Distribution of hepatitis С virus drug resistance mutations among patients with recurrence of the disease during therapy with direct antiviral drugs

The aim of the study was to identify the prevalence of drug resistance mutations in the hepatitis C virus among patients with relapse of the disease on therapy with direct antiviral drugs.Materials and methods. The study material included 31 blood plasma samples from patients with chronic hepatitis C with relapse of the disease on therapy with direct antiviral drugs. Samples were screened for the presence of HCV RNA. In case of detection of HCV RNA, amplification was carried out using a set of primers jointly flanking the NS3, NS5A, NS5B genes. After sequencing the nucleotide sequences of these genes, the subtype of the virus was determined and drug resistance mutations were identified.Results and discussion. The age of the patients ranged from 33 to 62 and averaged 45.8±8.38 years. The number of men in the group prevailed compared to women — 21 (67%) and 10 (33%), respectively. Viral load determination results ranged from 3.1×103 to 4.2×107 IU/ml. The distribution of genotypes was as follows: 1a — 26% (n=8), 1b — 29% (n=9), 3a — 45% (n=14). The nucleotide sequence of the NS3, NS5A, NS5B regions was determined in all samples. Mutations associated with drug resistance were detected in 87% (n=27). In all identified cases, the mutations resulted in viral resistance to at least one drug included in the patient’s current treatment regimen. In one patient, amino acid substitutions were found in three regions at once, which led to the emergence of resistance to two drugs in the regimen.Conclusion. Conducting a preliminary examination of patients to identify mutations of drug resistance to direct antiviral drugs can affect the effectiveness of the planned treatment and the choice of the optimal regimen.