Synergistic efficacy of combination of enfuvirtide and sifuvirtide, the first- and next-generation HIV-fusion inhibitors.

Enfuvirtide and sifuvirtide, the first- and next-generation HIV-fusion inhibitors, contain different functional domains and have distinct target sites. Here, we found that a combination of enfuvirtide and sifuvirtide resulted in potent synergism in inhibiting HIV-1-mediated cell-cell fusion and infection by X4 and R5 as well as enfuvirtide-resistant HIV-1 strains. These findings suggest that application of enfuvirtide and sifuvirtide in combination may improve their efficacy and resistant profile, leading to a reduction of the dosage and frequency of drug use.