Table 2.

Receptor interference between MLV Env proteins

Preinfecting virus	Relative titer of challenge virusa
	HEMV	M813	Ecotropic	10A1
None	1	1	1	1
HEMV	<3.1 × 10−6	<6.5 × 10−6	0.42	1.51
M813	<3.1 × 10−6	<6.5 × 10−6	2.03	0.13
Ecotropic	0.54	0.17	<2.6 × 10−6	0.73
Amphotropic	0.50	0.98	0.64	0.84
Polytropic	0.15	0.26	0.20	0.13
10A1	1.08	0.24	0.32	<1.96 × 10−4

^aData were calculated as the ratio of titers on preinfected cells and on uninfected cells. The data represent the averages of the results of at least two independent experiments. The variation between experiments was no more than 64% of the mean value in each case.