Investigation of stop codons (TGA) recurrent in the Hepatitis C Virus NS5A region

Abstract

The hepatitis C virus (HCV) is a single-strand positive RNA virus member of the Flaviviridae family. The infection leads to liver inflammation in general, asymptomatic, but when the infection becomes chronicle, it may cause problems like liver cirrhosis, fibrosis, and hepatocellular carcinoma. It is believed that about 150 million people in the world suffer from this disease. The treatment is based on interferon and ribavirin, but in serious cases, a liver transplant is needed. Due to the RNA genome, HCV has a high mutational rate, which classifies this virus in seven genotypes and different subtypes. Among its proteins, the NS5A shows to be important to act in the resistance of the virus to interferon as well as in the apoptotic processes of damaged cells, with a possible hole in the hepatocellular carcinogenesis. Recent studies found mutations that give rise to stop codons in the NS5A protein region recurrent in different patients. The presence of these stop codons would lead to early termination of the polyprotein translation preventing the translation of complete NS5A and as a consequence the following protein, the viral RNA dependent RNA polymerase NS5B. The TGA codon frequently leads to the stop of translation, however, in some cases, it may codify for a specific amino acid, the selenocysteine. The aim of this study is to evaluate in cell culture the impact of the presence of the TGA codon in the position 111 (originally TGG) of the NS5A protein in the translation of this protein.(AU)