Notes on Genus: Flavivirus

icosahedra
icosahedra

Type member: Yellow fever virus

Contents

General Description

This is one of the genera in the family Flaviviridae and consists of those viruses with a genome of 10-12kb that encodes three structural proteins (coat protein and two membrane proteins). Members infect both vertebrates and invertebrates and are mostly arthropod-borne. The name is from the Latin flavus = yellow, from the type member, Yellow fever virus.

Morphology

Virions enveloped and spherical about 50 nm in diameter. Mature virions contain two virus-encoded membrane proteins (M and E), while immature virions contain a membrane protein precursor.

Genome

Monopartite positive sense single-stranded RNA about 11kb in length, with a 5'-cap (m-7GpppAmp) and no 3'-polyA tail.

Genus Genomic Organization

There is a single polyprotein of about 380 kDa that is subsequently processed into a number of structural and non-structural proteins:
  • Core (capsid) protein C, 10-14 kDa in anchored form with smaller mature protein
  • Membrane glycoprotein M (8-11 kDa) produced from a larger precursor
  • Envelope protein E, 53-54 kDa
  • Non-structural protein 1, 39-46 kDa
  • Non-structural protein 2a, 18-25 kDa
  • Non-structural protein 2b, 13.5-15 kDa
  • Non-structural protein 3 (protease and helicase), 69 kDa
  • Non-structural protein 4a, 16-32 kDa
  • 2K protein, 2-3 kDa
  • Non-structural protein 4b, 12-28 kDa
  • Non-structural protein 5 (polymerase and methyltransferase), 97-115 kDa

Type Member Genomic Organization

There is a single polyprotein of about 380 kDa that is subsequently processed into a number of structural and non-structural proteins:
  • Anchored core (capsid) protein C, 13.6 kDa with mature protein of 11.5 kDa
  • Membrane glycoprotein M (8.5 kDa) produced from a larger precursor (18.7 kDa)
  • Envelope protein E, 53.6 kDa
  • Non-structural protein 1, 39.7 kDa
  • Non-structural protein 2a, 24.1 kDa
  • Non-structural protein 2b, 13.8 kDa
  • Non-structural protein 3 (protease and helicase), 69.0 kDa
  • Non-structural protein 4a, 13.6 kDa
  • 2K protein, 2.4 kDa
  • Non-structural protein 4b, 27.3 kDa
  • Non-structural protein 5 (polymerase and methyltransferase), 103.9 kDa