A Phenotypic High-Throughput Screen with RSV-Infected Primary Human Small Airway Epithelial Cells (SAECs)

Respiratory syncytial virus (RSV) is a commonly occurring pathogen that can cause severe disease in children, the elderly, and immunocompromised individuals with a large, unmet clinical need. We developed a high-throughput, primary cell-based antiviral RSV assay to enable identification of small molecules using cytopathic effect (CPE) as a phenotypic end point. To provide increased biological relevance, we developed our assay with primary human small airway epithelial cells (SAECs), which originate from known sites of RSV infection and replication instead of a more traditional immortalized cell line. Using purchased low-passage cells, cost-effective large-scale culture methods were developed to provide assay-ready frozen SAECs. A high-throughput screening campaign using the GSK Screening Collection was performed. The screen was executed in 384-well plates over a 12-week period with an average Z' of 0.5. The screen yielded 17 post-entry hits with activity in the primary cells, which were not active in immortalized cells. Potencies for this class of compounds were equal between the primary and immortalize cell lines. For entry inhibitors, the number was much lower, with increased potency observed in immortalized cells. This is the first known use of frozen primary human cells for an RSV high-throughput screening phenotypic campaign.

Discovery of selective small molecule type III phosphatidylinositol 4-kinase alpha (PI4KIIIα) inhibitors as anti hepatitis C (HCV) agents

Hepatitis C virus (HCV) assembles many host cellular proteins into unique membranous replication structures as a prerequisite for viral replication, and PI4KIIIα is an essential component of these replication organelles. RNA interference of PI4KIIIα results in a breakdown of this replication complex and cessation of HCV replication in Huh-7 cells. PI4KIIIα is a lipid kinase that interacts with the HCV nonstructural 5A protein (NS5A) and enriches the HCV replication complex with its product, phosphoinositol 4-phosphate (PI4P). Elevated levels of PI4P at the endoplasmic reticulum have been linked to HCV infection in the liver of HCV infected patients. We investigated if small molecule inhibitors of PI4KIIIα could inhibit HCV replication in vitro. The synthesis and structure-activity relationships associated with the biological inhibition of PI4KIIIα and HCV replication are described. These efforts led directly to identification of quinazolinone 28 that displays high selectivity for PI4KIIIα and potently inhibits HCV replication in vitro.

Substituted N-{3-[(1,1-dioxido-1,2-benzothiazol-3-yl)(phenyl)amino]propyl}benzamide analogs as potent Kv1.3 ion channel blockers. Part 2

We report the synthesis and in vitro activity of a series of novel substituted N-{3-[(1,1-dioxido-1,2-benzothiazol-3-yl)(phenyl)amino]propyl}benzamide analogs. These analogs showed potent inhibitory activity against Kv1.3. Several demonstrated similar potency to the known Kv1.3 inhibitor PAP-1 when tested under the IonWorks patch clamp assay conditions. Two compounds 13i and 13rr were advanced further as potential tool compounds for in vivo validation studies.

N-{3-[(1,1-dioxido-1,2-benzothiazol-3-yl)(phenyl)amino]propyl}benzamide analogs as potent Kv1.3 inhibitors. Part 1

We report the synthesis and in vitro activity of a series of novel N-{3-[(1,1-dioxido-1,2-benzothiazol-3-yl)(phenyl)amino]propyl}benzamide analogs. These analogs showed potent inhibitory activity against Kv1.3. Several compounds, including compound 8b, showed similar potency to the known Kv1.3 inhibitor PAP-1 when tested under the IonWorks patch clamp assay conditions.

Development of scintillation-proximity assays for alpha adrenoceptors

Binding assays have long been used to determine compound affinity and selectivity for various seven-transmembrane receptors. Over time, the degree of complexity has significantly reduced, whereas the throughput of the various assays has greatly increased. In this article, we detail the development of a filter-binding assay and a scintillation-proximity assay (SPA) designed to quantify a compound's affinity for the three alpha1-adrenoceptor subtypes, alpha1A, alpha1B, and alpha1D. The various components of the assays such as ease of assay performance, robustness, cost, and generation of radioactive waste are compared and contrasted. On the basis of the results, the SPA offers many advantages of high-throughput assay formats over the traditional filter-binding assay. To follow up on the success of the alpha1-adrenoceptor SPA, SPAs for the three alpha2-adrenoceptors were developed and are detailed in this article. Affinity data generated for a select number of alpha2 compounds agree with reported literature values. These assays, like those for alpha1 subtypes, are very amenable to high-throughput screening campaigns. In conclusion, scintillation-proximity assays offer significant advantages over filter-binding assays.