TABLE 1.

Virus coreceptor use and sensitivity to neutralization by autologous sera

Virus clonea	Isolation dayb	Coreceptor use					IC90 at time (days) from onset of acute infection symptomsd:
		Infectivity (103 FFU/ml) for NP2/CD4:				Classificationc
		CD4 alone	CCR3	CCR5	CXCR4		20	81	608	957
8.2.50	12	0.3	1,200	1,400	0.3	R3/R5	<10f	10	20	40
8.2.51	12	—e	150	90	0.3	R3/R5	<10	10	80	80
8.4.51	32	0.2	10	270	1	R3/R5	<10	10	40	40
8.8.3	608	—	80	120	0.1	R3/R5	<10	10	80	80
8.8.4	608	—	40	470	2	R3/R5	<10	10	20	20
8.8.8	608	—	6	150	0.4	R3/R5	<10	10	80	80
8.9.B	957	—	110	280	230	R3/R5/X4	<10	<10	<10	<10
8.9.D	957	—	280	700	320	R3/R5/X4	<10	<10	<10	<10
8.9.F	957	—	0.2	1	—	R3/R5	<10	<10	20	10
8.9.H	957	—	140	340	590	R3/R5/X4	<10	<10	<10	<10
8.9.I	957	—	—	740	2	R5	<10	<10	<10	<10
8.9.J	957	—	70	140	150	R3/R5/X4	<10	<10	<10	<10
8.9.K	957	—	—	120	—	R5	<10	<10	<10	<10
YU2g	NAh	—	1,700	4,800	—	R3/R5	NDi	ND	ND	ND
SDM4j	NA	—	9	16	—	R3/R5	<10	<10	<10	<10

^aReplication-competent molecular clone containing gp120 cloned directly from patient peripheral blood mononuclear cells (days 12 and 32) or plasma (days 608 and 957), and inserted into an HIV-1_HXB2 based vector.

^bTime point from which the patient envelope was amplified, in days from onset of symptoms characteristic of primary HIV-1 infection.

^cViruses were classified as dual-or triple-tropic if their titer on alternative coreceptors was within 1.5 log₁₀ of the titer obtained on the dominant coreceptor cell line.

^dTiters are expressed as the reciprocal dilution of serum required to reduce infectivity by ≥90% (IC₉₀), as measured by immunostaining of infected NP2/CD4/CCR5 cells against virus incubated with 10% (1:10) normal human serum.

^e—, ≤100 FFU/ml.

^fLess than 90% neutralization was observed at the lowest serum dilution (1:10) tested.

^gThe titer the of prototypical CCR3-using HIV-1 virus YU2 on NP2 cells has been included for comparison.

^hNA, not applicable.

ⁱND, not determined.

^jSDM4, site-directed mutant 4 (see Fig. 3>).