Table 1.

Combination index (CI) and potency increase (%) for inhibition of HIV-1-mediated cell-cell fusion and HIV-1 infection by combination of Enfuvirtide and Sifuvirtide

Inhibition of		Enfuvirtide			Sifuvirtide
	CI#	IC50(nM)		Potency increase	IC50 (nM)		Potency increase
		Alone	In mixture		Alone	In mixture
cell-cell fusion
	0.182	27.29	3.83	612%	7.53	0.96	684%
infection by HIV-1
Bal (R5)	0.449	3.18	0.66	382%	2.70	0.66	309%
IIIB (X4)	0.547	15.63	4.65	236%	7.90	2.32	241%
NL4-3V38A*	0.36	313.04	36.19	765%	1.58	0.45	249%
NL4-3V38A/N42D*	0.123	2,645.98	170.25	1,454%	40.50	2.13	1,801%

^*Enfuvirtide-resistant HIV-1 strain. Data are representative of two separate experiments. Each sample was tested in triplicate and the mean values were presented.

^#CI <1: synergism (<0.1: very strong synergism; 0.1–0.3: strong synergism; 0.3–0.7: synergism; 0.7–0.85: moderate synergism; and 0.85–0.90: slight synergism); and CI > 1: antagonism [7].