The present invention relates to an isolated immunogenic peptide chimera comprising a first peptide moiety comprising the amino acid sequence of SEQ ID NO: 1, or at least a contiguous 5 amino acid fragment thereof, a second peptide moiety comprising the amino acid sequence of SEQ ID NO: 2, or at least a contiguous 5 amino acid fragment thereof, and a linker joining the first and second peptide moieties, wherein the first peptide moiety is at the immunogenic peptide chimeras N-terminus and the second peptide moiety is at the immunogenic peptide chimeras C-terminus. Also disclosed is an immunogenic peptide including the amino acid sequence corresponding to SEQ ID NO: 6, or at least a contiguous 5 amino acid fragment thereof, having a length sufficient to form β-hairpin structure. A further aspect of the present invention is an immunogenic peptide including the amino acid sequence corresponding to SEQ ID NO: 15, or at least a contiguous 5 amino acid fragment thereof, capable of folding into an alpha-helical structure. These immunogenic peptides can be inserted into an immunogenic scaffold protein to form an immunogenic polypeptide. The immunogenic peptides or immunogenic polypeptides can be used in an immunogenic vaccine composition and in methods of inducing a neutralizing antibody response, or inducing a protective and non-neutralizing antibody response, or protective antibodies, against HIV-1 gp120 in a subject. Isolated antibodies and methods of detecting are also disclosed.
