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Emergence of a novel lamivudine-resistant hepatitis B virus variant with a substitution outside the YMDD motif.

ABSTRACT: Lamivudine is a major drug approved for treatment of chronic hepatitis B virus (HBV) infection. Emergence of drug-resistant mutants with amino acid substitutions in the YMDD motif is a well-documented problem during long-term lamivudine therapy. Here we report a novel lamivudine-resistant strain of HBV with an intact YMDD motif, which included an amino acid substitution, rtA181T, in the reverse transcriptase (RT) domain of HBV polymerase. The substitution also induced a unique amino acid substitution (W172L) in the overlapping hepatitis B surface (HBs) protein. The YMDD mutant strains were not detected even by using the sensitive peptide nucleic acid-mediated PCR clamping method. The detected nucleotide substitution was accompanied by the emergence of an additional nucleotide substitution that induced amino acid change (S331C) in the spacer domain. The rtA181T mutant strain displayed a threefold decrease in susceptibility to lamivudine in in vitro experiments in comparison with the wild type. In vivo analysis using human hepatocyte-chimeric mice confirmed the resistance of this mutant strain to lamivudine. We developed a method to detect this novel rtA181T mutation and a previously reported rtA181T mutation with the HBs stop codon using restriction fragment length polymorphism PCR and identified one patient with the latter pattern among 40 patients with lamivudine resistance. In conclusion, although the incidence is not high, we have to be careful regarding the emergence of lamivudine-resistant mutant strains with intact YMDD motif.

SUBMITTER: Yatsuji H

PROVIDER: S-EPMC1635170 | biostudies-literature | 2006 Nov

REPOSITORIES: biostudies-literature

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Emergence of a novel lamivudine-resistant hepatitis B virus variant with a substitution outside the YMDD motif.

Yatsuji Hiromi H Noguchi Chiemi C Hiraga Nobuhiko N Mori Nami N Tsuge Masataka M Imamura Michio M Takahashi Shoichi S Iwao Eiji E Fujimoto Yoshifumi Y Ochi Hidenori H Abe Hiromi H Maekawa Toshiro T Tateno Chise C Yoshizato Katsutoshi K Suzuki Fumitaka F Kumada Hiromitsu H Chayama Kazuaki K

Antimicrobial agents and chemotherapy 20060918 11

Lamivudine is a major drug approved for treatment of chronic hepatitis B virus (HBV) infection. Emergence of drug-resistant mutants with amino acid substitutions in the YMDD motif is a well-documented problem during long-term lamivudine therapy. Here we report a novel lamivudine-resistant strain of HBV with an intact YMDD motif, which included an amino acid substitution, rtA181T, in the reverse transcriptase (RT) domain of HBV polymerase. The substitution also induced a unique amino acid substit ...[more]

PMID: 16982790

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Project description:BackgroundRecurrence of Hepatitis B Virus infection in patients undergoing liver transplanted (LT) is a serious and often fatal problem. Lamivudine (LAM) and Hepatitis B Immunoglobulin (HBIG) are widely used to manage hepatitis B recurrence after liver transplantation. However, the outcomes in patients are less elucidated.ObjectivesThe current study aimed to evaluate the YMDD motif mutations profile among the patients undergoing LT infected with HBV and treated with LAM/HBIG at least for one year.Patients and methodsThirty patients with liver transplantation due to HBV were enrolled, while DNA level remained under detection limit of 50 IU/mL before transplantation and abnormal higher levels of liver enzymes after LT. The HBV genome detection was performed by two different Polymerase Chain Reaction methods following viral quantification by commercial Real-Time PCR. HbsAg detection, besides liver function tests were conducted as complementary assays. To assess nucleotide analogue mutations, the major part of polymerase gene (aa 80 - 240) was amplified by Nested-PCR, introduced to sequencing and subjected to phylogenetic analysis.ResultsTotally, according to the laboratory criteria there were 13 cases with detectable HBV genome, while the mean liver enzyme levels were higher in recurrent patients and HBsAg was detected only in four out of the 13 cases. Phylogenetic analysis demonstrated that all isolated genomes belonged to genotype D. Critical M204I mutation, as a proof for resistance to LAM, was detected among 46% of the subjects and natural entecavir resistance (S202I) was also distinguished in one subject. Viral quantification showed higher titer in LAM resistant group in comparison to the group with undetectable drug resistance mutant (P > 0.05).ConclusionsAlthough the patients carrying M204I mutation were more likely to show lack of responses to LAM therapy, LAM replacing by other nucleoside/tide analogs plus HBIG maybe still effective in decreasing hepatitis B recurrence after liver transplantation. However, it is suggested that drug resistance test should be considered by clinicians during therapeutic management to avoid the following viral breakthrough.

Project description:AimTo investigate the relationship between hepatitis B virus (HBV) genotype with spontaneous YMDD mutations and hepatocellular carcinoma (HCC) in HBV-related cirrhosis.MethodsWe investigated 264 liver cirrhosis patients who were not treated with antiviral drugs, including 81 patients with HCC. YMDD mutations were detected by fluorescent hybridization bioprobe polymerase chain reaction (PCR) and melting curve assay using the Diagnosis Kit for HBV YMDD Mutation. Serum HBV genotypes were detected by real-time PCR using genotype-specific TaqMan probes. Statistical analysis was performed according to data type using the t test, χ(2) test and unconditional logistic regression analysis.ResultsIn the HCC group, genotype C strains, spontaneous YMDD mutations, and genotype C strains with YMDD mutations were detected in 33 (40.74%), 13 (16.05%) and 11 (13.58%) patients, respectively. In the liver cirrhosis (LC) group, HBV genotype C strains, spontaneous YMDD mutations, and genotype C strains with YMDD mutations were detected in 33 (18.03%), 7 (3.83%) and 2 (1.09%) patients, respectively. The differences in genotype C strains, spontaneous YMDD mutations, and genotype C strains with YMDD mutations between the two groups were statistically significant (χ(2) = 15.441, P = 0.000; χ(2) = 11.983, P = 0.001; P = 0.000). In the HCC and LC groups, there were seven patients infected by genotype B strains with YMDD mutations and 13 by genotype C strains with YMDD mutations. Further research revealed that HCC occurred in 2 patients infected by genotype B strains with YMDD mutations and 11 infected by genotype C strains with YMDD mutations. The difference was statistically significant (P = 0.000). Unconditional logistic regression analysis revealed that patients infected by genotype C strains with spontaneous YMDD mutations had a 7.775-fold higher risk for the development of HBV-related HCC than patients infected by other type HBV strains (P = 0.013, 95%CI: 1.540-39.264).ConclusionGenotype C strains with spontaneous YMDD mutations are an independent risk factor for HCC in LC patients and are important for early warning of HCC.

Dataset Information

Emergence of a novel lamivudine-resistant hepatitis B virus variant with a substitution outside the YMDD motif.

Publications

Emergence of a novel lamivudine-resistant hepatitis B virus variant with a substitution outside the YMDD motif.

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