Recent advances in prevention and treatment of hepatitis C virus infections

Molecular Techniques for Blood and Blood Product Screening

Blood product safety is a high priority for manufacturing industries, hospitals, and regulatory agencies. An important step in ensuring safety is the screening of donated blood for infectious diseases. Molecular technologies for screening infectious diseases have improved remarkably over the years. Molecular biological assay significantly reduced the risk of transfusion-transmitted infections. Unlike previous methods, molecular technologies for screening infectious diseases are specific, efficient, easy to use, and economical. A new era in molecular biology is coming to the field of blood safety.

Synthesis and SAR optimization of diketo acid pharmacophore for HCV NS5B polymerase inhibition

Hepatitis C virus (HCV) NS5B polymerase is a key target for anti-HCV therapeutics development. Here we report the synthesis and biological evaluation of a new series of α,γ-diketo acids (DKAs) as NS5B polymerase inhibitors. We initiated structure-activity relationship (SAR) optimization around the furan moiety of compound 1a [IC(50) = 21.8 μM] to achieve more active NS5B inhibitors. This yielded compound 3a [IC(50) = 8.2 μM] bearing the 5-bromobenzofuran-2-yl moiety, the first promising lead compound of the series. Varying the furan moiety with thiophene, thiazole and indazole moieties resulted in compound 11a [IC(50) = 7.5 μM] bearing 3-methylthiophen-2-yl moiety. Finally replacement of the thiophene ring with a bioisosteric phenyl ring further improved the inhibitory activity as seen in compounds 21a [IC(50) = 5.2 μM] and 24a [IC(50) = 2.4 μM]. Binding mode of compound 24a using glide docking within the active site of NS5B polymerase will form the basis for future SAR optimization.

Structure-based virtual screening, synthesis and SAR of novel inhibitors of hepatitis C virus NS5B polymerase

Hepatitis C virus (HCV) NS5B polymerase is a key target for the development of therapeutic agents aimed at the treatment of HCV infections. Here we report on the identification of novel allosteric inhibitors of HCV NS5B through a combination of structure-based virtual screening, synthesis and structure-activity relationship (SAR) optimization approach. Virtual screening of 260,000 compounds from the ChemBridge database against the tetracyclic indole inhibitor binding pocket of NS5B (allosteric pocket-1, AP-1), sequentially down-sized the library by 4 orders of magnitude to yield 23 candidates. In vitro evaluation of the NS5B inhibitory activity of the in-silico selected compounds resulted in 17% hit rate, identifying two novel chemotypes. Of these, compound 3, bearing the rhodanine scaffold, proved amenable for productive SAR exploration and synthetic modification. As a result, 25 derivatives that exhibited IC₅₀ values ranging from 7.7 to 68.0 μM were developed. Docking analysis of lead compound 28 within the tetracyclic indole- and benzylidene-binding allosteric pockets (AP-1 and AP-3, respectively) of NS5B revealed topological similarities between these two pockets. Compound 28, a novel rhodanine analog with NS5B inhibitory potency in the low micromolar level range may be a promising lead for future development of more potent NS5B inhibitors.

Molecular Techniques for Blood and Blood Product Screening

“Blood banking has become a manufacturing industry, an industry that must conform to high standards and quality control requirements comparable to those of pharmaceutical companies or other regulated industries,” said David A. Kessler, M.D., former FDA commissioner (Revelle, 1995). Screening donated blood for infectious diseases that can be transmitted through blood transfusion is very important in ensuring safety. The United States has the safest blood supply in the world (Revelle, 1995), and the Food and Drug Administration (FDA) is striving to keep it safe by decreasing the risk of infectious disease transmission. The regulatory agency is continuously updating its requirements and standards for collecting and processing blood. An important step in ensuring safety is the screening of donated blood for infectious diseases. In the United States, tests for infectious diseases are routinely conducted on each unit of donated blood, and these tests are designed to comply with regulatory requirements (Table 21.1). The field of clinical microbiology and virology is now moving into the focus of molecular technology. Currently, nucleic acid testing techniques have been developed to screen blood and plasma products for evidence of very recent viral infections that could be missed by conventional serologic tests. It is time for all blood safety staffs to use molecular detection techniques. This approach can significantly aid in blood safety to reduce the risk of transmission of serious disease by transfusion. This chapter will review the current antigen/antibody–based technology, molecular biological technology, and published regulatory policy data for blood safety.