Notes on Family: ss satellite RNAs

no particles of their own
no particles of their own

Contents

General Description

Satellites are sub-viral agents composed of nucleic acid molecules that depend for their replication on co-infection of a host cell with a specific helper virus. Nucleotide sequences are substantially distinct from those of the genomes of the helper virus and of the host. Replication of the helper virus is often decreased and virus symptoms may be modified.

Satellite nucleic acids consist of those satellites that do not encode their own coat protein (unlike satellite viruses) but are encapsidated in that of the helper virus. Particles containing satellite nucleic acid are therefore antigenically identical to those of the helper virus but can sometimes be distinguished by physical features such as sedimentation rates.

Single stranded satellite RNAs are all associated with plant viruses and several subgroups are recognised on the basis of their replication strategies.

Morphology

There are no distinctive virions because they are encapsidated in the coat protein of their helper virus.

Genomen

Linear or circular. Monopartite, ssRNA. 350 - c.1500 nucleotides long.

Genera in the Family

Large satellite RNAs (0.8-1.5 kb, encoding a non-structural protein)
Small linear satellite RNAs (less than about 0.9 kb, encoding no functional protein; always linear)
Circular satellite RNAs (c. 350 nucleotides, encoding no functional protein; some circular molecules present)