The genus is distinguished on the basis of genetic characters.
No surface morphology is visible by EM.
Physicochemical and physical properties
Avihepatoviruses are both heat and acid stable.
Genome (Kim et al., 2006): up to 7,792 nt (5′-UTR: 625–655 nt, ORF: 6,750–6,756 nt, 3′-UTR: c. 318 nt). The 5′-UTR contains a type IV IRES. The location of the cre has not been identified.
Genome organization and replication
The deduced polyproteins of the three types are of 2,249–2,251 amino acids. There is no L protein. The 1AB polypeptide remains uncleaved and lacks a myristoylation signal. The genome sequences of all three duck hepatitis A virus (DHAV) types have three 2A motifs: i) NPGP; ii) AIG1-type guanine nucleotide-binding domain (GxxGxGKS NTP-binding motif); and iii) a H-box/NC motif. However, it is not clear if this genome region encodes one, two or three mature polypeptides. 3Dpol exhibits a CSG rather than PSG sequence motif.
DHAV causes a highly contagious, fatal disease of young ducklings, 1–28 days of age. The onset of the disease is very rapid, it spreads quickly through the flock and may cause up to 90% mortality. Sick ducklings develop spasmodic contractions of their legs and die within an hour in a typical "arched-backward" position. The liver is enlarged and shows hemorrhagic spots. A DHAV-1 live-attenuated vaccine is widely used.
Avihepatoviruses are divided into three genetic types, DHAV-1 to DHAV-3. DHAV-2 and DHAV-3 are not neutralized by DHAV-1 antiserum; however, the relationship between DHAV-2 and DHAV-3 remains unstudied.
Derivation of names
Avihepatovirus: from avian and Greek hepatos, "liver"
Species demarcation criteria
There is only a single species in the genus.