M Cell-Targeting Ligand and Consensus Dengue Virus Envelope Protein Domain III Fusion Protein Production in Transgenic Rice Calli

The spread of dengue (DEN) virus is becoming a major concern due to the possibility of primary infection with one of the four dengue serotypes (DEN 1–4) and secondary infection with other heterotypes, which can further aggravate clinical manifestations. A gene encoding consensus envelope protein domain III (cEDIII) of dengue virus with neutralizing activity against four dengue virus serotypes was fused to M cell-targeting peptide ligand (Co1) to increase its mucosal immunogenicity and was introduced into rice calli under the control of the inducible rice amylase 3D promoter expression system. The integration and expression of scEDIII–Co1 fusion gene in transgenic rice calli were confirmed by genomic DNA PCR amplification, Northern and Western blot analyses, respectively. The deliveries of cEDIII–Co1 fusion proteins into mucosal immune inductive site (including M cells) were confirmed by in vitro and in vivo antigen uptake assays. These results showed that plant-produced M cell-targeting peptide ligand, Co1, fusion antigen proteins have the potential to be targeted to the mucosal immune system for improvement of immune responses.