Hepatitis C virus (HCV) is a global health problem requiring novel approaches for effective treatment of this disease. The HCV NS5B polymerase has been demonstrated to be a viable target for the development of HCV therapies. β-d-2′-Deoxy-2′-α-fluoro-2′-β-C-methyl nucleosides are selective inhibitors of the HCV NS5B polymerase and have demonstrated potent activity in the clinic. Phosphoramidate prodrugs of the 5′-phosphate derivative of the β-d-2′-deoxy-2′-α-fluoro-2′-β-C-methyluridine nucleoside were prepared and showed significant potency in the HCV subgenomic replicon assay (<1 μM) and produced high levels of triphosphate 6 in primary hepatocytes and in the livers of rats, dogs, and monkeys when administered in vivo. The single diastereomer 51 of diastereomeric mixture 14 was crystallized, and an X-ray structure was determined establishing the phosphoramidate stereochemistry as Sp, thus correlating for the first time the stereochemistry of a phosphoramidate prodrug with biological activity. 51 (PSI-7977...

Discovery of a β-d-2'-deoxy-2'-α-fluoro-2'-β-C-methyluridine nucleotide prodrug (PSI-7977) for the treatment of hepatitis C virus.

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.21781

Telaprevir and pegylated interferon-alpha-2a inhibit wild-type and resistant genotype 1 hepatitis C virus replication in patients.

Drug development for HIV has been the major driving force in antiviral research The strategies that are now being pursued for combating hepatitis C virus (HCV) are remarkably reminiscent of those established for HIV Here, De Clercq reviews aspects of the medicinal chemistry and history of drug design for HIV and HCV

The design of drugs for HIV and HCV

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.22549

Naturally occurring dominant resistance mutations to hepatitis c virus protease and polymerase inhibitors in treatment-naive patients

The availability of the first molecular clone of the hepatitis C virus (HCV) genome allowed the identification and biochemical characterization of two viral enzymes that are targets for antiviral therapy: the protease NS3-4A and the RNA-dependent RNA polymerase NS5B. With the advent of cell culture systems that can recapitulate either the intracellular steps of the viral replication cycle or the complete cycle, additional drug targets have been identified, most notably the phosphoprotein NS5A, but also host cell factors that promote viral replication, such as cyclophilin A. Here, we review insights into the structures of these proteins and the mechanisms by which they contribute to the HCV replication cycle, and discuss how these insights have facilitated the development of new, directly acting antiviral compounds that have started to enter the clinic.

The molecular and structural basis of advanced antiviral therapy for hepatitis C virus infection

In vitro selected Con1 subgenomic replicons resistant to 2'-C-methyl-cytidine or to R1479 show lack of cross resistance.

Human respiratory syncytial virus (RSV) is the primary cause of acute lower respiratory tract infections in children and the elderly worldwide, for which neither a vaccine nor an effective therapy is approved. The entry of RSV into the host cell is mediated by stepwise structural changes in the surface RSV fusion (RSV-F) glycoprotein. Recent progress in structural and functional studies of RSV-F glycoprotein revealed conformation-dependent neutralizing epitopes which have become attractive targets for vaccine and therapeutic development. As RSV-F is present on viral surface in a trimeric form, a trivalent binding interaction between a candidate fusion inhibitor and the respective epitopes on each of the three monomers is expected to prevent viral infection at higher potency than a monovalent or bivalent inhibitor. Here we demonstrate a novel RSV entry inhibitory approach by implementing a trimeric DNA nanostructure as a template to display up to three linear peptide moieties that simultaneously target an epitope on the surface of the prefusion RSV-F protein. In order to design synthetic binding peptides that can be coupled to the DNA nanostructure, the prefusion RSV-F-specific monoclonal antibody (D25) was selected. Complementarity-determining region 3 (CDR3) derived peptides underwent truncation and alanine-scanning mutagenesis analysis, followed by systematic sequence modifications using non-canonical amino acids. The most effective peptide candidate was used as a binding moiety to functionalize the DNA nanostructure. The designed DNA-peptide construct was able to block RSV infection on cells more efficiently than the monomeric peptides, however a more moderate reduction of viral load was observed in the lungs of infected mice upon intranasal application, likely due to dissociation or absorption of the underlying DNA structure by cells in the lungs. Taken together, our results point towards the inhibitory potential of a novel trimeric DNA-peptide based approach against RSV and open the possibility to apply this platform to target other viral infections.

/pdf/prefusion-specific-antibody-derived-peptides-trivalently-1gdq92p7.pdf

Dave Smith

Papers

In vitro selected Con1 subgenomic replicons resistant to 2'-C-methyl-cytidine or to R1479 show lack of cross resistance.

Prefusion-specific antibody-derived peptides trivalently presented on DNA-nanoscaffolds as an innovative strategy against RSV entry