Subfamily: Orthohepevirinae

Genus: Avihepevirus

Distinguishing features

Members of the genus Avihepevirus are phylogenetically distinct from other viruses in the subfamily, and have a different host range, being found only in birds.

Biology

Avihepevirus magniiecur includes strains of avian hepatitis E virus detected in chickens (Payne et al., 1999, Haqshenas et al., 2001, Haqshenas et al., 2002, Huang et al., 2002). Infection in chickens is widespread with approximately 71% of chicken flocks and 30% of chickens in the United States positive for IgG antibodies to the virus (Huang et al., 2002). Infection has also been reported in wild birds (Zhang et al., 2017) and can be experimentally transmitted to turkeys but not monkeys, mice or pigs. The clinical disease in infected chickens has been referred to as big liver and spleen (BLS) disease, and hepatitis-splenomegaly (HS) syndrome. Disease in infected chickens is associated with increased mortality and decreased egg production. Virus replication occurs in the liver as well as extrahepatic tissues, including the gastrointestinal tract. Avihepevirus magniiecur strains have been divided into 4 genotypes that differ from each other by 18% in complete nucleotide sequence (Bilic et al., 2009, Banyai et al., 2012). These genotypes have different geographical distributions; genotype 1 is restricted to Australia, genotypes 2 and 3 have been detected in the USA, Europe and Asia, and genotype 4 in Hungary and Asia.

Species demarcation criteria

Members of different species in the genus are phylogenetically distinct based upon analysis of ORF1 codon positions 1−450 (methyltransferase), ORF1 codon positions 971–1692 (RNA-directed RNA polymerase) and ORF2 codon positions 121−473 (capsid protein not including the region encoded by the overlapping ORF3). Members of different species may also have different host ranges, although limited data is available.