Hepatitis C virus (HCV) infection is a serious cause of chronic liver disease worldwide with more than 170 million infected individuals at risk of developing significant morbidity and mortality. Current interferon-based therapies are suboptimal especially in patients infected with HCV genotype 1, and they are poorly tolerated, highlighting the unmet medical need for new therapeutics. The HCV-encoded NS3 protease is essential for viral replication and has long been considered an attractive target for therapeutic intervention in HCV-infected patients. Here we identify a class of specific and potent NS3 protease inhibitors and report the evaluation of BILN 2061, a small molecule inhibitor biologically available through oral ingestion and the first of its class in human trials. Administration of BILN 2061 to patients infected with HCV genotype 1 for 2 days resulted in an impressive reduction of HCV RNA plasma levels, and established proof-of-concept in humans for an HCV NS3 protease inhibitor. Our results further illustrate the potential of the viral-enzyme-targeted drug discovery approach for the development of new HCV therapeutics.

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A fragment of the mouse mammary tumor virus (MMTV) promoter was reconstituted from pure histones into a dinucleosome with uniquely positioned octamer cores. Core boundaries for the in vitro-assembled dinucleosome corresponded to the observed in vivo phasing pattern for long terminal repeat nucleosomes A and B. Nuclear factor 1 (NF1), a constituent of the MMTV transcription initiation complex, was excluded from the assembled dinucleosome, whereas the glucocorticoid receptor was able to bind. During transcription of MMTV in vivo, displacement of nucleosome B was necessary to permit assembly of the initiation complex. These results indicate that the nucleoprotein structure of the promoter can provide differential access to sequence-specific DNA-binding proteins and that active chromatin remodeling can occur during transcription activation.The DNA in eucaryotic cells is continuously wrapped on a series of repeating histone octamer cores, giving rise to long polynucleosome arrays. In its path around the nucleosome, the DNA molecule is intimately associated with the histones. The influence that this organization may have on interactions between diffusible control proteins and their recognition sites on the DNA template is poorly understood (for reviews, see references 8, 15, 18, and 25). Regions of DNA hypersensitive to nucleolytic attack are often inferred to be nucleosome free, but it is not clear whether octamer cores are excluded from these regions during some particular period of nucleosome instability, such as replication, or whether preexisting cores can actually be displaced from the template. Furthermore, we now know of several examples for which the octamer cores can be quite precisely positioned, or phased, with regard to specific sequences. In these particular cases, the effect of nucleosome position on the binding of a given transcription factor is of potential significance.Inducible genes present an obvious possibility to examine this issue directly. The yeast PH05 locus and the long terminal repeat (LTR) of mouse mammary tumor virus (MMTV) are two examples of inducible promoters whose chromatin structure has been well characterized (1, 31). The MMTV LTR reproducibly acquires a series of six positioned nucleosomes when introduced in mammalian cells. Although this phasing pattern was originally described with MMTV DNA sequences on highly amplified episomes (27), we have recently established that the same positioning is observed for integrated MMTV sequences (2, 31a). MMTV LTR sequences therefore include information specifying a reproducible nucleoprotein structure, although the mechanism(s) by which this chromatin pattern is acquired are not understood. Changes to this nucleoprotein structure occur quite rapidly, eliminating the elements of cell growth, differentiation, and division that are coincident with the establishment of many previously characterized alterations in chromatin structure. * Several proteins involved in hormone-dependent activation of the MMTV promoter have been characterized, includ...

An assay recapitulating the 3′ processing activity of HIV-1 integrase (IN) was used to screen the Boehringer Ingelheim compound collection. Hit-to-lead and lead optimization beginning with compound 1 established the importance of the C3 and C4 substituent to antiviral potency against viruses with different aa124/ aa125 variants of IN. The importance of the C7 position on the serum shifted potency was established. Introduction of a quinoline substituent at the C4 position provided a balance of potency and metabolic stability. Combination of these findings ultimately led to the discovery of compound 26 (BI 224436), the first NCINI to advance into a phase Ia clinical trial.

Herpes simplex virus infections are the cause of significant morbidity, and currently used therapeutics are largely based on modified nucleoside analogs that inhibit viral DNA polymerase function. To target this disease in a new way, we have identified and optimized selective thiazolylphenyl-containing inhibitors of the herpes simplex virus (HSV) helicase-primase enzyme. The most potent compounds inhibited the helicase, the primase and the DNA-dependent ATPase activities of the enzyme with IC50 (50% inhibitory concentration) values less than 100 nM. Inhibition of the enzymatic activities was through stabilization of the interaction between the helicase-primase and DNA substrates, preventing the progression through helicase or primase catalytic cycles. Helicase-primase inhibitors also prevented viral replication as demonstrated in viral growth assays. One compound, BILS 179 BS, displayed an EC50 (effective concentration inhibiting viral growth by 50%) of 27 nM against viral growth with a selectivity index greater than 2,000. Antiviral activity was also demonstrated for multiple strains of HSV, including strains resistant to nucleoside-based therapies. Most importantly, BILS 179 BS was orally active against HSV infections in murine models of HSV-1 and HSV-2 disease and more effective than acyclovir when the treatment frequency per day was reduced or when initiation of treatment was delayed up to 65 hours after infection. These studies validate the use of helicase-primase inhibitors for the treatment of acute herpesvirus infections and provide new lead compounds for optimization and design of superior anti-HSV agents.