FIG. 2.

In vitro survival of human serum-treated vector from various PCL. Amphotropic or xenotropic retroviral vector packaged by human 293- or canine D17-derived PCL was incubated with serum as described in Materials and Methods. Vector titers were standardized at approximately 10⁴ BCFU/ml, and all vectors were tested against a panel of three human sera. Each vector was tested at least twice, with a representative result shown here. Percent survival is defined relative to FBS-treated controls as for Fig. 1.