(A) Neighbor joining trees created with representatives from all four CoV genogroups showing the genetic similarity of CoV nsp12 (RNA dependent RNA polymerase) and CoV Spike glycoprotein, which mediates host tropism and entry into cells. Text color of virus strain label corresponds to virus host species on left. (B) Top panel, antiviral efficacy of GS-5734 in HAE cells against group 1 human circulating CoV (hCoV-NL63) and bat CoV from group 2b (HKU3, SHC014, WIV1) and 2c (HKU5). HAE cells were infected at an MOI of 0.5 in the presence of GS-5734 in duplicate. After 48hr, virus produced was titrated via plaque assay. Each data point represents the titer per culture. Bottom panel, quantitative RT-PCR for CoV ORF1 and ORFN mRNA in total RNA from the cultures in top panel.