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Journal of Hepatology, 2019. 70(6), 1093-1102, DOI: https://doi.org/10.1016/j.jhep.2019.02.006
Identification of a quadruple mutation that confers tenofovir resistance in chronic hepatitis B patients
Eun-Sook Park, Ah Ram Lee; Doo Hyun Kim; Jeong-Hoon Lee; Jeong-Ju Yoo; Sung Hyun Ahn; Heewoo Sim; Soree Park; Hong Seok Kang; Juhee Won; Yea Na Ha; Gu-Choul Shin; So Young Kwon; Yong Kwang Park; Byeong-Sun Choi; Yun Bin Lee; Nakcheol Jeong; Yohan An; Young Seok Ju; Su Jong Yu; Hee Bok Chae; Kyung-Sang Yu; Yoon Jun Kim; Jung-Hwan Yoon; Fabien Zoulim; Kyun-Hwan Kim
• Among oral antivirals for HBV infection, only tenofovir has revealed no genotypically resistant HBV.
• However, there are patients with incomplete viral response during tenofovir-containing treatment.
• We consistently identified 7 common mutations including rtS106C (C), rtH126Y (Y), rtD134E (E), and rtL269I (I).
• The mutations C, Y, and E were novel mutations associated with drug resistance.
• The quadruple CYEI mutation increases the amount of tenofovir required to inhibit HBV by 15.3-fold in IC50 and 26.3-fold in IC90.
• All tenofovir-resistant mutants with/without entecavir resistance were susceptible to a novel capsid assembly modulator.
Background & Aims
Tenofovir disoproxil fumarate (TDF) is one the most potent nucleot(s)ide analogues for treating chronic hepatitis B virus (HBV) infection. Phenotypic resistance caused by genotypic resistance to TDF has not been reported. This study aimed to characterize HBV mutations that confer tenofovir resistance.
Two patients with viral breakthrough during treatment with TDF-containing regimens were prospectively enrolled. The gene encoding HBV reverse tranase was sequenced. Eleven HBV clones harboring a series of mutations in the reverse tranase gene were constructed by site-directed mutagenesis. Drug susceptibility of each clone was determined by Southern blot analysis and real-time PCR. The relative frequency of mutants was evaluated by ultra-deep sequencing and clonal analysis.
Five mutations (rtS106C [C], rtH126Y [Y], rtD134E [E], rtM204I/V, and rtL269I [I]) were commonly found in viral isolates from 2 patients. The novel mutations C, Y, and E were associated with drug resistance. In assays for drug susceptibility, the IC50 value for wild-type HBV was 3.8 ± 0.6 µM, whereas the IC50 values for CYE and CYEI mutants were 14.1 ± 1.8 and 58.1 ± 0.9 µM, respectively. The IC90 value for wild-type HBV was 30 ± 0.5 µM, whereas the IC90 values for CYE and CYEI mutants were 185 ± 0.5 and 790 ± 0.2 µM, respectively. Both tenofovir-resistant mutants and wild-type HBV had similar susceptibility to the capsid assembly modulator NVR 3–778 (IC50 <0.4 µM vs. IC50 = 0.4 µM, respectively).
Our study reveals that the quadruple (CYEI) mutation increases the amount of tenofovir required to inhibit HBV by 15.3-fold in IC50 and 26.3-fold in IC90. These results demonstrate that tenofovir-resistant HBV mutants can emerge, although the genetic barrier is high.
Tenofovir is the most potent nucleotide analogue for the treatment of chronic hepatitis B virus infection and there has been no hepatitis B virus mutation that confers >10-fold resistance to tenofovir up to 8 years. Herein, we identified, for the first time, a quadruple mutation that conferred 15.3-fold (IC50) and 26.3-fold (IC90) resistance to tenofovir in 2 patients who experienced viral breakthrough during tenofovir treatment.
- DOI: https://doi.org/10.1016/j.jhep.2019.02.006
- ISBN or ISSN: 0168-8278
- 본 연구는 질병관리본부 연구개발과제연구비를 지원받아 수행되었습니다.
- This research was supported by a fund by Research of Korea Centers for Disease Control and Prevention.