A novel cell-based 384-well, label-free assay for discovery of inhibitors of influenza A virus

Fuli Jia¹, Clinton Maddox², Alice Gao³, Louie Tran³, William Severson¹, E Lucile White², Lynn Rasmussen², Anju Dang³, Colleen B Jonsson^1,4

¹Department of Biochemistry and Molecular Biology, Southern Research Institute, Birmingham, AL, USA; ²High-Throughput Screening Center, Southern Research Institute, Birmingham, AL, USA; ³Corning Life Science, Corning, NY, USA; ⁴Department of Microbiology and Immunology, University of Louisville, Louisville, KY, USA

Abstract: Resonance wave-guide (RWG) biosensor technology allows label-free measurements of global cellular responses of the dynamic mass redistribution (DMR). We hypothesized that the DMR signals to extracellular stimulations occurring upon entry of a virus, could provide a new approach for the development of physiologically relevant cell-based assays for screening of small molecules. We explored this technology with influenza virus (A/Udorn/72, H3N2) using MDCK and Vero E6 cell lines in a 384-well format. The MDCK cell line assay was optimized with a fibronectin-coated surface microplate with 6000 cells per well that were infected at a multiplicity of infection (MOI) of 1. Under this set of optimized conditions, for the vero E6 cells, an assay window of 1130 pm shift were obtained at 24 hours. The Vero E6 cell line assay was optimized using a poly-D-lysine-coated surface with seeding density of 6000 cells per well that were infected at a MOI of 5. Under this set of optimized conditions for the MDCK cells, an assay window of >600 units and Z values of 0.6–0.7 were obtained at 24 h. A small library of 1120 compounds was screened using the MDCK, which demonstrates the feasibility of the approach for high-throughput screening.

Keywords: small molecule screening, label-free technology, antivirals