HCV RNA Genome
The HCV RNA (genome) consists of a single-stranded, positive-sense RNA approximately 9,600 nucleotide bases in length. The HCV genome contains a single, long, open reading frame (3,006-3037 codons) flanked by 5' and 3' untranslated regions (UTRs). The HCV RNA genome is used both for translation and transcription. The 5' region, which is upstream from the open reading frame, is approximately 340 nucleotides long and contains 4 highly structured domains: domain I consists of a short stem loop and domains II-IV form the internal ribosomal entry site (IRES). The IRES is a highly structured regulatory element that mediates binding of the HCV RNA to the host ribosomal subunits (and cellular factors), which is essential in the translation of the open reading frame. The 3' region is approximately 225 nucleotides long and it consists of three components: variable, a long poly (U/UC) tract, and 3'X region. The 3'X region serves as a key factor in switching between translation and RNA transcription of the HCV RNA.