English: Dicistroviridae. Genome structure of cricket paralysis virus. The RNA genome contains two non-overlapping ORFs separated by an intergenic region (IGR). The 5′-proximal ORF encodes the nonstructural proteins: RNA helicase (Hel), cysteine protease (Pro), and RNA-dependent RNA polymerase (RdRP). The structural proteins are encoded by the 3′-proximal ORF and are expressed as a polyprotein that is subsequently processed to yield three major structural proteins (VP1, VP2 and VP3). A fourth structural protein, VP4, is the N-terminal extension of VP3, which is cleaved from the precursor VP0. This small peptide is considered to be involved in membrane alterations required for genome transfer to the cytoplasm of host cells during infection. Indeed, recent independent studies have shown that recombinant VP4 from both cricket paralysis virus and triatoma virus forms pores in model membranes (Sanchez-Eugenia et al., 2015, Kerr et al., 2015). Distinct internal ribosome entry sites (IRES) are located in the 5′-UTR and IGR. The genome has a small peptide covalently linked to the 5′-end (genome-linked virus protein, VPg) and a 3′-polyadenylated terminus.