Antiviral treatment of chronic hepatitis B virus infections: the past, the present and the future

Férir, Geoffrey; Kaptein, Suzanne; Neyts, Johan; Clercq, Erik De

doi:10.1002/rmv.554

Cited by 65 publications

(45 citation statements)

References 128 publications

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“…Nucleoside analogs have long been the backbone therapy for the treatment of viral diseases such as HIV, HBV, and HSV infections (1)(2)(3)(4)(5). Recent studies have suggested that nucleoside analogs may be useful for treating hepatitis C virus (HCV) 3 infection (4, 6 -8).…”

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confidence: 99%

Mechanism of Activation of PSI-7851 and Its Diastereoisomer PSI-7977

Murakami¹,

Tolstykh²,

Bao³

et al. 2010

Journal of Biological Chemistry

268

308

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A phosphoramidate prodrug of 2-deoxy-2-␣-fluoro-␤-Cmethyluridine-5-monophosphate, PSI-7851, demonstrates potent anti-hepatitis C virus (HCV) activity both in vitro and in vivo. PSI-7851 is a mixture of two diastereoisomers, PSI-7976 and PSI-7977, with PSI-7977 being the more active inhibitor of HCV RNA replication in the HCV replicon assay. To inhibit the HCV NS5B RNA-dependent RNA polymerase, PSI-7851 must be metabolized to the active triphosphate form. The first step, hydrolysis of the carboxyl ester by human cathepsin A (CatA) and/or carboxylesterase 1 (CES1), is a stereospecific reaction. Western blot analysis showed that CatA and CES1 are both expressed in primary human hepatocytes. However, expression of CES1 is undetectable in clone A replicon cells. Studies with inhibitors of CatA and/or CES1 indicated that CatA is primarily responsible for hydrolysis of the carboxyl ester in clone A cells, although in primary human hepatocytes, both CatA and CES1 contribute to the hydrolysis. Hydrolysis of the ester is followed by a putative nucleophilic attack on the phosphorus by the carboxyl group resulting in the spontaneous elimination of phenol and the production of an alaninyl phosphate metabolite, PSI-352707, which is common to both isomers. The removal of the amino acid moiety of PSI-352707 is catalyzed by histidine triad nucleotide-binding protein 1 (Hint1) to give the 5-monophosphate form, PSI-7411. siRNA-mediated Hint1 knockdown studies further indicate that Hint1 is, at least in part, responsible for converting PSI-352707 to PSI-7411. PSI-7411 is then consecutively phosphorylated to the diphosphate, PSI-7410, and to the active triphosphate metabolite, PSI-7409, by UMP-CMP kinase and nucleoside diphosphate kinase, respectively.Nucleoside analogs have long been the backbone therapy for the treatment of viral diseases such as HIV, HBV, and HSV infections (1-5). Recent studies have suggested that nucleoside analogs may be useful for treating hepatitis C virus (HCV) 3 infection (4, 6 -8). The most advanced anti-HCV nucleoside, RG7128, is a diisobutyrate nucleoside prodrug of ␤-D-2Ј-deoxy-2Ј-␣-fluoro-2Ј-␤-C-methylcytidine (PSI-6130) and is currently in phase IIb clinical studies. PSI-6130 demonstrated potent activity in the subgenomic HCV replicon assay (9); the incubation of radiolabeled PSI-6130 with either replicon cells or primary human hepatocytes resulted in the formation of the 5Ј-mono-, di-, and triphosphate metabolites of . The triphosphate metabolite (PSI-6130-TP) was shown to be a potent inhibitor of HCV NS5B RNA-directed RNA polymerase (RdRp) (11). However, incubation of replicon cells with the uridine analog, PSI-6206, resulted in no inhibition of HCV RNA production due to the inability of PSI-6206 to be phosphorylated by cellular nucleoside kinases to its monophosphate, 12). Biochemical studies showed that PSI-7411 was consecutively phosphorylated to its diphosphate, PSI-7410, by UMP-CMP kinase and its triphosphate, PSI-7409, by nucleoside diphosphate kinase (12). Inhibition studies using the replic...

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confidence: 99%

Mechanism of Activation of PSI-7851 and Its Diastereoisomer PSI-7977

Murakami¹,

Tolstykh²,

Bao³

et al. 2010

Journal of Biological Chemistry

268

308

View full text Add to dashboard Cite

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“…21 The anticancer drug oxaliplatin, 22,23 the histamine H 2 receptor antagonist cimetidine, 24,25 and the antiviral drug lamivudine 19,20 are substrates for both OCT1 and OCT3. Notably, hepatocytes are the pharmacological target cells of lamivudine, when it is used to treat chronic hepatitis B, 26 and of metformin. 27 The impact of an altered OCT1-mediated drug transport on pharmacokinetics can be exemplified by metformin.…”

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confidence: 99%

Expression of Organic Cation Transporters OCT1 (SLC22A1) and OCT3 (SLC22A3) Is Affected by Genetic Factors and Cholestasis in Human Liver†

et al. 2009

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An important function of hepatocytes is the biotransformation and elimination of various drugs, many of which are organic cations and are taken up by organic cation transporters (OCTs) of the solute carrier family 22 (SLC22). Because interindividual variability of OCT expression may affect response to cationic drugs such as metformin, we systematically investigated genetic and nongenetic factors of OCT1/SLC22A1 and OCT3/SLC22A3 expression in human liver. OCT1 and OCT3 expression (messenger RNA [mRNA], protein) was analyzed in liver tissue samples from 150 Caucasian subjects. Hepatic OCTs were localized by way of immunofluorescence microscopy. Matrixassisted laser desorption/ionization time-of-flight mass spectrometry and genome-wide singlenucleotide polymorphism microarray technology served to genotype 92 variants in the SLC22A1-A3/ OCT1-3 gene cluster. Transport of metformin by recombinant human OCT1 and OCT3 was compared using transfected cells. OCT1 mRNA and protein expression varied 113-and 83-fold, respectively; OCT3 mRNA expression varied 27-fold. OCT1 transcript levels were on average 15-fold higher compared with OCT3. We localized the OCT3 protein to the basolateral hepatocyte membrane and identified metformin as an OCT3 substrate. OCT1 and OCT3 expression are independent of age and sex but were significantly reduced in liver donors diagnosed as cholestatic (P < 0.01). Several haplotypes for OCT1 and OCT3 were identified. Multivariate analysis adjusted for multiple testing showed that only the OCT1-Arg61Cys variant (rs12208357) strongly correlated with decreased OCT1 protein expression (P < 0.0001), and four variants in OCT3 (rs2292334, rs2048327, rs1810126, rs3088442) were associated with reduced OCT3 mRNA levels (P ‫؍‬ 0.03). Conclusion: We identified cholestasis and genetic variants as critical determinants for considerable interindividual variability of hepatic OCT1 and OCT3 expression. This indicates consequences for hepatic elimination of and response to OCT substrates such as metformin.

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“…Current treatments are unable to clear viral infection and are prone to the appearance of drug-resistant mutants (4)(5)(6)(7)(8). Efforts to produce better treatments remain an active goal of HBV research.…”

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confidence: 99%

Structurally Similar Woodchuck and Human Hepadnavirus Core Proteins Have Distinctly Different Temperature Dependences of Assembly

Kukreja

Wang

Pierson

et al. 2014

J Virol

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Woodchuck hepatitis virus (WHV), a close relative of human hepatitis B virus (HBV), has been a key model for disease progression and clinical studies. Sequences of the assembly domain of WHV and HBV core proteins (wCp149 and hCp149, respectively) have 65% identity, suggesting similar assembly behaviors. We report a cryo-electron microscopy (cryo-EM) structure of the WHV capsid at nanometer resolution and characterization of wCp149 assembly. At this resolution, the T‫4؍‬ capsid structures of WHV and HBV are practically identical. In contrast to their structural similarity, wCp149 demonstrates enhanced assembly kinetics and stronger dimer-dimer interactions than hCp149: at 23°C and at 100 mM ionic strength, the pseudocritical concentrations of assembly of wCp149 and hCp149 are 1.8 M and 43.3 M, respectively. Transmission electron microscopy reveals that wCp149 assembles into predominantly T‫4؍‬ capsids with a sizeable population of larger, nonicosahedral structures. Charge detection mass spectrometry indicates that T‫3؍‬ particles are extremely rare compared to the ϳ5% observed in hCp149 reactions. Unlike hCp149, wCp149 capsid assembly is favorable over a temperature range of 4°C to 37°C; van't Hoff analyses relate the differences in temperature dependence to the high positive values for heat capacity, enthalpy, and entropy of wCp149 assembly. Because the final capsids are so similar, these findings suggest that free wCp149 and hCp149 undergo different structural transitions leading to assembly. The difference in the temperature dependence of wCp149 assembly may be related to the temperature range of its hibernating host. IMPORTANCEIn this paper, we present a cryo-EM structure of a WHV capsid showing its similarity to HBV. We then observe that the assembly properties of the two homologous proteins are very different. Unlike human HBV, the capsid protein of WHV has evolved to function in a nonhomeostatic environment. These studies yield insight into the interplay between core protein self-assembly and the host environment, which may be particularly relevant to plant viruses and viruses with zoonotic cycles involving insect vectors.

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Antiviral treatment of chronic hepatitis B virus infections: the past, the present and the future

Cited by 65 publications

References 128 publications

Mechanism of Activation of PSI-7851 and Its Diastereoisomer PSI-7977

Mechanism of Activation of PSI-7851 and Its Diastereoisomer PSI-7977

Expression of Organic Cation Transporters OCT1 (SLC22A1) and OCT3 (SLC22A3) Is Affected by Genetic Factors and Cholestasis in Human Liver†

Structurally Similar Woodchuck and Human Hepadnavirus Core Proteins Have Distinctly Different Temperature Dependences of Assembly

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