(A) Isolation of BHK cells displaying M2e-specific scFv. BHK cells were infected with the scFv-κ Sindbis virus library at an MOI of 0.1 and stained as indicated. Sindbis-positive cells displaying M2e-specific scFv in the upper right quadrant were sorted. Note that cells in the lower right quadrant (M2e-positive but Sindbis-negative) are infected with a replication-defective form of the virus. (B) Rescreening for M2e-specific antibodies. Two to three days after sorting, BHK cells in wells showing signs of viral infection were analyzed for binding to RNAse-M2e. Nine representative samples are shown, including cells showing strong binding (D005, E040, F052), intermediate binding (D036, E012, F058), or no binding (D021, E016, F080).