Efficiency of recombining genes into pBG60 vector. A. Bacterial colonies obtained from recombination reactions. B. Structure of the pBG78 2nd SGP and position of asymmetric colony PCR primer pair. C. Colony PCR of 14 independent clones from colonies in Figure 2A. D. pBG78 plasmids produce replication-competent RNA in BHK cells. BHK cells were transfected with one random pBG78 clone and fluorescence signal was detected 48 hours post transfection.