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Abstract

This invention discloses the development of a novel platform for recombinant production of bioactive glycoproteins and cancer specific vaccines in plants. Plants and plant cell cultures have been humanized with respect to human mucin-type protein O-glycosylation. A panel of plant cell factories for production of recombinant glycoproteins with designed human O-glycosylation, including an improved cancer vaccine candidate, has been developed. The platform provides basis for i) production of an essentially unlimited array of O-glycosylated human glycoprotein therapeutics, such as human interferon α2B and podoplanin, and ii) for further engineering of additional cancer specific O-glycans on glycoproteins of therapeutical value. Currently, mammalian cells are required for human O-glycosylation, but plants offer a unique cell platform for engineering O-glycosylation since they do not perform human type O-glycosylation. Introduction of O-glycosylation into plant cells requires i) that wild-type plant cells do not modify the target peptide substrates and ii) that the appropriate enzymes and substrates are introduced into of plant cells such that O-glycosylation in the secretory pathway proceed and the glycosylated peptide substrates are preferentially exported to the exterior of the cell or accumulated in the cell. In this invention i) the integrity of transiently and stably expressed ‘mucin’ type target peptides in plants cells has been determined and ii) mucin-type O-glycosylation has been established in plants by transient and stable introduction of a Pseudomonas aeruginosa C4-epimerase, the human polypeptide GalNAc-transferases T2 and T4 (GalNAc-T2 and T4) and various human target peptides or proteins. In the present invention GalNAc-T2 and -T4 have been used to produce a Tn cancer glycoform of MUC1.

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First Claim