SCREENING OF PROTEASE INHIBITORS RESISTANCE MUTATIONS IN HEPATITIS C VIRUS ISOLATES INFECTING ROMANIAN PATIENTS UNEXPOSED TO TRIPLE THERAPY

Abstract

Although the European recommendations include the use of new antiviral drugs for the treatment of hepatitis C, in Romania the current treatment remains interferon plus ribavirin. First generation viral protease inhibitors (i.e. boceprevir, telaprevir), which have raised the chances of obtaining viral clearance in up to 70% of infection cases produced by genotype 1 isolates, have not been introduced yet as standard treatment in our country. The success of these new antivirals is limited by the occurrence and selection of resistance mutations during therapy. We set-up a molecular study aiming to detect any resistance mutations to boceprevir and telaprevir harbored by hepatitis C isolates infecting Romanian patients naïve to viral protease inhibitors. Since these new antivirals are efficient and approved for genotype 1 infection, viral samples were genotyped following a protocol previously developed by our research group. We analyzed by both population sequencing and molecular cloning and sequencing the NS3 protease region of hepatitis C virus isolates infecting patients which were not previously exposed to boceprevir and telaprevir. All the analyzed samples were subtype 1b and resembled the samples collected in recent years from Romanian patients. Molecular cloning followed by sequencing showed great intra-host diversity, which is known to represent the source of isolates with different resistance phenotypes. Both population sequencing and molecular cloning followed by clone sequencing revealed two boceprevir resistance mutations (T54S and V55A), respectively, a telaprevir resistance mutation (T54S) in the sequences obtained from a patient with chronic hepatitis C. To our knowledge, this is the first study indicating the existence of pre-treatment resistance mutations to boceprevir and telaprevir in hepatitis C virus isolates infecting Romanian patients.