Repurposing Plant Virus Nanoparticles

The biological roles of CD47 in ovarian cancer progression

Ovarian cancer is one of the most lethal malignant tumors, characterized by high incidence and poor prognosis. Patients relapse occurred in 65-80% after initial treatment. To date, no effective treatment has been established for these patients. Recently, CD47 has been considered as a promising immunotherapy target. In this paper, we reviewed the biological roles of CD47 in ovarian cancer and summarized the related mechanisms. For most types of cancers, the CD47/Sirpα immune checkpoint has attracted the most attention in immunotherapy. Notably, CD47 monoclonal antibodies and related molecules are promising in the immunotherapy of ovarian cancer, and further research is needed. In the future, new immunotherapy regimens targeting CD47 can be applied to the clinical treatment of ovarian cancer patients.

Engineering Alkaline-Stable Barley Stripe Mosaic Virus-Like Particles for Efficient Surface Modification

Viruses and virus-like particles are powerful templates for materials synthesis because of their capacity for precise protein engineering and diverse surface functionalization. We recently developed a recombinant bacterial expression system for the production of barley stripe mosaic virus-like particles (BSMV VLPs). However, the applicability of this biotemplate was limited by low stability in alkaline conditions and a lack of chemical handles for ligand attachment. Here, we identify and validate novel residues in the BSMV Caspar carboxylate clusters that mediate virion disassembly through repulsive interactions at high pH. Point mutations of these residues to create attractive interactions that increase rod length ~2 fold, with an average rod length of 91 nm under alkaline conditions. To enable diverse chemical surface functionalization, we also introduce reactive lysine residues at the C-terminus of BSMV coat protein, which is presented on the VLP surface. Chemical conjugation reactions with this lysine proceed more quickly under alkaline conditions. Thus, our alkaline-stable VLP mutants are more suitable for rapid surface functionalization of long nanorods. This work validates novel residues involved in BSMV VLP assembly and demonstrates the feasibility of chemical functionalization of BSMV VLPs for the first time, enabling novel biomedical and chemical applications.

SARS-CoV-2 and its new variants: a comprehensive review on nanotechnological application insights into potential approaches

SARS-CoV-2 (COVID-19) spreads and develops quickly worldwide as a new global crisis which has left deep socio-economic damage and massive human mortality. This virus accounts for the ongoing outbreak and forces an urgent need to improve antiviral therapeutics and targeted diagnosing tools. Researchers have been working to find a new drug to combat the virus since the outbreak started in late 2019, but there are currently no successful drugs to control the SARS-CoV-2, which makes the situation riskier. Very recently, new variant of SARS-CoV-2 is identified in many countries which make the situation very critical. No successful treatment has yet been shown although enormous international commitment to combat this pandemic and the start of different clinical trials. Nanomedicine has outstanding potential to solve several specific health issues, like viruses, which are regarded a significant medical issue. In this review, we presented an up-to-date drug design strategy against SARS-CoV-2, including the development of novel drugs and repurposed product potentials were useful, and successful drugs discovery is a constant requirement. The use of nanomaterials in treatment against SARS-CoV-2 and their use as carriers for the transport of the most frequently used antiviral therapeutics are discussed systematically here. We also addressed the possibilities of practical applications of nanoparticles to give the status of COVID-19 antiviral systems.

Bioresource-Functionalized Quantum Dots for Energy Generation and Storage: Recent Advances and Feature Perspective

The exponential increase in global energy demand in daily life prompts us to search for a bioresource for energy production and storage. Therefore, in developing countries with large populations, there is a need for alternative energy resources to compensate for the energy deficit in an environmentally friendly way and to be independent in their energy demands. The objective of this review article is to compile and evaluate the progress in the development of quantum dots (QDs) for energy generation and storage. Therefore, this article discusses the energy scenario by presenting the basic concepts and advances of various solar cells, providing an overview of energy storage systems (supercapacitors and batteries), and highlighting the research progress to date and future opportunities. This exploratory study will examine the systematic and sequential advances in all three generations of solar cells, namely perovskite solar cells, dye-sensitized solar cells, Si cells, and thin-film solar cells. The discussion will focus on the development of novel QDs that are economical, efficient, and stable. In addition, the current status of high-performance devices for each technology will be discussed in detail. Finally, the prospects, opportunities for improvement, and future trends in the development of cost-effective and efficient QDs for solar cells and storage from biological resources will be highlighted.

A comprehensive review and meta-analysis of recent advances in biotechnology for plant virus research and significant accomplishments in human health and the pharmaceutical industry

Secondary metabolites made by plants and used through their metabolic routes are today's most reliable and cost-effective way to make pharmaceuticals and improve health. The concept of genetic engineering is used for molecular pharming. As more people use plants as sources of nanotechnology systems, they are adding to this. These systems are made up of viruses-like particles (VLPs) and virus nanoparticles (VNPs). Due to their superior ability to be used as plant virus expression vectors, plant viruses are becoming more popular in pharmaceuticals. This has opened the door for them to be used in research, such as the production of medicinal peptides, antibodies, and other heterologous protein complexes. This is because biotechnological approaches have been linked with new bioinformatics tools. Because of the rise of high-throughput sequencing (HTS) and next-generation sequencing (NGS) techniques, it has become easier to use metagenomic studies to look for plant virus genomes that could be used in pharmaceutical research. A look at how bioinformatics can be used in pharmaceutical research is also covered in this article. It also talks about plant viruses and how new biotechnological tools and procedures have made progress in the field.

Bioinspired and Biomimetic Nanomedicines for Targeted Cancer Therapy

Undesirable side effects and multidrug resistance are the major obstacles in conventional chemotherapy towards cancers. Nanomedicines provide alternative strategies for tumor-targeted therapy due to their inherent properties, such as nanoscale size and tunable surface features. However, the applications of nanomedicines are hampered in vivo due to intrinsic disadvantages, such as poor abilities to cross biological barriers and unexpected off-target effects. Fortunately, biomimetic nanomedicines are emerging as promising therapeutics to maximize anti-tumor efficacy with minimal adverse effects due to their good biocompatibility and high accumulation abilities. These bioengineered agents incorporate both the physicochemical properties of diverse functional materials and the advantages of biological materials to achieve desired purposes, such as prolonged circulation time, specific targeting of tumor cells, and immune modulation. Among biological materials, mammalian cells (such as red blood cells, macrophages, monocytes, and neutrophils) and pathogens (such as viruses, bacteria, and fungi) are the functional components most often used to confer synthetic nanoparticles with the complex functionalities necessary for effective nano-biointeractions. In this review, we focus on recent advances in the development of bioinspired and biomimetic nanomedicines (such as mammalian cell-based drug delivery systems and pathogen-based nanoparticles) for targeted cancer therapy. We also discuss the biological influences and limitations of synthetic materials on the therapeutic effects and targeted efficacies of various nanomedicines.

Plant Virus Nanoparticles for Anti-cancer Therapy

Plant virus nanoparticles (VNPs) are inexpensive to produce, safe, biodegradable and efficacious as treatments. The applications of r plant virus nanoparticles range from epitope carriers for vaccines to agents in cancer immunotherapy. Both VNPs and virus-like particles (VLPs) are highly immunogenic and are readily phagocytosed by antigen presenting cells (APCs), which in turn elicit antigen processing and display of pathogenic epitopes on their surfaces. Since the VLPs are composed of multiple copies of their respective capsid proteins, they present repetitive multivalent scaffolds which aid in antigen presentation. Therefore, the VLPs prove to be highly suitable platforms for delivery and presentation of antigenic epitopes, resulting in induction of more robust immune response compared to those of their soluble counterparts. Since the tumor microenvironment poses the challenge of self-antigen tolerance, VLPs are preferrable platforms for delivery and display of self-antigens as well as otherwise weakly immunogenic antigens. These properties, in addition to their diminutive size, enable the VLPs to deliver vaccines to the draining lymph nodes in addition to promoting APC interactions. Furthermore, many plant viral VLPs possess inherent adjuvant properties dispensing with the requirement of additional adjuvants to stimulate immune activity. Some of the highly immunogenic VLPs elicit innate immune activity, which in turn instigate adaptive immunity in tumor micro-environments. Plant viral VLPs are nontoxic, inherently stable, and capable of being mass-produced as well as being modified with antigens and drugs, therefore providing an attractive option for eliciting anti-tumor immunity. The following review explores the use of plant viruses as epitope carrying nanoparticles and as a novel tools in cancer immunotherapy.

The pharmacology of plant virus nanoparticles

The application of nanoparticles for medical purposes has made enormous strides in providing new solutions to health problems. The observation that plant virus-based nanoparticles (VNPs) can be repurposed and engineered as smart bio-vehicles for targeted drug delivery and imaging has launched extensive research for improving the therapeutic and diagnostic management of various diseases. There is evidence that VNPs are promising high value nanocarriers with potential for translational development. This is mainly due to their unique features, encompassing structural uniformity, ease of manufacture and functionalization by means of expression, chemical biology and self-assembly. While the development pipeline is moving rapidly, with many reports focusing on engineering and manufacturing aspects to tailor the properties and efficacy of VNPs, fewer studies have focused on gaining insights into the nanotoxicity of this novel platform nanotechnology. Herein, we discuss the pharmacology of VNPs as a function of formulation and route of administration. VNPs are reviewed in the context of their application as therapeutic adjuvants or nanocarrier excipients to initiate, enhance, attenuate or impede the formulation's toxicity. The summary of the data however also underlines the need for meticulous VNP structure-nanotoxicity studies to improve our understanding of their in vivo fates and pharmacological profiles to pave the way for translation of VNP-based formulations into the clinical setting.

Modulation of Antigen Display on PapMV Nanoparticles Influences Its Immunogenicity

Background: The papaya mosaic virus (PapMV) vaccine platform is a rod-shaped nanoparticle made of the recombinant PapMV coat protein (CP) self-assembled around a noncoding single-stranded RNA (ssRNA) template. The PapMV nanoparticle induces innate immunity through stimulation of the Toll-like receptors (TLR) 7 and 8. The display of the vaccine antigen at the surface of the nanoparticle, associated with the co-stimulation signal via TLR7/8, ensures a strong stimulation of the immune response, which is ideal for the development of candidate vaccines. In this study, we assess the impact of where the peptide antigen is fused, whether at the surface or at the extremities of the nanoparticles, on the immune response directed to that antigen. Methods: Two different peptides from influenza A virus were used as model antigens. The conserved M2e peptide, derived from the matrix protein 2 was chosen as the B-cell epitope, and a peptide derived from the nucleocapsid was chosen as the cytotoxic T lymphocytes (CTL) epitope. These peptides were coupled at two different positions on the PapMV CP, the N- (PapMV-N) or the C-terminus (PapMV-C), using the transpeptidase activity of Sortase A (SrtA). The immune responses, both humoral and CD8+ T-cell-mediated, directed to the peptide antigens in the two different fusion contexts were analyzed and compared. The impact of coupling density at the surface of the nanoparticle was also investigated. Conclusions: The results demonstrate that coupling of the peptide antigens at the N-terminus (PapMV-N) of the PapMV CP led to an enhanced immune response to the coupled peptide antigens as compared to coupling to the C-terminus. The difference between the two vaccine platforms is linked to the enhanced capacity of the PapMV-N vaccine platform to stimulate TLR7/8. We also demonstrated that the strength of the immune response increases with the density of coupling at the surface of the nanoparticles.

Virus-mimetic systems for cancer diagnosis and therapy

Over past decades, various strategies have been developed to enhance the delivery efficiency of therapeutics and imaging agents to tumor tissues. However, the therapeutic outcome of tumors to date have not been significantly improved, which can be partly attributed to the weak targeting ability, fast elimination, and low stability of conventional delivery systems. Viruses are the most efficient agents for gene transfer, serving as a valuable source of inspiration for designing nanoparticle-based delivery systems. Based on the properties of viruses, including well-defined geometry, precise composition, easy modification, stable construction, and specific infection, researchers attempt to design biocompatible delivery vectors by mimicking virus assembly and using the vector system to selectively concentrate drugs or imaging probes in tumors with mitigated toxicity and improved efficacy. In this review, we introduce common viruses features and provide an overview of various virus-mimetic strategies for cancer therapy and diagnosis. The challenges faced by virus-mimetic systems are also discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Virus as nanocarrier for drug delivery redefining medical therapeutics - A status report

Over the last two decades, drug delivery systems have evolved at a tremendous rate. Synthetic nanoparticles have played an important role in the design of vaccine and their delivery as many of them have shown improved safety and efficacy over conventional formulations. Nanocarriers formulated by natural, biological building blocks have become an important tool in the field biomedicine. A successful nanocarrier must have certain properties like evading the host immune system, target specificity, cellular entry, escape from endosomes, and ability to release material into the cytoplasm. Some or all of these functions can be performed by viruses making them a suitable candidate for naturally occurring nanocarriers. Moreover, viruses can be made non-infectious and non-replicative without compromising their ability to penetrate cells thus making them useful for a vast spectrum of applications. Currently, various carrier molecules are under different stages of development to become bio-nano capsules. This review covers the advances made in the field of viruses as potential nanocarriers and discusses the related technologies and strategies to target specific cells by using virus inspired nanocarriers. In future, these virus-based nano-formulations will be able to provide solutions towards pressing and emerging infectious diseases.

Superior Properties and Biomedical Applications of Microorganism-Derived Fluorescent Quantum Dots

Quantum dots (QDs) are fluorescent nanocrystals with superb photo-physical properties. Applications of QDs have been exponentially increased during the past decade. They can be employed in several disciplines, including biological, optical, biomedical, engineering, and energy applications. This review highlights the structural composition and distinctive features of QDs, such as resistance to photo-bleaching, wide range of excitations, and size-dependent light emission features. Physical and chemical preparation of QDs have prominent downsides, including high costs, regeneration of hazardous byproducts, and use of external noxious chemicals for capping and stabilization purposes. To eliminate the demerits of these methods, an emphasis on the latest progress of microbial synthesis of QDs by bacteria, yeast, and fungi is introduced. Some of the biomedical applications of QDs are overviewed as well, such as tumor and microRNA detection, drug delivery, photodynamic therapy, and microbial labeling. Challenges facing the microbial fabrication of QDs are discussed with the future prospects to fully maximize the yield of QDs by elucidating the key enzymes intermediating the nucleation and growth of QDs. Exploration of the distribution and mode of action of QDs is required to promote their biomedical applications.

Protein cages and virus-like particles: from fundamental insight to biomimetic therapeutics

Protein cages (viral and non-viral) found in nature have evolved for a variety of purposes and are found in all kingdoms of life. The main functions of these nanoscale compartments are the protection and delivery of nucleic acids e.g. virus capsids, or the enrichment and sequestration of metabolons e.g. bacterial microcompartments. This review focuses on recent developments of protein cages for use in immunotherapy and therapeutic delivery. In doing so, we highlight the unique ways in which protein cages have informed on fundamental principles governing bio-nano interactions. With the enormous existing design space among naturally occurring protein cages, there is still much to learn from studying them as biomimetic particles.

How Computational Epitope Mapping Identifies the Interactions between Nanoparticles Derived from Papaya Mosaic Virus Capsid Proteins and Immune System

Background

Nanoparticles derived from plant viruses possess fascinating structures, versa-tile functions and safe properties, rendering them valuable for a variety of applications. Papaya mosaic Virus-Like Particles (VLPs) are nanoparticles that contain a repetitive number of virus capsid proteins (PMV-CP) and are considered to be promising platforms for vaccine design. Previous studies have re-ported the antigenicity of PMV nanoparticles in mammalian systems.

Materials and Methods

As experiments that concern vaccine development require careful design and can be time consuming, computational experiments are of particular importance. Therefore, prior to ex-pressing PMV-CP in E. coli and producing nanoparticles, we performed an in silico analysis of the virus particles using software programs based on a series of sophisticated algorithms and modeling networks as useful tools for vaccine design. A computational study of PMV-CP in the context of the immune sys-tem reaction allowed us to clarify particle structure and other unknown features prior to their introduc-tion in vitro.

Results

The results illustrated that the produced nanoparticles can trigger an immune response in the absence of fusion with any foreign antigen.

Conclusion

Based on the in silico analyses, the empty capsid protein was determined to be recognised by different B and T cells, as well as cells which carry MHC epitopes.

Molecular Modelling and Insilico Engineering of PapMV-CP Towards Display and Development of Capripox Viral Like Particles Based on Immunogenic P32 Envelop Protein is the Homologous of the Vaccinia-Viral H3L Gene: An Insilico Approach

Viral-like particles are assembled from capsid protein structural subunits of different viruses and have ability to establish research in biomedicals, like construction of novel safety vaccines, gene therapy vectors by delivering systems for nucleic acids, small biomolecules and diagnostics. Papaya Mosaic Viral nanoparticals can provide as a vaccine candidate helps to increase the immunity by fusing the epitope based peptide antigen. Capripox viruses are the genus comprises Lymphy skin-disease, Sheep and Goat pox Viruses are notified by The World Animal Health Organization (OIE) based on their economic impotence act as a transboundary animal diseases viruses of sheep, goat, and cattle’s respectively. Plant viral based innovative vaccines have been emerged ineffective vaccine development. This research describes the engineering and development of a new vaccine candidate by display immunogenic peptide using the carrier capsid protein of Papaya Mosaic Virus. The Capripox virus P32 immunogenic protein is homologous of the vaccinia virus H3L gene displayed PapMV CP. The antigenicity of P32 protein epitope lowest score among epitopes C-terminally docked epitopes are EP6 > EP3 > EP8 as well the lowest score among epitopes N-terminally docked epitopes are EP8 > EP3 > EP6 presented on the N-terminus of PMV CP region which are found to be suitable for epitope display. And these modelled immunogenic peptide could be used to develop a viral like particles. Epitope based Antibody developed against immunogenic epitopic regions can contribute to a novel and robust protection from infection. As well might be used for developing cost effective detection kits for Transboundary animal disease viruses.

Field-Effect Sensors for Virus Detection: From Ebola to SARS-CoV-2 and Plant Viral Enhancers

Coronavirus disease 2019 (COVID-19) is a novel human infectious disease provoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, no specific vaccines or drugs against COVID-19 are available. Therefore, early diagnosis and treatment are essential in order to slow the virus spread and to contain the disease outbreak. Hence, new diagnostic tests and devices for virus detection in clinical samples that are faster, more accurate and reliable, easier and cost-efficient than existing ones are needed. Due to the small sizes, fast response time, label-free operation without the need for expensive and time-consuming labeling steps, the possibility of real-time and multiplexed measurements, robustness and portability (point-of-care and on-site testing), biosensors based on semiconductor field-effect devices (FEDs) are one of the most attractive platforms for an electrical detection of charged biomolecules and bioparticles by their intrinsic charge. In this review, recent advances and key developments in the field of label-free detection of viruses (including plant viruses) with various types of FEDs are presented. In recent years, however, certain plant viruses have also attracted additional interest for biosensor layouts: Their repetitive protein subunits arranged at nanometric spacing can be employed for coupling functional molecules. If used as adapters on sensor chip surfaces, they allow an efficient immobilization of analyte-specific recognition and detector elements such as antibodies and enzymes at highest surface densities. The display on plant viral bionanoparticles may also lead to long-time stabilization of sensor molecules upon repeated uses and has the potential to increase sensor performance substantially, compared to conventional layouts. This has been demonstrated in different proof-of-concept biosensor devices. Therefore, richly available plant viral particles, non-pathogenic for animals or humans, might gain novel importance if applied in receptor layers of FEDs. These perspectives are explained and discussed with regard to future detection strategies for COVID-19 and related viral diseases.

From stars to stripes: RNA-directed shaping of plant viral protein templates-structural synthetic virology for smart biohybrid nanostructures

The self-assembly of viral building blocks bears exciting prospects for fabricating new types of bionanoparticles with multivalent protein shells. These enable a spatially controlled immobilization of functionalities at highest surface densities-an increasing demand worldwide for applications from vaccination to tissue engineering, biocatalysis, and sensing. Certain plant viruses hold particular promise because they are sustainably available, biodegradable, nonpathogenic for mammals, and amenable to in vitro self-organization of virus-like particles. This offers great opportunities for their redesign into novel "green" carrier systems by spatial and structural synthetic biology approaches, as worked out here for the robust nanotubular tobacco mosaic virus (TMV) as prime example. Natural TMV of 300 x 18 nm is built from more than 2,100 identical coat proteins (CPs) helically arranged around a 6,395 nucleotides ssRNA. In vitro, TMV-like particles (TLPs) may self-assemble also from modified CPs and RNAs if the latter contain an Origin of Assembly structure, which initiates a bidirectional encapsidation. By way of tailored RNA, the process can be reprogrammed to yield uncommon shapes such as branched nanoobjects. The nonsymmetric mechanism also proceeds on 3'-terminally immobilized RNA and can integrate distinct CP types in blends or serially. Other emerging plant virus-deduced systems include the usually isometric cowpea chlorotic mottle virus (CCMV) with further strikingly altered structures up to "cherrybombs" with protruding nucleic acids. Cartoon strips and pictorial descriptions of major RNA-based strategies induct the reader into a rare field of nanoconstruction that can give rise to utile soft-matter architectures for complex tasks. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Future of cancer immunotherapy using plant virus-based nanoparticles

Immunotherapy potentiates a patient’s immune response against some forms of cancer, including malignant tumors. In this Special Report, we have summarized the use of nanoparticles that have been designed for use in cancer immunotherapy with particular emphasis on plant viruses. Plant virus-based nanoparticles are an ideal choice for therapeutic applications, as these nanoparticles are not only capable of targeting the desired cells but also of being safely delivered to the body without posing any threat of infection. Plant viruses can be taken up by tumor cells and can be functionalized as drug delivery vehicles. This Special Report describes how the future of cancer immunotherapy could be a success through the merger of computer-based technology using plant-virus nanoparticles.

The nonpathogenic nature of plant viral nanoparticles makes them an ideal choice for therapeutic applications such as cancer. Understanding the molecular mechanisms behind the immune response to cancer has facilitated the use of nanotechnology as an effective cancer therapy. Biologically active self-replicating plant virus particles can be introduced to the bloodstream of the human body and used as effective drug delivery vehicles. This Special Report describes how a combination of computer-based technology and plant-virus nanoparticles can assist in cancer immunotherapy.

Physalis Mottle Virus-like Nanoparticles for Targeted Cancer Imaging

One of the greatest challenges in nanomedicine is the low efficiency with which nanoparticles are delivered to lesions such as tumors in vivo. Here, we show that Physalis mottle virus (PhMV)-like nanoparticles can be developed as bimodal contrast agents to achieve long circulation, specific targeting capability, and efficient delivery to tumors in vivo. The self-assembling coat protein nanostructure offers various opportunities to modify the internal and external surfaces separately. After loading the internal cavity of the particles with the fluorescent dye Cy5.5 and paramagnetic Gd(III) complexes, we modified the outer surface by PEGylation and conjugation with targeting peptides. Using this combined approach, we were able to monitor a human prostate tumor model for up to 10 days by near-infrared fluorescence and magnetic resonance imaging, with up to 6% of the injection dose remaining. Our results show that PhMV-like nanoparticles provide a promising and innovative platform for the development of next-generation diagnostic and therapeutic agents.

Intracellular trafficking and endocytic uptake pathway of Pepper vein banding virus-like particles in epithelial cells

Aim: Plant virus-like particles (VLPs) have emerged as a novel platform for delivery of drugs/antibodies. The aim of the present investigation is to establish the entry mechanism of flexuous rod-shaped virus particles into mammalian cells. Methods: Far-Western blot analysis, pull-down and ELISA were used to characterize vimentin and Hsp60 interaction with VLPs. The mode/kinetics of internalization of VLPs was deciphered using pharmacological inhibitors/endosomal markers. Results & discussion: The flexuous rod-shaped VLPs of Pepper vein banding virus (PVBV) enter HeLa and HepG2 cells via cell-surface proteins: vimentin and Hsp60, respectively. VLPs internalize via different modes of endocytosis in HeLa, HepG2 cells and are biodegradable. Vimentin and Hsp60 could be potential epithelial ligands that facilitate targeting of nanoparticles to tumor cells.

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.

Plant Viruses in Plant Molecular Pharming: Toward the Use of Enveloped Viruses

Plant molecular pharming has emerged as a reliable platform for recombinant protein expression providing a safe and low-cost alternative to bacterial and mammalian cells-based systems. Simultaneously, plant viruses have evolved from pathogens to molecular tools for recombinant protein expression, chimaeric viral vaccine production, and lately, as nanoagents for drug delivery. This review summarizes the genesis of viral vectors and agroinfection, the development of non-enveloped viruses for various biotechnological applications, and the on-going research on enveloped plant viruses.