title: Inducing efficient cross-priming using antigen-coated yeast particles.
abstract: Saccharomyces cerevisiae stimulates dendritic cells (DCs) and represents a promising candidate for cancer vaccine development. Effective cross-presentation of antigen delivered to DCs is necessary for successful induction of cellular immunity. Here, we present a yeast-based vaccine approach that is independent of yeast's ability to express the chosen antigen, which is instead produced separately and conjugated to the yeast cell wall. The conjugation method is site-specific (based on the SNAP-tag) and designed to facilitate antigen release in the DC phagosome and subsequent translocation for cross-presentation. We demonstrate that nonsite-specific chemical conjugation of the same protein hinders cross-presentation. Phagosomal antigen release was further expedited through the insertion of the invariant chain ectodomain as a linker, which is rapidly cleaved by Cathepsin S. The dose of delivered antigen was increased in several ways: by using yeast strains with higher surface amine densities, by using yeast hulls (cell wall fragments) instead of whole cells, and by conjugating multiple layers of antigen. The novel multilayer conjugation scheme takes advantage of Sfp phosphopantetheinyl transferase and remains site-specific; it enables the antigen dose to grow linearly with the number of layers. We show that whole yeast cells coated with 1 layer of the cancer-testis antigen NY-ESO-1 and yeast hulls bearing 3 layers were able to cross-prime naive CD8 T cells in vitro, with the latter resulting in higher frequencies of antigen-specific cells after 10 days. This cross-presentation-efficient antigen conjugation scheme is not limited to yeast and can readily be applied toward the development of other particulate vaccines.
authors.affiliation: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Shanshan W
authors.initials: SW
authors.lastname: Howland
authors.forename: Takemasa
authors.initials: T
authors.lastname: Tsuji
authors.forename: Sacha
authors.initials: S
authors.lastname: Gnjatic
authors.forename: Gerd
authors.initials: G
authors.lastname: Ritter
authors.forename: Lloyd J
authors.initials: LJ
authors.lastname: Old
authors.forename: Karl Dane
authors.initials: KD
authors.lastname: Wittrup
mesh_terms: D000586:Amination; D017951:Antigen Presentation / Q000276:immunology*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology; D000951:Antigens, Neoplasm / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000956:Antigens, Viral / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D019496:Cancer Vaccines / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D018699:Coated Vesicles / Q000276:immunology; D045142:Cross-Priming / Q000276:immunology*; D003587:Cytomegalovirus / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D004926:Escherichia coli; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D010750:Phosphoproteins / Q000235:genetics / Q000276:immunology; D021381:Protein Transport / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000276:immunology; D013736:Testicular Neoplasms / Q000276:immunology / Q000628:therapy; D014763:Viral Matrix Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000944:Antigens, Differentiation, B-Lymphocyte; D000951:Antigens, Neoplasm; D000956:Antigens, Viral; C104948:CTAG1B protein, human; D019496:Cancer Vaccines; D000949:Histocompatibility Antigens Class II; D008565:Membrane Proteins; D010446:Peptide Fragments; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D014763:Viral Matrix Proteins; C065418:cytomegalovirus matrix protein 65kDa; C045084:invariant chain; D007371:Interferon-gamma; D019853:O(6)-Methylguanine-DNA Methyltransferase