FIG. 4.

IM binding and transduction efficiencies of parental and chimeric GPs. The values in the Binding columns show IM binding measured on the indicated cell lines as previously described (19, 27). The percentage of cells showing a positive shift in each representative experiment is indicated in the right-hand part of the graph. Control, secondary antibody only. GP-pseudotyped retroviral vectors were generated as previously described (27) and used to transduce indicated cell types. The titers were determined by fluorescence-activated cell sorting (FACS) as transducing units per ml (TU/ml) and are shown approximated to the nearest factor of 10 (N/A, not available due to lack of activity in A(G4) GP; -, not applicable). FITC, fluorescein isothiocyanate.