Notes on Genus: Brambyvirus
Type member: Blackberry virus Y
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 protein||unknown function || ||41 kDa|
|"6K1"||unknown function || ||6 kDa|
|CI ||Cylindrical inclusion putative helicase|| ||71 kDa|
|"6K2"||unknown function || ||6 kDa|
|VPg||Genome-linked protein || ||22 kDa|
|NIa-Pro||Nuclear Inclusion protease || ||26 kDa|
|NIb||Nuclear Inclusion polymerase || ||61 kDa|
|CP|| ||Coat protein || ||41 kDa|
An additional small ORF (PIPO) is generated by frameshifting within the third cistron (P3).