Discovery and preclinical evaluation of potent, orally bioavailable, metabolically stable cyclopropylindolobenzazepine acylsulfonamides as thumb site 1 inhibitors of the hepatitis c virus NS5B RNA-dependent, RNA polymerase.

Herein, we describe the synthesis, antiviral structure-activity relationships (SAR), metabolic stability, and pharmacokinetic (PK) properties for a series of cyclopropylindolobenzazepine acylsulfonamide HCV NS5B polymerase inhibitors. Optimization of SAR, metabolic stability and PK led to the identification of compound 19 which was advanced into pre-IND enabling toxicology studies.

Cell-based antiviral screening against coronaviruses: developing virus-specific and broad-spectrum inhibitors.

To combat the public health threat from emerging coronaviruses (CoV), the development of antiviral therapies with either virus-specific or pan-coronaviral activities is necessary. An important step in antiviral drug development is the screening of potential inhibitors in cell-based systems. The recent emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) necessitates adapting methods that have been used to identify antivirals against severe acute respiratory syndrome coronavirus (SARS-CoV) and developing new approaches to more efficiently screen antiviral drugs. In this article we review cell-based assays using infectious virus (BSL-3) and surrogate assays (BSL-2) that can be implemented to accelerate antiviral development against MERS-CoV and future emergent coronaviruses. This paper forms part of a series of invited articles in Antiviral Research on "From SARS to MERS: 10years of research on highly pathogenic human coronaviruses."

Characterization of the polyadenylation activity in a replicase complex from Bamboo mosaic virus-infected Nicotiana benthamiana plants.

Bamboo mosaic virus (BaMV) has a positive-sense single-stranded RNA genome with a 5' cap and a 3' poly(A) tail. To characterize polyadenylation activity in the BaMV replicase complex, we performed the in vitro polyadenylation with various BaMV templates. We conducted a polyadenylation activity assay for BaMV RNA by using a partially purified BaMV replicase complex. The results showed that approximately 200 adenylates at the 3' end of the RNA were generated on the endogenous RNA templates. Specific fractions derived from uninfected Nicotiana benthamiana plants enhanced the polyadenylation activity, implying that host factors are involved in polyadenylation. Furthermore, polyadenylation can be detected in newly synthesized plus-strand RNA in vitro when using the exogenous BaMV minus-strand minigenome. For polyadenylation on the exogenous plus-strand minigenome, the 3' end requires at least 4A to reach 22% polyadenylation activity. The results indicate that the BaMV replicase complex recognizes the 3' end of BaMV for polyadenylation.