Diversity of 1,213 hepatitis C virus NS3 protease sequences from a clinical virology laboratory database in Marseille university hospitals, southeastern France.

Infection with hepatitis C virus (HCV) represents a major public health concern worldwide. Recent therapeutic advances have been considerable, HCV genotype continuing to guide therapeutic management. Since 2008, HCV genotyping in our clinical microbiology laboratory at university hospitals of Marseille, Southeastern France, has been based on NS3 protease gene population sequencing, to allow concurrent HCV genotype and protease inhibitor (PI) genotypic resistance determinations. We aimed, first, to analyze the genetic diversity of HCV NS3 protease obtained from blood samples collected between 2003 and 2013 from patients monitored at university hospitals of Marseille and detect possible atypical sequences; and, second, to identify NS3 protease amino acid patterns associated with decreased susceptibility to HCV PIs. A total of 1,213 HCV NS3 protease sequences were available in our laboratory sequence database. We implemented a strategy based on bioinformatic tools to determine whether HCV sequences are representative of our local HCV genetic diversity, or divergent. In our 2003-2012 HCV NS3 protease sequence database, we delineated 32 clusters representative of the majority HCV genetic diversity, and 61 divergent sequences. Five of these divergent sequences showed less than 85% nucleotide identity with their top GenBank hit. In addition, among the 294 sequences obtained in 2013, three were divergent relative to these 32 previously delineated clusters. Finally, we detected both natural and on-treatment genotypic resistance to HCV NS3 PIs, including a substantial prevalence of Q80K substitutions associated with decreased susceptibility to simeprevir, a second generation PI.