title: Clonal evolution of multidrug resistant hepatitis B virus during entecavir rescue therapy.
abstract: Analysing the mutation pattern of multidrug resistance (MDR) is important in the treatment of chronic hepatitis B (CHB). In this study, the evolutionary pattern of MDR mutations was investigated in patients receiving entecavir (ETV) rescue therapy.
  
  
  
  Eight CHB patients with lamivudine (LAM)- and adefovir (ADV)-resistant mutations showing suboptimal response to ETV and to subsequent ETV-plus-ADV therapy were enrolled. The clonal evolution of the mutation pattern was investigated through direct sequencing, multiplex restriction fragment mass polymorphism (RFMP), and clonal analysis and the utility of these methods was compared.
  
  
  
  Among 160 clones at baseline, wild-type hepatitis B virus (HBV) was present in 62 (38.8%), LAM-resistant mutations in 92 (57.6%) and ADV-resistant mutations in 55 (34.4%). LAM-resistant mutations increased to 70.6% at the end of ETV therapy and increased to 74.4% at the 12th month of ETV-plus-ADV therapy. During the same time periods, ETV-resistant mutations were present in 46.3% and 38.8%, and ADV-resistant mutations were present in 3.1% and 9.4% respectively. When 256 nucleotides from 32 samples were examined for mutations, clonal analysis detected 93 mutations (36.3%), direct sequencing detected 36 mutations (14.1%) and RFMP detected 73 mutations (28.5%). The sensitivity (73.1%, 95% CI; 64.1-82.1%) and specificity (96.9%, 95% CI; 94.4-99.4%) of RFMP were high, showing a concordance rate of 88.3% with the results from clonal analysis. All mutations exceeding 40% of the total clones detected by clonal analysis were also detected by RFMP.
  
  
  
  The clonal evolution of the mutation pattern in MDR HBV showed the selection of LAM-resistant (±ETV-resistant) HBV during ETV rescue therapy, which may be the primary reason for patients' suboptimal response. Multiplex RFMP is a useful method for detecting MDR mutations in clinical practice.
authors: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea.
authors: Young E
authors: YE
authors: Chon
authors: Brain Korea 21 plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.
authors: Bora
authors: B
authors: Jin
authors: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea.
authors: Sang H
authors: SH
authors: Ahn
authors: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea.
authors: Seungtaek
authors: S
authors: Kim
authors: New Drug Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, Daegu, Korea.
authors: Nam D
authors: ND
authors: Kim
authors: Department of Microbiology and Immunology, Yonsei University College of Medicine, Seoul, Korea.
authors: Jeon H
authors: JH
authors: Park
authors: Department of Biostatistics, Yonsei University College of Medicine, Seoul, Korea.
authors: Chung M
authors: CM
authors: Nam
authors: Department of Pharmacology and Center for Cancer Research and Diagnostic Medicine, IBST, School of Medicine, Konkuk University, Seoul, Korea.
authors: Kyun-Hwan
authors: KH
authors: Kim
authors: Research and Development Center, GeneMatrix Inc., Seongnam, Korea.
authors: Sun P
authors: SP
authors: Hong
authors: Brain Korea 21 plus Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.
authors: Sung H
authors: SH
authors: Choi
authors: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea.
authors: Do Y
authors: DY
authors: Kim
authors: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea.
authors: Jun Y
authors: JY
authors: Park
authors: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.|Liver Cirrhosis Clinical Research Center, Yonsei University Health System, Seoul, Korea.
authors: Kwang-Hyub
authors: KH
authors: Han
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000627:therapeutic use; D000328:Adult; D000998:Antiviral Agents / Q000627:therapeutic use*; D060965:Clonal Evolution / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics*; D004359:Drug Therapy, Combination; D005838:Genotype; D006147:Guanine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000188:drug therapy*; D006801:Humans; D019259:Lamivudine / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009154:Mutation; D063065:Organophosphonates / Q000627:therapeutic use; D019562:Viral Load
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D063065:Organophosphonates; D019259:Lamivudine; C413685:entecavir; D006147:Guanine; C053001:adefovir; D000225:Adenine
keywords: chronic hepatitis B; clonal analysis; colocation; drug resistance; entecavir; hepatitis B virus; multidrug resistance