Plant glycans: friend or foe in vaccine development?

Plants are an attractive platform for the production of N-glycosylated subunit vaccines. Wild type glycosylation of plants can be exploited to produce vaccines that antigen-presenting cells effectively take up, degrade and present to cells of the adaptive immune system. Alternatively, glycoengineered plants can be used to produce humanized antigens. Glycoengineering also allows the construction of plants that are able to produce vaccines with custom-made N-glycan structures aiding the construction of vaccines that can be delivered to antigen-presenting cells in a target-oriented approach. The knowledge of innate immune receptors and their role in antigen uptake and presentation is rapidly increasing. In this article, aspects of plant glycosylation and immunology are reviewed and we discuss the possibilities to use this knowledge for the rational design of plant-expressed vaccines.