title: Prevalence of polymorphisms with significant resistance to NS5A inhibitors in treatment-naive patients with hepatitis C virus genotypes 1a and 3a in Sweden.
abstract: BACKGROUND
  The future treatment of hepatitis C virus (HCV) infection will be combinations of direct-acting antivirals (DAAs) that not only target multiple viral targets, but are also effective against different HCV genotypes. Of the many drug targets in HCV, one promising target is the non-structural 5A protein (NS5A), against which inhibitors, namely daclatasvir, ledipasvir and ombitasvir, have shown potent efficacy. However, since HCV is known to have very high sequence diversity, development of resistance is a problem against but not limited to NS5A inhibitors (i.e. resistance also found against NS3-protease and NS5B non-nucleoside inhibitors), when used in suboptimal combinations. Furthermore, it has been shown that natural resistance against DAAs is present in treatment-naïve patients and such baseline resistance will potentially complicate future treatment strategies.
  
  
  METHODS
  A pan-genotypic population-sequencing method with degenerated primers targeting the NS5A region was developed. We have investigated the prevalence of baseline resistant variants in 127 treatment-naïve patients of HCV genotypes 1a, 1b, 2b and 3a.
  
  
  RESULTS
  The method could successfully sequence more than 95% of genotype 1a, 1b and 3a samples. Interpretation of fold resistance data against the NS5A inhibitors was done with the help of earlier published phenotypic data. Baseline resistance variants associated with high resistance (1000-50,000-fold) was found in three patients: Q30H or Y93N in genotype 1a patients and further Y93H in a genotype 3a patient.
  
  
  CONCLUSIONS
  Using this method, baseline resistance can be examined and the data could have a potential role in selecting the optimal and cost-efficient treatment for the patient.
authors: From the 1 Clinical Virology, Department of Medical Sciences, Uppsala University , Uppsala.
authors: Ida
authors: I
authors: Lindström
authors: Midori
authors: M
authors: Kjellin
authors: Navaneethan
authors: N
authors: Palanisamy
authors: Kåre
authors: K
authors: Bondeson
authors: Lars
authors: L
authors: Wesslén
authors: Anders
authors: A
authors: Lannergard
authors: Johan
authors: J
authors: Lennerstrand
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002219:Carbamates; D024882:Drug Resistance, Viral / Q000235:genetics; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects* / Q000235:genetics*; D006526:Hepatitis C / Q000821:virology*; D019698:Hepatitis C, Chronic / Q000821:virology*; D007093:Imidazoles / Q000627:therapeutic use; D020125:Mutation, Missense; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D015995:Prevalence; D011480:Protease Inhibitors / Q000627:therapeutic use; D011759:Pyrrolidines; D017421:Sequence Analysis; D013548:Sweden / Q000453:epidemiology; D014633:Valine / Q000031:analogs & derivatives; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D002219:Carbamates; D007093:Imidazoles; D011480:Protease Inhibitors; D011759:Pyrrolidines; D014633:Valine; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C549273:daclatasvir
keywords: Hepatitis C virus; NS5A; baseline resistance; polymorphism; prevalence