Table 1. HIV virus strains studied.

Virus isolate	Derivation	HIV clade	Designation	Catalogue #*
AZT Intermediate	Clinical	B	C-B	1073
HIV 92UG029	Clinical	A	C-A	1650
xxHIVLAI	Laboratory	B	L-B	2969
HIV ELI	Laboratory	D	L-D	2521
pNL4-3 gp41(36G) V38A, N42D†	Laboratory	B	TB1	9488
pNL4-3 gp41(36G) N42S†	Laboratory	B	TB2	9495

^*NARRRP catalogue number. All isolates are CXCR4-tropic.

^†T-20 resistant isolates, amino acid changes noted.