The hepatitis C virus NS5A protein and response to interferon alpha: mutational analyses in patients with chronic HCV genotype 3a infection from India

Med Microbiol Immunol. 2007 Mar;196(1):11-21. doi: 10.1007/s00430-006-0024-z. Epub 2006 Sep 6.

Abstract

The hepatitis C virus (HCV) non-structural (NS)5A protein is linked to interferon alpha resistance in vitro and higher numbers of NS5A amino acid (aa) variations in HCV 1a/b isolates are associated with virologic response to interferon alpha-based therapy in vivo. Here, we aimed to study NS5A aa variations in Indian patients undergoing interferon alpha/ribavirin treatment infected with HCV 3a. The NS5A region [aa 2194-2401, comprising interferon sensitivity determining region, protein kinase resource (PKR) binding domain, V3 region] was sequenced from pre-treatment sera of 24 patients with HCV 3a infection. Mean number and physicochemical properties of aa variations (conserved vs. non-conserved) were assessed. Additionally, published NS5A sequences [NS5A region (n = 61), PKR binding domain (n = 111)] of characterized HCV 3a isolates were analyzed. The mean number of NS5A aa variations was not correlated with treatment response in our cohort. When all available NS5A sequences were included, a higher number of non-conserved aa variations within PKR binding domain and an extended V3 region of NS5A was associated with virologic response (P = 0.004 and 0.05, respectively). Mutational analyses of a large number of NS5A sequences suggest, that a higher number of non-conserved aa variations within the PKR binding domain and the extended V3 region is correlated with virologic response in HCV 3a infected patients.

MeSH terms

  • Adult
  • Amino Acid Sequence
  • Antiviral Agents / therapeutic use*
  • Cohort Studies
  • Drug Resistance, Viral / genetics
  • Female
  • Hepacivirus / drug effects
  • Hepacivirus / genetics*
  • Hepacivirus / metabolism
  • Hepatitis C Antigens / metabolism
  • Hepatitis C, Chronic / drug therapy*
  • Hepatitis C, Chronic / virology*
  • Humans
  • India
  • Interferon-alpha / therapeutic use*
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Mutation
  • Protein Structure, Secondary
  • Ribavirin / therapeutic use
  • Sequence Alignment
  • Viral Nonstructural Proteins / genetics*
  • Viral Nonstructural Proteins / metabolism

Substances

  • Antiviral Agents
  • Hepatitis C Antigens
  • Interferon-alpha
  • Viral Nonstructural Proteins
  • Ribavirin
  • NS-5 protein, hepatitis C virus