This family represents the internal ribosome entry site (IRES) of the pestiviruses. The pestivirus IRES allows cap and end-independent translation of mRNA in the host cell. The IRES achieves this by mediating the internal initiation of translation by recruiting a ribosomal 43S pre-initiation complex directly to the initiation codon and eliminates the requirement for the eukaryotic initiation factor, eIF4F.^[1] The classical swine fever virus UTR described appears to be longer at the 5' end than other pestivirus UTRs.^[1] This family represents the conserved core.