title: Evolution of hepatitis C virus NS5A region in breakthrough patients during pegylated interferon and ribavirin therapy*.
abstract: Investigating the evolution of the hepatitis C viral (HCV) genome in the small number of patients that experience viral breakthrough might shed light on the problem of resistance to interferon therapy. Within the HCV genome, sequence diversity of the viral nonstructural 5A protein-coding region (NS5A) has been linked to interferon responsiveness. We analysed the temporal sequence changes within NS5A in genotype 1a patients: 6 breakthrough (BT), 12 sustained virologic responders (SVR) and 12 non-responders (NR), all of whom had received full dose peg-interferon and ribavirin therapy. The entire NS5A region was amplified by reverse transcription (RT)-PCR followed by direct sequencing of serum samples from baseline and three on-treatment time points for each group. Comparing baseline sequences with week 12 and later time points, BT patients resembled SVR patients in having a higher number of amino acid substitutions at week 12 than NR patients; however, the number of amino acid substitutions in this group decreased at and after BT. Substitutions were focused in the V3 and flanking regions in BT patients but not in SVR patients. The high number of substitutions in NS5A in both BT and SVR groups suggests that selective pressure is associated with viral response to therapy. Our results provide evidence that amino acid substitutions within the NS5A coding region may reflect a host response that drives selective pressure for viral adaptation.
authors: Divisions of Digestive and Liver Diseases and Infectious Diseases, UT Southwestern Medical Center at Dallas, Dallas, TX, USA.
authors: H J
authors: HJ
authors: Yuan
authors: M
authors: M
authors: Jain
authors: K K
authors: KK
authors: Snow
authors: M
authors: M
authors: Gale
authors: W M
authors: WM
authors: Lee
mesh_terms: D000328:Adult; D019943:Amino Acid Substitution / Q000235:genetics; D000998:Antiviral Agents / Q000627:therapeutic use*; D016000:Cluster Analysis; D024882:Drug Resistance, Viral; D019143:Evolution, Molecular; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics; D006526:Hepatitis C / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000627:therapeutic use*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D011092:Polyethylene Glycols / Q000627:therapeutic use*; D012367:RNA, Viral / Q000097:blood / Q000235:genetics; D011994:Recombinant Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012254:Ribavirin / Q000627:therapeutic use*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011092:Polyethylene Glycols; D012367:RNA, Viral; D011994:Recombinant Proteins; D012254:Ribavirin; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C100416:peginterferon alfa-2a