Production of active single-chain antibodies in seeds using trimeric polyoleosin fusion

Abstract

A variety of single-chain variable fragments (scFv) that had been previously developed to the surface epitopes of infective Trichostrongylus colubriformis L3 pathogenic gut nematodes of sheep were fused to a trimeric version of polyoleosin (three head-to-tail repeats of oleosin) and expressed in planta under the control of an Arabidopsis oleosin promoter. The fusion products were found to accumulate in oil bodies (OBs) at the range of 0.25-0.9% of the total seed protein which is comparable with the main 18 kDa isoform of Arabidopsis seed oleosin. Immunofluorescence microscopy and immuno-binding were used to demonstrate that it is possible to both purify the recombinant protein via enrichment for OBs as well as use the OBs emulsion to deliver functional recombinant scFv. This work presents a novel fusion strategy platform to boost the productivity and simplify the delivery of recombinant single chain antibodies and other like proteins.