Table 2.

Infectivity on HT1080 cells of pelleted gag pol RNA particles^*

Experiment	G418-resistant colonies, no./ml
gag pol RNA only†	0
gag pol RNA + Polybrene‡	0
gag pol RNA + Lipofectin§	3.6  ×  105
gag pol RNA + Lipofectin + Polybrene	1.5  ×  105
gag pol RNA + RNase + Lipofectin¶	3.2  ×  105
gag pol RNA + DNase + Lipofectin¶	3.5  ×  105
Lipofectin on cells + gag pol RNA‖	2.0  ×  104

^*In a number of experiments, the unpelleted conditioned medium from 293GP-LZRNL cells in the presence of Lipofectin contained 100–400 G418-resistant colony-forming units/ml. 

^†gag pol RNA particles used in this experiment are from 293GP-LZRNL cells and were concentrated as described in the text. 

^‡Polybrene was used at 8 μg/ml (final concentration). 

^§Lipofectin (GIBCO/BRL) was used (8 μg; 8 μl of 1 mg/ml) for infecting cells in 2 ml of medium. 

^¶gag pol RNA particles were treated with RNase and DNase at a final concentration of 10 μg/ml and were incubated at 37°C for 30 min. 

^‖Lipofectin and gag pol RNA particles were added separately to the cells without preincubation.