Abstract: Immunogenic HIV-1 envelope polypeptides are provided, wherein specific amino acid residues are mutated to repress immunosuppression in GP41, thereby boosting the immune response against HIV-1. Specifically, mutation of those specific residues does not affect the fusogenic properties of the viral particle and/or the overall protein structure of the viral envelope protein. The invention further provides peptides and antigens based on the immunogenic HIV-1 envelopes as well as nucleic acid sequences and vectors encoding those. Moreover, biological entities such as viral particles are provided, as well as use of the provided components for preparation of a vaccine against HIV-1/AIDS.