Leaf-Encapsulated Vaccines: Agroinfiltration and Transient Expression of the Antigen Staphylococcal Endotoxin B in Radish Leaves

How Long Will It Take to Launch an Effective Helicobacter pylori Vaccine for Humans?

Helicobacter pylori infection often occurs in early childhood, and can last a lifetime if not treated with medication. H. pylori infection can also cause a variety of stomach diseases, which can only be treated with a combination of antibiotics. Combinations of antibiotics can cure H. pylori infection, but it is easy to relapse and develop drug resistance. Therefore, a vaccine is a promising strategy for prevention and therapy for the infection of H. pylori. After decades of research and development, there has been no appearance of any H. pylori vaccine reaching the market, unfortunately. This review summarizes the aspects of candidate antigens, immunoadjuvants, and delivery systems in the long journey of H. pylori vaccine research, and also introduces some clinical trials that have displayed encouraging or depressing results. Possible reasons for the inability of an H. pylori vaccine to be available over the counter are cautiously discussed and some propositions for the future of H. pylori vaccines are outlined.

Agroinfiltration Mediated Scalable Transient Gene Expression in Genome Edited Crop Plants

Agrobacterium-mediated transformation is one of the most commonly used genetic transformation method that involves transfer of foreign genes into target plants. Agroinfiltration, an Agrobacterium-based transient approach and the breakthrough discovery of CRISPR/Cas9 holds trending stature to perform targeted and efficient genome editing (GE). The predominant feature of agroinfiltration is the abolishment of Transfer-DNA (T-DNA) integration event to ensure fewer biosafety and regulatory issues besides showcasing the capability to perform transcription and translation efficiently, hence providing a large picture through pilot-scale experiment via transient approach. The direct delivery of recombinant agrobacteria through this approach carrying CRISPR/Cas cassette to knockout the expression of the target gene in the intercellular tissue spaces by physical or vacuum infiltration can simplify the targeted site modification. This review aims to provide information on Agrobacterium-mediated transformation and implementation of agroinfiltration with GE to widen the horizon of targeted genome editing before a stable genome editing approach. This will ease the screening of numerous functions of genes in different plant species with wider applicability in future.

Radish sprouts as an efficient and rapidly available host for an agroinfiltration-based transient gene expression system

Agroinfiltration, the infiltration of plants with Agrobacterium harboring a plasmid that contains a specific gene, is used to transiently express a gene in a heterologous organism. Using the "Tsukuba system", greater amounts of target protein accumulate compared with usual expression plasmids. Reported host plants, including Nicotiana benthamiana, a common plant for agroinfiltration, need several weeks after sowing to grow enough for infection. To shorten the culture period and, thereby, improve target protein production, we tested sprouts as host plants. Sprouts were grown in the dark to encourage elongation so that vacuum infiltration becomes easier, and this was followed by a few days of exposure to illumination before infection with pBYR2HS-EGFP, the EGFP expression plasmid of the Tsukuba system. Among six tested species of Fabaceae and Brassicaceae, radish showed the highest transient expression. Among six tested radish cultivars, Kaiware, Hakata, and Banryoku provided the best results. Culturing for 5 day, including 1 day of imbibition and 1 to 2 day of exposure to illumination resulted in EGFP fluorescence in 80% of the cotyledon area. Thus, a remarkable amount of EGFP was obtained only 8 day after seed imbibition. The EGFP amount in Kaiware cotyledons was comparable with Rubisco at ∼0.7 mg/g fresh weight. Kaiware sold in supermarkets could also be used, but resulted in lower expression levels.

Target-specific gene delivery in plant systems and their expression: Insights into recent developments

In order to improve crop plants in terms of their yield, drought resistance, pest resistance, nutritional value, etc., modern agriculture has relied upon plant genetic engineering. Since the advent of recombinant DNA technology, several tools have been used for genetic transformations in plants such as Agrobacterium tumefaciens, virus-mediated gene transfer, direct gene transfer systems such as electroporation, particle gun, microinjection and chemical methods. All these traditional methods lack specificity and the transgenes are integrated at random sites in the plant DNA. Recently novel techniques for gene targeting have evolved such as engineered nucleases such as Zinc Finger Nucleases, Transcription Activator like effector nucleases, Clustered regular interspaced short palindromic repeats. Other advances include improvement in tools for delivery of gene editing components which include carrier proteins, and carbon nanotubes. The present review focuses on the latest techniques for target specific gene delivery in plants, their expression and future directions in plant biotechnology.

Freeze-Drying To Produce Efficacious CPMV Virus-like Particles

In situ cancer vaccination that uses immune stimulating agents is revolutionizing the way that cancer is treated. In this realm, viruses and noninfectious virus-like particles have gained significant traction in reprogramming the immune system to recognize and eliminate malignancies. Recently, cowpea mosaic virus-like particles (VLPs) have shown exceptional promise in their ability to fight a variety of cancers. However, the current methods used to produce CPMV VLPs rely on agroinfiltration in plants. These protocols remain complicated and labor intensive and have the potential to introduce unwanted immunostimulatory agents, like lipopolysaccharides. This Letter describes a simple "post-processing" method to remove RNA from wild-type CPMV, while retaining the structure and function of the capsid. Lyophilization was able to eject encapsulated RNA to form lyo-eCPMV and, when purified, eliminated nearly all traces of encapsulated RNA. Lyo-eCPMV was characterized by cryo-electron microscopy single particle reconstruction to confirm the structural integrity of the viral capsid. Finally, lyo-eCPMV showed  equivalent anticancer efficacy as eCPMV, produced by agroinfiltration, when using an invasive melanoma model. These results describe a straightforward method to prepare CPMV VLPs from infectious virions.