title: Fine characterization of a V3-region neutralizing epitope in human immunodeficiency virus type 2.
abstract: We have previously identified two distinct antigenic sites in the third variable region (V3) of human immunodeficiency virus type 2 (HIV-2) corresponding to the principal neutralizing determinant (PND) of HIV-1, the conserved Phe-His-Ser-Gln and Trp-Cys-Arg motifs (positions 315-318 and 329-331), which possibly interact to form a discontinuous antigenic site. The aim of this study was to further identify and characterize the immunogenic sites in the V3-loop of HIV-2 that are important in the binding of neutralizing antibodies and to study in detail the importance of different configurations of peptides corresponding to this region. Peptides representing modifications of the V3-region of HIV-2(SBL6669-ISY) were used for immunization of guinea pigs. With one exception, both the Phe-His-Ser-Gln and the Trp-Cys-Arg motifs were required in the peptide sequences to obtain neutralizing hyperimmune guinea pig sera, and the highest titers were obtained after immunization with 20-27 amino acids (aa) long peptides. Neither substitutions nor deletions of residues between the two motifs, nor the addition of peptide sequences representing a T-helper epitope improved the induction of neutralizing antibodies. Computer simulation modeling revealed that the Phe-315, His-316, Trp-329 and Cys-330 are likely to participate in the formation of a discontinuous epitope. Taken together, these data support the hypothesis that the well conserved motifs FHSQ (positions 315-318) and WCR (positions 329-331) of the HIV-2(SBL6669) V3 region are important targets for neutralizing antibodies, and this may have implications for the design of a future HIV-2 vaccine.
authors.affiliation: Microbiology and Tumorbiology Center, Karolinska Institute, Stockholm, Sweden. andreas.morner@mtc.ki.se
authors.forename: A
authors.initials: A
authors.lastname: Mörner
authors.forename: A
authors.initials: A
authors.lastname: Achour
authors.forename: M
authors.initials: M
authors.lastname: Norin
authors.forename: R
authors.initials: R
authors.lastname: Thorstensson
authors.forename: E
authors.initials: E
authors.lastname: Björling
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D015686:Gene Products, env / Q000378:metabolism; D006168:Guinea Pigs; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000276:immunology*; D015498:HIV-2 / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007106:Immune Sera / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology*; D011485:Protein Binding; D011487:Protein Conformation; D011498:Protein Precursors / Q000378:metabolism; D014611:Vaccination; D054299:env Gene Products, Human Immunodeficiency Virus
chemical_list: D000939:Epitopes; D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D007106:Immune Sera; D010446:Peptide Fragments; D011498:Protein Precursors; D054299:env Gene Products, Human Immunodeficiency Virus; C066316:gp125 envelope protein, Human immunodeficiency virus 2