Plant-derived secretory component forms secretory IgA with shiga toxin 1-specific dimeric IgA produced by mouse cells and whole plants
A key module, secretory component (SC), was efficiently expressed in Arabidopsis thaliana. The plant-based SC and immunoglobulin A of animal or plant origin formed secretory IgA that maintains antigen-binding activity.
Plant expression systems are suitable for scalable and cost-effective production of biologics. Secretory immunoglobulin A (SIgA) will be useful as a therapeutic antibody against mucosal pathogens. SIgA is equipped with a secretory component (SC), which assists the performance of SIgA on the mucosal surface. Here we produced SC using a plant expression system and formed SIgA with dimeric IgAs produced by mouse cells as well as by whole plants. To increase the expression level, an endoplasmic reticulum retention signal peptide, KDEL (Lys-Asp-Glu-Leu), was added to mouse SC (SC-KDEL). The SC-KDEL cDNA was inserted into a binary vector with a translational enhancer and an efficient terminator. The SC-KDEL transgenic Arabidopsis thaliana produced SC-KDEL at the level of 2.7% of total leaf proteins. In vitro reaction of the plant-derived SC-KDEL with mouse dimeric monoclonal IgAs resulted in the formation of SIgA. When reacted with Shiga toxin 1 (Stx1)-specific ones, the antigen-binding activity was maintained. When an A. thaliana plant expressing SC-KDEL was crossed with one expressing dimeric IgA specific for Stx1, the plant-based SIgA exhibited antigen-binding activity. Leaf extracts of the crossbred transgenic plants neutralized Stx1 cytotoxicity against Stx1-sensitive cells. These results suggest that transgenic plants expressing SC-KDEL will provide a versatile means of SIgA production.
KeywordsTransgenic plant Secretory component Secretory immunoglobulin A Plant-based therapeutic antibody
This work was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers JP15H04660 and JP25670063 to YI; JP25·10915 to KN as well as by a research grant from the University of Shizuoka. We thank Mr. N.J. Halewood for language editing services.
Compliance with ethical standards
Conflict of interest
The authors declared that they have no conflict of interest.
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