The invention relates to a truncated form of the HIV-1 p17 protein, designated as AT96, which consists of the residues from 1 to 96 of the full-length p17 protein, as well as the corresponding nucleic acid sequences. The truncated AT96 protein has the same immunological features as the full-length p17 protein but at the same time is devoid of the typical detrimental biological activities of the HIV-1 p17 protein.