Roger Maurice

Peptide-based inhibitors of the hepatitis C virus serine protease

Hexapeptide DDIVPC-OH is a competitive inhibitor of the hepatitis C virus (HCV) NS3 protease complexed with NS4A cofactor peptide. This hexapeptide corresponds to the N-terminal cleavage product of an HCV dodecapeptide substrate derived from the NS5A/5B cleavage site. Structure-activity studies on Ac-DDIVPC-OH revealed that side chains of the P4, P3 and P1 residues contribute the most to binding and that the introduction of a D-amino acid at the P5 position improves potency considerably. Furthermore, there is a strong preference for cysteine at the P1 position and conservative replacements, such as serine, are not well tolerated.

Studies on the C-terminal of hexapeptide inhibitors of the hepatitis C virus serine protease

Replacement of the C-terminal carboxylic acid functionality of peptide inhibitors of hepatitis C virus (HCV) NS3 protease (complexed with NS4A peptide cofactor) by activated carbonyl groups does not produce any substantial increase in potency. These latter inhibitors also inhibit a variety of other serine and cysteine proteases whereas the carboxylic acids are specific. Norvaline was identified as a chemically stable replacement for the P1 residue of Ac-DDIVPC-OH which was also compatible with activated carbonyl functionalities.

Highly potent and selective peptide-based inhibitors of the hepatitis C virus serine protease : Towards smaller inhibitors

Structure-activity studies on a hexapeptide N-terminal cleavage product of a dodecamer substrate led to the identification of very potent and highly specific inhibitors of the HCV NS3 protease/NS4A cofactor peptide complex. The largest increase in potency was accomplished by the introduction of a (4R)-naphthalen-1-yl-4-methoxy substituent to the P2 proline. N-Terminal truncation resulted in tetrapeptides containing a C-terminal carboxylic acid, which exhibited low micromolar activity against the HCV serine protease.

Sensitivity of NS3 Serine Proteases from Hepatitis C Virus Genotypes 2 and 3 to the Inhibitor BILN 2061

ABSTRACT Hepatitis C virus (HCV) displays a high degree of genetic variability. Six genotypes and more than 50 subtypes have been identified to date. In this report, kinetic profiles were determined for NS3 proteases of genotypes 1a, 1b, 2ac, 2b, and 3a, revealing no major differences in activity. In vitro sensitivity studies with BILN 2061 showed a decrease in affinity for proteases of genotypes 2 and 3 (Ki, 80 to 90 nM) compared to genotype 1 enzymes (Ki, 1.5 nM). To understand the reduced sensitivity of genotypes 2 and 3 to BILN 2061, active-site residues in the proximity of the inhibitor binding site were replaced in the genotype-1b enzyme with the corresponding genotype-2b or -3a residues. The replacement of five residues at positions 78, 79, 80, 122, and 132 accounted for most of the reduced sensitivity of genotype 2b, while replacement of residue 168 alone could account for the reduced sensitivity of genotype 3a. BILN 2061 remains a potent inhibitor of these non-genotype-1 NS3-NS4A proteins, with Ki values below 100 nM. This in vitro potency, in conjunction with the good pharmacokinetic data reported for humans, suggests that there is potential for BILN 2061 as an antiviral agent for individuals infected with non-genotype-1 HCV.

Solution Structure of Substrate-based Ligands When Bound to Hepatitis C Virus NS3 Protease Domain

The interactions of the NS3 protease domain with inhibitors that are based on N-terminal cleavage products of peptide substrates were studied by NMR methods. Transferred nuclear Overhauser effect experiments showed that these inhibitors bind the protease in a well defined, extended conformation. Protease-induced line-broadening studies helped identify the segments of inhibitors which come into contact with the protease. A comparison of the NMR data of the free and protease-bound states suggests that these ligands undergo rigidification upon complexation. This work provides the first structure of an inhibitor when bound to NS3 protease and should be valuable for designing more potent inhibitors.

In Vitro Resistance Profile of the Hepatitis C Virus NS3 Protease Inhibitor BI 201335

ABSTRACT The in vitro resistance profile of BI 201335 was evaluated through selection and characterization of variants in genotype 1a (GT 1a) and genotype 1b (GT 1b) replicons. NS3 R155K and D168V were the most frequently observed resistant variants. Phenotypic characterization of the mutants revealed shifts in sensitivity specific to BI 201335 that did not alter susceptibility to alpha interferon. In contrast to macrocyclic and covalent protease inhibitors, changes at V36, T54, F43, and Q80 did not confer resistance to BI 201335.