Ipomovirus

Ipomovirus is a genus of viruses, in the family Potyviridae. There are currently six species in this genus including the type species Sweet potato mild mottle virus.[1][2] They infect plants and are transmitted by whiteflies (Bemisia tabaci). The name of the genus is derived from Ipomoea - the generic name of sweet potato.

Ipomovirus
Virus classification
Group:
Group IV ((+)ssRNA)
Family:
Potyviridae
Genus:
Ipomovirus
Species
  • Cassava brown streak virus disease
  • Sweet potato mild mottle virus

Taxonomy

Group: ssRNA(+)

[2]

Structure

Viruses in Ipomovirus are non-enveloped, with flexuous and filamentous geometries. The diameter is around 12-15 nm, and may have a variety of lengths depending on the species (200-300 nanometers (nm): 500-600 nm: 650-900 nm).[1] The capsid has helical symmetry with a pitch of 3.4 nm. They induce characteristic inclusion bodies (pinwheels) within infected plant cells.

GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
IpomovirusFilamentousHelicalNon-envelopedLinearSegmented

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. The virus exits the host cell by tubule-guided viral movement. Plants serve as the natural host. The virus is transmitted via a vector (white fly). Transmission routes are vector and mechanical.[1]

GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
IpomovirusPlantsNoneViral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical inoculation: white fly

Genome

The genome is a monpartite linear, single stranded RNA genome of positive polarity about 10-11 kilobases in length. The 3’ terminus has a poly (A) tract and the 5’ terminus has a genome linked protein (VPg).[1]

It encodes a single polypeptide with a predicted molecular weight of 390 kiloDaltons (kDa) which is cleaved into ~10 proteins. In 5'-3' order these proteins are

  • P1 (a serine protease): 83 kDa
  • HC (a protease): 51 kDa
  • P3: 34 kDa
  • 6K1: 5 kDa
  • Cl (helicase): 71 kDa
  • 6K2: 6 kDa
  • VPg (the 5' binding protein): 20 kDa
  • NIa-Pro (a protease): 27 kDa
  • NIb (RNA dependent RNA polymerase): 57 kDa
  • Capsid protein: 34 kDa

There may be some variation in the number of the proteins depending on the species.

References
  1. "Viral Zone". ExPASy. Retrieved 15 June 2015.
  2. ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
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