Notes on Genus: Brambyvirus

flexuous filaments
flexuous filaments

Type member: Blackberry virus Y


General Description

This is one of the genera 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 a very large P1 protein containing an AlkB domain. The vector is not known. Like all the genera except the genus Bymovirus, it has a monopartite genome. Its name is derived from bramble, one of the common names for the host of the type member, Blackberry virus Y.


Virions filamentous, not enveloped, usually flexuous, about 800 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.


Monopartite, linear, single stranded, positive sense RNA, about 11,000 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 is similar to that of other members of the family Potyviridae. The genome is translated into a single polyprotein, which is subsequently processed into about ten products, with the coat protein at the C-terminus. An additional small ORF (PIPO) is generated by frameshifting within the third cistron (P3).

Type Member Genomic Organization

The genome is translated into a single polyprotein of 394 kDa, from which an estimated ten functional products are produced by proteolytic processing:
P1 protein     putative protease    84 kDa
HC-Pro putative helper component protease    37 kDa
P3 proteinunknown function     41 kDa
"6K1"unknown function     6 kDa
CI Cylindrical inclusion putative helicase    71 kDa
"6K2"unknown function     6 kDa
VPgGenome-linked protein     22 kDa
NIa-ProNuclear Inclusion protease     26 kDa
NIbNuclear Inclusion polymerase     61 kDa
CP Coat protein     41 kDa
An additional small ORF (PIPO) is generated by frameshifting within the third cistron (P3).