title: Yeast-derived human immunodeficiency virus type 1 p55(gag) virus-like particles activate dendritic cells (DCs) and induce perforin expression in Gag-specific CD8(+) T cells by cross-presentation of DCs.
abstract: To evaluate the immunogenicity of human immunodeficiency virus (HIV) type 1 p55(gag) virus-like particles (VLPs) released by budding from yeast spheroplasts, we have analyzed the effects of yeast VLPs on monocyte-derived dendritic cells (DCs). Yeast VLPs were efficiently incorporated into DCs via both macropinocytosis and endocytosis mediated by mannose-recognizing receptors, but not the mannose receptor. The uptake of yeast VLPs induced DC maturation and enhanced cytokine production, notably, interleukin-12 p70. We showed that yeast membrane components may contribute to DC maturation partly through Toll-like receptor 2 signaling. Thus, Gag particles encapsulated by yeast membrane may have an advantage in stimulating Gag-specific immune responses. We found that yeast VLPs, but not the control yeast membrane fraction, were able to activate both CD4(+) and CD8(+) T cells of HIV-infected individuals. We tested the effect of cross-presentation of VLP by DCs in two subjects recruited into a long-term nonprogressor-slow progressor cohort. When yeast VLP-loaded DCs of these patients were cocultured with peripheral blood mononuclear cells for 7 days, approximately one-third of the Gag-specific CD8(+) T cells were activated and became perforin positive. However, some of the Gag-specific CD8(+) T cells appeared to be lost during in vitro culture, especially in a patient with a high virus load. Our results suggest that DCs loaded with yeast VLPs can activate Gag-specific memory CD8(+) T cells to become effector cells in chronically HIV-infected individuals, but there still remain unresponsive Gag-specific T-cell populations in these patients.
authors.affiliation: Department of Immunology, National Institute of Infectious Diseases, Shinjuku-ku, Japan. yyokota@nih.go.jp
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Tsunetsugu-Yokota
authors.forename: Yuko
authors.initials: Y
authors.lastname: Morikawa
authors.forename: Maya
authors.initials: M
authors.lastname: Isogai
authors.forename: Ai
authors.initials: A
authors.lastname: Kawana-Tachikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Odawara
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Fernanda
authors.initials: F
authors.lastname: Grassi
authors.forename: Brigitte
authors.initials: B
authors.lastname: Autran
authors.forename: Aikichi
authors.initials: A
authors.lastname: Iwamoto
mesh_terms: D017951:Antigen Presentation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000502:physiology*; D015683:Gene Products, gag / Q000502:physiology*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000502:physiology; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D011498:Protein Precursors / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015398:Signal Transduction; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors; D014771:Virion / Q000502:physiology*
chemical_list: D015683:Gene Products, gag; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D011498:Protein Precursors; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D051193:Toll-Like Receptors; C059767:p55 gag precursor protein, Human immunodeficiency virus 1; D054353:Perforin; D018664:Interleukin-12; D007371:Interferon-gamma