TABLE 1.

JSRV vector transduction rate is increased by Polybrene but not by Survanta^a

Vector transduction conditions	JSRV vector titer (FFU/ml)	Fold increase	Amphotropic vector titer (FFU/ml)	Fold increase
No additions	8.1 × 103	1	1.6 × 104	1
Polybrene	3.1 × 105	38	1.4 × 105	9
Survanta	9.7 × 103	1.2	1.0 × 104	0.6
Polybrene + Survanta	3.5 × 105	43	7.9 × 104	5

^aSSF and HT-1080 cells were plated at 10⁵ cells per 3.5-cm-diameter well of six-well plates. The following day the culture medium was removed and replaced with either medium alone or medium containing 5 μg of Polybrene per ml, 10 μg of Survanta per ml, or both 5 μg of Polybrene and 10 μg of Survanta per ml. JSRV [LAPSN(PJ4)] or amphotropic [LAPSN(PA317)] vectors were then added to the SSF and HT-1080 cells, respectively, and the cells were fixed and stained for alkaline phosphatase-positive foci 3 days later. Results are means from two to three experiments. Titer determinations in separate experiments varied by less than twofold.