The Role of Virus-Like Particles in Medical Biotechnology

Nanoplatform Based Intranasal Vaccines: Current Progress and Clinical Challenges

Multiple vaccine platforms have been employed to develop the nasal SARS-CoV-2 vaccines in preclinical studies, and the dominating pipelines are viral vectored as protein-based vaccines. Among them, several viral vectored-based vaccines have entered clinical development. Nevertheless, some unsatisfactory results were reported in these clinical studies. In the face of such urgent situations, it is imperative to rapidly develop the next-generation intranasal COVID-19 vaccine utilizing other technologies. Nanobased intranasal vaccines have emerged as an approach against respiratory infectious diseases. Harnessing the power of nanotechnology, these vaccines offer a noninvasive yet potent defense against pathogens, including the threat of COVID-19. The improvements made in vaccine mucosal delivery technologies based on nanoparticles, such as lipid nanoparticles, polymeric nanoparticles, inorganic nanoparticles etc., not only provide stability and controlled release but also enhance mucosal adhesion, effectively overcoming the limitations of conventional vaccines. Hence, in this review, we overview the evaluation of intranasal vaccine and highlight the current barriers. Next, the modern delivery systems based on nanoplatforms are summarized. The challenges in clinical application of nanoplatform based intranasal vaccine are finally discussed.

Decoration of Burkholderia Hcp1 protein to virus-like particles as a vaccine delivery platform

Virus-like particles (VLPs) are protein-based nanoparticles frequently used as carriers in conjugate vaccine platforms. VLPs have been used to display foreign antigens for vaccination and to deliver immunotherapy against diseases. Hemolysin-coregulated proteins 1 (Hcp1) is a protein component of the Burkholderia type 6 secretion system, which participates in intracellular invasion and dissemination. This protein has been reported as a protective antigen and is used in multiple vaccine candidates with various platforms against melioidosis, a severe infectious disease caused by the intracellular pathogen Burkholderia pseudomallei. In this study, we used P22 VLPs as a surface platform for decoration with Hcp1 using chemical conjugation. C57BL/6 mice were intranasally immunized with three doses of either PBS, VLPs, or conjugated Hcp1-VLPs. Immunization with Hcp1-VLPs formulation induced Hcp1-specific IgG, IgG1, IgG2c, and IgA antibody responses. Furthermore, the serum from Hcp1-VLPs immunized mice enhanced the bacterial uptake and opsonophagocytosis by macrophages in the presence of complement. This study demonstrated an alternative strategy to develop a VLPs-based vaccine platform against Burkholderia species.

A novel three-plasmid packaging system for chimeric SFV/SIN VRPs derived from Semliki Forest virus and Sindbis virus as a candidate gene delivery vector

Semliki Forest virus (SFV) viral replicon particles (VRPs) have been frequently used in various animal models and clinical trials. Chimeric replicon particles offer different advantages because of their unique biological properties. We here constructed a novel three-plasmid packaging system for chimeric SFV/SIN VRPs. The capsid and envelope of SIN structural proteins were generated using two-helper plasmids separately, and the SFV replicon contained the SFV replicase gene, packaging signal of SIN, subgenomic promoter followed by the exogenous gene, and 3' UTR of SIN. The chimeric VRPs carried luciferase or eGFP as reporter genes. The fluorescence and electron microscopy results revealed that chimeric VRPs were successfully packaged. The yield of the purified chimeric VRPs was approximately 2.5 times that of the SFV VRPs (1.38 × 107 TU/ml vs. 5.41 × 106 TU/ml) (p < 0.01). Furthermore, chimeric VRPs could be stored stably at 4°C for at least 60 days. Animal experiments revealed that mice immunized with chimeric VRPs (luciferase) had stronger luciferase expression than those immunized with equivalent amount of SFV VRPs (luciferase) (p < 0.01), and successfully expressed luciferase for approximately 12 days. Additionally, the chimeric VRPs expressed the RBD of SARS-CoV-2 efficiently and induced robust RBD-specific antibody responses in mice. In conclusion, the chimeric VRPs constructed here met the requirements of a gene delivery tool for vaccine development and cancer therapy.

Protein-based delivery systems for RNA delivery

RNA-based therapeutics have emerged as promising approaches to modulate gene expression and generate therapeutic proteins or antigens capable of inducing immune responses to treat a variety of diseases, such as infectious diseases, cancers, immunologic disorders, and genetic disorders. However, the efficient delivery of RNA molecules into cells poses significant challenges due to their large molecular weight, negative charge, and susceptibility to degradation by RNase enzymes. To overcome these obstacles, viral and non-viral vectors have been developed, including lipid nanoparticles, viral vectors, proteins, dendritic macromolecules, among others. Among these carriers, protein-based delivery systems have garnered considerable attention due to their potential to address specific issues associated with nanoparticle-based systems, such as liver accumulation and immunogenicity. This review provides an overview of currently marketed RNA drugs, underscores the significance of RNA delivery vector development, delineates the essential characteristics of an ideal RNA delivery vector, and introduces existing protein carriers for RNA delivery. By offering valuable insights, this review aims to serve as a reference for the future development of protein-based delivery vectors for RNA therapeutics.

An Efficient and Scalable Method for the Production of Immunogenic SARS-CoV-2 Virus-like Particles (VLP) from a Mammalian Suspension Cell Line

The rapid evolution of new SARS-CoV-2 variants poses a continuing threat to human health. Vaccination has become the primary therapeutic intervention. The goal of the current work was the construction of immunogenic virus-like particles (VLPs). Here, we describe a human cell line for cost-efficient and scalable production of immunogenic SARS-CoV-2 VLPs. The modular design of the VLP-production platform facilitates rapid adaptation to new variants. Methods: The N, M-, and E-protein genes were integrated into the genome of Expi293 cells (ExpiVLP_MEN). Subsequently, this cell line was further modified for the constitutive expression of the SARS-CoV-2 spike protein. The resulting cell line (ExpiVLP_SMEN) released SARS-CoV-2 VLP upon exposure to doxycycline. ExpiVLP_SMEN cells were readily adapted for VLP production in a 5 L bioreactor. Purified VLPs were quantified by Western blot, ELISA, and nanoparticle tracking analysis and visualized by electron microscopy. Immunogenicity was tested in mice. Results: The generated VLPs contained all four structural proteins, are within the size range of authentic SARS-CoV-2 virus particles, and reacted strongly and specifically with immunoserum from naturally infected individuals. The VLPs were stable in suspension at 4 °C for at least 10 weeks. Mice immunized with VLPs developed neutralizing antibodies against lentiviruses pseudotyped with the SARS-CoV-2 spike protein. The flexibility of the VLP-production platform was demonstrated by the rapid switch of the spike protein to a new variant of concern (BA.1/Omicron). The present study describes an efficient, scalable, and adaptable production method of immunogenic SARS-CoV-2 VLPs with therapeutic potential.

Perspective vaccines for emerging viral diseases in farm animals

The world has watched the emergence of numerous animal viruses that may threaten animal health which were added to the perpetual growing list of animal pathogens. This emergence drew the attention of the experts and animal health groups to the fact that it has become necessary to work on vaccine development. The current review aims to explore the perspective vaccines for emerging viral diseases in farm animals. This aim was fulfilled by focusing on modern technologies as well as next generation vaccines that have been introduced in the field of vaccines, either in clinical developments pending approval, or have already come to light and have been applied to animals with acceptable results such as viral-vectored vaccines, virus-like particles, and messenger RNA-based platforms. Besides, it shed the light on the importance of differentiation of infected from vaccinated animals technology in eradication programs of emerging viral diseases. The new science of nanomaterials was explored to elucidate its role in vaccinology. Finally, the role of Bioinformatics or Vaccinomics and its assist in vaccine designing and developments were discussed. The reviewing of the published manuscripts concluded that the use of conventional vaccines is considered an out-of-date approach in eliminating emerging diseases. However, these types of vaccines are considered the suitable plan especially in countries with few resources and capabilities. Piloted vaccines that rely on genetic-based technologies with continuous analyses of current viruses should be the aim of future vaccinology. Smart genomics of emerging viruses will be the gateway to choosing appropriate vaccines, regardless of the evolutionary rates of viruses.

Uses and Challenges of Antiviral Polyclonal and Monoclonal Antibody Therapies

Viral diseases represent a major public health concerns and ever-present risks for developing into future pandemics. Antiviral antibody therapeutics, either alone or in combination with other therapies, emerged as valuable preventative and treatment options, including during global emergencies. Here we will discuss polyclonal and monoclonal antiviral antibody therapies, focusing on the unique biochemical and physiological properties that make them well-suited as therapeutic agents. We will describe the methods of antibody characterization and potency assessment throughout development, highlighting similarities and differences between polyclonal and monoclonal products as appropriate. In addition, we will consider the benefits and challenges of antiviral antibodies when used in combination with other antibodies or other types of antiviral therapeutics. Lastly, we will discuss novel approaches to the characterization and development of antiviral antibodies and identify areas that would benefit from additional research.

P22-Based Nanovaccines against Enterohemorrhagic Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) is an important causative agent of diarrhea in humans that causes outbreaks worldwide. Efforts have been made to mitigate the morbidity and mortality caused by these microorganisms; however, the global incidence is still high, causing hundreds of deaths per year. Several vaccine candidates have been evaluated that demonstrate some stability and therapeutic potential but have limited overarching effect. Virus-like particles have been used successfully as nanocontainers for the targeted delivery of drugs, proteins, or nucleic acids. In this study, phage P22 nanocontainers were used as a carrier for the highly antigenic T3SS structural protein EscC that is conserved between EHEC and other enteropathogenic bacteria. We were able to stably incorporate the EscC protein into P22 nanocontainers. The EscC-P22 particles were used to intranasally inoculate mice, which generated specific antibodies against EscC. These antibodies increased the phagocytic activity of murine macrophages infected with EHEC in vitro and reduced bacterial adherence to Caco-2 epithelial cells in vitro, illustrating their functionality. The EscC-P22-based particles are a potential nanovaccine candidate for immunization against EHEC O157:H7 infections. IMPORTANCE This study describes the initial attempt to use P22 viral-like particles as nanocontainers expressing enterohemorrhagic Escherichia coli (EHEC) proteins that are immunogenic and could be used as effective vaccines against EHEC infections.

A perspective on SARS-CoV-2 virus-like particles vaccines

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) first appeared in Wuhan, China, in December 2019. The 2019 coronavirus disease (COVID-19) pandemic, caused by SARS-CoV-2, has spread to almost all corners of the world at an alarming rate. Vaccination is important for the prevention and control of the COVID-19 pandemic. Efforts are underway worldwide to develop an effective vaccine against COVID-19 using both traditional and innovative vaccine strategies. Compared to other vaccine platforms, SARS-CoV-2 virus-like particles （VLPs ）vaccines, as a new vaccine platform, have unique advantages: they have artificial nanostructures similar to natural SARS-CoV-2, which can stimulate good cellular and humoral immune responses in the organism; they have no viral nucleic acids, have good safety and thermal stability, and can be mass-produced and stored; their surfaces can be processed and modified, such as the adjuvant addition, etc.; they can be considered as an ideal platform for COVID-19 vaccine development. This review aims to shed light on the current knowledge and progress of VLPs vaccines against COVID-19, especially those undergoing clinical trials.

Virus-like nanoparticles as a theranostic platform for cancer

Virus-like nanoparticles (VLPs) are natural polymer-based nanomaterials that mimic viral structures through the hierarchical assembly of viral coat proteins, while lacking viral genomes. VLPs have received enormous attention in a wide range of nanotechnology-based medical diagnostics and therapies, including cancer therapy, imaging, and theranostics. VLPs are biocompatible and biodegradable and have a uniform structure and controllable assembly. They can encapsulate a wide range of therapeutic and diagnostic agents, and can be genetically or chemically modified. These properties have led to sophisticated multifunctional theranostic platforms. This article reviews the current progress in developing and applying engineered VLPs for molecular imaging, drug delivery, and multifunctional theranostics in cancer research.

Assembly of Protein Cages for Drug Delivery

Nanoparticles (NPs) have been widely used as target delivery vehicles for therapeutic goods; however, compared with inorganic and organic nanomaterials, protein nanomaterials have better biocompatibility and can self-assemble into highly ordered cage-like structures, which are more favorable for applications in targeted drug delivery. In this review, we concentrate on the typical protein cage nanoparticles drugs encapsulation processes, such as drug fusion expression, diffusion, electrostatic contact, covalent binding, and protein cage disassembly/recombination. The usage of protein cage nanoparticles in biomedicine is also briefly discussed. These materials can be utilized to transport small molecules, peptides, siRNA, and other medications for anti-tumor, contrast, etc.

Quality assessment of virus-like particle: A new transmission electron microscopy approach

Transmission electron microscopy (TEM) is a gold standard analytical method for nanoparticle characterization and is playing a valuable role in virus-like particle (VLP) characterization extending to other biological entities such as viral vectors. A dedicated TEM facility is a challenge to both small and medium-sized enterprises (SMEs) and companies operating in low-and-middle income countries (LMICs) due to high start-up and running costs. A low-voltage TEM solution with assisted image acquisition and analysis such as the MiniTEM system, coupled with Vironova Imaging and Analysis Software (VIAS) could provide an affordable and practical alternative. The MiniTEM system has a small footprint and software that enables semi-automated data collection and image analysis workflows using built-in deep learning methods (convolutional neural networks) for automation in analysis, increasing speed of information processing and enabling scaling to larger datasets. In this perspective we outline the potential and challenges in the use of TEM as mainstream analytical tool in manufacturing settings. We highlight the rationale and preliminary findings from our proof-of-concept study aiming to develop a method to assess critical quality attributes (CQAs) of VLPs and facilitate adoption of TEM in manufacturing settings. In our study we explored all the steps, from sample preparation to data collection and analysis using synthetic VLPs as model systems. The applicability of the method in product development was verified at pilot-scale during the technology transfer of dengue VLPs development from a university setting to an LMIC- based vaccine manufacturing company, demonstrating the applicability of this analytical technique to VLP vaccine characterization.

Micro-Nanocarriers Based Drug Delivery Technology for Blood-Brain Barrier Crossing and Brain Tumor Targeting Therapy

The greatest obstacle to using drugs to treat brain tumors is the blood-brain barrier (BBB), making it difficult for conventional drug molecules to enter the brain. Therefore, how to safely and effectively penetrate the BBB to achieve targeted drug delivery to brain tumors has been a challenging research problem. With the intensive research in micro- and nanotechnology in recent years, nano drug-targeted delivery technologies have shown great potential to overcome this challenge, such as inorganic nanocarriers, organic polymer-carriers, liposomes, and biobased carriers, which can be designed in different sizes, shapes, and surface functional groups to enhance their ability to penetrate the BBB and targeted drug delivery for brain tumors. In this review, the composition and overcoming patterns of the BBB are detailed, and then the hot research topics of drug delivery carriers for brain tumors in recent years are summarized, and their mechanisms of action on the BBB and the factors affecting drug delivery are described in detail, and the effectiveness of targeted therapy for brain tumors is evaluated. Finally, the challenges and dilemmas in developing brain tumor drug delivery systems are discussed, which will be promising in the future for targeted drug delivery to brain tumors based on micro-nanocarriers technology.

Engineered Protein Nanocages for Concurrent RNA and Protein Packaging In Vivo

Protein nanocages have emerged as an important engineering platform for biotechnological and biomedical applications. Among naturally occurring protein cages, encapsulin nanocompartments have recently gained prominence due to their favorable physico-chemical properties, ease of shell modification, and highly efficient and selective intrinsic protein packaging capabilities. Here, we expand encapsulin function by designing and characterizing encapsulins for concurrent RNA and protein encapsulation in vivo. Our strategy is based on modifying encapsulin shells with nucleic acid-binding peptides without disrupting the native protein packaging mechanism. We show that our engineered encapsulins reliably self-assemble in vivo, are capable of efficient size-selective in vivo RNA packaging, can simultaneously load multiple functional RNAs, and can be used for concurrent in vivo packaging of RNA and protein. Our engineered encapsulation platform has potential for codelivery of therapeutic RNAs and proteins to elicit synergistic effects and as a modular tool for other biotechnological applications.

Can Virus-like Particles Be Used as Synergistic Agent in Pest Management?

Among novel strategies proposed in pest management, synergistic agents are used to improve insecticide efficacy through an elevation of intracellular calcium concentration that activates the calcium-dependent intracellular pathway. This leads to a changed target site conformation and to increased sensitivity to insecticides while reducing their concentrations. Because virus-like particles (VLPs) increase the intracellular calcium concentration, they can be used as a synergistic agent to synergize the effect of insecticides. VLPs are self-assembled viral protein complexes, and by contrast to entomopathogen viruses, they are devoid of genetic material, which makes them non-infectious and safer than viruses. Although VLPs are well-known to be used in human health, we propose in this study the development of a promising strategy based on the use of VLPs as synergistic agents in pest management. This will lead to increased insecticides efficacy while reducing their concentrations.

Virus-Like Particles: Revolutionary Platforms for Developing Vaccines Against Emerging Infectious Diseases

Virus-like particles (VLPs) are nanostructures that possess diverse applications in therapeutics, immunization, and diagnostics. With the recent advancements in biomedical engineering technologies, commercially available VLP-based vaccines are being extensively used to combat infectious diseases, whereas many more are in different stages of development in clinical studies. Because of their desired characteristics in terms of efficacy, safety, and diversity, VLP-based approaches might become more recurrent in the years to come. However, some production and fabrication challenges must be addressed before VLP-based approaches can be widely used in therapeutics. This review offers insight into the recent VLP-based vaccines development, with an emphasis on their characteristics, expression systems, and potential applicability as ideal candidates to combat emerging virulent pathogens. Finally, the potential of VLP-based vaccine as viable and efficient immunizing agents to induce immunity against virulent infectious agents, including, SARS-CoV-2 and protein nanoparticle-based vaccines has been elaborated. Thus, VLP vaccines may serve as an effective alternative to conventional vaccine strategies in combating emerging infectious diseases.

Multifaceted roles of a bioengineered nanoreactor in repressing radiation-induced lung injury

Radiation-induced lung injury (RILI) is a potentially fatal and dose-limiting complication of thoracic cancer radiotherapy. However, effective therapeutic agents for this condition are limited. Here, we describe a novel strategy to exert additive effects of a non-erythropoietic EPO derivative (ARA290), along with a free radical scavenger, superoxide dismutase (SOD), using a bioengineered nanoreactor (SOD@ARA290-HBc). ARA290-chimeric nanoreactor makes SOD present in a confined reaction space by encapsulation into its interior to heighten stability against denaturing stimuli. In a RILI mouse model, intratracheal administration of SOD@ARA290-HBc was shown to significantly ameliorate acute radiation pneumonitis and pulmonary fibrosis. Our investigations revealed that SOD@ARA290-HBc performs its radioprotective effects by protecting against radiation induced alveolar epithelial cell apoptosis and ferroptosis, suppressing oxidative stress, inhibiting inflammation and by modulating the infiltrated macrophage phenotype, or through a combination of these mechanisms. In conclusion, SOD@ARA29-HBc is a potential therapeutic agent for RILI, and given its multifaceted roles, it may be further developed as a translational nanomedicine for other related disorders.