Nucleotide sequences of retroviral antigens HIV-1 group (or subgroup) or.

The invention relates to a protein of retroviruses HIV-1 group (or subgroup) O, O polypeptide or peptide natural or synthetic comprising at least a portion of said protein, SUSCEPTIBLE TO BE RECOGNIZED BY ANTIBODY SUSCEPTIBLE TO BE ISOLATED FROM SERUM obtained after infection with an HIV-1 group O VAU strain, or a strain HIV-1 group (or subgroup, or DUR.