Early vaccine availability represents an important public health advance for the control of pandemic influenza

Plant-Based Vaccines: The Way Ahead?

Severe virus outbreaks are occurring more often and spreading faster and further than ever. Preparedness plans based on lessons learned from past epidemics can guide behavioral and pharmacological interventions to contain and treat emergent diseases. Although conventional biologics production systems can meet the pharmaceutical needs of a community at homeostasis, the COVID-19 pandemic has created an abrupt rise in demand for vaccines and therapeutics that highlight the gaps in this supply chain's ability to quickly develop and produce biologics in emergency situations given a short lead time. Considering the projected requirements for COVID-19 vaccines and the necessity for expedited large scale manufacture the capabilities of current biologics production systems should be surveyed to determine their applicability to pandemic preparedness. Plant-based biologics production systems have progressed to a state of commercial viability in the past 30 years with the capacity for production of complex, glycosylated, "mammalian compatible" molecules in a system with comparatively low production costs, high scalability, and production flexibility. Continued research drives the expansion of plant virus-based tools for harnessing the full production capacity from the plant biomass in transient systems. Here, we present an overview of vaccine production systems with a focus on plant-based production systems and their potential role as "first responders" in emergency pandemic situations.

Edible Vaccines: Promises and Challenges

Vaccines are biological preparations that improve immunity to particular diseases and form an important innovation of 19th century research. It contains a protein that resembles a disease-causing microorganism and is often made from weak or killed forms of the microbe. Vaccines are agents that stimulate the body’s immune system to recognize the antigen. Now, a new form of vaccine was introduced which will have the power to mask the risk side of conventional vaccines. This type of vaccine was produced from plants which are genetically modified. In the production of edible vaccines, the gene-encoding bacterial or viral disease-causing agent can be incorporated in plants without losing its immunogenic property. The main mechanism of action of edible vaccines is to activate the systemic and mucosal immunity responses against a foreign disease-causing organism. Edible vaccines can be produced by incorporating transgene in to the selected plant cell. At present edible vaccine are developed for veterinary and human use. But the main challenge faced by edible vaccine is its acceptance by the population so that it is necessary to make aware the society about its use and benefits. When compared to other traditional vaccines, edible vaccines are cost effective, efficient and safe. It promises a better prevention option from diseases.

Biotechnology, In Vitro Production of Natural Bioactive Compounds, Herbal Preparation, and Disease Management (Treatment and Prevention)

Biotechnology uses living systems to develop products and plant biotechnology generates useful products or services, e.g., different bioactive secondary metabolites including alkaloids, flavonoids and other phenolics, saponins, terpenoids, steroids, glycosides, tannins, volatile oils, etc., from plant cells, tissues or organs culture independent of geographical and climatic factors under aseptic conditions. These bioactive compounds are economically important as drugs (pharmaceuticals), flavors, perfumes (fragrances), pigments (dyes), agrochemicals as well as cosmetics, food additives, etc. Different strategies, e.g., genetic transformation of plants with Agrobacterium rhizogenes, hairy roots and others can be applied for the improvement of production of bioactive compounds of secondary metabolic origin. Recombinant DNA techniques can be used to manipulate metabolic pathways and produce protein pharmaceuticals such as antibodies, and protein hormones. Bioinformatics and genomics can find application in drug discovery from plant-based products and biotechnological procedures can enhance and advance the studies of medicinal plants. Molecular biotechnology uses laboratory techniques to study and modify nucleic acids and proteins for applications in areas such as human and animal health, agriculture, and the environment. Herbal extracts are now widely used in the management of chronic diseases like diabetes, hypertension, cancer, etc., as a part of CAM therapy. Plant-derived immune stimulators diverse small or large molecules (saponins, tomatine, inulin, polysaccharides), fungal β-glucans, complex molecules from marine sponge (α-galactosylceramide), shrimp chitin (chitosan), etc., have established adjuvant activity. Immunotherapy may be activation immunotherapy or suppression immunotherapy. Vaccines provide immune protection against diseases and plant-based edible vaccine production mainly involves the integration of transgene into the plant cells to produce the antigen protein for specific disease.

Assessing the benefits of early pandemic influenza vaccine availability: a case study for Ontario, Canada

New vaccine production technologies can significantly shorten the timelines for availability of a strain-specific vaccine in the event of an influenza pandemic. We sought to evaluate the potential benefits of early vaccination in reducing the clinical attack rate (CAR), taking into account the timing and speed of vaccination roll-out. Various scenarios corresponding to the transmissibility of a pandemic strain and vaccine prioritization strategies were simulated using an agent-based model of disease spread in Ontario, the largest Canadian province. We found that the relative reduction of the CAR reached 60% (90%CI: 44-100%) in a best-case scenario, in which the pandemic strain was moderately transmissible, vaccination started 4 weeks before the first imported case, the vaccine administration rate was 4 times higher than its average for seasonal influenza, and the vaccine efficacy was up to 90%. But the relative reductions in the CAR decreased significantly when the vaccination campaign was delayed or the administration rate reduced. In urban settings with similar characteristics to our population study, early availability and high rates of vaccine administration has the potential to substantially reduce the number of influenza cases. Low rates of vaccine administration or uptake can potentially offset the benefits of early vaccination.

Plant-based vaccines against respiratory diseases: current status and future prospects

INTRODUCTION

Respiratory infections have an enormous, worldwide epidemiologic impact on humans and animals. Among the prophylactic measures, vaccination has the potential to neutralize this impact. New technologies for vaccine production and delivery are of importance in this field since they offer the potential to develop new immunization approaches overriding the current limitations that comprise high cost, safety issues, and limited efficacy. Areas covered: In the present review, the state of the art in developing plant-based vaccines against respiratory diseases is presented. The review was based on the analysis of current biomedical literature. Expert commentary: Preclinical and clinical evaluations of several vaccine candidates against influenza, tuberculosis, respiratory syncytial virus, pneumonia, anthrax and asthma are discussed and placed in perspective.

Plant-Based Vaccines: Production and Challenges

Plant-based vaccine technologies involve the integration of the desired genes encoding the antigen protein for specific disease into the genome of plant tissues by various methods. Agrobacterium-mediated gene transfer and transformation via genetically modified plant virus are the common methods that have been used to produce effective vaccines. Nevertheless, with the advancement of science and technology, new approaches have been developed to increase the efficiency of former methods such as biolistic, electroporation, agroinfiltration, sonication, and polyethylene glycol treatment. Even though plant-based vaccines provide many benefits to the vaccine industry, there are still challenges that limit the rate of successful production of these third-generation vaccines. Even with all the limitations, continuous efforts are still ongoing in order to produce efficient vaccine for many human and animals related diseases owing to its great potentials. This paper reviews the existing conventional methods as well as the development efforts by researchers in order to improve the production of plant-based vaccines. Several challenges encountered during and after the production process were also discussed.