Abstract
Zein is a water-insoluble polymer from maize seeds that has been widely used to produce carrier particles for the delivery of therapeutic molecules. We encapsulated a recombinant model vaccine antigen in newly formed zein bodies in planta by generating a fusion construct comprising the ectodomain of hemagglutinin subtype 5 and the N-terminal part of γ-zein. The chimeric protein was transiently produced in tobacco leaves, and H5-containing protein bodies (PBs) were used to immunize mice. An immune response was achieved in all mice treated with H5-zein, even at low doses. The fusion to zein markedly enhanced the IgG response compared the soluble H5 control, and the effect was similar to a commercial adjuvant. The co-administration of adjuvants with the H5-zein bodies did not enhance the immune response any further, suggesting that the zein portion itself mediates an adjuvant effect. While the zein portion used to induce protein body formation was only weakly immunogenic, our results indicate that zein-induced PBs are promising production and delivery vehicles for subunit vaccines.
Highlights
Polymers are widely used as carrier biomaterials for the delivery of therapeutic molecules (Petros and DeSimone, 2010)
The sequence corresponding to the H5 ectodomain of hemagglutinin from the A/Hatay/2004/(H5N1) influenza strain (GenBank Q5QQ29) was amplified as described (Phan et al, 2014) and a plant codon-optimized signal peptide sequence derived from a murine antibody was added to the N-terminus to direct the protein into the secretory pathway (Vaquero et al, 1999)
Previous studies have shown that the biogenesis of protein bodies (PBs) by zein is influenced by the fusion partner, and that not all fusion proteins support the efficient formation of PBs
Summary
Polymers are widely used as carrier biomaterials for the delivery of therapeutic molecules (Petros and DeSimone, 2010). Biopolymer-based nanoparticles have proven suitable for clinical applications due to their biocompatibility and biodegradability (Panyam and Labhasetwar, 2003; Nitta and Numata, 2013). A protein-based polymer found in maize seeds, has been widely used as a carrier because of favorable properties such as biocompatibility, insolubility and low water uptake, mechanical and chemical stability, and its propensity to form coatings and microparticles (Liu et al, 2005; Lai and Guo, 2011; Wang et al, 2011; Lau et al, 2013). Zein is generally regarded as safe (GRAS) for food use and resists digestion, making it suitable as an encapsulation polymer for oral drugs
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