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The genus is distinguished on the basis of genetic characters.
No details are available on the morphology of the virions.
Genome (Lau et al., 2014, Honkavuori et al., 2011, Boros et al., 2014b, Liao et al., 2014, Phan et al., 2013, Kim et al., 2015, Boros et al., 2017, Wang et al., 2017), (R. Zell, C.K. Yinda, J. Esefeld, H.U. Peter and J. Matthijnssens (unpublished)): 8,541–10,101 nt (5′-UTR: >461–833 nt; ORF: 7,455–8,916 nt; 3′-UTR: 175-671 nt). 5′-UTR contains a type IV-B IRES with exception of harrier megrivirus which has a type II IRES; 3′-UTR is exceptionally long. The location of the cre has not been identified.
The deduced polyprotein ranges from 2,485 to 2,972 aa. Only members of Megrivirus E have a L protein. 1AB remains uncleaved and has a N-terminal myristoylation signal. There are 1–4 2A proteins, the last of which exhibiting a H-box/NC motif. A second functional ORF has been proposed at the 3′-end of the genome but not yet demonstrated. Sequence data indicate interspecies recombination in the evolution of megriviruses (Lau et al., 2014, Boros et al., 2014b).
The virus is suspected to be the etiological agent of turkey viral hepatitis (Honkavuori et al., 2011, Tzianabos and Snoeyenbos 1965). The natural host is poultry (turkey and chicken). Viral RNA was detected in liver, bile, intestine, serum and cloacal swabs of turkeys suffering from turkey viral hepatitis; RNAs of related viruses have been detected in chickens, ducks, feral pigeons, harriers and penguins.
Members of a species of the genus Megrivirus share an essentially common genome organization.
The divergence (number of differences per site between sequences) of members of different Megrivirus species ranges from 0.52–0.67 for P1 and 0.31–0.53 for 3CD. Megrivirus taxonomy is complicated by an apparent interspecies recombination event in the evolution of viruses belonging to the Megrivirus A and Megrivirus C species.
Sequence data of capsid protein-encoding gene regions indicate at least 10 types (Megrivirus A: 3 types, Megrivirus B: 2 types, Megrivirus C: 3 types, Megrivirus D: 1 type, Megrivirus E: 1 type).
Megri-: from the host (turkey) genus name Meleagris
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