Detection of Hepatitis B virus drug resistance mutations pyrosequencing method

The development of drug resistance mutations to nucleos(t)ide analogues during long term therapy of chronic hepatitis B virus (HBV) infection is a major concern leading to treatment failure. The aim of this study is to investigate of HBV drug resistance gene mutations in patients with chronic hepatitis B infection by pyrosequencing method. Between December 2013 and May 2014, serum samples collected from 137 patients of which 89 untreated (naive) and 48 treated patients with chronic hepatitis B infection were analyzed with real-time PCR test followed by pyrosequencing method (PyroStar HBV Drug Resistance Test, Altona Diagnostics, Germany) for drug resistance mutations associated with lamivudin (LAM), adefovir (ADV), telbivudin (TEL), entecavir (ETV) and tenofovir (TDF). Among 89 untreated patients, rtA194T mutation that may reduce susceptibility to TDF was found in 1 (1.1%) case. In 48 treated patients, rtM204I mutation causing drug resistance to LAM, TEL and also cross-resistance to ETV was detected in 1 (2.1%) case. Compensatory mutation rtL180M was observed in 2 (4.2%) patients. The presence of rtM204V combined with rtT184S mutation indicating ETV resistance was detected in 1 (2.1%) patient. In conclusion, the incidence of drug resistance mutations were found as 8.3% in treated and 1.1% in untreated patient group. Early detection of drug resistance mutations by pyrosequencing method before and during treatment of patients with chronic hepatitis B infection would contribute to the selection of appropriate antiviral drug. Key Words: Hepatitis B virus drug resistance, pyrosequencing method, lamivudin, adefovir, telbivudin, entecavir, tenofovir.