title: NS5A inhibitor resistance-associated polymorphisms in Brazilian treatment-naive patients infected with genotype 1 hepatitis C virus.
abstract: OBJECTIVE
  Several promising NS5A protein inhibitors for hepatitis C virus (HCV) treatment, showing good antiviral activity, are currently being evaluated in clinical trials. However, viral breakthroughs associated with resistant variants have been observed, especially in patients infected with HCV-1a. We aimed to evaluate the occurrence of potential resistance mutations in the NS5A gene of HCV among Brazilian treatment-naive patients.
  
  
  METHODS
  Direct sequencing of the HCV NS5A gene was performed in serum samples of 106 treatment-naive patients infected with subtypes 1a (n = 52) and 1b (n = 54). The sequence variability, signature patterns in amino acid sequences and variants associated with NS5A inhibitors were evaluated.
  
  
  RESULTS
  The M28T and Y93H mutations were found in the subtype 1a sequences of two (3.85%) patients, and seven (13.46%) other patients presented the secondary mutation(s) H58P, E62D or H58P-E62D. For subtype 1b, the Y93H mutation was found in two (3.70%) patients and the substitutions R30Q, L31M, P58S and I280V were found in eight (14.81%) patients. Two distinct HCV-1a clades were distinguished by a phylogenetic analysis performed along with representative HCV-1a sequences and sequences containing HCV NS5A inhibitor resistance mutations retrieved from the Los Alamos database. All Brazilian sequences formed a large group of related sequences inside clade 1. It is noteworthy that 65.85% of sequences with substitution at sites 28, 30, 31 and 93 were found in clade 1.
  
  
  CONCLUSIONS
  Brazilian HCV-1a sequences presented a peculiar pattern of amino acid composition, mutations and frequencies, which is distinct from other previously characterized sequences from other locations. The association of these findings with the outcome of treatment with NS5A inhibitors awaits further analysis.
authors.affiliation: Laboratório de Hepatites Virais, Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ, Brazil.
authors.forename: Allan
authors.initials: A
authors.lastname: Peres-da-Silva
authors.affiliation: Laboratório de Hepatites Virais, Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ, Brazil Hospital Universitário Gaffrée e Guinle/UNIRIO, Rio de Janeiro, RJ, Brazil.
authors.forename: Adilson José
authors.initials: AJ
authors.lastname: de Almeida
authors.affiliation: Laboratório de Hepatites Virais, Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ, Brazil elampe@ioc.fiocruz.br.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Lampe
mesh_terms: D000998:Antiviral Agents / Q000627:therapeutic use; D001938:Brazil; D002986:Clinical Trials as Topic; D016000:Cluster Analysis; D024882:Drug Resistance, Viral; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D019698:Hepatitis C, Chronic / Q000188:drug therapy / Q000821:virology*; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D044967:Serum / Q000821:virology; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase
keywords: DAAs; HCV; NS5A gene