ABSTRACT
The
RNA-dependent RNA polymerase of hepatitis C virus (HCV) is the
catalytic subunit of the viral RNA amplification machinery and is an
appealing target for the development of new therapeutic agents against
HCV infection. Nonnucleoside inhibitors based on a benzimidazole
scaffold have been recently reported. Compounds of this class are
efficient inhibitors of HCV RNA replication in cell culture, thus
providing attractive candidates for further development. Here we report
the detailed analysis of the mechanism of action of selected
benzimidazole inhibitors. Kinetic data and binding experiments
indicated that these compounds act as allosteric inhibitors that block
the activity of the polymerase prior to the elongation step. Escape
mutations that confer resistance to these compounds map to proline 495,
a residue located on the surface of the polymerase thumb domain and
away from the active site. Substitution of this residue is sufficient
to make the HCV enzyme and replicons resistant to the inhibitors.
Interestingly, proline 495 lies in a recently identified noncatalytic
GTP-binding site, thus validating it as a potential allosteric site
that can be targeted by small-molecule inhibitors of HCV
polymerase.
Detection of Anti-Hepatitis C virus and Hepatitis C virus RNA in Dried Blood Spot Specimens using Whatman no. 1 Filter Paper
