title: Replication-Competent Foamy Virus Vaccine Vectors as Novel Epitope Scaffolds for Immunotherapy.
abstract: The use of whole viruses as antigen scaffolds is a recent development in vaccination that improves immunogenicity without the need for additional adjuvants. Previous studies highlighted the potential of foamy viruses (FVs) in prophylactic vaccination and gene therapy. Replication-competent FVs can trigger immune signaling and integrate into the host genome, resulting in persistent antigen expression and a robust immune response. Here, we explored feline foamy virus (FFV) proteins as scaffolds for therapeutic B and T cell epitope delivery in vitro. Infection- and cancer-related B and T cell epitopes were grafted into FFV Gag, Env, or Bet by residue replacement, either at sites of high local sequence homology between the epitope and the host protein or in regions known to tolerate sequence alterations. Modified proviruses were evaluated in vitro for protein steady state levels, particle release, and virus titer in permissive cells. Modification of Gag and Env was mostly detrimental to their function. As anticipated, modification of Bet had no impact on virion release and affected virus titers of only some recombinants. Further evaluation of Bet as an epitope carrier was performed using T cell epitopes from the model antigen chicken ovalbumin (OVA), human tyrosinase-related protein 2 (TRP-2), and oncoprotein E7 of human papillomavirus type 16 (HPV16E7). Transfection of murine cells with constructs encoding Bet-epitope chimeric proteins led to efficient MHC-I-restricted epitope presentation as confirmed by interferon-gamma enzyme-linked immunospot assays using epitope-specific cytotoxic T lymphocyte (CTL) lines. FFV infection-mediated transduction of cells with epitope-carrying Bet also induced T-cell responses, albeit with reduced efficacy, in a process independent from the presence of free peptides. We show that primate FV Bet is also a promising T cell epitope carrier for clinical translation. The data demonstrate the utility of replication-competent and -attenuated FVs as antigen carriers in immunotherapy.
authors.affiliation: Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Janet
authors.initials: J
authors.lastname: Lei
authors.affiliation: Division of Translational Immunology, Research Program Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Osen
authors.affiliation: Division of Translational Immunology, Research Program Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Adriane
authors.initials: A
authors.lastname: Gardyan
authors.affiliation: Bioinformatics Core Facility, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Agnes
authors.initials: A
authors.lastname: Hotz-Wagenblatt
authors.affiliation: Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Guochao
authors.initials: G
authors.lastname: Wei
authors.affiliation: Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Gissmann
authors.affiliation: Division of Translational Immunology, Research Program Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Eichmüller
authors.affiliation: Division of Molecular Diagnostics of Oncogenic Infections, Research Program Infection and Cancer, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Löchelt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D045744:Cell Line, Tumor; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D005822:Genetic Vectors / Q000378:metabolism*; D057809:HEK293 Cells; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D007167:Immunotherapy; D007371:Interferon-gamma / Q000276:immunology; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000276:immunology; D010455:Peptides / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016092:Spumavirus / Q000502:physiology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014612:Vaccines / Q000276:immunology*; D015678:Viral Structural Proteins / Q000737:chemistry / Q000378:metabolism; D014779:Virus Replication
chemical_list: D000951:Antigens, Neoplasm; D018984:Epitopes, T-Lymphocyte; D015395:Histocompatibility Antigens Class I; D010455:Peptides; D011993:Recombinant Fusion Proteins; D014612:Vaccines; D015678:Viral Structural Proteins; D007371:Interferon-gamma; D010047:Ovalbumin