Table 2.

Virus neutralization by sera and mAbs

Serum or mAb	Immunogen	HIV-1/IIIB		HIV-1/IIIBx
		50%	90%	50%	90%
Serum
Rabbit 1169	IIIB	1,934	132	3,081	287
Rabbit 1170	IIIB	1,869	109	93,756	5,616
Rabbit 1171	8x	>10,240	1,005	>163,840	13,748
Rabbit 1172	8x	1,552	94	64,295	4,426
Human ZT02575		1,616	46	20,894	4,195
Human JT02140		155	11	892	187
		IIIB-V3BaL		8x-V3BaL
		50%	90%	50%	90%
mAb
17b		14	90	2	15
48d		>5,000	>5,000	3	>200*
50.1		95	375	45	610

For serum neutralizations, equivalent amounts of HIV-1 IIIB and IIIBx were used to infect MAGI cells. Infection was determined 72 hr after infection as previously described (33). For mAbs 17b, 48d, and 50.1, equivalent amounts of luciferase reporter viruses bearing the IIIB-V3BaL or 8x-V3BaL Envs were used to infect GHOST-CCR5 cells that were lysed 48 hr after infection. For all infections, virus and serial dilutions of human sera, rabbit sera, or different concentrations of mAbs were mixed for 1 hr before addition to target cells. The dilution of sera or the concentration of mAb (ng/ml) required to neutralize 50% and 90% of input virus is indicated. mAb 48d did not neutralize IIIB-V3BaL under any condition tested, and only 88% neutralization of 8x-V3BaL was achieved by this mAb at a concentration of 200 ng/ml (indicated by ∗ in table). mAb 50.1 is directed against the BaL V3-loop (43).