Sobemovirus
Sobemovirus is a genus of non-enveloped, positive-strand RNA viruses which infect plants.. Plants serve as natural hosts. There are 21 species in this genus. Diseases associated with this genus include: mosaics and mottles. Structure Viruses in Sobemovirus are non-enveloped, with icosahedral geometries, and T=3 symmetry. The diameter is around 30 nm. Genome The genome is a single piece of linear, positive-sense, single-stranded RNA, 4,100–5,700 nucleotides in length. The genome encodes five open reading frames: ORF1, ORFs 2a and 2b, ORF3 and ORFx. ORF1 encodes P1 which plays a role in suppression of silencing and virus movement. ORFs 2a and 2b encode the replicational polyproteins P2a and P2ab. Translation of ORF2a from the genomic RNA is dependent on a leaky scanning mechanism. ORF3 encodes the coat protein. ORFx is conserved in all sobemoviruses. It overlaps the 5' end of ORF2a in the +2 reading frame and also extends some distance upstream of ORF2a. It lacks an AUG initiation codon and its expression is predicted to depend on low level initiation at near-cognate non-AUG codons, such as CUG, by a proportion of the ribosomes that are scanning the region between the ORF1 and ORF2a initiation codons. Its function is unknown but it