imported>Lcovelli at 11:49, 15 March 2010

2010-03-15T11:49:51Z

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{{Element
|genbank=[http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=53830360 53830360]
|type=
|genus= Badnavirus
|subfamily= Class 2
|family= Caulimoviridae
|group= LTR retroelements
|description=''Banana streak virus'' (BSV), the causal agent of viral "leaf streak disease" of banana and plantain (''Musa'' spp.) ([[Literature:100630|Lockhart, 1986]]), is a member of the plant pararetrovirus genus ''Badnavirus'' of ''Caulimoviridae'' family (''International Committee on the Taxonomy of Viruses'' -ICTV- [[Literature:100589|Fauquet ''et al''. 2005]]). Several isolated have been studied, one of which is BSVaV infecting ''Musa acuminata siamea'' species (A genome) from Vietnam ([[Literature:92815|Lheureux ''et al.'' 2007]]). According to [[Literature:100596|Llorens ''et al''. 2009]], BSVaV belongs to ''Badnavirus'' genus within Class 2 of the [[Caulimoviridae|''Caulimoviridae'']] family.

BSVaV has bacilliform-shaped virions and a 7801 bp long circular dsDNA genome containing three open reading frames (ORFs I, II, III). Unlike the other BSV species, BSVaV has no overlapping ORFs. According to the ''Badnavirus'' genome structure, BSVaV also potentially encode for a virion associated protein (VAP) (ORF I), for an unknown protein with a molecular weight of 14.4 kDa (ORF II) and for a polyprotein showing motifs related to the movement protein (MOV), RNA binding (COAT-''gag''), aspartate protease (PR), reverse transcriptase (RT) and ribonuclease H (RH) (ORF III). ORF I and ORF II are separated by 92 nt, wheras ORF II and ORF III are divided by only one codon. As observed in the genome of BSMyV, BSVaV-ORF I has also a non-conventional start codon ([[Literature:92815|Lheureux ''et al.'' 2007]]). The ''gag''-like region includes a large region (only observed in Badna- and Tungroviruses), which is rich in zinc finger (CCHC) array duplications similarly to those of several LTR retroelement nucleocapsids ([[Literature:100605|Hull 1996]]; [[Literature:8054|Bouhida ''et al.'' 1993]]; [[Literature:100596|Llorens ''et al''. 2009]]).

The viral "leaf streak disease" was first described in Ivory Coast, Africa in 1968 ([[Literature:100631|Lassoudiere 1974]]), but now is probably distributed worldwide in cultivated banana and plantain crops. The symptoms are correlated with variations in virus concentration and may vary from faint broken chlorotic lines to necrosis of young leaves, internal necrosis of the pseudostem and plant death. The bunch size and fruit quality are also compromised ([[Literature:100630|Lockhart, 1986]]). The virus is transmitted naturally by the two mealybug vectors (''Pseudococcidae'') ''Planococcus citri'' and ''Saccharicoccus sacchari'' (both of which colonize banana), as well as by seed, even if the vegetative propagation is the principal method of virus spread. The ability of ''P. citri'' to act as a vector of BSVaV has been demonstrated ([[Literature:92815|Lheureux ''et al.'' 2007]]).

Unlike the petuvirus ''Petunia vein clearing virus'' (PVCV, [[Literature:63308|Richert-Pöggeler and Shepherd 1997]]), no obvious integrase motif could be identified in the BSV sequence ([[Literature:100632|Harper and Hull 1998]]). However, multiple DNA sequences (Endogenous pararetrovirus, EPRV) related to the virus are found integrated into the nuclear genome of different ''Musa'' cvv. ([[Literature:100635|Harper ''et al.'' 1999]]; [[Literature:100608|Ndowora ''et al.'' 1999]]; [[Literature:100633| Geering ''et al.'' 2005]] [[Literature:89695|Gayral ''et al.'' 2008]]; [[Literature:89696|Gayral and Iskra-Caruana 2009]]). Two types of BSV-EPRV sequences have been described in banana genome. The first type sequences, defined as noninfectious (with nonfunctional viral ORFs and/or incomplete viral genomes), are present in the two most common ''Musa'' species ''Musa acuminata'' (denoted A) and ''Musa balbisiana'' (denoted B) that, together to ''Musa schizocarpa'' (denoted S) are the wild progenitors of the domesticated banana ([[Literature:100633|Geering ''et al.'' 2005]]). The second EPRV sequences, so-called infectious type, contain the complete functional viral genome and have been detected in some ''Musa'' genotypes (i.e AAB and BB groups, [[Literature:100633| Geering ''et al.'' 2005]]; [[Literature:89695|Gayral ''et al.'' 2008]]).
The increasing of BSV outbreaks observed among banana breeding lines and micro-propagated interspecific ''Musa'' hybrids has been mainly linked to the presence of integrated sequences in ''M. balbisiana'' genome (B) that, under stress conditions, could become infectious by reconstituting a complete replication competent viral genome ([[Literature:100634|Dallot ''et al.'' 2001]]; [[Literature:100635|Harper ''et al.'' 1999]]; [[Literature:100608|Ndowora ''et al.'' 1999]]; [[Literature:43478|Lheureux ''et al.'' 2003]]).
The presence of BSVaV-integrated sequences in ''Musa'' genotypes has been studied ([[Literature:92815|Lheureux ''et al.'' 2007]]). No BSVaV-EPRVs have been isolated from any analized M. balbisiana genotypes, whereas partial sequences have been observed in several ''M. acuminata'' and interspecies genotypes indicating that BSVaV-EPRVs are restricted to the genotype A ([[Literature:92815|Lheureux ''et al.'' 2007]]).
|structure=BSVaV.png
|host=Musa sp
|hostpic=Musa_sp.gif
|literature=
|picowner=[http://www.biotechvana.com Image, Carlos Llorens, <br>Copyright, GyDB, Biotech Vana]
}}
[[Category:Element]]

Element:BSVAV - Revision history

imported>Lcovelli at 11:49, 15 March 2010