Fig. 4.

Representation of different technological innovations for recombinant secretory IgA production. a In vitro reconstitution, a process of auto-association of secretory component (SC) and dimeric IgA (dIgA) in solution; b production of monomeric (mIgA), dimeric (dIgA) and secretory (SIgA) IgA in CHO cells by transfection of respective constituting protein-chain encoding genes; c method for generating stable plant lines expressing SIgA by sequential crossing of plants expressing the constituting elements (indicated below the plants); d transient expression in Nicotiana benthamiana leaves via a needle-less syringe based infiltration of transformed Agrobacterium tumefaciens for rapid production of SIgAs; e Co-transformation of Arabidopsis with VHH-IgA, J chain and SC to produce lines expressing VHH-IgA based, monomeric (mVHH-IgA), dimeric (dVHH-IgA) and simplified secretory IgA (sSIgA). The protein domains and the gene elements coding for the heavy chain are indicated in light blue, the light chain in lime-green, the joining chain (J chain) in brown, the SC in cyan, and the VHH domain in magenta