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 protein32.4 kDa unknown function
HC-Pro 51.9 kDahelper component (insect transmission)
P3 protein41.5 kDa unknown function
6K1 6.0 kDaunknown function
CI 71.4 kDaCylindrical inclusion protein possibly involved in cell to cell movement
6K2 5.5 kDaunknown function
VPg 21.7 kDa Genome-linked protein
NIa-pro 27.7 kDaNuclear Inclusion proteinase
NIb 59.8 kDaNuclear Inclusion polymerase
CP 29.8 kDacoat protein
An additional small ORF (PIPO) is generated by frameshifting within the third (P3) cistron.