Emerging Biomedical Applications of the Vesicular Stomatitis Virus Glycoprotein

Protective Effects of Rat Bone Marrow Mesenchymal Stem Cells-Derived Fusogenic Plasma Membrane Vesicles Containing VSVG Protein Mediated Mitochondrial Transfer on Myocardial Injury In Vitro

Overexpression of spike glycoprotein G of vesicular stomatitis virus (VSVG) can induce the release of fusogenic plasma membrane vesicles (fPMVs), which can transport cytoplasmic, nuclear, and surface proteins directly to target cells. This study aimed to investigate the roles of rat bone marrow mesenchymal stem cells (rBMSCs)-derived fPMVs containing VSVG protein in myocardial injury and their related mechanisms. The plasmids of pLP-VSVG were used to transfect rBMSCs, and then fPMVs were obtained by mechanical extrusion. After that, H9c2 cells were first treated with hypoxia reoxygenation (HR) to establish a cardiomyocyte injury model, and then were treated with fPMVs to evaluate the rescue of rBMSCs-derived fPMVs on HR-induced cardiomyocyte injury. FPMVs containing VSVG protein were successfully prepared from rBMSCs with VSVG overexpression. Compared with control fPMVs, ACTB, HDAC1, VSVG, CD81, MTCO1, and TOMM20 were significantly up-regulated (p < 0.05), while eEF2 was significantly down-regulated (p < 0.05) in the fPMVs containing VSVG protein. Additionally, it was obvious fPMVs could carry mitochondria into H9c2 cells, and HR treatment significantly inhibited viability and induced apoptosis of H9c2 cells, as well as significantly increased the contents of TNF-α and IL-1β, and ROS levels both in cells and cellular mitochondria, while evidently reducing the levels of ATP, MRCC IV, and MT-ND1 (p < 0.05). However, fPVMs could remarkably reverse the changes in these indexes caused by HR (p < 0.05). RBMSCs-derived fPMVs containing VSVG protein may have protective effects on myocardial injury by mediating mitochondrial transfer and regulating mitochondrial functions.

Development and application of a high-titer VSV-based HCoV-NL63 pseudovirus system via C-terminal 14 amino acid truncation of spike

To provide efficient tools for the development of novel antiviral drugs and vaccines of HCoV-NL63, it is urgently necessary to establish a safe, widely applicable, and high-titer NL63 pseudotyped particles (NL63pp) production system. In this research, we conducted a comparative analysis of several NL63pps, each with a truncated spike (S) protein missing part of its C-terminal amino acids. We discovered that deleting the C-terminal 14 amino acid sequence of the S protein (D14) led to a remarkable approximately 10-fold increase in the infection titer of VSV-based NL63pp. This value is higher than the titers of NL63pp packaged with S proteins having deletions of 18 or 24 amino acids at the C-terminus. Moreover, adding the VSV-G tag to the D14 C-terminus (D14V) resulted in an additional 30 % increase. We then constructed the recent prevalent HCoV-NL63 subgenotype C3 dual-reporter pseudovirus system C3-D14V, and found that C3-D14V had a higher infection efficiency. Utilizing this system, we investigated the susceptibility of several cell lines and observed that cells derived from liver (Huh7.5.1), small intestine (Caco-2) and lung (Calu-3) exhibited higher susceptibility. Furthermore, we applied this system to assess several bis-benzylisoquinoline alkaloids, notably, Cepharanthine demonstrated the highest inhibitory efficiency against NL63pp infection with EC50 0.61 μM. In conclusion, we have identified that S protein with a 14 amino acids deletion at the C-terminus significantly enhances the infection titer of HCoV-NL63 pseudovirus and provides an efficient VSV-based HCoV-NL63 dual-reporter (mCherry and luciferase2) pseudovirus system for various applications such as drug screening and antibody development in the future.

Pseudotyped Viruses: A Useful Platform for Pre-Clinical Studies Conducted in a BSL-2 Laboratory Setting

The study of pathogenic viruses has always posed significant biosafety challenges. In particular, the study of highly pathogenic viruses requires methods with low biological risk but relatively high sensitivity and convenience in detection. In recent years, pseudoviruses, which consist of a backbone of one virus and envelope proteins of another virus, have become one of the most widely used tools for exploring the mechanisms of viruses binding to cells, membrane fusion and viral entry, as well as for screening the libraries of antiviral substances, evaluating the potential of neutralizing monoclonal antibodies, developing neutralization tests, and therapeutic platforms. During the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), pseudotyped virus-based assays played a pivotal role in advancing our understanding of virus-cell interactions and the role of its proteins in disease pathogenesis. Such tools facilitated the search for potential therapeutic agents and accelerated epidemiological studies on post-infection and post-vaccination humoral immunity. This review focuses on the use of pseudoviruses as a model for large-scale applications to study enveloped viruses.

Vesicular Stomatitis Virus: Insights into Pathogenesis, Immune Evasion, and Technological Innovations in Oncolytic and Vaccine Development

Vesicular stomatitis virus (VSV) represents a significant advancement in therapeutic medicine, offering unique molecular and cellular characteristics that make it exceptionally suitable for medical applications. The bullet-shaped morphology, RNA genome organization, and cytoplasmic replication strategy provide fundamental advantages for both vaccine development and oncolytic applications. VSV's interaction with host cells through the low-density lipoprotein receptor (LDL-R) and its sophisticated transcriptional regulation mechanisms enables precise control over therapeutic applications. The virus demonstrates remarkable versatility through its rapid replication cycle, robust immune response induction, and natural neurotropism. Recent technological innovations in VSV engineering have led to enhanced safety protocols and improved therapeutic modifications, particularly in cancer treatment. Attenuation strategies have successfully addressed safety concerns while maintaining the therapeutic efficacy of the virus. The molecular and cellular interactions of VSV, particularly its immune modulation capabilities and tumor-selective properties, have proven valuable in the development of targeted therapeutic strategies. This review explores these aspects, while highlighting the continuing evolution of VSV-based therapeutic approaches in precision medicine.

Characterization of human tibrovirus envelope glycoproteins

Tibroviruses are novel rhabdoviruses detected in humans, cattle, and arthropods. Four tibroviruses are known to infect humans: Bas-Congo virus (BASV), Ekpoma virus 1 (EKV-1), Ekpoma virus 2, and Mundri virus. However, since none of them has been isolated, their biological properties are largely unknown. We aimed to characterize the human tibrovirus glycoprotein (G), which likely plays a pivotal role in viral tropism and pathogenicity. Human tibrovirus Gs were found to share some primary structures and display 14 conserved cysteine residues, although their overall amino acid homology was low (29%-48%). Multiple potential glycosylation sites were found on the G molecules, and endoglycosidase H- and peptide-N-glycosidase F-sensitive glycosylation was confirmed. AlphaFold-predicted three-dimensional (3D) structures of human tibrovirus Gs were overall similar. Membrane fusion mediated by these tibrovirus Gs was induced by acidic pH. The low pH-induced conformational change that triggers fusion was reversible. Virus-like particles (VLPs) were produced by transient expression of Gs in cultured cells and used to produce mouse antisera. Using vesicular stomatitis Indiana virus pseudotyped with Gs, we found that the antisera to the respective tibrovirus VLPs showed limited cross-neutralizing activity. It was also found that human C-type lectins and T-cell immunoglobulin mucin 1 acted as attachment factors for G-mediated entry into cells. Interestingly, BASV-G showed the highest ability to utilize these molecules. The viruses infected a wide range of cell lines with preferential tropism for human-derived cells whereas the preference of EKV-1 was unique compared with the other human tibroviruses. These findings provide fundamental information to understand the biological properties of the human tibroviruses.

IMPORTANCE

Human tibroviruses are poorly characterized emerging rhabdoviruses associated with either asymptomatic infection or severe disease with a case fatality rate as high as 60% in humans. However, the extent and burden of human infection as well as factors behind differences in infection outcomes are largely unknown. In this study, we characterized human tibrovirus glycoproteins, which play a key role in virus-host interactions, mainly focusing on their structural and antigenic differences and cellular tropism. Our results provide critical information for understanding the biological properties of these novel viruses and for developing appropriate preparedness interventions such as diagnostic tools, vaccines, and effective therapies.

Improved Manufacturing Methods of Extracellular Vesicles Pseudotyped with the Vesicular Stomatitis Virus Glycoprotein

Extracellular vesicles (EV), which expose the vesicular stomatitis virus glycoprotein (VSVG) on their surface, are used for delivery of nucleic acids and proteins in human cell lines. These particles are biomanufactured using methods that are difficult to scale up. Here, we describe the development of the first EV-VSVG production process in serum-free media using polyethylenimine (PEI)-based transient transfection of HEK293 suspension cells, as well as the first EV-VSVG purification process to utilize both ultracentrifugation and chromatography. Three parameters were investigated for EV-VSVG production: cell density, DNA concentration, and DNA:PEI ratio. The best production titer was obtained with 3 × 106 cells/mL, a plasmid concentration of 2 µg/mL, and a DNA:PEI ratio of 1:4. The production kinetics of VSVG was performed and showed that the highest amount of VSVG was obtained 3 days after transfection. Addition of cell culture supplements during the transfection resulted in an increase in VSVG production, with a maximum yield obtained with 2 mM of sodium butyrate added 18 h after transfection. Moreover, the absence of EV-VSVG during cell transfection with a GFP-coding plasmid revealed to be ineffective, with no fluorescent cells. An efficient EV-VSVG purification procedure consisting of a two-step concentration by low-speed centrifugation and sucrose cushion ultracentrifugation followed by a heparin affinity chromatography purification was also developed. Purified bioactive EV-VSVG preparations were characterized and revealed that EV-VSVG are spherical particles of 176.4 ± 88.32 nm with 91.4% of protein similarity to exosomes.

Pralatrexate inhibited the replication of varicella zoster virus and vesicular stomatitis virus: An old dog with new tricks

Varicella zoster virus (VZV) is associated with herpes zoster (HZ) or herpes zoster ophthalmicus (HZO). All antiviral agents currently licensed for the management of VZV replication via modulating different mechanisms, and the resistance is on the rise. There is a need to develop new antiviral agents with distinct mechanisms of action and adequate safety profiles. Pralatrexate (PDX) is a fourth-generation anti-folate agent with an inhibitory activity on folate (FA) metabolism and has been used as an anti-tumor drug. We observed that PDX possessed potent inhibitory activity against VZV infection. In this study, we reported the antiviral effects and the underlying mechanism of PDX against VZV infection. The results showed that PDX not only inhibited VZV replication in vitro and in mice corneal tissues but also reduced the inflammatory response and apoptosis induced by viral infection. Furthermore, PDX treatment showed a similar anti-VSV inhibitory effect in both in vitro and in vivo models. Mechanistically, PDX inhibited viral replication by interrupting the substrate supply for de novo purine and thymidine synthesis. In conclusion, this study discovered the potent antiviral activity of PDX with a novel mechanism and presented a new strategy for VZV treatment that targets a cellular metabolic mechanism essential for viral replication. The present study provided a new insight into the development of broad-spectrum antiviral agents.

Engineered Living Materials for Advanced Diseases Therapy

Natural living materials serving as biotherapeutics exhibit great potential for treating various diseases owing to their immunoactivity, tissue targeting, and other biological activities. In this review, the recent developments in engineered living materials, including mammalian cells, bacteria, viruses, fungi, microalgae, plants, and their active derivatives that are used for treating various diseases are summarized. Further, the future perspectives and challenges of such engineered living material-based biotherapeutics are discussed to provide considerations for future advances in biomedical applications.