Enfuvirtide is an envelope fusion inhibitor used to treat HIV-infected patients. The peptide binds to the HIV envelope glycoprotein gp41 and prevents viral fusion with the target cell membrane. Enfuvirtide (Fuzeon/Roche) was approved by the FDA in 2003.Ac-Tyr-Thr-Ser-Leu-Ile-His-Ser-Leu-Ile-Glu-Glu-Ser-Gln-Asn-Gln-Gln-Glu-Lys-Asn-Glu-Gln-Glu-Leu-Leu-Glu-Leu-Asp-Lys-Trp-Ala-Ser-Leu-Trp-Asn-Trp-Phe-NH2 or H-YTSLIHSLIEESQNQQEKNEQELLELDKWASLWNWF-NH2