Preclinical Studies on Immunogenicity of the HIV-1 p17-Based Synthetic Peptide AT20-KLH Simona Fiorentini 1 Elena Marini 1 Luisa Bozzo 1 Laura Trainini 1 Lamiaa Saadoune 1 Manuela Avolio 1 Angela Pontillo 2 Carlo Bonfanti 1 Paolo Sarmientos 2 Arnaldo Caruso 1 1 Department of Experimental and Applied Medicine, University of Brescia Medical School, Brescia, Italy 2 Primm Srl, Milan, Italy Received 28 May 2004; accepted 8 July 2004 Published online 13 September 2004 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/bip.20130 Abstract: Several studies have suggested that HIV-1 p17 matrix protein may play an important role in AIDS pathogenesis, since anti-p17 antibodies represent a serological marker of disease progression during HIV-1 infection both in adults and children. Moreover, it has been recently reported that the viral protein is capable of significantly increasing the proliferation of preactivated T lymphocytes and the release of proinflammatory cytokines. Recombinant HIV-1 p17 also has induced an increased rate of HIV-1 replication in vitro. All p17 biological activities are exerted after its binding to a specific cellular receptor expressed on activated T lymphocytes. The functional p17 epitope involved in receptor binding was found to be located at the NH 2 -terminal region of the viral protein. Immunization of C57BL/6 mice with a 20 amino acid synthetic peptide representative of the HIV-1 p17 functional region (AT20) coupled to the carrier protein keyhole limpet hemocyanin (KLH) and given in Freund’s incomplete adjuvant, resulted in the development of p17-neutralizing antibodies capable of blocking p17/p17 receptor interaction, and consequently, all biological activities of the viral protein. Moreover, it was possible to skew the humoral response induced by priming mice with AT20-KLH toward cell-mediated immune responses, boosting animals with p17. Our findings may provide a new strategy to develop a synthetic AIDS vaccine based on a potentially effective and safe subunit vaccine against the HIV-1 cytokine-like matrix protein p17. Preclinical immunogenicity data for AT20-KLH provide the basis for evaluation of the peptide-basedvaccine, alone and in combination with p17 or p17 DNA vaccines, in Phase I clinical trials. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 76: 334 –343, 2004 Keywords: HIV-1; p17; synthetic peptide; immunization; neutralizing antibody; vaccine Correspondence to: Simona Fiorentin; email: sfiorent@med. unibs.it Contract grant sponsor: Istituto Superiore di Sanità (ISS) and Medestea Internazionale, Turin, Italy Contract grant number: 45D/1.05 (ISS) Biopolymers (Peptide Science), Vol. 76, 334 –343 (2004) © 2004 Wiley Periodicals, Inc. 334