Members of the subfamily are distinct by phylogenetic analysis of the methyltransferase, helicase and RNA polymerase domains, and have been detected in mammals and birds; members of the subfamily Parahepevirinae have only been detected in fish. Members of the subfamily share a common genome organisation with a short 5′-untranslated region, a long ORF1 followed by the overlapping and shorter ORF2 and ORF3, with a poly-A tail at the end of ORF2.
Genus demarcation criteria
Members of the four genera have different host ranges and are distinct by phylogenetic analysis of complete coding region nucleotide sequence and of partial amino acid sequence from the methyltransferase, helicase and RNA polymerase domains (Smith et al., 2014, Smith et al., 2015). Members of the genus Paslahepevirus have been identified in mammals including humans, pigs, deer, rabbits, camels, cattle, sheep, goats, mongooses, and bottlenose dolphins. Members of the genus Avihepevirus are restricted to birds, primarily chickens, and have been allocated to several genotypes, although these are more closely related to each other than are genotypes of species in the genus Paslahepevirus. The genus Rocahepevirus includes viruses from rodents, eulipotyphlids and mustelids. Bats remain the only source from which viruses of species in the genus Chirohepevirus have been reported.