Notes on Family: Togaviridae

enveloped spheres
enveloped spheres

Contents

General Description

This family is characterised by enveloped spherical virions 60-70 nm in diameter and a single component of single-stranded RNA, which has a polyA tail. The RNA encodes two polyproteins that are subsequently processed into a number of structural and non-structural proteins.

Morphology

Virions enveloped and spherical 60-70 nm in diameter, with glycoprotein spikes.

Genomen

Monopartite positive sense single-stranded RNA of about 9-12kb with a 5' cap and a 3'-polyA tail. The RNA encodes two polyproteins that are subsequently processed into a number of structural and non-structural proteins. The 3'- (structural) ORF is translated from a subgenomic RNA.

Genera in the Family

  • Alphavirus: particles 70nm in diameter with three membrane proteins; multiply in their insect vectors; genome 11-12kb
  • Rubivirus: particles 60nm in diameter with two membrane proteins; no known insect vectors (dispersed in aerosols); genome <10kb