Table 1.

Infection of mouse NIH 3T3 and hamster CHO cells expressing the xenotropic receptor by different LAPSN pseudotypes

LAPSN pseudotype	LAPSN vector titer on NIH 3T3 cells expressing the following receptors, cfu/ml			LAPSN vector titer on CHO cells expressing the following receptors, cfu/ml
	None	Xenotropic	RD114/type D	None	Xenotropic	RD114/type D	Amphotropic
Xenotropic	<2	4  × 104	<2	50	1.5  × 106	30	20
Polytropic	1.5  × 108	2  × 108	1.5  × 108	<2	2  × 104	<2	<2
Amphotropic	6  × 106	8  × 106	9  × 106	<2	<2	<2	4 × 106
RD114	<2	<2	2  × 104	<2	<2	3 × 103	<2
GALV	<2	<2	<2	60	50	50	20

NIH 3T3 and CHO cells expressing the XPR1 xenotropic, RD114/type D (31), amphotropic (26), or no exogenous receptor (empty vector only) were generated by transduction of the cells with L(XPR1)SN, L(RDR)SN, L(Pit2)SN, or LXSN, respectively, followed by selection in G418 to generate polyclonal populations. For assay, 10⁵ target cells were plated in 35-mm-diameter dishes on day 1. On day 2, the medium was replaced with 1 ml of medium containing 4 μg/ml Polybrene and serial dilutions of indicated pseudotypes of the LAPSN vector. Cells were stained for alkaline phosphatase⁺ foci on day 4 as described (26). Results are average values from duplicate dishes in a representative experiment.