Genus: Avihepatovirus


Genus: Avihepatovirus

Distinguishing features

The genus is distinguished on the basis of genetic characters.

Virion

Morphology

No surface morphology is visible by EM. 

Physicochemical and physical properties

Avihepatoviruses are both heat and acid stable.

Nucleic acid

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 organization and replication

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 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 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.

Antigenicity

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.

Biology

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.

Species demarcation criteria

There is only a single species in the genus.

Member species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Avihepatovirus Aduck hepatitis A virus 1R85952DQ226541NC_008250Complete genomeDHAV-1
Avihepatovirus Aduck hepatitis A virus 2duck/90D/TaiwanEF067924DHAV-2
Avihepatovirus Aduck hepatitis A virus 3duck/AP-03337/KOR/2003-4DQ256132DHAV-3

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.

Derivation of names

Avihepato-: from avian and Greek hepatos, "liver"