Search

Background/Aims Molecular diagnostic methods have enabled the rapid diagnosis of drug-resistant mutations in hepatitis B virus (HBV) and have reduced both unnecessary therapeutic interventions and medical costs. In this study we evaluated the analytical and clinical performances of the HepB Typer-Entecavir kit (GeneMatrix, Korea) in detecting entecavir-resistance-associated mutations. Methods The HepB Typer-Entecavir kit was evaluated for its limit of detection, interference, cross-reactivity, and precision using HBV reference standards made by diluting high-titer viral stocks in HBV-negative human serum. The performance of the HepB Typer-Entecavir kit for detecting mutations related to entecavir resistance was compared with direct sequencing for 396 clinical samples from 108 patients. Results Using the reference standards, the detection limit of the HepB Typer-Entecavir kit was found to be as low as 500 copies/mL. No cross-reactivity was observed, and elevated levels of various interfering substances did not adversely affect its analytical performance. The precision test conducted by repetitive analysis of 2,400 replicates with reference standards at various concentrations showed 99.9% agreement (2398/2400). The overall concordance rate between the HepB Typer-Entecavir kit and direct sequencing assays in 396 clinical samples was 99.5%. Conclusions The HepB Typer-Entecavir kit showed high reliability and precision, and comparable sensitivity and specificity for detecting mutant virus populations in reference and clinical samples in comparison with direct sequencing. Therefore, this assay would be clinically useful in the diagnosis of entecavir-resistance-associated mutations in chronic hepatitis B. more...

Whether multidrug-resistant (MDR) hepatitis B virus (HBV) harbors mutations co-located in the same HBV clones that confer reduced sensitivity to antiviral therapy remains uncertain. This study investigated the evolution of MDR HBV strains developed from sequential monotherapy with lamivudine (LAM), adefovir (ADV), and entecavir (ETV) during LAM plus ADV salvage therapy. Sera were obtained from six patients who had developed sequential resistance to LAM, ADV, and ETV before and during LAM plus ADV therapy. The HBV genomes from each patient were amplified, cloned, and sequenced. Among 6 sets of 20 clones obtained before salvage therapy, all clones harbored the rtM204V mutation, and ETV-resistant mutations were detected with the rtM204V in 108 clones. The rtA181 mutation was not detected at baseline, but emerged in five patients during therapy. Among 9 sets of 20 clones obtained during salvage therapy, 39 clones harbored rtA181T/V ± rtN236T mutations, which were detected in the absence of rtM204 and ETV-resistant mutations in 37 clones (94.9%). Only two clones (5.1%) harbored both rtA181T/V and ETV-resistant mutations. The rtA181T/V mutation emerged after reversion from ETV-resistant mutants to wild-type HBV. Five patients achieved a partial virologic response to LAM plus ADV therapy. In conclusion, the majority of MDR mutations existed in different genomes. Suboptimal response to LAM plus ADV therapy may not result from the co-localization of MDR HBV mutations in the same genome, but instead the low antiviral potency of these drugs. Thus, more potent antiviral drug combinations may be an effective salvage therapy for patients infected with MDR HBV. more...

This study explored the combined effect of number and pattern of mutations in the X/precore regions of the hepatitis B virus (HBV) genome, mutational complex genotype (MCG), on hepatocellular carcinoma (HCC) development. Sequence variations were determined by direct sequencing and multiplex restriction fragment mass polymorphism analysis in 150 age-, sex- and hepatitis B e antigen (HBeAg) status-matched patients with and without HCC. In addition, a longitudinal study and an external validation of MCG were conducted. All were HBV subgenotype C2. Eight high-frequency mutations (G1613A, C1653T, T1753V, A1762T, G1764A, A1846T, G1896A and G1899A) were significantly associated with HCC. Whereas C1653T, T1753V, G1764A and A1846T were independent mutational factors for HCC, the significance of these individual mutations was negligible when analyzed with all clinico-virological variables. The total number of mutations was the only independent viral factor for HCC, irrespective of HBeAg status. There was a significant dose–risk relationship between the number of mutations and HCC, in which high risks for HCC were associated with mutation numbers ≥6. Pattern analysis of the mutations revealed disparity in distribution among the top seven high-risk mutation combination patterns, which accounted for 40 and 2.7% of HCC and non-HCC cases, respectively. The predictive accuracy of the high-risk mutations for HCC was similar to that of α-fetoprotein. Longitudinal and external validation studies also supported the association of mutation number with HCC development. MCG in the HBV X/precore regions is a risk indicator for HCC, and might serve as a new guide to the HCC screening scheme for chronic HBV carriers. (Cancer Sci 2012; 103: 296–304) more...

Background Drug resistance is a major limitation to the long-term efficacy of controlling chronic hepatitis B (CHB). There is a growing need to analyse multiple mutations associated with drug resistance because sequential or combinational use of antivirals is increasingly being used in treatment. In this study, we introduced a multiplex restriction fragment mass polymorphism (RFMP) assay for detecting mutations conferring entecavir and lamivudine resistance, and compared its performance with direct or clonal sequencing assays. Methods Multiplex PCR was performed with mixed primers designed to interrogate rt184, rt202, rt204 and rt250. The PCR products were digested with restriction enzymes and the resulting fragments were analysed by mass spectrometry. A total of 251 serum samples, taken serially from 45 patients who received entecavir treatment after confirmed diagnosis of lamivudine resistance and inadequate adefovir dipivoxil response, were analysed by the multiplex RFMP assay. Results The multiplex RFMP assay correctly identified known viral sequences with sufficient analytical sensitivity to detect as few as 100 IU/ml of HBV and with superior ability to determine haplotypes composed of neighbouring variations. Complex mutational patterns and relative abundances determined by multiplex RFMP assay were in good concordance with results obtained by direct or clonal sequencing analyses. Defined mixtures were successfully and consistently identified at 2% relative concentration of mutant versus wild-type virus by the assay. Conclusions The multiplex RFMP assay is an accurate and sensitive means to detect entecavir and lamivudine resistance mutations, simultaneously. The method is expected to enable early and efficient diagnosis of multiple drug resistance mutations for optimal management of CHB. more...

Background The efficacy of entecavir (ETV) monotherapy in treatment-experienced patients with chronic hepatitis B (CHB) is debatable. Methods A total of 22 hepatitis B e antigen (HBeAg)-positive CHB patients who had shown viral breakthrough or suboptimal response with lamivudine (3TC) and adefovir disoproxil (ADV) therapy were treated with 1.0 mg of ETV. Clinical and virological parameters were monitored every 3 months. Restriction fragment mass polymorphism assays were used to detect antiviral resistance. Results During 3TC and ADV therapy, 11 patients had rtM204V/I mutations, 2 had rtA181V/T or rtN236T, 7 had both and 2 had no 3TC- or ADV-related mutations. After switching to ETV monotherapy, the median change in serum hepatitis B virus (HBV) DNA level was -2.1 log10 copies/ml. Virological response (HBV DNAConclusions ETV monotherapy resulted in a limited virological response in patients who had previously failed 3TC and ADV rescue therapy. The limited efficacy might be associated with residual or reselected rtM204V/I mutations leading to ETV resistance. Combination treatment including potent antiviral agents should be recommended for patients with pre-existing rtM204V/I mutations. more...

Adefovir has a potent antiviral activity as a rescue treatment against lamivudine-resistant strains. The aim of this study was to assess the patterns of lamivudine-resistant mutations and their influence on the virologic response to adefovir rescue therapy in patients with lamivudine-resistant chronic hepatitis B. Sixty-seven patients with lamivudine-resistant chronic hepatitis B were treated with adefovir monotherapy. Baseline blood samples were analyzed for lamivudine-resistant mutations via restriction fragment mass polymorphism. Virologic responses, ALT normalization and loss of HBeAg were assessed. Serum HBV DNA levels were measured using real-time PCR at baseline and 24 weeks of adefovir therapy. Of the 67 patients with chronic hepatitis B, 65 patients (97%) had lamivudine-resistant mutations in the YMDD motif [27 (41%) rtM204I, 22 (34%) rtM204V, and 16 (25%) rtM204I/V]. In addition to the YMDD mutations, the rtL180M, rtL80I, and rtV173L mutations were also present in 78%, 43%, and 11% of patients, respectively. The rtM204V mutation always accompanied rtL180M, and rtL80I was always observed in conjunction with rtM204I. Decrease in mean serum HBV did not differ between patients carrying the rtM204I versus rtM204V mutant at week 24 (-3.3 vs. -3.3 log(10) copies/ml, respectively; P = 0.303). The presence of the rtL180M, rtL80I, and rtV173L did not significantly affect viral load reduction during adefovir administration. These results demonstrate that the rtL80I mutant is co-selected with rtM204I as a compensatory mutation in the same manner as rtL180M with rtM204V, and that adefovir shows similar antiviral efficacy against all of the evaluated patterns of lamivudine-resistant HBV mutations. more...

Background: To evaluate the effect of reversion to YMDD wild-type on emergence of adefovir (ADV)-resistant mutation and antiviral activity of ADV in lamivudine (LAM)- resistant patients. Methods: We determined YMDD mutations and ADV-resistant mutations before and every 3 months during ADV monotherapy in 33 LAM-resistant patients using the restriction fragment mass polymorphism (RFMP) method. Results: Reversion to pure YMDD wild-type hepatitis B virus (HBV) occurred in 6% (2/33), 9% (3/33), 20% (4/20) and 35% (6/17) of patients after 12, 24, 36 and 48 weeks, respectively. Five (29%) patients were found to have pure YMDD mutants at 48 weeks of therapy. Among 33 patients, 4 (12%) patients developed ADV-resistant mutations at 48 weeks of therapy. Adefovir-resistant mutants emerged in all patients after reversion to YMDD wild-type HBV. The mean serum HBV reductions, evaluated at 24 weeks of therapy, were not different between patients with and without reversion to YMDD wild-type HBV (−3.1 log10 copies/mL vs−3.4 log10 copies/mL, P > 0.05). Conclusions: ADV-resistant mutations emerged after reversion to YMDD wild-type in LAM-resistant patients who received ADV monotherapy. Thus, ADV add-on therapy may be necessary to reduce the incidence of developing ADV resistance in patients with LAM resistance. more...

Background: Adefovir dipivoxil (ADV) is a potent nucleotide analogue against both the wild-type and lamivudine (LMV) resistant hepatitis B virus (HBV). The cumulative incidence of ADV resistant mutations in the nucleoside/-tide treatment naive chronic hepatitis B patient (CHB) at weeks 48, 96, and 144 was 0, 0.8–3%, and ∼5.9%, respectively. Aims: The aim of this study was to characterise the genotypic and phenotypic mutation profiles to ADV in 67 LMV resistant CHB patients who were treated with ADV. Methods: Serum HBV DNA was quantified by real time polymerase chain reaction. The ADV mutant was detected using matrix assisted laser desorption/ionisation time of flight mass spectrometry based genotyping assays, termed restriction fragment mass polymorphism (RFMP). Results: RFMP analysis revealed that a total of 11 amino acid substitutions developed in the rt domain of the HBV polymerase in nine patients. The cumulative incidence of genotypic ADV resistance at months 12 and 24 was 6.4% and 25.4%, respectively. The rtA181V, rtN236T, and rtA181T mutations were detected in five, four, and two of the 67 patients at treatment months 12–17, 3–19, and 7–20, respectively. Serial quantification of serum HBV DNA revealed that two patients with the rtA181V mutation, with or without the rtN236T mutation, and one patient with the rtA181T mutation displayed HBV DNA rebound. Conclusion: Emergence of the ADV mutation in LMV resistant patients who are treated with ADV appeared to present earlier and more frequently than was reported in previous studies on nucleoside/-tide treatment naive patients. more...

Hepatitis B virus (HBV) tyrosine, methionine, aspartate, aspartate (YMDD) mutants with or without additional compensatory mutations occur in chronically infected patients during lamivudine therapy and may be associated with accompanying viral breakthrough. The aim of this study was to determine whether a predominance of YMDD mutants could be a prognostic marker for occurrence of viral DNA breakthrough.YMDD genotypes in 740 consecutive samples collected from 116 patients throughout lamivudine treatment were retrospectively analyzed using a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)-based genotyping assay, termed restriction fragment mass polymorphism (RFMP). RFMP exploits differences in molecular masses between wild-type and variant bases of rtM204V/I following PCR amplification of HBV DNA with a lower limit of detection being 100 copies/mL.The study demonstrated that YMDD mutants occur throughout the course of lamivudine therapy irrespective of occurrence of viral DNA breakthrough, indicating that a mere detection of YMDD mutants could not sufficiently predict the viral DNA breakthrough, although presence of YMDD mutants is associated with high incidence of viral DNA breakthrough (odds ratio, 7.8; P = .0012; relative risk = 8.7%), and a 5-fold predominance of YMDD mutant to wild-type virus was significantly associated with viral DNA breakthrough (odds ratio, 604.5; P.0001; relative risk = 93.8%).Close and periodical testing by RFMP assay should be useful to detect the predominance of YMDD mutants for monitoring drug resistance, enabling early intervention and prevention. more...

The early emergence of lamivudine (3TC)-resistant tyro-sine–methionine–aspartate–aspartate (YMDD) mutants has been reported during 3TC therapy in patients with chronic hepatitis B (CHB) in hepatitis B virus (HBV)-endemic areas; however, its clinical impact during long-term 3TC therapy is unknown. This study was performed to investigate the impact of the early emergence of YMDD mutants 3 months after the initiation of treatment on the outcomes of long-term 3TC therapy in HBV e antigen (HBeAg)-positive CHB. We analysed YMDD genotypes in consecutive samples from 30 patients with HBeAg positive CHB throughout 3TC treatment using both restriction fragment length polymorphism and mass spectrometric assays. Long-term outcome was compared between patients who had YMDD mutations detected at 3 months and those who had no mutations. YMDD mutation was detected in 16 (53.3%) out of 30 patients at 3 months and only the rtM204I mutation was found. Cumulative HBeAg loss rates at 3 years was 12.5% and 57.4% in patients who had the rtM204I mutant and wild-type virus at 3 months, respectively ( P=0.010). Cumulative viral breakthrough rates at 3 years was 75.0% and 14.3% in patients who had the rtM204I mutant and wild-type virus at 3 months, respectively ( P=0.002). Logistic regression revealed that YMDD mutation at 3 months was significantly related to viral breakthrough within 24 months ( P=0.003). In conclusion, early detection for HBV YMDD mutation at 3 months may be useful to predict the long-term outcomes of 3TC therapy in patients with HBeAg-positive CHB in HBV-endemic areas. more...

Background/Aims Mutations in hepatitis B virus (HBV) to lamivudine resistance that arise during prolonged treatment frequently cause amino acid substitutions in the YMDD motif of HBV DNA polymerase. Current methods of detecting such variants are time-consuming, labor intensive, and unsuitable for screening large numbers of samples. Here, we describe the development of a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) genotyping assay suitable for detecting HBV variants in a sensitive and specific manner. Methods The assay is based on PCR amplification and mass measurement of oligonucleotides containing sites of mutation of the YMDD motif. Results The MALDI-TOF MS-based genotyping assay is sufficiently sensitive to detect as few as 100 copies of HBV genome per millilitre of serum, with superior specificity for determining mixtures of wild-type and variant viruses. When sera from 40 patients were analyzed, the MALDI-TOF MS-based assay correctly identified known viral variants and additional viral quasi-species not detected by previous methods, as well as their relative abundance. Conclusions The sensitivity, accuracy and amenability to high-throughput analysis makes the MALDI-TOF MS-based assay suitable for mass screening of HBV infected patients receiving lamivudine, and can help provide further understanding of disease progression and response to therapy. more...

Hepatitis B virus (HBV) is the etiologic agent of mankind's most serious liver disease. While the availability of a vaccine has reduced the number of new HBV infections, the vaccine does not benefit the approximately 350 million people already chronically infected by the virus. Most of the drugs approved by the FDA for the treatment of hepatitis B target the reverse transcriptase (RT or P gene product) and are nucleoside RT inhibitors (NRTIs) that suppress viral replication. However, prolonged monotherapies directed against a single target result in the emergence of viral resistance. HBV genotypic differences affect NRTI resistance, and because the reading frames of the S (surface antigen) and P genes partially overlap, genomic differences that affect the surface of the virus may also alter the viral polymerase sequence, function and drug susceptibility. The scope of this review is to assess the effects of HBV genotypic variation on the development of drug resistance to NRTIs. Some RT residues that vary among different genotypes are in the vicinity of residues that mutate and give rise to NRTI resistance. Interactions between these amino acids can help explain the effect of HBV genotype on the development of NRTI resistance during antiviral therapies, and might help in the design of improved therapeutic strategies. more...

BackgroundLarge clinical studies assessing long-term adefovir dipivoxil salvage monotherapy in patients with lamivudine-resistant chronic hepatitis B (CHB) are lacking, particularly in patients positive for hepatitis B e antigen (HBeAg). We assessed the efficacy and resistance profile of adefovir dipivoxil monotherapy for up to 5 years in a large cohort of Korean patients with lamivudine-resistant CHB.MethodsA total of 320 patients (81.3% HBeAg-positive; 100% genotype C) with confirmed genotypic lamivudine-resistant CHB were switched to adefovir dipivoxil 10 mg once daily. Liver function tests and HBV DNA were monitored every 3 months. Genotypic resistance to adefovir dipivoxil was performed in patients with detectable HBV DNA.ResultsThe overall cumulative virological response rate at 5 years of adefovir dipivoxil therapy was 48.8%. The virological response rate was significantly higher in HBeAg-negative patients (62.0% versus 45.9%; P=0.010). Most cases of virological response (131/134, 97.8%) occurred within the first 36 months of therapy. The 5-year cumulative probability of genotypic resistance and virological breakthrough was 65.6% and 61.8%, respectively. Predictive factors for a virological response included baseline HBeAg seronegativity, HBV DNA≤8 log10copies/ml and achievement of an on-treatment initial virological response.ConclusionsAdefovir dipivoxil salvage monotherapy for lamivudine-resistant CHB resulted in a modest cumulative virological response rate at 5 years, which was associated with progressive antiviral resistance. Consequently, adefovir monotherapy is not preferable as a first-line strategy for lamivudine resistance where combination lamivudine plus adefovir dipivoxil therapy is available. more...

A 60-year-old woman with end stage liver cirrhosis caused by genotype 2 hepatitis C virus (HCV) infection received an orthotopic liver transplantation (OLT). The patient was negative for the hepatitis B surface antigen (HBsAg) and positive for the anti-hepatitis B surface antibody (anti-HBs) prior to and one and a half months following the OLT. Due to reactivation of hepatitis C, treatment with interferon-alpha and Ribavirin started two months following the OLT and resulted in a sustained virological response. We performed a liver biopsy because a biochemical response was not achieved. Surprisingly, liver pathology showed HBsAg-positive hepatocytes with a lobular hepatitis feature, which had been negative in the liver biopsy specimen obtained one and a half months post-OLT. High titers of both HBsAg and HBeAg were detected, while anti-HBs antibodies were not found. Tests for IgM anti-hepatitis B core antibody and anti-delta virus antibodies were negative. The serum HBV DNA titer was over 1×10(7) copies/mL. A sequencing analysis showed no mutation in the "a" determinant region, but revealed a mixture of wild and mutant strains at an overlapping region of the S and P genes (S codon 213 (Leu/Ile); P codons 221 (Phe/Tyr) and 222 (Ala/Thr)). These findings suggest that de novo hepatitis B can develop in patients with HCV infection during the post-OLT period despite the presence of protective anti-HBs. more...

Evolution of precore genes can occur during lamivudine therapy in HBV infection. This study investigated the changes in precore regions in patients treated with lamivudine and the pattern during relapse.The sequences of codon 28 in precore region in serial samples of 16 patients with HBV (11 HBeAg-positive and 5 HBeAg-negative) treated with lamivudine were analyzed by restriction fragment mass polymorphism.Among 9 patients who had wild-type virus, the wild-type virus was replaced by A1896 during relapse after initial treatment in 2 patients, and a pure population with A1896 selected during relapse in all 4 patients with mixed infection. In 5 patients with A1896 during relapse, 3 patients initially reverted to wild-type and later selected A1896, and 2 patients maintained A1896 during lamivudine retreatment. In 8 patients showing HBeAg negative reactivation, 3 patients showed A1896 and 5 patients showed wildtype virus.Lamivudine therapy induced initial reversion from precore mutants to wild-type virus, but precore mutants reappeared in patients infected with precore mutants. In some patients infected by wildtype HBV, wild-type HBV was replaced by precore mutants, resulting in a flare-up of hepatitis after cessation of lamivudine administration, and HBeAg negativity did not always correspond to the presence of precore mutants. more...

Immunogenetic factors may play a role in determining the susceptibility of an individual to viral infection. CCR5 promoter polymorphisms are known to be associated with HIV infection. However, there has been no report on the association between CCR5 promoter polymorphism and HBV infection. Therefore, we investigated the relationship between the CCR5 promoter polymorphism and HBV infection.A total of 377 patients were classified into two groups according to their HBV infection status: (1) the spontaneous clearance group (SC); HBsAg (-), anti-HBc (+), anti-HBs (+) (2) the chronic HBsAg (+) carrier group (CC); HBsAg (+), anti-HBc (+), anti-HBs (-). CCR5 polymorphisms were detected by employing matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)- based SNP scoring assay, termed Restriction Fragment Mass Polymorphism (RFMP), which exploits the differences in molecular masses between the common allele and rare allele bases of interest.We found that the genotype frequencies of CCR5 A59029G significantly differed between the SC group (n=138) and CC group (n=239) (P0.05). The CCR5 59029A allelic genotype was associated with an increased risks of chronic infection rather than spontaneous clearance (P=0.002), and the presence of the CCR5 59029G allele was significantly associated with the spontaneous clearance of HBV (P=0.001). Strong linkage disequilibrium between the CCR5-59029 and the CCR5-59353 polymorphic variants was identified. None of the 377 subjects had the CCR5-32 bp deletion mutation.The CCR5 promoter polymorphisms at position 59029 might play a role in the clearance of HBV infection. This primary experimental evidence needs further studies to clarify the clinical usefulness of CCR5 promoter polymorphisms as a target for the screening or treatment of HBV infection. more...

A matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based genotyping assay, termed restriction fragment mass polymorphism (RFMP) has been recently developed for detecting hepatitis B virus (HBV) mutants. The assay is based on PCR amplification and mass measurement of oligonucleotides containing sites of mutations that confer resistance to lamivudine. We compared the efficacy and usefulness of the RFMP assay with a commercial assay using a reverse hybridization line probe technology, namely INNO-LiPA HBV DR (referred to henceforth as the LiPA assay), for the detection of lamivudine-resistant HBV mutants. A total of 60 patient samples were analysed for the presence of mutations at rtL180M and rtM204I/V of HBV polymerase by the LiPA and RFMP assays. The ability to detect mutations at rtM204I/V was compared with defined mixtures of wild-type and mutant HBV cloned in plasmids at relative concentrations ranging from 1–25%. Concordance between methods was found to be 95.0% (57/60) when only the presence of resistance mutations was considered, regardless of quasispecies. In three cases, additional minor populations of resistant viruses were identified by RFMP. Defined mixtures were consistently successfully identified at a 1% relative concentration of mutant versus wild-type viruses by the RFMP assay and 4% by the LiPA assay. The RFMP assay proved to be an accurate and reliable tool for detection of lamivudine-resistant mutations and was more sensitive than the LiPA assay in detecting mixtures of mutant and wild-type viruses. The improved sensitivity of the RPMP assay can help monitor drug resistance as it develops, enabling early intervention and prevention. more...

The levels of HBV replication in the nonreplicative phase are not clear. We conducted this study to evaluate the levels of viral replication during the nonreplicative phase in chronic HBV-infected Korean patients using real-time PCR. A total of 125 patients were classified into three groups: inactive HBsAg carriers, inactive liver cirrhosis patients, and resolved chronic HBV-infected patients with loss of HBsAg. The real-time PCR detected HBV DNA in 112 cases (89.6%). The mean levels of HBV DNA were 3.84, 4.10, and 3.31 log copies/ml in the three groups, respectively (P0.01). Ninety-five percent of inactive HBsAg carriers showed levels of HBV DNA lower than 6 x 10(4) copies/ml. In conclusion, we showed different levels of HBV DNA exactly in three groups during nonreplicative phases. We suggest that the cutoff level of HBV DNA in inactive HBsAg carriers should be readjusted to a lower level in future studies. more...

Recent studies have shown that the genotype of hepatitis B virus (HBV) may correlate with the disease natural history and treatment outcome. However, several of these studies used low sensitivity assays in a small number of patients, and this has precluded an accurate evaluation of Korean HBV genotypes. We analyzed Korean HBV genotypes in a large population by employing a new technology, restriction fragment mass polymorphism (RFMP) using MALDI-TOF mass spectrometry, in a sensitive and specific manner.Between February 1995 and December 2003, a total of 475 patients with chronic HBV infection were enrolled. The assay is based on the mass measurement of oligonucleotides having genotypic variations of the S gene. Clinical features including the virologic status and disease progression were also evaluated.The median age of the total patients was 35.5 years. Out of 475 patients, there were 162 (34.1%) inactive carriers, 172 (36.2%) had chronic hepatitis, 77 (16.2%) had liver cirrhosis and 64 (13.5%) had hepatocellular carcinoma (HCC). There were 454 patients (95.6%) with genotype C, 4 patients (0.8%) with genotype A, 16 patients (3.4%) with the mixed A and C genotype [7 patients (1.4%) with AC versus 9 patients (2.0%) with CA], and 1 patient (0.2%) with B genotype. Comparing genotype A and C, genotype A patients were all inactive carriers without HCC, whereas genotype C patients included those with chronic hepatitis, liver cirrhosis and HCC.HBV genotype C is highly prevalent in Korea. Although it is a small percentage, genotype A also exists and it seems to take a more benign clinical course than genotype C. Further studies are necessitated to assess the relationship between HBV genotypes and the various aspects of the diseases' clinical course. more...

Background/Aims: Adefovir dipivoxil (adefovir) effectively inhibits both wild-type and lamivudine-resistant hepatitis B virus (HBV) replication. The development of adefovir resistance is both delayed and infrequent compared with lamivudine resistance. The aim of this study was to characterize the serologic, biochemical, and virologic response to adefovir, and to explore the factors affecting initial virologic response (IVR, defined as a decrease in serum HBV below 4 log10copies/mL after 6 month of treatment) and adefovir resistance in lamivudine resistant HBV-infected patients. Methods: This study population comprised 76 patients with lamivudine-resistance who had received adefovir for more than 12 months between March 2004 and December 2006. The adefovir-resistant mutant was assayed at 6 months and 12 months during adefovir administration. Restriction- fragment mass polymorphism analysis was used for detecting YMDD and adefovir mutants. Results: After adefovir administration, an IVR was observed in 31% of the patients with lamivudine resistance. Factors associated with an IVR were HBeAg negativity (P=0.04) and the presence of liver cirrhosis (P=0.04). Age, sex, pretreatment levels of alanine aminotransferase and aspartate aminotransferase, pretreatment HBV DNA levels, presence of precore mutation, and type of YMDD mutants were not related to an IVR during adefovir treatment. The prevalence of adefovir resistance was 5% and 13% at 6 months and 12 months after therapy, respectively. Mixed infection of the precore mutant was a risk factors for the emergence of adefovir resistance (P=0.01). Conclusions: Lamivudine-resistant HBV patients exhibiting HBeAg negativity and liver cirrhosis were more likely to achieve an IVR after adefovir therapy. Adefovir resistance was associated with mixed infection of the precore mutant. (Korean J Hepatol 2008;14:58-66) more...