FIG. 7.

The presence of the receptor for the transactivating RBD is necessary to confer susceptibility to PERV-A, -B, and -C viruses on nonpermissive hamster cells. CHO cells (control) or the CHO cell derivative (CE-hPit1) that expresses the GALV receptor hPit1 and the ecotropic MuLV receptor mCAT1 were infected by wild-type and fusion-defective mutant LacZ viruses in the absence or presence of GALV RBD or Friend MuLV RBD. The hamster cells were completely resistant to PERVs unless RBDs were present that could bind to receptors on the target cells. The data are representative of three independent experiments. Ga, GALV; GadelH, ΔH GALV; MO, Mo-MuLV; ModelH, ΔH Mo-MuLV; Fr, Friend MuLV.