SiRNA downregulation of receptor expression. (A) Viral entry was determined in cells transfected with siRNA against entry receptors: nectin-1 (a), HVEM (b), 2-OST (c), nectin-1 and HVEM (d), and nectin-1, HVEM, and 2-OST (e). Cells transfected with an equal amount of scrambled siRNA were used as control. (B) Determination of surface expression of the receptors by cell-ELISA. Cell-ELISA was performed with cells transfected with siRNA against entry receptors nectin-1 (a), HVEM (b), 2-OST (c), nectin-1 and HVEM (d), and nectin-1, HVEM, and 2-OST. Primary antibodies specific to each receptor and FITC-conjugated secondary antibodies were used for the ELISA. Data shown are the means of triplicate measures.