EB inhibits CPXV and MPXV in vitro. A) Yield reduction assay. BSC-1 cells in 24-well plates were infected at a m.o.i. of 0.01 with the indicated virus or with virus pre-treated for one hour with EB. Three days post-infection, cells were harvested by scraping, lysed by repeated cycles of freezing and thawing, and titered on BSC-1 cells. Data represent the average of three independent assays. B) Plaque reduction assay. BSC-1 cells in 6-well plates were infected with approximately 100 pfu virus/well with or without peptide. One hr post-infection, the wells were overlaid with 2% agarose. Plates were fixed 3 days post-infection and plaques were enumerated. Data represent the average of four independent assays. Circles, CPXV; triangles, MPXV. Closed symbols, EB; opens symbols, EBX.