Table 1.

IC₅₀ and fold resistance of multi-drug resistant HIV-1 protease variants.

HIV-1 Proteases	IC50 of HIV-1 protease inhibitors * in nM
	DRV	ATV	LPV	TPV	NFV	APV	SQV	IDV	RTV
NL4-3	0.26	0.19	0.28	0.24	1.6	0.43	0.50	0.47	0.34
MDR 769	0.74	2.9	0.50	0.65	110	4.8	290	120	61
MDR 807	2.0	7.6	1.2	0.63	210	2.9	850	280	14.6
MDR 1385	3.0	4.6	2.3	2.8	230	3.1	29	140	8.0
MDR 3761	0.89	2.2	0.39	0.63	430	4.1	110	210	21

Inhibitor abbreviations: DRV (darunavir), ATV (atazanavir), LPV (lopinavir), TPV (tipranavir), NFV (nelfinavir), APV (amprenavir), SQV (saquinavir), IDV (indinavir), RTV (ritonavir). * The protease inhibitors were requested from the NIH AIDS Research and Reference Reagent Program (www.aidsreagent.org).