scholarly journals Basal Core Promoter and Precore Mutations in the Hepatitis B Virus Genome Enhance Replication Efficacy of Lamivudine-Resistant Mutants

2004 ◽  
Vol 78 (16) ◽  
pp. 8524-8535 ◽  
Author(s):  
Frank Tacke ◽  
Christina Gehrke ◽  
Tom Luedde ◽  
Albert Heim ◽  
Michael P. Manns ◽  
...  
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Virus Replication ◽  
Drug Sensitivity ◽  
Core Promoter ◽  
Basal Core Promoter ◽  
B Virus ◽  
Resistant Mutants

ABSTRACT During chronic hepatitis B virus (HBV) infection, mutations in the precore (PC) or basal core promoter (BCP) region affecting HBV e antigen (HBeAg) expression occur commonly and represent the predominant virus species in patients with HBeAg-negative chronic hepatitis B. The PC mutation (G1896A+C1858T) creates a translational stop codon resulting in absent HBeAg expression, whereas BCP mutations (A1762T/G1764A) reduce HBeAg expression by transcriptional mechanisms. Treatment of chronic HBV infection with lamivudine (LMV) often selects drug-resistant strains with single (rtM204I) or double (rtL180M+rtM204V) point mutations in the YMDD motif of HBV reverse transcriptase. We cloned replication-competent HBV vectors (genotype A, adw2) combining mutations in the core (wild type [wt], PC, and BCP) and polymerase gene (wt, rtM204I, and rtL180M/M204V) and analyzed virus replication and drug sensitivity in vitro. Resistance to LMV (rtM204I/rtL180M+rtM204V) was accompanied by a reduced replication efficacy as evidenced by reduced pregenomic RNA, encapsidated progeny DNA, polymerase activity, and virion release. PC mutations alone did not alter virus replication but restored replication efficacy of the LMV-resistant mutants without affecting drug resistance. BCP mutants had higher replication capacities than did the wt, also in combination with LMV resistance mutations. All nine HBV constructs showed similar sensitivities to adefovir. In conclusion, BCP-PC mutations directly impact the replication capacity of LMV-resistant mutants. PC mutations compensated for replication inefficiency of LMV-resistant mutants, whereas BCP mutations increased viral replication levels to above the wt baseline values, even in LMV-resistant mutants, without affecting drug sensitivity in vitro. Adefovir may be an effective treatment when combinations of core and polymerase mutations occur.

scholarly journals Hypoxia inducible factors regulate hepatitis B virus replication by activating the basal core promoter

2021 ◽  
Author(s):  
Peter AC. Wing ◽  
Peter Jianrui Liu ◽  
James M. Harris ◽  
Andrea Magri ◽  
Thomas Michler ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Virus Replication ◽  
Core Promoter ◽  
Basal Core Promoter ◽  
Hypoxia Inducible Factors ◽  
B Virus

scholarly journals Identification and Characterization of Clevudine-Resistant Mutants of Hepatitis B Virus Isolated from Chronic Hepatitis B Patients

2010 ◽  
Vol 84 (9) ◽  
pp. 4494-4503 ◽  
Author(s):  
So Young Kwon ◽  
Yong Kwang Park ◽  
Sung Hyun Ahn ◽  
Eun Sook Cho ◽  
Won Hyeok Choe ◽  
...  
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Chronic Hepatitis B ◽  
Drug Susceptibility ◽  
Compensatory Mutation ◽  
B Virus ◽  
Resistant Mutants

ABSTRACT Clevudine (CLV) is a nucleoside analog with potent antiviral activity against chronic hepatitis B virus (HBV) infection. Viral resistance to CLV in patients receiving CLV therapy has not been reported. The aim of this study was to characterize CLV-resistant HBV in patients with viral breakthrough (BT) during long-term CLV therapy. The gene encoding HBV reverse transcriptase (RT) was analyzed from chronic hepatitis B patients with viral BT during CLV therapy. Sera collected from the patients at baseline and at the time of viral BT were studied. To characterize the mutations of HBV isolated from the patients, we subjected the HBV mutants to in vitro drug susceptibility assays. Several conserved mutations were identified in the RT domain during viral BT, with M204I being the most common. In vitro phenotypic analysis showed that the mutation M204I was predominantly associated with CLV resistance, whereas L229V was a compensatory mutation for the impaired replication of the M204I mutant. A quadruple mutant (L129M, V173L, M204I, and H337N) was identified that conferred greater replicative ability and strong resistance to both CLV and lamivudine. All of the CLV-resistant clones were lamivudine resistant. They were susceptible to adefovir, entecavir, and tenofovir, except for one mutant clone. In conclusion, the mutation M204I in HBV RT plays a major role in CLV resistance and leads to viral BT during long-term CLV treatment. Several conserved mutations may have a compensatory role in replication. Drug susceptibility assays reveal that adefovir and tenofovir are the most effective compounds against CLV-resistant mutants. These data may provide additional therapeutic options for CLV-resistant patients.

scholarly journals Effect of basal core promoter and pre-core mutations on hepatitis B virus replication

2008 ◽  
Vol 89 (4) ◽  
pp. 901-909 ◽  
Author(s):  
Saffie Jammeh ◽  
Fiona Tavner ◽  
Roger Watson ◽  
Howard C. Thomas ◽  
Peter Karayiannis
Keyword(s):  
Hepatitis B Virus ◽  
Hepatitis B ◽  
Virus Replication ◽  
Stop Codon ◽  
Core Promoter ◽  
Replication Capacity ◽  
Basal Core Promoter ◽  
Appreciable Effect ◽  
Huh7 Cells ◽  
B Virus

There are two hypotheses explaining a fulminant outcome after hepatitis B virus (HBV) infection, both of which may be applicable at the same time: (i) basal core promoter (BCP) mutations increase viral replication, allowing rapid spread of the virus through the liver, and (ii) pre-core (pre-C) mutations abrogating hepatitis B e antigen (HBeAg) synthesis remove its tolerogenic effect, leading to a vigorous immune response. This study investigated the effect of these mutations on virus replication efficiency and HBeAg production. Substitutions A1762T/G1764A and T1753C, C1766T and T1768A in the BCP region, and G1896A and G1899A in the pre-C region, were examined either alone or in combination, using a common genetic background. Huh7 cells were transfected with these constructs and real-time PCR was used to quantify released virion-associated and intracellular HBV DNA, pregenomic RNA and pre-C mRNA. In addition, culture supernatants were tested for hepatitis B surface antigen (HBsAg) and HBeAg. The double BCP mutation (A1762T/G1764A) and the pre-C mutations (G1896A, G1899A), either alone or in combination, had no appreciable effect on the replication capacity of the virus. In contrast, clones with mutations at positions 1766/1768, 1762/1764/1766 and 1753/1762/1764 exhibited increased-replication phenotypes. HBeAg was undetectable in all cultures transfected with constructs bearing the G1896A stop-codon mutation, as expected. In contrast, constructs with additional mutations in the BCP region had appreciably lower levels of HBeAg expression than the wild type. Thus, core promoter mutations other than those at 1762/1764 appear to upregulate viral DNA replication and, at the same time, greatly reduce HBeAg production.

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