Genus: Megrivirus


Genus: Megrivirus

Virion

Nucleic acid

Length of genome (Lau et al., 2014, Honkavuori et al., 2011, Boros et al., 2014, Liao et al., 2014, Phan et al., 2013, Kim et al., 2015): 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'UTRIRES-IVB[1AB-1C-1D/2A1-2A2-2A3-2A4H-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, 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 melegriviruses (Lau et al., 2014, Boros et al., 2014).

Antigenicity

See discussion under family description.

Biology

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 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 megriviruses ranges from 0.56-0.64 for P1 and 0.37-0.44 for 3CD. Sequence data suggest the existence of two additional megrivirus species. Megrivirus taxonomy is complicated by an apparent interspecies recombination event in the evolution of viruses belonging to the Melegrivirus A species. A final disposition is pending.

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

Member species

SpeciesVirus name(s)Exemplar isolateExemplar accession numberExemplar RefSeq numberAvailable sequenceOther isolatesOther isolate accession numbersVirus abbreviationIsolate abbreviation
Megrivirus Aduck megrivirusLYKC663628NC_024120Complete genomeMeV-A
Megrivirus Bpigeon mesivirus 1HK21KC876003Complete coding genomeMeV-B
Megrivirus Cchicken megrivirusBL21KF961186Complete genomeMeV-C
Megrivirus Dharrier megrivirusMR-01KY488458NC_034617Complete genomeMeV-D
Megrivirus Epenguin megriviruspenguin/KGI-BHS-P5MF405436Complete genomeMeV-E

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

Derivation of names

Megri: from the host (turkey) genus name Meleagris

Melegri: from the host (turkey genus name Meleagris

Related, unclassified viruses

Virus name

Accession number

Virus abbreviation

Mesivirus 1 [HK21]

KC876003

MeV-1

Mesivirus 2 [pigeon/GALII5-PiMeV/2011/HUN]

KC811837

MeV-2

Chicken megrivirus [chicken/B21-CHV/2012/HUN]

KF961186

ChkMeV

Chicken megrivirus [chicken/CHK-IV-CHV/2013/HUN]

KF961187

ChkMeV

Chicken proventriculitis virus [CPV/Korea/03]

KJ690629

CPV

Chicken picornavirus [27C]

KF979336

ChkPV

Duck megrivirus [LY]

KC663628

DuMV

Goose megrivirus [W18]

KY369299

GMV

Goose megrivirus [HN56]

KY369300

GMV

Virus names and virus abbreviations are not official ICTV designations.