Comparison of antibody responses to different forms of HIV-1 core antigens by epitope mapping

The specificity of antibodies to HIV-1 capsid (p24CA) and matrix (p17MA) proteins, produced in mice against unprocessed immature assembled polyprotein (wild-type p55 virus-like particles or chimeric p55 virus-like particles) or against the monomeric mature form (rp24CA/rp17MA), was analyzed by a microplate epitope mapping assay using a panel of synthetic peptides covering the entire p24CA plus p17MA sequences of HIV-1LAI. All immunized mice developed anti-p24CA and anti-p17MA antibodies, although the spectrum of specificity of these antibodies was different. Four p24 CA epitopes (residues 176-192, 201-218, 233-253, 285-304) were recognized by anti-rp24CA/rp17MA antibodies, whereas one p17MA epitope (residues 11-25) and one p24CA epitope (residues 176-192) were constantly recognized by anti-p55 virus-like particle antibodies. These results suggest a different specificity pattern of anti-p24CA and anti-p17MA antibodies depending on whether they are produced against the soluble mature form or the immature assembled form of the gag proteins.