ESCRT recruitment to SARS-CoV-2 spike induces virus-like particles that improve mRNA vaccines

Engineered multi-domain lipid nanoparticles for targeted delivery

Engineered lipid nanoparticles (LNPs) represent a breakthrough in targeted drug delivery, enabling precise spatiotemporal control essential to treat complex diseases such as cancer and genetic disorders. However, the complexity of the delivery process-spanning diverse targeting strategies and biological barriers-poses significant challenges to optimizing their design. To address these, this review introduces a multi-domain framework that dissects LNPs into four domains: structure, surface, payload, and environment. Engineering challenges, functional mechanisms, and characterization strategies are analyzed across each domain, along with a discussion of advantages, limitations, and in vivo fate (e.g., biodistribution and clearance). The framework also facilitates comparisons with natural exosomes and exploration of alternative administration routes, such as intranasal and intraocular delivery. We highlight current characterization techniques, such as cryo-TEM and multiscale molecular dynamics simulations, as well as the recently emerging artificial intelligence (AI) applications-ranging from LNP structure screening to the prospective use of generative models for de novo design beyond traditional experimental and simulation paradigms. Finally, we examine how engineered LNPs integrate active, passive, endogenous, and stimuli-responsive targeting mechanisms to achieve programmable delivery, potentially surpassing biological sophistication in therapeutic performance.

A modular mRNA vaccine platform encoding antigen-presenting capsid virus-like particles enhances the immunogenicity of the malaria antigen Pfs25

The COVID-19 pandemic has emphasized the potential of mRNA vaccines in fighting pandemics, owing to their rapid development, strong immunogenicity and adaptability. However, a drawback is their dose-limiting reactogenicity and inability to generate durable humoral immunity. Here we introduce a modular nucleotide vaccine platform combining the advantages of genetic and capsid virus-like-particle-based vaccines. This platform allows for the display of various antigens on different capsid virus-like particles, improving the magnitude, quality and longevity of the vaccine-induced immune responses. We applied this technology to enhance the immunogenicity of the Pfs25 antigen. Immunization with lipid-nanoparticle-formulated mRNA encoding Pfs25 capsid virus-like particles resulted in higher and potentially more durable anti-Pfs25 antibody responses, along with enhanced functional activity, compared with an mRNA vaccine encoding soluble Pfs25. By improving both humoral and cellular immune responses, this approach may reduce the dose and number of administrations required for effective protection. As a result, it can improve the feasibility of both DNA- and mRNA-based vaccines targeting pandemic and endemic infectious diseases.

Novel universal vaccines to mitigate emerging avian influenza viruses

Frequent spillovers and recent geospatial expansion of avian influenza virus (AIV) pose significant economic and public health threats. Recent advances in vaccine technologies, bioinformatics, and artificial intelligence will provide newer approaches to target genetically diverse and rapidly evolving AIVs. Here, we review recent advances in, and perspectives on, developing universal vaccines needed for the effective control of AIVs.

Revolutionizing immunization: a comprehensive review of mRNA vaccine technology and applications

Messenger RNA (mRNA) vaccines have emerged as a transformative platform in modern vaccinology. mRNA vaccine is a powerful alternative to traditional vaccines due to their high potency, safety, and efficacy, coupled with the ability for rapid clinical development, scalability and cost-effectiveness in manufacturing. Initially conceptualized in the 1970s, the first study about the effectiveness of a mRNA vaccine against influenza was conducted in 1993. Since then, the development of mRNA vaccines has rapidly gained significance, especially in combating the COVID-19 pandemic. Their unprecedented success during the COVID-19 pandemic, as demonstrated by the Pfizer-BioNTech and Moderna vaccines, highlighted their transformative potential. This review provides a comprehensive analysis of the mRNA vaccine technology, detailing the structure of the mRNA vaccine and its mechanism of action in inducing immunity. Advancements in nanotechnology, particularly lipid nanoparticles (LNPs) as delivery vehicles, have revolutionized the field. The manufacturing processes, including upstream production, downstream purification, and formulation are also reviewed. The clinical progress of mRNA vaccines targeting viruses causing infectious diseases is discussed, emphasizing their versatility and therapeutic potential. Despite their success, the mRNA vaccine platform faces several challenges, including improved stability to reduce dependence on cold chain logistics in transport, enhanced delivery mechanisms to target specific tissues or cells, and addressing the risk of rare adverse events. High costs associated with encapsulation in LNPs and the potential for unequal global access further complicate their widespread adoption. As the world continues to confront emerging viral threats, overcoming these challenges will be essential to fully harness the potential of mRNA vaccines. It is anticipated that mRNA vaccines will play a major role in defining and shaping the future of global health.

SARS CoV-2 spike adopts distinct conformational ensembles in situ

Engineered recombinant Spike (S) has been invaluable for determining S structure and dynamics and is the basis for the design of most prevalent vaccines. While these vaccines have been highly efficacious for short-term protection from infection, protection waned with the emergence of variants (alpha through omicron). Here we report differences in conformational dynamics between native, membrane-embedded full-length S and recombinant S. Our virus-like particle (VLP) model mimics the native SARS CoV-2 virion by displaying S assembled with auxiliary E, M, and N proteins in a native membrane environment that captures the entirety of quaternary interactions mediated by S. Display of S on VLP obviates the requirement for stabilizing modifications that have been engineered into recombinant S for enhanced expression and solubility. Amide hydrogen/deuterium exchange mass spectrometry (HDXMS) reveals altered interprotomer contacts in VLP S trimers attributable to the presence of auxiliary proteins, membrane anchoring, and lack of engineered modifications. Our results reveal decreased dynamics in the S2 subunit and at sites spanning interprotomer contacts in VLP S with minimal differences in the N-terminal domain (NTD) and receptor binding domain (RBD). This carries implications for display of epitopes beyond NTD and RBD. In summary, despite affording efficient structural characterization, recombinant S distorts the intrinsic conformational ensemble of native S displayed on the virus surface.

Self-assembling of coiled-coil peptides into virus-like particles: Basic principles, properties, design, and applications with special focus on vaccine design and delivery

Self-assembling peptide nanoparticles (SAPN) based delivery systems, including virus-like particles (VLP), have shown great potential for becoming prominent in next-generation vaccine and drug development. The VLP can mimic properties of natural viral capsid in terms of size (20-200 nm), geometry (i.e., icosahedral structures), and the ability to generate a robust immune response (with multivalent epitopes) through activation of innate and/or adaptive immune signals. In this regard, coiled-coil (CC) domains are suitable building blocks for designing VLP because of their programmable interaction specificity, affinity, and well-established sequence-to-structure relationships. Generally, two CC domains with different oligomeric states (trimer and pentamer) are fused to form a monomeric protein through a short, flexible spacer sequence. By using combinations of symmetry axes (2-, 3- and 5- folds) that are unique to the geometry of the desired protein cage, it is possible, in principle, to assemble well-defined protein cages like VLP. In this review, we have discussed the crystallographic rules and the basic principles involved in the design of CC-based VLP. It also explored the functions of numerous noncovalent interactions in generating stable VLP structures, which play a crucial role in improving the properties of vaccine immunogenicity, drug delivery, and 3D cell culturing.

A Universal Therapeutic Vaccine Leveraging Autologous Pre-Existing Immunity to Eliminate in Situ Uniformly Engineered Heterogeneous Tumor Cells

Tumor vaccines that activate the autologous immune system to eliminate tumor cells represent a promising approach in cancer immunotherapy. However, challenges such as tumor heterogeneity, limited antigen selection, insufficient antigen presentation, and the slow onset of de novo immune responses have resulted in poor universality and suboptimal response rates. In contrast, pathogen-specific pre-existing immunity acquired through infection or vaccination, can rapidly generate a more potent and enduring immune response upon re-encounter with the same antigen. Here, an adeno-associated virus (AAV)-based therapeutic vaccine capable of genetically modifying diverse tumor cells to uniformly overexpress and efficiently present the highly immunogenic transmembrane SARS-CoV-2 receptor binding domain (RBD), and to release RBD-enveloped virus-like particles, which awaken and enhance the RBD-specific pre-existing immunity, leading to significant tumor remission, is engineered. Mechanistically, this therapeutic vaccine leverages the robust RBD-specific pre-existing immunity and heightened antibody-mediated phagocytosis to eliminate engineered tumor cells while inducing antigen spreading, thereby provoking a more diverse tumor-specific cellular immune responses. Notably, widespread administration of vaccines against various pathogens has provided a versatile pool of pre-existing immunity that can be redirected to eradicate tumors. These findings offer a novel perspective on overcoming the limitations posed by tumor heterogeneity and personalized medicine.

Tuning the tropism and infectivity of SARS-CoV-2 virus-like particles for mRNA delivery

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus-like particles (VLPs) are ∼100-nm-sized bioinspired mimetics of the authentic virus. We undertook molecular engineering to optimize the VLP platform for messenger RNA (mRNA) delivery. Cloning the nucleocapsid protein upstream of M-IRES-E resulted in a three-plasmid (3P) VLP system that displayed ∼7-fold higher viral entry efficiency compared with VLPs formed by co-transfection with four plasmids. More than 90% of human ACE2-expressing cells could be transduced using these 3P VLPs. Viral tropism could be programmed by switching glycoproteins from other viral strains, including other betacoronaviruses and the vesicular stomatitis virus G protein. An infectious two-plasmid VLP system was also advanced where one vector carried the viral surface glycoprotein and the second carried the remaining SARS-CoV-2 structural proteins and reporter gene. SARS-CoV-2 VLPs could be engineered to carry up to four transgenes, including functional Cas9 mRNA for genome editing. Gene editing of specific target cell types was feasible by modifying VLP tropism. Successful mRNA delivery to mouse lungs suggests that the SARS-CoV-2 VLPs can overcome natural biological barriers to enable pulmonary gene delivery. Overall, the study describes the advancement of the SARS-CoV-2 VLP platform for robust mRNA delivery both in vitro and in vivo.

Sequences in the Cytoplasmic Tail Contribute to the Intracellular Trafficking and the Cell Surface Localization of SARS-CoV-2 Spike Protein

Spike protein is a surface glycoprotein of the SARS-CoV-2 coronavirus, providing interaction of the coronavirus with angiotensin-converting enzyme 2 (ACE2) on the host cell. The cytoplasmic tail of the S protein plays an important role in an intracellular transport and translocation of the glycoprotein to the plasma membrane. The cytoplasmic domain of the S protein contains binding sites for COPI, COPII, and SNX27, which are required for the intracellular trafficking of this glycoprotein. In addition, the cytoplasmic domain of the S protein contains S-palmitoylation sites. S-palmitoylation increases the hydrophobicity of the S protein by regulating its transport to the plasma membrane. The cytoplasmic tail of the S protein has a signaling sequence that provides interaction with the ERM family proteins, which may mediate communication between the cell membrane and the actin cytoskeleton. This review examines the role of the cytoplasmic tail of the SARS-CoV-2 S protein in its intracellular transport and translocation to the plasma membrane. Understanding these processes is necessary not only for the development of vaccines based on mRNA or adenovirus vectors encoding the full-length spike (S) protein, but also for the therapy of the new coronavirus infection (COVID-19).

The Interplay of Furin Cleavage and D614G in Modulating SARS-CoV-2 Spike Protein Dynamics

We report a detailed analysis of the full-length SARS-CoV-2 spike dynamics within a native-like membrane environment and variants inaccessible to studies on soluble constructs by conducting hydrogen-deuterium exchange mass spectrometry (HDX-MS) on enveloped virus-like particles (eVLPs) displaying various spike constructs. We find that the previously identified open-interface trimer conformation is sampled in all eVLP-displayed spike variants studied including sequences from engineered vaccine constructs and native viral sequences. The D614G mutation, which arose early in the pandemic, favors the canonical 'closed-interface' prefusion conformation, potentially mitigating premature S1 shedding in the presence of a cleaved furin site and providing an evolutionary advantage to the virus. Remarkably, furin cleavage at the S1/S2 boundary allosterically increases the flexibility of the S2' site, which may facilitate increased TMPRSS2 processing, enhancing viral infectivity. The use of eVLPs in HDX-MS studies provides a powerful platform for studying viral and membrane proteins in near-native environments.

S6P mutation in Delta and Omicron variant spike protein significantly enhances the efficacy of mRNA COVID-19 vaccines

Background

The unrelenting emergence of SARS-CoV-2 variants has significantly challenged the efficacy of existing COVID-19 vaccines. Enhancing the stability and immunogenicity of the spike protein is critical for improving vaccine performance and addressing variant-driven immune evasion.

Methods

We developed an mRNA-based vaccine, RV-1730, encoding the Delta variant spike protein with the S6P mutation to enhance stability and immunogenicity. The vaccine's immunogenicity and protective efficacy were evaluated in preclinical models, including monovalent (RV-1730) and bivalent (RV-1731) formulations targeting the Delta and BA.1 variants. Additionally, the effectiveness of RV-1730 as a heterologous booster following primary vaccination with BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna-NIAID) was assessed.

Results

RV-1730 elicited significantly stronger B and T cell responses and more durable neutralizing antibodies compared to S2P-based vaccines. The bivalent RV-1731 vaccine demonstrated broad neutralizing activity against emerging variants, including XBB1.5 and JN.1. Importantly, RV-1730, when used as a heterologous booster following initial immunization with BNT162b2 or mRNA-1273, significantly enhanced neutralizing antibody titers against multiple variants, including Delta and Omicron. Both RV-1730 and RV-1731 provided superior protection in preclinical models, indicating enhanced efficacy due to the S6P mutation.

Conclusion

The incorporation of the S6P mutation into the Delta variant spike protein significantly enhances the immunogenicity and efficacy of mRNA-based COVID-19 vaccines. The strong performance of RV-1730 as a heterologous booster and the broad-spectrum activity of the bivalent RV-1731 vaccine underscore their potential as versatile and effective vaccination strategies against SARS-CoV-2 and its evolving variants.

Nanoparticles in Subunit Vaccines: Immunological Foundations, Categories, and Applications

Subunit vaccines, significant in next-generation vaccine development, offer precise targeting of immune responses by focusing on specific antigens. However, this precision often comes at the cost of eliciting strong and durable immunity, posing a great challenge to vaccine design. To address this limitation, recent advancements in nanoparticles (NPs) are utilized to enhance antigen delivery efficiency and boost vaccine efficacy. This review examines how the physicochemical properties of NPs influence various stages of the immune response during vaccine delivery and analyzes how different NP types contribute to immune activation and enhance vaccine performance. It then explores the unique characteristics and immune activation mechanisms of these NPs, along with their recent advancements, and highlights their application in subunit vaccines targeting infectious diseases and cancer. Finally, it discusses the challenges in NP-based vaccine development and proposes future directions for innovation in this promising field.

Advances in RNA-Based Therapeutics: Challenges and Innovations in RNA Delivery Systems

Nucleic acids, as carriers of genetic information, have found wide applications in both medical and research fields, including gene editing, disease diagnostics, and drug development. Among various types of nucleic acids, RNA offers greater versatility compared to DNA due to its single-stranded structure, ability to directly encode proteins, and high modifiability for targeted therapeutic and regulatory applications. Despite its promising potential in biomedicine, RNA-based medicine still faces several challenges. Notably, one of the most significant technical hurdles is achieving efficient and targeted RNA delivery while minimizing immune responses. Various strategies have been developed for RNA delivery, including viral vectors, virus-like particles (VLPs), lipid nanoparticles (LNPs), and extracellular vesicles (EVs). In this review, we explore the applications of these delivery methods, highlight their advantages and limitations, and discuss recent research advancements, providing insights for the future of RNA-based therapeutics.

SARS-CoV-2 Evolution: Implications for Diagnosis, Treatment, Vaccine Effectiveness and Development

The COVID-19 pandemic, driven by the rapid evolution of the SARS-CoV-2 virus, presents ongoing challenges to global public health. SARS-CoV-2 is characterized by rapidly evolving mutations, especially in (but not limited to) the spike protein, complicating predictions about its evolutionary trajectory. These mutations have significantly affected transmissibility, immune evasion, and vaccine efficacy, leading to multiple pandemic waves with over half a billion cases and seven million deaths globally. Despite several strategies, from rapid vaccine development and administration to the design and availability of antivirals, including monoclonal antibodies, already having been employed, the persistent circulation of the virus and the emergence of new variants continue to result in high case numbers and fatalities. In the past four years, immense research efforts have contributed much to our understanding of the viral pathogenesis mechanism, the COVID-19 syndrome, and the host-microbe interactions, leading to the development of effective vaccines, diagnostic tools, and treatments. The focus of this review is to provide a comprehensive analysis of the functional impact of mutations on diagnosis, treatments, and vaccine effectiveness. We further discuss vaccine safety in pregnancy and the implications of hybrid immunity on long-term protection against infection, as well as the latest developments on a pan-coronavirus vaccine and nasal formulations, emphasizing the need for continued surveillance, research, and adaptive public health strategies in response to the ongoing SARS-CoV-2 evolution race.

Mechanism to disrupt ESCRT-mediated intracellular trafficking through Vps28-small molecules interaction: an in silico approach

The ESCRT (Endosomal Sorting Complex Required for Transport) machinery comprising protein complexes ESCRT-0 to ESCRT-III and Vps4 plays a pivotal role in intracellular trafficking, a process of endocytosing cell surface proteins into the cell for various biological activities. The ESCRT protein complexes are sequentially assembled which interact amongst each other to form a functional ESCRT machinery. Deregulation of these events are shown to be involved in various disease development including tumor formation and viral infections. Recently upregulation of a crucial ESCRT protein, Vps28 has been shown to be implicated in tumor formation. However, Vps28 in ESCRT-I interacts with Vps36 in ESCRT-II to function as a connecting protein during ESCRT machinery formation. Until now biomolecular approaches to inhibit the formation/assembly of ESCRT machinery have not been developed. Hence, we hypothesized that disrupting Vps28/Vps36 interaction would prevent assembly of ESCRT machinery and offer therapeutic potential to restrict disease development and progression. To address this, we utilized a virtual screening approach using a flavonoid-based library to identify potential small molecule inhibitors that can bind to Vps28 active site. Based on the binding affinity, top-hit compounds were identified. Molecular dynamics simulations set over a 500 ns timescale demonstrated the stability of the Vps28-small molecule complexes. Per-residue decomposition analysis using Molecular Mechanics/Poisson-Boltzmann surface area highlighted the significant contributions of active site residues Asn189, Arg190, Arg193 and Asn210 in Vps28 for interaction with small molecules. Absorption, Distribution, Metabolism, Excretion, and Toxicity analysis for toxicity evaluation indicates that molecules Z0131, H0194, Z0199 and DQ00112 exhibited physicochemical properties suitable for drug development.

Neutralizing antibodies elicited in macaques recognize V3 residues on altered conformations of HIV-1 Env trimer

Eliciting broadly neutralizing antibodies that protect against diverse HIV-1 strains is a primary goal of AIDS vaccine research. We characterized Ab1456 and Ab1271, two heterologously-neutralizing antibodies elicited in non-human primates by priming with an engineered V3-targeting SOSIP Env immunogen and boosting with increasingly native-like SOSIP Envs derived from different strain backgrounds. Structures of Env trimers in complex with these antibodies revealed V3 targeting, but on conformational states of Env distinct from the typical closed, prefusion trimeric SOSIP structure. Env trimers bound by Ab1456 adopted conformations resembling CD4-bound open Env states in the absence of soluble CD4, whereas trimers bound by Ab1271 exhibited a trimer apex-altered conformation to accommodate antibody binding. The finding that elicited antibodies cross-neutralized by targeting altered, non-closed, prefusion Env trimer conformations provides important information about Env dynamics that is relevant for HIV-1 vaccine design aimed at raising antibodies to desired epitopes on closed pre-fusion Env trimers.

A substitution at the cytoplasmic tail of the spike protein enhances SARS-CoV-2 infectivity and immunogenicity

BACKGROUND

Global dissemination of SARS-CoV-2 Omicron sublineages has provided a sufficient opportunity for natural selection, thus enabling beneficial mutations to emerge. Characterisation of these mutations uncovers the underlying machinery responsible for the fast transmission of Omicron variants and guides vaccine development for combating the COVID-19 pandemic.

METHODS

Through systematic bioinformatics analysis of 496,606 sequences of Omicron variants, we obtained 40 amino acid substitutions that occurred with high frequency in the S protein. Utilising pseudoviruses and a trans-complementation system of SARS-CoV-2, we identified the effect of high-frequency mutations on viral infectivity and elucidated the molecular mechanisms. Finally, we evaluated the impact of a key emerging mutation on the immune protection induced by the SARS-CoV-2 VLP mRNA vaccine in a murine model.

FINDINGS

We identified a proline-to-leucine substitution at the 1263rd residue of the Spike protein, and upon investigating the relative frequencies across multiple Omicron sublineages, we found a trend of increasing frequency for P1263L. The substitution significantly enhances the capacity for S-mediated viral entry and improves the immunogenicity of a virus-like particle mRNA vaccine. Mechanistic studies showed that this mutation is located in the FERM binding motif of the cytoplasmic tail and impairs the interaction between the S protein and the Ezrin/Radixin/Moesin proteins. Additionally, this mutation facilitates the incorporation of S proteins into SARS-CoV-2 virions.

INTERPRETATION

This study offers mechanistic insight into the constantly increasing transmissibility of SARS-CoV-2 Omicron variants and provides a meaningful optimisation strategy for vaccine development against SARS-CoV-2.

FUNDING

This study was supported by grants from the National Key Research and Development Plan of China (2021YFC2302405, 2022YFC2303200, 2021YFC2300200 and 2022YFC2303400), the National Natural Science Foundation of China (32188101, 32200772, 82422049, 82241082, 32270182, 82372254, 82271872, 82341046, 32100755 and 82102389), Shenzhen Medical Research Fund (B2404002, A2303036), the Shenzhen Bay Laboratory Startup Fund (21330111), Shenzhen San-Ming Project for Prevention and Research on Vector-borne Diseases (SZSM202211023), Yunnan Provincial Science and Technology Project at Southwest United Graduate School (202302AO370010). The New Cornerstone Science Foundation through the New Cornerstone Investigator Program, and the Xplorer Prize from Tencent Foundation.

A nucleoside-modified mRNA vaccine forming rabies virus-like particle elicits strong cellular and humoral immune responses against rabies virus infection in mice

Rabies is a lethal zoonotic disease that threatens human health. As the only viral surface protein, the rabies virus (RABV) glycoprotein (G) induces main neutralizing antibody (Nab) responses; however, Nab titre is closely correlated with the conformation of G. Virus-like particles (VLP) formed by the co-expression of RABV G and matrix protein (M) improve retention and antigen presentation, inducing broad, durable immune responses. RABV nucleoprotein (N) can elicit humoral and cellular immune responses. Hence, we developed a series of nucleoside-modified RABV mRNA vaccines encoding wild-type G, soluble trimeric RABV G formed by an artificial trimer motif (tG-MTQ), membrane-anchored prefusion-stabilized G (preG). Furthermore, we also developed RABV VLP mRNA vaccine co-expressing preG and M to generate VLPs, and VLP/N mRNA vaccine co-expressing preG, M, and N. The RABV mRNA vaccines induced higher humoral and cellular responses than inactivated rabies vaccine, and completely protected mice against intracerebral challenge. Additionally, the IgG and Nab titres in RABV preG, VLP and VLP/N mRNA groups were significantly higher than those in G and tG-MTQ groups. A single administration of VLP or VLP/N mRNA vaccines elicited protective Nab responses, the Nab titres were significantly higher than that in inactivated rabies vaccine group at day 7. Moreover, RABV VLP and VLP/N mRNA vaccines showed superior capacities to elicit potent germinal centre, long-lived plasma cell and memory B cell responses, which linked to high titre and durable Nab responses. In summary, our data demonstrated that RABV VLP and VLP/N mRNA vaccines could be promising candidates against rabies.

Advanced technologies for the development of infectious disease vaccines

Vaccines play a critical role in the prevention of life-threatening infectious disease. However, the development of effective vaccines against many immune-evading pathogens such as HIV has proven challenging, and existing vaccines against some diseases such as tuberculosis and malaria have limited efficacy. The historically slow rate of vaccine development and limited pan-variant immune responses also limit existing vaccine utility against rapidly emerging and mutating pathogens such as influenza and SARS-CoV-2. Additionally, reactogenic effects can contribute to vaccine hesitancy, further undermining the ability of vaccination campaigns to generate herd immunity. These limitations are fuelling the development of novel vaccine technologies to more effectively combat infectious diseases. Towards this end, advances in vaccine delivery systems, adjuvants, antigens and other technologies are paving the way for the next generation of vaccines. This Review focuses on recent advances in synthetic vaccine systems and their associated challenges, highlighting innovation in the field of nano- and nucleic acid-based vaccines.

Structure and organization of full-length Epidermal Growth Factor Receptor in extracellular vesicles by cryo-electron tomography

We report here transport of the Epidermal Growth Factor Receptor (EGFR), Insulin Receptor, 7-pass transmembrane receptor Smoothened, and 13-pass Sodium-iodide symporter to extracellular vesicles (EVs) for structural and functional studies. Mass spectrometry confirmed the transported proteins as the most abundant in EV membranes, and the presence of many receptor-interacting proteins demonstrates the utility of EVs for characterizing membrane protein interactomes. Cryo-electron tomography of EGFR-containing EVs reveals that EGFR forms clusters in the presence of EGF with a ∼3 nm gap between the inner membrane and cytoplasmic density. EGFR extracellular regions do not form regular arrays, suggesting that clustering is mediated by the intracellular region. Subtomogram averaging of the EGFR extracellular region (ECR) yielded a 15 Å map into which the crystal structure of the ligand-bound EGFR ECR dimer fits well. These findings refine our understanding of EGFR activation, clustering, and signaling, and they establish EVs as a versatile platform for structural and functional characterization of human membrane proteins in a native-like environment.

Significance Statement

Atomic or near-atomic resolution structural studies of proteins embedded in cell membranes have proven challenging. We show that transporting integral membrane proteins to cell-derived extracellular vesicles enables structural and functional studies of human membrane proteins in a native membrane environment. We have used this approach to visualize an active form of full-length Epidermal Growth Factor Receptor (EGFR) and show that it forms clusters in the membrane and projects its cytoplasmic signaling domains ∼3 nm away from the membrane surface. EGFR is essential for normal development, but abnormal EGFR activity is associated with several human cancers and is the target of many anticancer therapies. Our studies refine current models of how ligand binding to EGFR transmits signals across cell membranes.

Design of customized coronavirus receptors

Although coronaviruses use diverse receptors, the characterization of coronaviruses with unknown receptors has been impeded by a lack of infection models1,2. Here we introduce a strategy to engineer functional customized viral receptors (CVRs). The modular design relies on building artificial receptor scaffolds comprising various modules and generating specific virus-binding domains. We identify key factors for CVRs to functionally mimic native receptors by facilitating spike proteolytic cleavage, membrane fusion, pseudovirus entry and propagation for various coronaviruses. We delineate functional SARS-CoV-2 spike receptor-binding sites for CVR design and reveal the mechanism of cell entry promoted by the N-terminal domain-targeting S2L20-CVR. We generated CVR-expressing cells for 12 representative coronaviruses from 6 subgenera, most of which lack known receptors, and show that a pan-sarbecovirus CVR supports propagation of a propagation-competent HKU3 pseudovirus and of authentic RsHuB2019A3. Using an HKU5-specific CVR, we successfully rescued wild-type and ZsGreen-HiBiT-incorporated HKU5-1 (LMH03f) and isolated a HKU5 strain from bat samples. Our study demonstrates the potential of the CVR strategy for establishing native receptor-independent infection models, providing a tool for studying viruses that lack known susceptible target cells.

Personalized mRNA vaccines in glioblastoma therapy: from rational design to clinical trials

Glioblastomas (GBMs) are the most common and aggressive malignant brain tumors, presenting significant challenges for treatment due to their invasive nature and localization in critical brain regions. Standard treatment includes surgical resection followed by radiation and adjuvant chemotherapy with temozolomide (TMZ). Recent advances in immunotherapy, including the use of mRNA vaccines, offer promising alternatives. This review focuses on the emerging use of mRNA vaccines for GBM treatment. We summarize recent advancements, evaluate current obstacles, and discuss notable successes in this field. Our analysis highlights that while mRNA vaccines have shown potential, their use in GBM treatment is still experimental. Ongoing research and clinical trials are essential to fully understand their therapeutic potential. Future developments in mRNA vaccine technology and insights into GBM-specific immune responses may lead to more targeted and effective treatments. Despite the promise, further research is crucial to validate and optimize the effectiveness of mRNA vaccines in combating GBM.

HRS Facilitates Newcastle Disease Virus Replication in Tumor Cells by Promoting Viral Budding

Newcastle disease virus (NDV) is a highly pathogenic avian infectious disease agent and also a promising oncolytic virus with broad application prospects. The Endosomal Sorting Complex Required for Transport (ESCRT) machinery has been increasingly recognized for its crucial role in the life cycles of enveloped viruses, influencing processes such as viral entry, replication, and budding. In this study, we employed an RNA interference screening approach to identify key ESCRT components that regulate NDV replication in tumor cells. qPCR, immunofluorescence, and Western blot assays demonstrated that knockdown of HRS, CHMP4A, CHMP4B, and CHMP4C significantly impaired NDV replication in HeLa cells, with HRS exhibiting the most pronounced inhibitory effect. Additionally, HRS knockout significantly inhibited viral budding and suppressed NDV-induced cell death in HeLa cells. Notably, NDV infection was shown to significantly upregulate HRS gene and protein expression in a time-dependent manner. In conclusion, this study systematically identifies critical ESCRT components involved in NDV replication within tumor cells, with a particular focus on the role of HRS in promoting NDV's replication by promoting viral budding, offering new insights for the development of NDV-based oncolytic therapies.

Development of a P30 protein-based indirect ELISA for detecting African swine fever antibodies utilizing the HEK293F expression system

African swine fever (ASF) is an acute, febrile, and highly lethal infectious disease in pigs caused by the African swine fever virus (ASFV). Effective detection methods and strict biosecurity measures are crucial for preventing and controlling ASF, especially since there are currently no commercially available vaccines or antiviral drugs to combat ASFV infection effectively. However, the emergence of low-virulence strains of ASFV in recent years has led to false-positive results, highlighting the importance of early-produced antibody detection methods. Therefore, detecting antibodies against ASFV produced early in the infection can facilitate the prompt identification of infected pigs. This study focused on the p30 protein, an early expressed protein during ASFV infection, to develop an indirect ELISA. This method was established using the HEK293F suspension cell expression system, which has the ability to produce large quantities of correctly folded proteins with normal functionality. In this study, we developed an indirect ELISA test utilizing the p30 recombinant protein produced by the HEK293F suspension cell expression system as the antigen coating. The concentration of the p30 protein obtained from the HEK293F suspension cell expression system was measured at 4.668 mg/mL, serving as the foundation for establishing the indirect ELISA. Our findings indicate that the indirect ELISA method exhibits a sensitivity of 1:12800. Furthermore, it demonstrates high specificity and excellent reproducibility. Comparing our results to those obtained from the commercial kit, we found a coincidence rate of 98.148 % for the indirect ELISA. In summary, we have developed a sensitive method for detecting ASFV, providing a valuable tool for monitoring ASFV infection in pig herds.

Immune responses in COVID-19 patients: Insights into cytokine storms and adaptive immunity kinetics

SARS-CoV-2 infection can trigger cytokine storm in some patients, which characterized by an excessive production of cytokines and chemical mediators. This hyperactive immune response may cause significant tissue damage and multiple organ failure (MOF). The severity of COVID-19 correlates with the intensity of cytokine storm, involving elements such as IFN, NF-κB, IL-6, HMGB1, etc. It is imperative to rapidly engage adaptive immunity to effectively control the disease progression. CD4+ T cells facilitate an immune response by improving B cells in the production of neutralizing antibodies and activating CD8+ T cells, which are instrumental in eradicating virus-infected cells. Meanwhile, antibodies from B cells can neutralize virus, obstructing further infection of host cells. In individuals who have recovered from the disease, virus-specific antibodies and memory T cells were observed, which could confer a level of protection, reducing the likelihood of re-infection or attenuating severity. This paper discussed the roles of macrophages, IFN, IL-6 and HMGB1 in cytokine release syndrome (CRS), the intricacies of adaptive immunity, and the persistence of immune memory, all of which are critical for the prevention and therapeutic strategies against COVID-19.

SEMPER: Stoichiometric expression of mRNA polycistrons by eukaryotic ribosomes for compact, ratio-tunable multi-gene expression

Here, we present a method for expressing multiple open reading frames (ORFs) from single transcripts using the leaky scanning model of translation initiation. In this approach termed "stoichiometric expression of mRNA polycistrons by eukaryotic ribosomes" (SEMPER), adjacent ORFs are translated from a single mRNA at tunable ratios determined by their order in the sequence and the strength of their translation initiation sites. We validate this approach by expressing up to three fluorescent proteins from one plasmid in two different cell lines. We then use it to encode a stoichiometrically tuned polycistronic construct encoding gas vesicle acoustic reporter genes that enables efficient formation of the multi-protein complex while minimizing cellular toxicity. We also demonstrate that SEMPER enables polycistronic expression of recombinant monoclonal antibodies from plasmid DNA and of two fluorescent proteins from single mRNAs made through in vitro transcription. Finally, we provide a probabilistic model to elucidate the mechanisms underlying SEMPER. A record of this paper's transparent peer review process is included in the supplemental information.

Exosome for mRNA delivery: strategies and therapeutic applications

Messenger RNA (mRNA) has emerged as a promising therapeutic molecule with numerous clinical applications in treating central nervous system disorders, tumors, COVID-19, and other diseases. mRNA therapies must be encapsulated into safe, stable, and effective delivery vehicles to preserve the cargo from degradation and prevent immunogenicity. Exosomes have gained growing attention in mRNA delivery because of their good biocompatibility, low immunogenicity, small size, unique capacity to traverse physiological barriers, and cell-specific tropism. Moreover, these exosomes can be engineered to utilize the natural carriers to target specific cells or tissues. This targeted approach will enhance the efficacy and reduce the side effects of mRNAs. However, difficulties such as a lack of consistent and reliable methods for exosome purification and the efficient encapsulation of large mRNAs into exosomes must be addressed. This article outlines current breakthroughs in cell-derived vesicle-mediated mRNA delivery and its biomedical applications.

An Overview of Nanoparticle-Based Delivery Platforms for mRNA Vaccines for Treating Cancer

With its unique properties and potential applications, nanoparticle-based delivery platforms for messenger RNA (mRNA) vaccines have gained significant attention in recent years. Nanoparticles have the advantages of enhancing immunogenicity, targeting delivery, and improving stability, providing a new solution for drug and vaccine delivery. In some clinical studies, a variety of nanoparticle delivery platforms have been gradually applied to a wide range of vaccine applications. Current research priorities are exploring various types of nanoparticles as vaccine delivery systems to enhance vaccine stability and immunogenicity. Lipid nanoparticles (LNPs) have shown promising potential in preclinical and clinical studies on the efficient delivery of antigens to immune cells. Moreover, lipid nanoparticles and other nanoparticles for nucleic acids, especially for mRNA delivery systems, have shown vast potential for vaccine development. In this review, we present various vaccine platforms with an emphasis on nanoparticles as mRNA vaccine delivery vehicles. We describe several novel nanoparticle delivery platforms for mRNA vaccines, such as lipid-, polymer-, and protein-based nanoparticles. In addition, we provide an overview of the anti-tumor immunity of nanovaccines against different tumors in cancer immunotherapy. Finally, we outline future perspectives and remaining challenges for this promising technology of nanoparticle-based delivery platforms for vaccines.

Calmodulin-like 5 promotes PEDV replication by regulating late-endosome synthesis and innate immune response

The infection caused by porcine epidemic diarrhea virus (PEDV) is associated with high mortality in piglets worldwide. Host factors involved in the efficient replication of PEDV, however, remain largely unknown. Our recent proteomic study in the virus-host interaction network revealed a significant increase in the accumulation of CALML5 (EF-hand protein calmodulin-like 5) following PEDV infection. A further study unveiled a biphasic increase of CALML5 in 2 and 12 ​h after viral infection. Similar trends were observed in the intestines of piglets in the early and late stages of the PEDV challenge. Moreover, CALML5 depletion reduced PEDV mRNA and protein levels, leading to a one-order-of-magnitude decrease in virus titer. At the early stage of PEDV infection, CALML5 affected the endosomal trafficking pathway by regulating the expression of endosomal sorting complex related cellular proteins. CALML5 depletion also suppressed IFN-β and IL-6 production in the PEDV-infected cells, thereby indicating its involvement in negatively regulating the innate immune response. Our study reveals the biological function of CALML5 in the virology field and offers new insights into the PEDV-host cell interaction.

Overview of the recent advances in porcine epidemic diarrhea vaccines

Vaccination is the most effective means of preventing and controlling porcine epidemic diarrhea (PED). Conventional vaccines developed from porcine epidemic diarrhea virus (PEDV) GI-a subtypes (CV777 and SM98) have played a vital role in preventing classical PED. However, with the emergence of PEDV mutants in 2010, conventional PEDV GI-a subtype-targeting vaccines no longer provide adequate protection against PEDV GII mutants, thereby making novel-type PED vaccine development an urgent concern to be addressed. Novel vaccines, including nucleic acid vaccines, genetically engineered subunit vaccines, and live vector vaccines, are associated with several advantages, such as high safety and stability, clear targeting, high yield, low cost, and convenient usage. These vaccines can be combined with corresponding ELISA kits to differentiate infected from vaccinated animals, which is beneficial for disease confirmation. This review provides a detailed overview of the recent advancements in PED vaccines, emphasizing on the research and application evaluation of novel PED vaccines. It also considers the future directions and challenges in advancing these vaccines to widespread use in clinics.

Nanotechnology's frontier in combatting infectious and inflammatory diseases: prevention and treatment

Inflammation-associated diseases encompass a range of infectious diseases and non-infectious inflammatory diseases, which continuously pose one of the most serious threats to human health, attributed to factors such as the emergence of new pathogens, increasing drug resistance, changes in living environments and lifestyles, and the aging population. Despite rapid advancements in mechanistic research and drug development for these diseases, current treatments often have limited efficacy and notable side effects, necessitating the development of more effective and targeted anti-inflammatory therapies. In recent years, the rapid development of nanotechnology has provided crucial technological support for the prevention, treatment, and detection of inflammation-associated diseases. Various types of nanoparticles (NPs) play significant roles, serving as vaccine vehicles to enhance immunogenicity and as drug carriers to improve targeting and bioavailability. NPs can also directly combat pathogens and inflammation. In addition, nanotechnology has facilitated the development of biosensors for pathogen detection and imaging techniques for inflammatory diseases. This review categorizes and characterizes different types of NPs, summarizes their applications in the prevention, treatment, and detection of infectious and inflammatory diseases. It also discusses the challenges associated with clinical translation in this field and explores the latest developments and prospects. In conclusion, nanotechnology opens up new possibilities for the comprehensive management of infectious and inflammatory diseases.

Lipid Nanoparticle (LNP) Delivery Carrier-Assisted Targeted Controlled Release mRNA Vaccines in Tumor Immunity

In recent years, lipid nanoparticles (LNPs) have attracted extensive attention in tumor immunotherapy. Targeting immune cells in cancer therapy has become a strategy of great research interest. mRNA vaccines are a potential choice for tumor immunotherapy, due to their ability to directly encode antigen proteins and stimulate a strong immune response. However, the mode of delivery and lack of stability of mRNA are key issues limiting its application. LNPs are an excellent mRNA delivery carrier, and their structural stability and biocompatibility make them an effective means for delivering mRNA to specific targets. This study summarizes the research progress in LNP delivery carrier-assisted targeted controlled release mRNA vaccines in tumor immunity. The role of LNPs in improving mRNA stability, immunogenicity, and targeting is discussed. This review aims to systematically summarize the latest research progress in LNP delivery carrier-assisted targeted controlled release mRNA vaccines in tumor immunity to provide new ideas and strategies for tumor immunotherapy, as well as to provide more effective treatment plans for patients.

Antigen-display exosomes provide adjuvant-free protection against SARS-CoV-2 disease at nanogram levels of spike protein

As the only bionormal nanovesicle, exosomes have high potential as a nanovesicle for delivering vaccines and therapeutics. We show here that the loading of type-1 membrane proteins into the exosome membrane is induced by exosome membrane anchor domains, EMADs, that maximize protein delivery to the plasma membrane, minimize protein sorting to other compartments, and direct proteins into exosome membranes. Using SARS-CoV-2 spike as an example and EMAD13 as our most effective exosome membrane anchor, we show that cells expressing a spike-EMAD13 fusion protein produced exosomes that carry dense arrays of spike trimers on 50% of all exosomes. Moreover, we find that immunization with spike-EMAD13 exosomes induced strong neutralizing antibody responses and protected hamsters against SARS-CoV-2 disease at doses of just 0.5-5 ng of spike protein, without adjuvant, demonstrating that antigen-display exosomes are particularly immunogenic, with important implications for both structural and expression-dependent vaccines.

mRNA vaccine designs for optimal adjuvanticity and delivery

Adjuvanticity and delivery are crucial facets of mRNA vaccine design. In modern mRNA vaccines, adjuvant functions are integrated into mRNA vaccine nanoparticles, allowing the co-delivery of antigen mRNA and adjuvants in a unified, all-in-one formulation. In this formulation, many mRNA vaccines utilize the immunostimulating properties of mRNA and vaccine carrier components, including lipids and polymers, as adjuvants. However, careful design is necessary, as excessive adjuvanticity and activation of improper innate immune signalling can conversely hinder vaccination efficacy and trigger adverse effects. mRNA vaccines also require delivery systems to achieve antigen expression in antigen-presenting cells (APCs) within lymphoid organs. Some vaccines directly target APCs in the lymphoid organs, while others rely on APCs migration to the draining lymph nodes after taking up mRNA vaccines. This review explores the current mechanistic understanding of these processes and the ongoing efforts to improve vaccine safety and efficacy based on this understanding.

ESCRT machinery and virus infection

The endosomal sorting complex required for transport (ESCRT) machinery plays a significant role in the spread of human viruses. However, our understanding of how the host ESCRT machinery responds to viral infection remains limited. Emerging evidence suggests that the ESCRT machinery can be hijacked by viruses of different families to enhance their replication. Throughout their life cycle, these viruses can interfere with or exploit ESCRT-mediated physiological processes to increase their chances of infecting the host. In contrast, to counteract virus infection, the interferon-stimulated gene 15 (ISG15) or the E3 ISG15-protein ligase (HERC5) system within the infected cells is activated to degrade the ESCRT proteins. Many retroviral and RNA viral proteins have evolved "late (L) domain" motifs, which enable them to recruit host ESCRT subunit proteins to facilitate virus transport, replication, budding, mature, and even endocytosis, Therefore, the L domain motifs and ESCRT subunit proteins could serve as promising drug targets for antiviral therapy. This review investigated the composition and essential functions of the ESCRT, shedding light on the impact of ESCRT subunits and viral L domain motifs on the replication of viruses. Furthermore, the antiviral effects facilitated by the ESCRT machinery have been investigated, aiming to provide valuable insights to guide the development and utilization of antiviral drugs.

Nanoparticles and Antiviral Vaccines

Viruses have threatened human lives for decades, causing both chronic and acute infections accompanied by mild to severe symptoms. During the long journey of confrontation, humans have developed intricate immune systems to combat viral infections. In parallel, vaccines are invented and administrated to induce strong protective immunity while generating few adverse effects. With advancements in biochemistry and biophysics, different kinds of vaccines in versatile forms have been utilized to prevent virus infections, although the safety and effectiveness of these vaccines are diverse from each other. In this review, we first listed and described major pathogenic viruses and their pandemics that emerged in the past two centuries. Furthermore, we summarized the distinctive characteristics of different antiviral vaccines and adjuvants. Subsequently, in the main body, we reviewed recent advances of nanoparticles in the development of next-generation vaccines against influenza viruses, coronaviruses, HIV, hepatitis viruses, and many others. Specifically, we described applications of self-assembling protein polymers, virus-like particles, nano-carriers, and nano-adjuvants in antiviral vaccines. We also discussed the therapeutic potential of nanoparticles in developing safe and effective mucosal vaccines. Nanoparticle techniques could be promising platforms for developing broad-spectrum, preventive, or therapeutic antiviral vaccines.