Input strand translation of ∆ -NS1-WNV in BHK21-VEEV-empty and BHK21-VEEV-WNV-NS1 cells. An MOI of 5 of ∆-NS1-WNV was incubated at 37°C with (left) BHK21-VEEV-empty or (right) BHK21-WNV-VEEV-NS1 cells. At 1, 2, or 12 hours, cells were starved in cysteine-methionine deficient medium for 30 minutes, and then pulse-labeled with 35S-cysteine-methionine for an additional 30 minutes. Cells were lysed (see Methods), immunoprecipitation was performed with an anti-E protein MAb, proteins were electrophoresed, and gels were subjected to autoradiography. The arrow indicates the mobility of the E protein band. The results are representative of three independent experiments.