Notes on Family: Secoviridae

icosahedra

Contents

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

General Description

This family contains all the plant-infecting members of the order Picornavirales. The viruses included all have icosahedral particles and monopartite or bipartite genomes, which are translated as polyproteins for subsequent processing.

Morphology

Virions isometric, icosahedral, not enveloped and about 30 nm in diameter.

Genomen

Mono- or bi-partite with linear, single-stranded positive sense RNA. Total genome 9000-12000 nucleotides long. The 5'-terminus has a genome-linked protein (VPg) and a poly (A) tract is present almost invariably at the 3'-end. The genomic RNA(s) have a large open reading frame which is translated into a polyprotein for subsequent processing.

Genera in the Family

Classification into genera depends upon genome organisation and some biological properties, supported by phylogenetic analysis. The current genera are:

Genus	RNAs	RNA2 polyprotein (kDa)	Nos of coat proteins	Vector	Other features
Subfamily Comovirinae:
Comovirus	2	130	2	Beetles
Fabavirus	2	130	2	Aphids
Nepovirus	2	135-190	1	Nematodes
Other genera:
Cheravirus	2	100-110	3	Nematodes
Sadwavirus	2	171	2	Nematodes?
Sequivirus	1	-	3	Aphids	Requires helper virus for transmission. Genome may lack a 3'-polyA tail.
Torradovirus	2	134	3	Whiteflies?	Extra partially overlapping ORF at 5'-end of RNA2
Waikavirus	1	-	3	Beetles	Two small additional ORFs at 3'-end