Cauliflower mosaic virus 551284 225855145 2008-07-15T18:39:06Z BOT-Superzerocool 338065 robot Modifying: [[es:Cauliflower mosaic virus]] {{Taxobox | virus_group = vii | familia = ''[[Caulimoviridae]]'' | genus = ''[[Caulimovirus]]'' | species = '''''Cauliflower mosaic virus''''' }} '''''Cauliflower mosaic virus''''' ('''CaMV''') is the type member of the [[caulimovirus]]es, one of the six genera in the [[Caulimoviridae]] family, [[pararetrovirus]]es that infect [[plant]]s (Pringle, 1999). Pararetroviruses replicate through [[reverse transcription]] just like [[retrovirus]]es, but the viral particles contain [[DNA]] instead of [[RNA]] (Rothnie et al., 1994). == Structure == The CaMV particle is an [[icosahedron]] with a diameter of 52 nm built from 420 capsid protein (CP) subunits arranged with a triangulation T = 7, which surrounds a solvent-filled central cavity (Cheng et al., 1992). It contains a circular double-stranded DNA molecule of about 8.0 kB, interrupted by sitespecific discontinuities resulting from its replication by reverse transcription. After [[Viral_entry|entering]] the host, the single stranded nicks in the viral DNA are repaired, forming a supercoiled molecule that binds to histones. This DNA is translated into a full length, terminally redundant 35S RNA and a subgenomic 19S RNA. == Genome == The [[promoter]] of the 35S RNA is very strong, and well known for its use in [[Plant improvement|plant transformation]]. The 35S RNA is particularly complex, containing a highly structured 600 nucleotide long leader sequence with six to eight short open reading frames (ORFs) (Fütterer et al., 1988; Pooggin et al., 1998). This leader is followed by seven tightly arranged longer ORFs that encode all the viral proteins (reviewed by Hohn and Fütterer, 1997). The mechanism of expression of these proteins is very special. The ORF VI protein (encoded by the 19S RNA) controls translation reinitiation of major open reading frames on the polycistronic 35S RNA, which leads to [[viral shedding]]. TAV function depends on its association with polysomes and [[eukaryotic]] initiation factor eIF3 (Park et al., 2001). [[Image:CauliflowerMosaicRNA35S.png|thumb|right|200px|Genomic map of CaMV]] ORF I Movement protein ORF II Insect transmission factor ORF III ORF IV Capsid protein ORF V Protease, reverse transcriptase and RNaseH ORF VI Translational activator / Inclusion body protein ORF VII Unknown (dispensable) ==Replication== CaMV replicates by reverse transcription. Initially all the gaps present in the genome gets sealed. The covalently closed DNA associates with host histones to form a super coiled mini chromosome. Transcription of the former produces 35s RNA which translates protein as well as forms dsDNA by the process of reverse transcription. New viral particles are produced which gets targeted to inclusion body & is released outside. ==Process of Infection== CaMV produces a helper component ( product of coding region II & III) which attracts aphids thus leading to its transmission. ==External links== * [http://www.biotecnika.googlepages.com/camv.html Cauliflower Mosaic Virus] [[Category:Viruses]] [[Category:Plant pathogens and diseases]] [[Category:Crucifer diseases]] [[es:Cauliflower mosaic virus]]