid sequencing of the helicase and capsid regions of 18 avian HEV samples. For comparison, helicase and capsid sequences of completely sequenced avian HEVs from Europe, Australia and the USA were used. In addition, available helicase and capsid sequences of other avian HEVs and four mammalian HEVs were included. At least three genotypes within the avian HEV were revealed. These genotypes tend to be differentiated geographically. Altogether, the present investigation is of importance to understand the epidemiology of avian HEV infections in chickens and gives new insight into the phylogenetic relationships between isolates. Furthermore, we would like to propose that avian HEV represent a separate genus within the Hepeviridae consisting of different genotypes.