A method for inducing HIV antigen-specific immune responses is disclosed. The method comprises administering to a subject in need thereof a therapeutically effective amount of a chimeric fusion protein comprising: (a) a first polypeptidyl region comprising a Pseudomonas Exotoxin A (PE) binding domain and a PE translocation domain, located at the N-terminus of the fusion protein; and (b) a second polypeptidyl region with a fusion peptide of HIV gp120-C1-C5-gp41 with the amino acid sequence of SEQ ID NO: 7. A method for inducing neutralizing antibodies against HIV-1 is also disclosed.