 Enfuvirtide FuzeonTM was recently approved as an HIV-1 fusionentry inhibitor, a new class of treatment that prevents fusion of the HIV-1 virus to the CD4 cell membrane by preventing the conformational changes required for this fusion. Since the mechanism of action of Enfuvirtide is different from other classes of anti-HIV medication, it is effective in patients who have failed other therapies due to emergence of resistant virus. However, a recent study demonstrated the emergence of resistance to Enfuvirtide due to a mutation in viral gp41. 