Genus: Megrivirus

Virion

Nucleic acid

Length of genome [{Lau et al., 2014:24906980RJOHTXLau et al., 2014, Chickens host diverse picornaviruses originated from potential interspecies transmission with recombination, J Gen Virol, 95, Pt 9, 1929-44RJOMREFHonkavuori et al., 2011:21392440RJOHTXHonkavuori et al., 2011, Novel picornavirus in Turkey poults with hepatitis, California, USA, Emerg Infect Dis, 17, 3, 480-7RJOMREFBoros et al., 2014:24672039RJOHTXBoros et al., 2014, Comparative complete genome analysis of chicken and Turkey megriviruses (family Picornaviridae): long 3' untranslated regions with a potential second open reading frame and evidence for possible recombination, J Virol, 88, 11, 6434-43RJOMREFLiao et al., 2014:24933161RJOHTXLiao et al., 2014, Genomic characterization of a novel picornavirus in Pekin ducks, Vet Microbiol, 172, 1-2, 78-91RJOMREFPhan et al., 2013:24023772RJOHTXPhan et al., 2013, The viruses of wild pigeon droppings, PLoS One, 8, 9, e72787RJOMREFKim et al., 2015:25559673RJOHTXKim et al., 2015, Identification of a picornavirus from chickens with transmissible viral proventriculitis using metagenomic analysis, Arch Virol, 160, 3, 701-9}]: c. 9,740 nt (5'-UTR: 642 nt; ORF: 8,451 nt; 3'-UTR: 646 nt). 5' UTR contains a type IV-B IRES; 3' UTR is exceptionally long. The location of the cre has not been identified.

Genome organization and replication

Genome layout:

VPg+5'UTR^IRES-IVB[1AB-1C-1D/2A1-2A2-2A3-2A4^H-box/NC-2B-2C/3A-3B-3C-3D]3'UTR-poly(A)

The deduced polyprotein has a length of 2,817 aa. There is no L protein. 1AB remains uncleaved and has a N-terminal myristoylation signal. There are 2-4 2A proteins with the last of which exhibiting a H-box/NC motif. A second ORF has been proposed at the 3'-end of the genome but not yet demonstrated. Sequence data indicate interspecies recombination in the evolution of melegriviruses [{Lau et al., 2014:24906980RJOHTXLau et al., 2014, Chickens host diverse picornaviruses originated from potential interspecies transmission with recombination, J Gen Virol, 95, Pt 9, 1929-44RJOMREFBoros et al., 2014:24672039RJOHTXBoros et al., 2014, Comparative complete genome analysis of chicken and Turkey megriviruses (family Picornaviridae): long 3' untranslated regions with a potential second open reading frame and evidence for possible recombination, J Virol, 88, 11, 6434-43}].

Biology

The virus is suspected to be the etiological agent of turkey viral hepatitis [{Honkavuori et al., 2011:21392440RJOHTXHonkavuori et al., 2011, Novel picornavirus in Turkey poults with hepatitis, California, USA, Emerg Infect Dis, 17, 3, 480-7RJOMREFTzianabos and Snoeyenbos 1965:4955126RJOHTXTzianabos and Snoeyenbos 1965, Clinical, immunological, and serological observations on turkey virus hepatitis, Avian Dis, 9, 4, 578-91}]621. 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 and feral pigeons.

Species demarcation criteria

Members of a species of the genus Megrivirus share a common genome organization.

The divergence (number of differences per site between sequences) of known Megrivirus species ranges from 0.56-0.64 for P1 and 0.37-0.44 for 3CD. Sequence data suggest the existence of two additional melegrivirus species. Melegrivirus taxonomy is complicated by an apparent interspecies recombination event in the evolution of Melegrivirus A1. A final disposition is pending.

Members of Melegrivirus A species form three genotypes. Six further types are awaiting classification.

Member Species

Virus names, the choice of exemplar isolates, and virus abbreviations, are not official ICTV designations.
Download GenBank/EMBL query for sequences listed in the table here.

Derivation of names

Megri-: from the host (turkey) genus name Meleagris

Melegri-: from the host (turkey genus name Meleagris

Related, Unclassified Viruses