96-well yeast transformations were based on a one-step procedure [34] . The P TET essential yeast strains were grown to saturation overnight at 30uC in 96-well plates (1 ml per well). The cells were pelleted, suspended in 100 ml of transformation mix (0.18 M LiAc, pH 5.5, 36% polyethylene glycol-3350, 90 mM DTT, 0.5 mg/ml sheared salmon sperm DNA, and 20 mg/ml of each plasmid) per well and incubated at 30uC for 60 min. Cells then were heat shocked at 42uC for 20 min, pelleted, re-suspended in 20 ml sterile water per well and 10 ml was plated on solid media. Transformants were selected by complementation of auxotrophic markers. 96-well plates of transformed yeast were re-formatted to contain 48 strains in duplicate per plate so that strains could be analyzed in the absence of dox (allowing essential gene expression) or in the presence of dox (repressing essential gene expression). Strains containing BMV expression plasmids were grown overnight in medium containing raffinose, subcultured to a starting OD 600 = 0.1 in medium containing raffinose 610 mg/ml dox, grown for 24 hr subcultured to a starting OD 600 = 0.1 in medium containing galactose 610 mg/ml dox. Cells were analyzed at 24 hr and 48 hr post gal-induction of virus expression. Strains were grown in 96-well plates for luciferase assays and 14 ml culture tubes for Northern analysis.