Conditioned media induce pH-independent Eco-MLV infection.

(A) NIH3T3 cells were pretreated with ConA, and were inoculated with the Eco-MLV vector diluted with fresh or conditioned media. The transduction units obtained with DMSO-treated cells were set to 100%. These experiments were repeated in triplicate, and results are shown as the mean +/− SD. Asterisks indicate statistically significant differences compared to the value from the DMSO-treated cells. (B) Cathepsin B (left panel) and L (right panel) activities of TE671 and XC cell conditioned media were measured at pH 5.0 or 7.0. Fluorescence intensities were indicated. This experiment was repeated three times, and results are shown as means +/− SD.