NEW METHOD FOR DETERMINING HEPATITIS B VIRUS RESISTANCE MUTATIONS M204I/V TO NUCLEOS(T)IDE ANALOGUES IN PATIENTS WITH CHRONIC HEPATITIS B

Аnalogues of nucleos(t)ides (AN) such as lamivudine (LAM), telbivudine (TBV), adefovir (ADP), entecavir (ENT) are widely used for the treatment of chronic hepatitis B (CHB). However, the prolonged treatment using these drugs often leads to the development of drug resistance. The most common substitutions in the reverse transcriptase are methionine for valine (rtM204V), or methionine for isoleucine (rtM204I) at position 204. Early AN-resistant mutations detection is of great importance to determine the treatment strategy of patients with CHB. Currently there are many highly sensitive methods for detection of drug resistance mutations, such as next-generation sequencing, reverse hybridizationbased line probe assay (LiPA), mass spectrometry. However, these methods require expensive equipment and reagents, and they are not widely used in clinical laboratories. The aim of this study was to develop a simple and accurate real-time PCR method for detection of rtM204I/V mutation. This method showed high specificity and sensitivity (1000 copies/ml), it is less laborious and does not require additional equipment, fast and cost effective compared to other methods. HBV mutations of resistance to AN were determined in 5 groups of patients with CHB. Patients of the first group received monotherapy with pegylated interferon (n = 12), the second group — lamivudine (n = 10), the third group — telbivudine (n = 7), the fourth group — entecavir (n = 15). The fifth group consisted of patients who did not receive antiviral therapy (n = 3). The frequency of mutations in HBV polymerase YMDD-motif was determined among 47 patients with CHB: it was 10% for lamivudine treated patients, 20% — for entecavir, 28% — for telbivudine. YIDD/YVDD motifs were identified in two patients and YMDD/YIDD — in one patient. Real-time PCR method for the detection of AN-resistant rtM204I/V mutations in HBV polymerase can be used in routine diagnostics for primary screening of patients not responding to AN treatment. The application of this method can reduce the number of samples for in-depth study of primary and compensatory mutations of resistance to AN by sequencing method. The developed method versus Sanger-sequencing is fast, economical, and provides the detection of minor variants of HBV populations.