title: Hierarchy of CD4 T cell epitopes of the ANRS Lipo5 synthetic vaccine relies on the frequencies of pre-existing peptide-specific T cells in healthy donors.
abstract: The Agence National de Recherche sur le SIDA et les hepatitis Lipo5 vaccine is composed by five long fragments of HIV proteins and was recently shown to induce in seronegative volunteers a CD4 T cell response largely dominated by the G2 fragment. To understand this response profile, we submitted the five HIV fragments to HLA-DR-binding assays and evaluated the frequency of naive Lipo5-specific CD4 T lymphocytes in the blood of 22 healthy individuals. We enumerated the Lipo5-specific T cell lines induced in vitro by weekly rounds of specific stimulation. Four peptides and hence not only G2 exhibited a broad specificity for HLA-DR molecules. In contrast, most of the T cell lines specific for Lipo5 reacted with G2, revealing a G2-specific T cell repertoire superior to 2 cells per million, whereas it is close to 0.4 for the other peptides. We also found good cross-reactivity of all the peptides with clade B and C variants and that G2 and P1 are able to recruit T cells that recognize HIV-infected cells. We therefore mainly observed very good concordance between the frequency to individual Lipo5 peptides among vaccinees in a large-scale vaccine trial and the distribution of peptide specificity of the in vitro induced T cell lines. These findings underline the role of the size of the epitope-specific naive repertoire in shaping the CD4 T cell response after vaccination and highlight the value of evaluating the naive repertoire to predict vaccine immunogenicity.
authors: Commissariat à l'Energie Atomique, Institut de Biologie et de Technologies, Service d'Ingénierie Moléculaire des Protéines, F-91191 Gif Sur Yvette, France.
authors: Florence Anne
authors: FA
authors: Castelli
authors: Natacha
authors: N
authors: Szely
authors: Alexis
authors: A
authors: Olivain
authors: Nicoletta
authors: N
authors: Casartelli
authors: Caroline
authors: C
authors: Grygar
authors: Aurélie
authors: A
authors: Schneider
authors: Aurore
authors: A
authors: Besse
authors: Yves
authors: Y
authors: Levy
authors: Olivier
authors: O
authors: Schwartz
authors: Bernard
authors: B
authors: Maillère
mesh_terms: D016915:AIDS Vaccines / Q000276:immunology*; D000595:Amino Acid Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D016384:Consensus Sequence; D003429:Cross Reactions / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D006684:HLA-DR Antigens / Q000737:chemistry / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology*; D011485:Protein Binding / Q000276:immunology; D014614:Vaccines, Synthetic; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000276:immunology
chemical_list: D016915:AIDS Vaccines; D018984:Epitopes, T-Lymphocyte; D006684:HLA-DR Antigens; D010455:Peptides; D014614:Vaccines, Synthetic; D054301:gag Gene Products, Human Immunodeficiency Virus