Mosaic genomes of RNA viruses. A diagram of the genome architectures for a subset of double-strand RNA (dsRNA), positive-strand RNA ((+)RNA)) and a single-strand DNA (ssDNA) virus discussed in the text. The linear genomes of RNA viruses are shown approximately to scale; the circular ssDNA genome is on a different scale. Black lines correspond to noncoding regions, whereas rectangles designate open reading frames (ORFs), with known protein domains color-coded (RdRp, RNA-dependent RNA polymerase; S7, an RNA-binding domain; Met, methyltransferase/capping enzyme; S1H and S2H, superfamily 1 and 2 helicases, respectively; mCp, minor core protein; MOC, major outer capsid protein; CP, capsid protein; MP, movement protein; p19, suppressor of antiviral RNA interference response; RCRE, rolling-circle replication endonuclease). Proteins encoded in different coding frames are shown with an offset. For the Phytoreovirus, only the three segments relevant for the discussion are shown. Icons on the right show the virus hosts. Virus names are as follows: SsNs-L, Sclerotinia sclerotiorum nonsegmented virus L; GABrV-XL1, Gremmeniella abietina type B RNA virus XL1; PcV, Penicillium chrysogenum v irus; RDV, Rice dwarf virus; TBSV, Tomato bushy dwarf virus; OMV, Ourmia melon virus; RDHV, RNA-DNA hybrid virus.