Notes on Family: Alphatetraviridae



General Description

This family consists of ssRNA viruses with 40nm isometric particles and that infect insects. The name is derived from the Greek tettares = four, because of the T=4 symmetry of the virions. All tetraviruses were formerly classified in a single family but this has now been split because of large differences in the types of RNA polymerase and other genome differences. Most of the species are retained in this family (which has been renamed from Tetraviridae) but some are now classified in the families Carmotetraviridae and Permutotetraviridae.


Virions isometric (icosahedral), not enveloped, about 40 nm in diameter with T=4 icosahedral shell quasi-symmetry.


Mono- or Bi-partite positive sense single-stranded RNA without 3'-polyA tails. Total genome size less than 8 kb. There are two major ORFs, one encoding an RNA polymerase and the other a coat protein precursor.

Genera in the Family