Abstract: Peptide fragments of the p17 gag protein of HIV-1 from Clade C of from about 30 to about 50 amino acids, including the region extending from position 75 to position 129, raise antibodies recognizing other subtypes, including Clade A, Clade B, Clade E as well as peptides of non-coextensive but overlapping portions of the p17 gag protein. DNA sequences can be used to encode for the peptides of interest.