Genome organization of viruses from the genera flavivirus, pestivirus, and hepacivirus within the family Flaviviridae. The length of the viral RNA genomes are illustrated on top of each panel, and homologous regions between the genomes are indicated. Only the RNA of flaviviruses is capped at the 5′-end. The processing of the polyprotein into the individual structural and nonstructural proteins is indicated below. All the core proteins and the NS4A of flaviviruses are further processed at their C-terms (white boxes). For cytopathic pestiviruses, enhanced expression of NS3 is observed, whereas the uncleaved form, NS2-3, predominates in non-cytopathic pestiviruses. ns, non-structural; UTR, untranslated region. (A color version of this figure is available at www.vetres.org.)