Notes on Genus: Potyvirus

flexuous filaments

Type member: Potato virus Y

Contents

• Members of this Genus
• General Description
• Morphology
• Electron Micrograph
• Genome
• Genus Genomic Organization
• Genome Map
• Type Member Genomic Organization
• All Known Sequences
• Curated Sequences

General Description

This is the largest and best-studied genus in the family Potyviridae. Like the other genera, it is characterised by its flexuous filamentous particles, inclusion bodies in infected plant cells and by having a polyprotein genome strategy. It differs from most of the other genera in having insect transmission, and from the genus Macluravirus in having particles that are 700 nm or more in length. Like all the genera except the genus Bymovirus, it has a monopartite genome. It is named after its type member, potato virus Y.

Morphology

Virions filamentous, not enveloped, usually flexuous, 720-850 nm long and 12-15 nm in diameter. Symmetry helical with a pitch of 3.4 nm

Virions composed of 5 % nucleic acid and 95 % protein.

Genome

Monopartite, linear, single-stranded positive sense RNA up to about 10,000 nucleotides long. The 3' terminus has a poly(A) tract and the 5' terminus has a genome-linked protein (VPg).

Genus Genomic Organization

Genome organisation appears to be uniform throughout this genus and is similar to other members of the family Potyviridae. The genome is translated into a single polyprotein, which is subsequently processed into ten, products with the coat protein at the C-terminus. An additional small ORF (PIPO) is generated by frameshifting within the third (P3) cistron.

Type Member Genomic Organization

The genome of about 9,700 nucleotides is translated into a single polyprotein, which is subsequently processed into at least eight, and probably ten, products:

P1 protein	32.4 kDa	unknown function
HC-Pro	51.9 kDa	helper component (insect transmission)
P3 protein	41.5 kDa	unknown function
6K1	6.0 kDa	unknown function
CI	71.4 kDa	Cylindrical inclusion protein possibly involved in cell to cell movement
6K2	5.5 kDa	unknown function
VPg	21.7 kDa	Genome-linked protein
NIa-pro	27.7 kDa	Nuclear Inclusion proteinase
NIb	59.8 kDa	Nuclear Inclusion polymerase
CP	29.8 kDa	coat protein

An additional small ORF (PIPO) is generated by frameshifting within the third (P3) cistron.