Notes on Family: Carmotetraviridae

icosahedra

Contents

Members of this Family
General Description
Morphology
Genome
Genera in the Family
All Known Sequences
Curated Sequences

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. In this family,there are unstructured genome terminal sequences, a unique readthrough signal controlling RdRp expression and a large third ORF overlapping with the replication protein that has a distant relationship to the 'carmo' supergroup of plant viruses.

Morphology

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

Genome

Monopartite positive sense single-stranded RNA of about 6.2 kb without a 3'-polyA tail. There are three major ORFs, one encoding a replication protein with a readthrough strategy to express the RNA polymerase and the other a coat protein precursor. The third, and largest, ORF is of unknown function.

Genera in the Family

There is currently only one genus: