Notes on Family: Bromoviridae

icosahedra or bacilliform

Contents

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

General Description

This family is characterised by its isometric or quasi-isometric particles and its single strand, positive-sense, RNA in three genomic and one subgenomic segments. These are packaged separately, resulting in several different types of virion, which may or may not differ in size (depending on the genus).

Morphology

Virions isometric to quasi-isometric, elongated, not enveloped, 26-35 nm in diameter. Symmetry icosahedral (T = 3, or T = 1 in Alfamovirus Ta particle). Surface projections of nucleocapsid not present. Shell of virion has a single layer.

Particles contain 14-25 % nucleic acid.

Genome

Positive sense single-stranded RNA. There are three genomic RNAs (RNA1, 3200-3644 nt; RNA2, 2600-3050 nt; RNA3, 2100-2216 nt) and one encapsidated subgenomic derived from RNA3 (800-1000 nt) from which the coat protein is expressed. Total genome 7900-8910 nucleotides long. 3'-terminal sequences are conserved. The 5' terminus of each RNA has a methylated nucleotide cap with the sequence: m7G5'ppp5'Gp....

Genera in the Family