Oral Immunotherapy for Allergic Conjunctivitis Using Transgenic Rice Expressing Hypoallergenic Antigens.

Pollinosis, or allergic conjunctivitis and rhinitis induced by pollen, is one of the most common diseases worldwide. In Japan, Japanese cedar (Cryptomeria japonica) pollinosis is a predominant allergic condition that affects more than one-third of all Japanese individuals. Pharmacological treatments of allergic conjunctivitis include administration of antiallergic eye drops containing an antihistamine or mast cell stabilizer. However, these topical treatments provide transient relief from symptoms. The only available curative treatment for allergic diseases is allergen-specific immunotherapy. Sublingual immunotherapy for pollinosis has been found to be effective for suppression of ocular and nasal symptoms, but patient compliance is low. Oral administration of staple foods engineered to express allergens is a possible means of delivering antigens for immunotherapy, and its convenience would be expected to improve compliance. With the aim of developing more convenient, effective, and safe immunotherapies for allergic diseases, we have generated rice-based edible vaccines expressing antigens derived from dust mites or pollen from Japanese cedar, birch, or ragweed. In this study, we summarize the results of our immunotherapy studies using transgenic rice. Oral immunotherapy with transgenic rice seeds containing hypoallergenic modified forms of Japanese cedar pollen antigens was effective for both preventing allergic conjunctivitis and suppressing established disease in mice. Oral administration of transgenic rice seeds is thus a promising approach to immunotherapy for conjunctivitis and rhinitis induced by Japanese cedar pollen.

The Last Ten Years of Advancements in Plant-Derived Recombinant Vaccines against Hepatitis B.

Disease prevention through vaccination is considered to be the greatest contribution to public health over the past century. Every year more than 100 million children are vaccinated with the standard World Health Organization (WHO)-recommended vaccines including hepatitis B (HepB). HepB is the most serious type of liver infection caused by the hepatitis B virus (HBV), however, it can be prevented by currently available recombinant vaccine, which has an excellent record of safety and effectiveness. To date, recombinant vaccines are produced in many systems of bacteria, yeast, insect, and mammalian and plant cells. Among these platforms, the use of plant cells has received considerable attention in terms of intrinsic safety, scalability, and appropriate modification of target proteins. Research groups worldwide have attempted to develop more efficacious plant-derived vaccines for over 30 diseases, most frequently HepB and influenza. More inspiring, approximately 12 plant-made antigens have already been tested in clinical trials, with successful outcomes. In this study, the latest information from the last 10 years on plant-derived antigens, especially hepatitis B surface antigen, approaches are reviewed and breakthroughs regarding the weak points are also discussed.

Effect of rice-expressed amyloid ß in the Tg2576 Alzheimer's disease transgenic mouse model.

One of the main hallmarks of Alzheimer's disease (AD) is senile plaques composed of amyloid ß (Aß). We developed a new edible vaccine: rice expressing GFP-Aß42. In a previous report, we described the production of anti-Aß antibodies in B6 mice fed Aß rice mixed with cholera toxin B subunit (CTB). In this report, we investigated whether Aß rice had therapeutic effects in the Tg2576 AD model mice. The anti-Aß antibody titer was increased and levels of intracerebral Aß (soluble and insoluble) and serum Aß decreased. Because the value of IgG1/IgG2a in the Aß feeding group was >1, immunization via Aß rice may induce a non-inflammatory Th2 reaction. We also found that the Aß vaccine improved memory, as assessed in a Y-maze test. The number of arm entries in the Y-maze test was lower in the Aß feeding group than in the control group. These results suggest that the new edible vaccine Aß rice may have therapeutic effects in AD.

Transgenic rice expressing amyloid ß-peptide for oral immunization.

Various vaccine therapies for Alzheimer's disease (AD) have been investigated. Here we report transgenic rice expressing amyloid ß-peptide (Aß). The Aß42 gene fused with a green fluorescent protein gene was introduced into rice using the Agrobacterium method. When transgenic brown rice expressing Aß was orally administered to mice, serum anti-Aß antibody titers were elevated. The same results were observed when mice were fed boiled, transgenic brown rice. The results indicate that an edible vaccine against AD using rice may be feasible. A vaccine derived from rice would be far cheaper than existing medical vaccines.

Production of double repeated B subunit of Shiga toxin 2e at high levels in transgenic lettuce plants as vaccine material for porcine edema disease.

Pig edema disease is a bacterial disease caused by enterohemorrhagic Escherichia coli. E. coli produces Shiga toxin 2e (Stx2e), which is composed of one A subunit (Stx2eA) and five B subunits (Stx2eB). We previously reported production of Stx2eB in lettuce plants as a potential edible vaccine (Matsui et al. in Biosci Biotechnol Biochem 73:1628-1634, 2009). However, the accumulation level was very low, and it was necessary to improve expression of Stx2eB for potential use of this plant-based vaccine. Therefore, in this study, we optimized the Stx2eB expression cassette and found that a double repeated Stx2eB (2× Stx2eB) accumulates to higher levels than a single Stx2eB in cultured tobacco cells. Furthermore, a linker peptide between the two Stx2eB moieties played an important role in maximizing the effects of the double repeat. Finally, we generated transgenic lettuce plants expressing 2× Stx2eB with a suitable linker peptide that accumulate as much as 80 mg per 100 g fresh weight, a level that will allow us to use these transgenic lettuce plants practically to generate vaccine material.

Generation of a transgenic rice seed-based edible vaccine against house dust mite allergy.

As an alternative approach to conventional allergen-specific immunotherapy, transgenic rice seed expressing a major house dust mite (HDM) allergen, Der p 1, was developed as an edible vaccine. The C-terminal KDEL-tagged Der p 1 allergen specifically accumulated in seed endosperm tissue under the control of the endosperm-specific GluB1 promoter. Der p 1 reached a maximum concentration of 58 microg/grain and was deposited in the endoplasmic reticulum (ER)-derived protein body I (PB-I). Plant-derived Der p 1 was posttranslationally modified with high-mannose-type glycan structures. Glycosylated Der p 1 displayed reduced IgE binding capacity in comparison with its unglycosylated counterpart in vitro. Our results indicate that transgenic Der p 1 rice seeds are a safe, potential oral delivery vaccine for the treatment of HDM allergy.

Garden-variety vaccines: antigens derived from transgenic plants.

The discovery of new vaccines can result from deletion of virulence determinants from a specific pathogen or from identification of target antigens that stimulate a protective immune response. Vaccine development will become less empirical as applications of genomics, proteomics and reverse vaccinology are exploited, and new protective antigens will emerge for inclusion in the vaccines of the future. However, production and purification of these new antigens for oral and parenteral use using traditional expression systems, will be expensive and unattractive to vaccine manufacturers who see the vaccine market as economically uninviting. Cost is one of the persistent barriers to deployment of new vaccines to populations that need them most urgently. This factor will inhibit the development and distribution of safe and effective new vaccines against high priority pathogens.

[The new generations of vaccines against parasites]. / Nowe rodzaje szczepionek przeciwpasozytniczych.

The protection of humans and domestic animals against parasitic infections remains a major goal, especially in light of developing of drug resistant strains in many parasite species. "Classic" vaccines are based on attenuated infective stages of protozoan and helminth parasites. Although such vaccines are effective in confering host immunity against several protozoan (coccidiosis, giardiosis, toxoplasmosis) diseases and one helminth (dictyocaulosis) they are very unstable and expensive. Recombinant techniques enable to obtain protective antigens quickly and in considerable quantities, cultivating of the bacteria and purification of the recombinant protein is less expensive than the maintenance of host animals and isolation of the protective antigens from harvested parasites. Moreover, the cloned protective antigens may be deprived of epitopes responsible for immunopathology. However, at present only one anti-parasite recombinant protein vaccine is commercially available (TickGARD). Such a situation may result from that many protective parasitic antigens cannot be expressed in bacteria or yeast in anative from. DNA vaccines present many advantages over protein ones. Firstly, the antigenic proteins synthesised within the host cell possess an appropriate molecular structure and undergo a post-translational modifications specific for a native protein. The next advantage of DNA vaccines is that DNA is easier to handle and more resistant than proteins to temperature changes. DNA vaccines are likely to induce novel mechanisms of immune response, which may be beneficial in case of parasitic invasions. Costs of DNA vaccines are comparable, and may be even lower, in comparison to recombinant protein vaccines. The main obstacle preventing the use of DNA vaccines is still lack of the complete knowledge concerning mechanisms of their action. Vaccines based on transgenic plants (=edible vaccines), expressing the protective parasitic antigens, present another promising approach in research on anti-parasitic vaccines. Such vaccines may be of special importance in prevention of infections with gastrointestinal parasites.