Envelope glycoprotein is the primary target for human immunodeficiency virus (HIV) vaccine design. The N-terminal and the C-terminal regions of the gp41 interact with each other to form six helix bundle which is responsible for the fusion between the viral membrane and the target cell membrane. Monoclonal antibodies that disrupt the formation of the six helix bundle inhibit the HIV fusion. During the last decade, several human monoclonal antibodies of potent antiviral capacity for neutralizing primary isolates of different clades have been developed. The most broadly neutralizing monoclonal antibodies (mAbs) were screened from HIV-1 seropositive patients and recognized linear epitopes within the membrane proximal region of gp41. In this study, we developed a stable transfected eucaryot cell line expriming a well folded complex. Three mAbs against HIV-1 gp41 were prepared in mice. Our results show that the three mAbs were able to neutralize and inhibit the HIV-1 infection. Two of the mAbs bound to the recombinant folded gp140 and recognized HR1/HR2 regions while one of them recognized linear epitope within the HR2. Interestingly, the results showed that the three mAbs could inhibit the syncytium formation and block the interaction between the HR1 and the HR2 region
