Faculty Opinions recommendation of Viral replication. Structural basis for RNA replication by the hepatitis C virus polymerase.

2015 ◽  
Author(s):  
David N Frick
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Replication ◽  
Rna Replication ◽  
Structural Basis

Structural basis for RNA replication by the hepatitis C virus polymerase

Science ◽  
2015 ◽  
Vol 347 (6223) ◽  
pp. 771-775 ◽  
Author(s):  
T. C. Appleby ◽  
J. K. Perry ◽  
E. Murakami ◽  
O. Barauskas ◽  
J. Feng ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Replication ◽  
Structural Basis

scholarly journals Molecular and Structural Basis for the Roles of Hepatitis C Virus Polymerase NS5B Amino Acids 15, 223, and 321 in Viral Replication and Drug Resistance

2014 ◽  
Vol 58 (11) ◽  
pp. 6861-6869 ◽  
Author(s):  
Angela M. Lam ◽  
Thomas E. Edwards ◽  
Ralph T. Mosley ◽  
Eisuke Murakami ◽  
Shalini Bansal ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Replication ◽  
Rna Binding ◽  
Nonstructural Protein ◽  
Point Mutations ◽  
Resistance Mutation ◽  
Structural Basis ◽  
Nucleoside Triphosphate ◽  
Multiple Point

ABSTRACTResistance to the 2′-F-2′-C-methylguanosine monophosphate nucleotide hepatitis C virus (HCV) inhibitors PSI-352938 and PSI-353661 was associated with a combination of amino acid changes (changes of S to G at position 15 [S15G], C223H, and V321I) within the genotype 2a nonstructural protein 5B (NS5B), an RNA-dependent RNA polymerase. To understand the role of these residues in viral replication, we examined the effects of single and multiple point mutations on replication fitness and inhibition by a series of nucleotide analog inhibitors. An acidic residue at position 15 reduced replicon fitness, consistent with its proximity to the RNA template. A change of the residue at position 223 to an acidic or large residue reduced replicon fitness, consistent with its proposed proximity to the incoming nucleoside triphosphate (NTP). A change of the residue at position 321 to a charged residue was not tolerated, consistent with its position within a hydrophobic cavity. This triple resistance mutation was specific to both genotype 2a virus and 2′-F-2′-C-methylguanosine inhibitors. A crystal structure of the NS5B S15G/C223H/V321I mutant of the JFH-1 isolate exhibited rearrangement to a conformation potentially consistent with short primer-template RNA binding, which could suggest a mechanism of resistance accomplished through a change in the NS5B conformation, which was better tolerated by genotype 2a virus than by viruses of other genotypes.

scholarly journals Ketoamide Resistance and Hepatitis C Virus Fitness in Val55 Variants of the NS3 Serine Protease

2012 ◽  
Vol 56 (4) ◽  
pp. 1907-1915 ◽  
Author(s):  
Christoph Welsch ◽  
Sabine Schweizer ◽  
Tetsuro Shimakami ◽  
Francisco S. Domingues ◽  
Seungtaek Kim ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Molecular Mechanisms ◽  
Interaction Network ◽  
Rna Replication ◽  
Viral Fitness ◽  
Dynamics Simulation ◽  
Structural Flexibility ◽  
Residue Interaction

ABSTRACTDrug-resistant viral variants are a major issue in the use of direct-acting antiviral agents in chronic hepatitis C. Ketoamides are potent inhibitors of the NS3 protease, with V55A identified as mutation associated with resistance to boceprevir. Underlying molecular mechanisms are only partially understood. We applied a comprehensive sequence analysis to characterize the natural variability at Val55 within dominant worldwide patient strains. A residue-interaction network and molecular dynamics simulation were applied to identify mechanisms for ketoamide resistance and viral fitness in Val55 variants. An infectious H77S.3 cell culture system was used for variant phenotype characterization. We measured antiviral 50% effective concentration (EC50) and fold changes, as well as RNA replication and infectious virus yields from viral RNAs containing variants. Val55 was found highly conserved throughout all hepatitis C virus (HCV) genotypes. The conservative V55A and V55I variants were identified from HCV genotype 1a strains with no variants in genotype 1b. Topology measures from a residue-interaction network of the protease structure suggest a potential Val55 key role for modulation of molecular changes in the protease ligand-binding site. Molecular dynamics showed variants with constricted binding pockets and a loss of H-bonded interactions upon boceprevir binding to the variant proteases. These effects might explain low-level boceprevir resistance in the V55A variant, as well as the Val55 variant, reduced RNA replication capacity. Higher structural flexibility was found in the wild-type protease, whereas variants showed lower flexibility. Reduced structural flexibility could impact the Val55 variant's ability to adapt for NS3 domain-domain interaction and might explain the virus yield drop observed in variant strains.

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