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No surface morphology is visible by EM.
Avihepatoviruses are both heat and acid stable.
Length of 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). 5'-UTR contains a type IV IRES. The location of the cre has not been identified.
Genome layout: VPg+5'UTRIRES-IV[1AB-1C-1D-2A1npgp/2A2NTPase-2A3H-box/NC-2B-2C/3A-3B-3C-3D]3'UTR-poly(A)
The deduced polyproteins of the three types have lengths 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 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.
Avihepatoviruses are divided into three genetic types, duck hepatitis A virus (DHAV) 1 to DHAV-3. DHAV-2 and DHAV-3 are not neutralized by DHAV-1 antiserum; however, the relationship between types 2 and 3 remains unstudied.
DHAV causes a highly fatal contagious 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.
Avihepato: from avian and Greek hepatos, "liver"
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