TABLE 2.

Independent effects of coreceptor specificity and T-20 target site in HR1

Virus	Coreceptora	HR1b	IC50 (μg/ml)	Mean IC50c (μg/ml)	SD	Changed
NL-FLV3	R5	DIV	0.443	0.421	0.02	0.0
NFN-SM	R5	DIV	0.397
NFN-SP	R5	DIV	0.423
NL4.3	X4	DIV	0.120	0.125	0.01	−0.5
NL(Stu)Xba	X4	DIV	0.130
MX-FLV3	R5	GIV	0.056	0.032	0.01	−1.1
NFN-SX	R5	GIV	0.047
NLHX SF2 V3	R5	GIV	0.025
NLHX ADA V3B	R5	GIV	0.019
NLHX ADA V3	R5	GIV	0.024
NLHX SF162 V3	R5	GIV	0.032
NFN-MX	X4	GIV	0.008	0.007	0.00	−1.8
NLHX	X4	GIV	0.005

^aCoreceptor specificity of each chimeric virus. 

^bAmino acids 36 to 38 in the gp41 N-terminal heptad repeat that comprise a critical T-20 target site. 

^cCalculated for chimeric viruses grouped by coreceptor specificity and T-20 target site. 

^dIndependent effects of coreceptor specificity and T-20 target site represented on a log₁₀ scale using group mean IC₅₀s.