Reorientation of life style becomes necessary for staying healthy, especially during the challenging times as it is prevailing at present. Consumption of ample plant-based foods like vegetables could ...be an important step towards it. However, certain vegetables hold more significance as they boost immunity. Daily intake of vegetables with immunomodulation properties (modification of the immune response or the functioning of the immune system) seems promising. The immunomodulatory properties of these vegetables are attributed to the presence of certain phytoconstituents like polysachharides (e.g. RG-I in bell pepper; CMDP-4b in pumpkin; MOP-3 in drumstick), lectins (ASA I & ASA II in garlic; BOL in cauliflower), isothiocynates (Sulforaphane in broccoli), unsaturated fatty acids (pumpkin seeds), bryonolic acid (acorn squash), ribosomes inactivating protein (Lagenin in bottle gourd), glycoprotein (Luffaculin in ridge gourd), trypsin inhibitor (MoFTI in drumsticks) etc. The aim of this review is to highlight results of work done on immunomodulatory activity of vegetables. The roles of various vegetables and their phytoconstituents, which are accountable for immunomodulation and reduction in the risk of infectious as well as non-communicable diseases, have been discussed. Such information may be encouraging for researchers to carry out further advanced research on vegetables with potential immunomodulatory properties.
Plant cells are ideal bioreactors for the production and oral delivery of vaccines and biopharmaceuticals, eliminating the need for expensive fermentation, purification, cold storage, transportation ...and sterile delivery. Plant-made vaccines have been developed for two decades but none has advanced beyond Phase I. However, two plant-made biopharmaceuticals are now advancing through Phase II and Phase III human clinical trials. In this review, we evaluate the advantages and disadvantages of different plant expression systems (stable nuclear and chloroplast or transient viral) and their current limitations or challenges. We provide suggestions for advancing this valuable concept for clinical applications and conclude that greater research emphasis is needed on large-scale production, purification, functional characterization, oral delivery and preclinical evaluation.
Although the plant‐made vaccine field started three decades ago with the promise of developing low‐cost vaccines to prevent infectious disease outbreaks and epidemics around the globe, this goal has ...not yet been achieved. Plants offer several major advantages in vaccine generation, including low‐cost production by eliminating expensive fermentation and purification systems, sterile delivery and cold storage/transportation. Most importantly, oral vaccination using plant‐made antigens confers both mucosal (IgA) and systemic (IgG) immunity. Studies in the past 5 years have made significant progress in expressing vaccine antigens in edible leaves (especially lettuce), processing leaves or seeds through lyophilization and achieving antigen stability and efficacy after prolonged storage at ambient temperatures. Bioencapsulation of antigens in plant cells protects them from the digestive system; the fusion of antigens to transmucosal carriers enhances efficiency of their delivery to the immune system and facilitates successful development of plant vaccines as oral boosters. However, the lack of oral priming approaches diminishes these advantages because purified antigens, cold storage/transportation and limited shelf life are still major challenges for priming with adjuvants and for antigen delivery by injection. Yet another challenge is the risk of inducing tolerance without priming the host immune system. Therefore, mechanistic aspects of these two opposing processes (antibody production or suppression) are discussed in this review. In addition, we summarize recent progress made in oral delivery of vaccine antigens expressed in plant cells via the chloroplast or nuclear genomes and potential challenges in achieving immunity against infectious diseases using cold‐chain‐free vaccine delivery approaches.
With the on-going pandemic, vaccine developing methods have gained attention of the scientific community, specially towards the production, downstream and transport aspects, making it clear that new ...methods with less complex production and transport are needed, especially for developing countries. In this work we review the current methods used for vaccine production, downstream platforms, and distribution aspects along with the challenges faced by each of the approaches. Some studies have also been carried out proposing alternatives, the most attractive one being the concept of edible vaccines, which suppose a considerable expenditure cut for the production and distribution of vaccines, in this work we also review some of them, using mainly algae, yeast and bacteria. Algae, yeast and some bacteria have been granted the GRAS (Generally Recognized As Safe) state by the FDA and European food safety authority, making them ideal and safe as vaccine vectors and biofactories at the same time.
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EDIBLE VACCINES: AN ADVANCEMENT IN ORAL IMMUNIZATION Bhairy, Srinivas Rajesham; Hirlekar, Rajashree Shreeram
Asian journal of pharmaceutical and clinical research,
02/2017, Volume:
10, Issue:
2
Journal Article
Open access
Vaccines represent a useful contribution to the field of biotechnology as they supply protection against various diseases. But, the major obstacle to oral vaccination is the digestion of ...macromolecule antigenic protein within the stomach due to extremely acidic pH. To address this issue, scientist Arntzen introduced the concept of edible vaccines. Edible vaccines are prepared by using the science of genetic engineering in which the selected genes are introduced into the plants by means of various methods. The transgenic plant is then induced to manufacture the encoded protein which acts as a vaccine. Owing to its low cost, it will be affordable for developing countries like India. Edible vaccines are used to treat various diseases like malaria, measles, hepatitis B, stopping autoimmunity in type-1 diabetes, cholera, enterotoxicogenic E.coli (ETEC), HIV and anthrax. This review comprises mechanism of action, methods of development, candidate plants, applications, clinical trials and patents of edible vaccines.Keywords: Edible vaccines, Antigens, Oral immunization, Immunity.
At present, environmental degradation and the consistently growing population are two main problems on the planet earth. Fulfilling the needs of this growing population is quite difficult from the ...limited arable land available on the globe. Although there are legal, social and political barriers to the utilization of biotechnology, advances in this field have substantially improved agriculture and human life to a great extent. One of the vital tools of biotechnology is genetic engineering (GE) which is used to modify plants, animals and microorganisms according to desired needs. In fact, genetic engineering facilitates the transfer of desired characteristics into other plants which is not possible through conventional plant breeding. A variety of crops have been engineered for enhanced resistance to a multitude of stresses such as herbicides, insecticides, viruses and a combination of biotic and abiotic stresses in different crops including rice, mustard, maize, potato, tomato, etc. Apart from the use of GE in agriculture, it is being extensively employed to modify the plants for enhanced production of vaccines, hormones, etc. Vaccines against certain diseases are certainly available in the market, but most of them are very costly. Developing countries cannot afford the disease control through such cost-intensive vaccines. Alternatively, efforts are being made to produce edible vaccines which are cheap and have many advantages over the commercialized vaccines. Transgenic plants generated for this purpose are capable of expressing recombinant proteins including viral and bacterial antigens and antibodies. Common food plants like banana, tomato, rice, carrot, etc. have been used to produce vaccines against certain diseases like hepatitis B, cholera, HIV, etc. Thus, the up- and down-regulation of desired genes which are used for the modification of plants have a marked role in the improvement of genetic crops. In this review, we have comprehensively discussed the role of genetic engineering in generating transgenic lines/cultivars of different crops with improved nutrient quality, biofuel production, enhanced production of vaccines and antibodies, increased resistance against insects, herbicides, diseases and abiotic stresses as well as the safety measures for their commercialization.
Plants have been identified as promising expression systems for commercial production of vaccine antigens. In phase I clinical trials several plant-derived vaccine antigens have been found to be safe ...and induce sufficiently high immune response. Thus, transgenic plants, including edible plant parts are suggested as excellent alternatives for the production of vaccines and economic scale-up through cultivation. Improved understanding of plant molecular biology and consequent refinement in the genetic engineering techniques have led to designing approaches for high level expression of vaccine antigens in plants. During the last decade, several efficient plant-based expression systems have been examined and more than 100 recombinant proteins including plant-derived vaccine antigens have been expressed in different plant tissues. Estimates suggest that it may become possible to obtain antigen sufficient for vaccinating millions of individuals from one acre crop by expressing the antigen in seeds of an edible legume, like peanut or soybean. In the near future, a plethora of protein products, developed through ‘naturalized bioreactors’ may reach market. Efforts for further improvements in these technologies need to be directed mainly towards validation and applicability of plant-based standardized mucosal and edible vaccines, regulatory pharmacology, formulations and the development of commercially viable GLP protocols. This article reviews the current status of developments in the area of use of plants for the development of vaccine antigens.
Capable of inducing antigen-specific immune responses in both systemic and mucosal compartments without the use of syringe and needle, mucosal vaccination is considered ideal for the global control ...of infectious diseases. In this study, we developed a rice-based oral vaccine expressing cholera toxin B subunit (CTB) under the control of the endosperm-specific expression promoter 2.3-kb glutelin GluB-1 with codon usage optimization for expression in rice seed. An average of 30 μg of CTB per seed was stored in the protein bodies, which are storage organelles in rice. When mucosally fed, rice seeds expressing CTB were taken up by the M cells covering the Peyer's patches and induced CTB-specific serum IgG and mucosal IgA antibodies with neutralizing activity. When expressed in rice, CTB was protected from pepsin digestion in vitro. Rice-expressed CTB also remained stable and thus maintained immunogenicity at room temperature for >1.5 years, meaning that antigen-specific mucosal immune responses were induced at much lower doses than were necessary with purified recombinant CTB. Because they require neither refrigeration (cold-chain management) nor a needle, these rice-based mucosal vaccines offer a highly practical and cost-effective strategy for orally vaccinating large populations against mucosal infections, including those that may result from an act of bioterrorism.
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