title: Naturally occurring mutations associated with resistance to HCV NS5B polymerase and NS3 protease inhibitors in treatment-naïve patients with chronic hepatitis C.
abstract: BACKGROUND
  The detection of baseline resistance mutations to new direct-acting antivirals (DAAs) in HCV chronically infected treatment-naïve patients could be important for their management and outcome prevision. In this study, we investigated the presence of mutations, which have been previously reported to be associated with resistance to DAAs in HCV polymerase (NS5B) and HCV protease (NS3) regions, in sera of treatment-naïve patients.
  
  
  RESULTS
  HCV RNA from 152 naïve patients (84 % Italian and 16 % immigrants from various countries) infected with different HCV genotypes (21,1a; 21, 1b; 2, 2a; 60, 2c; 22, 3a; 25, 4d and 1, 4k) was evaluated for sequence analysis. Amplification and sequencing of fragments in the NS5B (nt 8256-8640) and NS3 (nt 3420-3960) regions of HCV genome were carried out for 152 and 28 patients, respectively. The polymorphism C316N/H in NS5B region, associated with resistance to sofosbuvir, was detected in 9 of the 21 (43 %) analysed sequences from genotype 1b-infected patients. Naturally occurring mutations V36L, and M175L in the NS3 protease region were observed in 100 % of patients infected with subtype 2c and 4.
  
  
  CONCLUSIONS
  A relevant proportion of treatment naïve genotype 1b infected patients evaluated in this study harboured N316 polymorphism and might poorly respond to sofosbuvir treatment. As sofosbuvir has been approved for treatment of HCV chronic infection in USA and Europe including Italy, pre-treatment testing for N316 polymorphism on genotype 1b naïve patients should be considered for this drug.
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Viral Hepatitis Unit, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161, Rome, Italy. angela.costantino@iss.it.
authors.forename: Angela
authors.initials: A
authors.lastname: Costantino
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Viral Hepatitis Unit, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161, Rome, Italy. enea.spada@iss.it.
authors.forename: Enea
authors.initials: E
authors.lastname: Spada
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy. michele.equestre@iss.it.
authors.forename: Michele
authors.initials: M
authors.lastname: Equestre
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Viral Hepatitis Unit, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161, Rome, Italy. roberto.bruni@iss.it.
authors.forename: Roberto
authors.initials: R
authors.lastname: Bruni
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Viral Hepatitis Unit, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161, Rome, Italy. elena.tritarelli@iss.it.
authors.forename: Elena
authors.initials: E
authors.lastname: Tritarelli
authors.affiliation: Department of Mental Health and Public Medicine, Section of Infectious diseases, Second University of Naples, Naples, Italy. nicola.coppola@unina2.it.
authors.forename: Nicola
authors.initials: N
authors.lastname: Coppola
authors.affiliation: Department of Experimental Medicine and Surgery F. Magrassi and A. Lanzara, Second University of Naples, Naples, Italy. sagnelli.caterina@libero.it.
authors.forename: Caterina
authors.initials: C
authors.lastname: Sagnelli
authors.affiliation: Department of Mental Health and Public Medicine, Section of Infectious diseases, Second University of Naples, Naples, Italy. Evangelista.SAGNELLI@unina2.it.
authors.forename: Evangelista
authors.initials: E
authors.lastname: Sagnelli
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Viral Hepatitis Unit, Istituto Superiore di Sanità, Viale Regina Elena, 299-00161, Rome, Italy. annarita.ciccaglione@iss.it.
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Ciccaglione
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D054242:Emigrants and Immigrants; D016174:Hepacivirus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D019698:Hepatitis C, Chronic / Q000453:epidemiology / Q000821:virology; D006801:Humans; D007558:Italy; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense; D011110:Polymorphism, Genetic; D011480:Protease Inhibitors / Q000494:pharmacology*; D012367:RNA, Viral / Q000097:blood / Q000235:genetics / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D000069474:Sofosbuvir / Q000494:pharmacology; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D055815:Young Adult; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D011480:Protease Inhibitors; D012367:RNA, Viral; D000069474:Sofosbuvir; D017361:Viral Nonstructural Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase