Effects of fungal N- and O-linked mannosylation on the immunogenicity of model vaccines

Abstract

Targeting dendritic cell mannose receptors by mannosylating antigens represents a promising vaccination strategy. Using the model antigen ovalbumin (OVA) expressed recombinantly in bacterial and yeast vectors, we have previously demonstrated fungal mannosylation enhances antigen immunogenicity in the context of CD4(+) T cell responses. However, because protection against many tumors and pathogens is thought to require MHC class I-restricted T cell responses, the capacity of differentially mannosylated OVA antigens to induce antigen-specific CD8(+) T cell proliferation was determined. We found that mannosylated yeast-derived OVA antigens were more potent than their unmannosylated counterparts at inducing antigen-specific T cell proliferation. However, the type of mannosylation was critical as addition of extensive O-linked mannosylation increased lymphoproliferative responses while the presence of N-linked mannosylation was associated with decreased responses. Mannosylated OVA failed to stimulate TNF-alpha and IL-12 production from dendritic cells. These data suggest that vaccines incorporating mannosylation must take into account how the mannose groups are linked to the core antigen and may need to include an adjuvant to stimulate cytokine production.

Production of therapeutic antibodies with controlled fucosylation

“…Non-human-derived recombinant proteins hold a risk of severe immunogenicity due to foreign sugar residues, e.g., α-1,3 fucose and β-1,2 xylose residues of plant and hyper-mannose antenna of yeast. 52,53 Gycoengineering of non-mammalian organisms to provide human-type glycosylation with consistent quality is essential for the production of glycosylated biopharmaceuticals. Hence, most biopharmaceutical processes have adopted mammalian cell lines as production hosts to circumvent issues of glycobiopharmaceutical immunogenicity.…”

Role of the Mannose Receptor in a Murine Model ofCryptococcus neoformansInfection

“…DCs were enriched by positive selection with CD11c ϩ magnetic beads. Mitomycin (50 g/ml)-treated DCs from wild-type mice were plated at 1 ϫ 10 4 per well in 96-well round-bottom plates (19,39). Statistics.…”

Delivery of antigen using a novel mannosylated dendrimer potentiates immunogenicity in vitro and in vivo

“…Extensive O-mannosylation of proteins greatly enhanced antigen delivery, and deglycosylation profoundly inhibited T cell responses [7]. The role of mannose residues in antigen delivery was also shown by the mannose polymer, mannan, which enhanced antigen-specific Th1/CTL and Th2/antibody responses in oxidized and reduced forms, respectively [9][10][11][12][13][14][15]. Oxidized mannan conjugated to recombinant MUC1 fusion protein has been used in Phase II/III cancer clinical trials [16][17][18][19].…”

“…Firstly, for nonglycosylated antigens, incorporation of new glycosylation sites entails the expression of recombinant proteins in yeast [6,7,14,20]. This protocol requires complicated characterization and optimization procedures based on genetic engineering methodology.…”