EV71-encoded 2A protease (2Apro) plays an important regulatory role in EV71 infection and replication. EV71-2Apro can help the viral immune escape by inhibiting host proteins, thereby disrupting the host antiviral immune response. However, the mechanism by which 2Apro proteins are regulated in host cells remains largely unknown. In this study, we identified USP21 that promotes EV71 infection. We discovered that USP21 downregulated K48-linked polyubiquitination of EV71-2Apro and stabilized 2Apro, ultimately promoting EV71 infection. Furthermore, the small-molecule inhibitor, BAY-805, reduced 2Apro levels and inhibited EV71 infection both in vivo and in vitro. Importantly, we found that the expression level of USP21 was positively correlated with the severity of EV71 infection. This study reveals the crucial regulatory role of USP21 in EV71 infection and provides a potential target for the treatment of EV71 infection.

Human enterovirus 71 (EV-A71), a member of the Picornaviridae family, is predominantly associated with hand, foot, and mouth disease in infants and young children. Additionally, EV-A71 can cause severe neurological complications, including aseptic meningitis, brainstem encephalitis, and fatalities. The molecular mechanisms underlying these symptoms are complex and involve the viral tissue tropism, evasion from the host immune responses, induction of the programmed cell death, and cytokine storms. This review article delves into the EV-A71 life cycle, with a particular emphasis on recent advancements in understanding the virion structure, tissue tropism, and the interplay between the virus and host regulatory networks during replication. The comprehensive review is expected to contribute to our understanding of EV-A71 pathogenesis and inform the development of antiviral therapies and vaccines.

Exosomes, small extracellular vesicles secreted by various cells, play crucial roles in the pathogenesis and treatment of oral diseases. Recent studies have highlighted their involvement in orthodontics, periodontitis, oral squamous cell carcinoma (OSCC), and hand, foot, and mouth disease (HFMD). Exosomes have a positive effect on the inflammatory environment of the oral cavity, remodeling and regeneration of oral tissues, and offer promising therapeutic options for bone and periodontal tissue restoration. In OSCC tumor-derived exosomes promote cancer progression through cell proliferation, migration, invasion, and angiogenesis, and serve as potential biomarkers for early diagnosis and prognosis. Additionally, engineered exosomes constructed specifically based on exosome properties hold great promise for targeted drug delivery and regenerative therapies such as bone regeneration in orthodontics and periodontal healing. With continued research, exosomes hold great potential for improving diagnosis and treatment in oral diseases, advancing personalized and regenerative therapies.

Viral nervous necrosis caused by the nervous necrosis virus (NNV) poses a significant threat to the global aquaculture industry. Developing preventive methods to minimize economic losses due to NNV infections is crucial. This study explored the role of the sorting nexin 27 (Snx27) gene, encoded by the orange-spotted grouper (Epinephelus coioides) and referred to as EcSnx27, as an immune regulator affecting red-spotted grouper nervous necrosis virus (RGNNV) infection in vitro. Our findings revealed that EcSnx27 negatively regulates interferon (IFN)-related cytokines and the promoter activities of fish ISRE and NF-κB. Furthermore, we identified the SNX-FERM and SNX-FERM-like domains as responsible for the interaction between EcSnx27 and RGNNV coat protein. Through the detection of viable virions associated with EcSnx27-containing exosomes, we propose that EcSnx27 may contribute to the release process of RGNNV by influencing the apoptosis-linked gene 2-interacting protein X (ALIX)-associated exosomal pathway. Consequently, our study suggests that EcSnx27 promotes RGNNV replication by inhibiting the IFN immune response and facilitating virus production and release through ALIX-mediated exosomal machinery.IMPORTANCERed grouper nervous necrosis virus (RGNNV), a member of the Nodaviridae family, has emerged as a significant cause of fish diseases worldwide, leading to high morbidity and mortality rates. This study investigated the sorting nexin 27 (Snx27) gene encoded by the orange-spotted grouper (Epinephelus coioides) on RGNNV infection in grouper kidney cells. Our findings revealed that EcSnx27 negatively regulated the interferon pathway, resulting in the promotion of RGNNV replication. Additionally, we observed that EcSnx27 could interact with apoptosis-linked gene 2-interacting protein X (ALIX) and the RGNNV coat protein, suggesting its potential involvement in viral release processes through modulation of the exosomal pathway. Our study identified EcSnx27 as a key target that RGNNV exploits to enhance viral production. This finding offers valuable insights into the immune evasion and viral release mechanisms of non-enveloped RNA viruses.

Previous studies demonstrated that EV71-infected cells secrete extracellular vesicles (EVs), facilitating the transfer of viral components to recipient cells and thereby promoting virus spread. Considering lipid signaling plays a crucial role in EVs-mediated cell-to-cell communication, we compared the lipid profile of EVs secreted from uninfected and EV71-infected cells (EVs-Mock and EVs-EV71) using the human rhabdomyosarcoma (RD) cell model. These two groups of EVs were purified by using size exclusion chromatography (SEC), respectively, and evaluated by transmission electron microscopy (TEM), nanoparticle tracking technology (NTA), and Western blotting (WB). In-depth lipidomic analysis of EVs identified 1705 lipid molecules belonging to 43 lipid classes. The data showed a significant increase in the lipid content of EVs after EV71 infection. Meanwhile, we deeply analyzed the changes in lipids and screened for lipid molecules with significant differences compared EVs-EV71 with EVs-Mock EVs. Altogether, we report the alterations in the lipid profile of EVs derived from RD-cells after EV71 infection, which may affect the function of the EVs in the recipient cells.

Hand, foot, and mouth disease (HFMD) is a prevalent infectious affliction primarily affecting children, with a small portion of cases progressing to neurological complications. Notably, in a subset of severe HFMD cases, neurological manifestations may result in significant sequelae and pose a risk of mortality. We systematically conducted literature retrieval from the databases PubMed (1957-2023), Embase (1957-2023), and Web of Science (1957-2023), in addition to consulting authoritative guidelines. Subsequently, we rigorously selected the most relevant articles within the scope of this review for comprehensive analysis. It is widely recognized that the severity of HFMD is attributed to a multifaceted array of pathophysiological mechanisms. The implication of multi-system dysfunction appears to be perturbances of the human defense system; therefore, it contributes to the severity of HFMD. In this review, we provide an overview and analysis of recent insights into the molecular mechanisms contributing to the severity of HFMD, with a particular focus on cytokine release syndrome, the involvement of the renin-angiotensin system, regional immunity, endothelial dysfunction, catecholamine storm, viral invasion, and the molecular mechanisms of neurological damage. We speculate that the domino effect of diverse physiological systems, initiated by damage to the central nervous system, serve as the primary mechanisms governing the severity of HFMD. Simultaneously, we emphasize the knowledge gaps and research urgently required to delineate a quick roadmap for ongoing and essential studies on HFMD.

Enterovirus 71 (EV71) causes hand-foot-and-mouth disease (HFMD), neurological complications, and even fatalities in infants. Clinically, the increase of extracellular vesicles (EVs) in EV71 patients' serum was highly associated with the severity of HFMD. EV71 boosts EVs biogenesis in an endosomal sorting complex required for transport (ESCRT)-dependent manner to facilitate viral replication. Yet, the impact of EVs-derived from ESCRT-independent pathway on EV71 replication and pathogenesis is highly concerned. Here, we assessed the effects of EV71-induced EVs from ESCRT-independent pathway on viral replication and pathogenesis by GW4869, a neutral sphingomyelinase inhibitor. Detailly, in EV71-infected mice, blockade of the biogenesis of tissue-derived EVs in the presence of GW4869 restored body weight loss, attenuated clinical scores, and improved survival rates. Furthermore, GW4869 dampens EVs biogenesis to reduce viral load and pathogenesis in multiple tissues of EV71-infected mice. Consistently, GW4869 treatment in a human intestinal epithelial HT29 cells decreased the biogenesis of EVs, in which the progeny EV71 particle was cloaked, leading to the reduction of viral infection and replication. Collectively, GW4869 inhibits EV71-induced EVs in an ESCRT-independent pathway and ultimately suppresses EV71 replication and pathogenesis. Our study provides a novel strategy for the development of therapeutic agents in the treatment for EV71-associated HFMD.

Exosomes play an important role in the spread of viral infections and immune escape. However, the exact ability and mechanisms by which exosomes produced during viral infections (vExos) infect host cells are still not fully understood. In this study, we developed a dual-color exosome labeling strategy that simultaneously labels the external and internal structures of exosomes with quantum dots to enable in situ monitoring of the transport process of vExos in live cells using the single-particle tracking technique. Our finding revealed that vExos contains the complete influenza A virus (IAV) genome and viral ribonucleoprotein complexes (vRNPs) proteins but lacks viral envelope proteins. Notably, these vExos have the ability to infect cells and produce progeny viruses. We also found that vExos are transported in three stages, slow-fast-slow, and move to the perinuclear region via microfilaments and microtubules. About 30% of internalized vExos shed the external membrane and release the internal vRNPs into the cytoplasm by fusion with endolysosomes. This study suggested that vExos plays a supporting role in IAV infection by assisting with IAV propagation in a virus-independent manner. It emphasizes the need to consider the infectious potential of vExos and draws attention to the potential risk of exosomes produced by viral infections.

Extracellular vesicles (EVs) are small membrane-enclosed structures that have gained much attention from researchers across varying scientific fields in the past few decades. Cells secrete diverse types of EVs into the extracellular milieu which include exosomes, microvesicles, and apoptotic bodies. These EVs play a crucial role in facilitating intracellular communication via the transport of proteins, lipids, DNA, rRNA, and miRNAs. It is well known that a number of viruses hijack several cellular pathways involved in EV biogenesis to aid in their replication, assembly, and egress. On the other hand, EVs can also trigger host antiviral immune responses by carrying immunomodulatory molecules and viral antigens on their surface. Owing to this intricate relationship between EVs and viruses, intriguing studies have identified various EV-mediated viral infections and interrogated how EVs can alter overall viral spread and longevity. This review provides a comprehensive overview on the EV-virus relationship, and details various modes of EV-mediated viral spread in the context of clinically relevant enveloped and non-enveloped viruses.

Oral diseases, such as periodontitis, salivary gland diseases, and oral cancers, significantly challenge health conditions due to their detrimental effects on patient's digestive functions, pronunciation, and esthetic demands. Delayed diagnosis and non-targeted treatment profoundly influence patients' prognosis and quality of life. The exploration of innovative approaches for early detection and precise treatment represents a promising frontier in oral medicine. Exosomes, which are characterized as nanometer-sized extracellular vesicles, are secreted by virtually all types of cells. As the research continues, the complex roles of these intracellular-derived extracellular vesicles in biological processes have gradually unfolded. Exosomes have attracted attention as valuable diagnostic and therapeutic tools for their ability to transfer abundant biological cargos and their intricate involvement in multiple cellular functions. In this review, we provide an overview of the recent applications of exosomes within the field of oral diseases, focusing on inflammation-related bone diseases and oral squamous cell carcinomas. We characterize the exosome alterations and demonstrate their potential applications as biomarkers for early diagnosis, highlighting their roles as indicators in multiple oral diseases. We also summarize the promising applications of exosomes in targeted therapy and proposed future directions for the use of exosomes in clinical treatment.

EV71 poses a significant health threat to children aged 5 and below. The process of EV71 infection and replication is predominantly influenced by ubiquitination modifications. Our previous findings indicate that EV71 prompts the activation of host deubiquitinating enzymes, thereby impeding the host interferon signaling pathway as a means of evading the immune response. Nevertheless, the precise mechanisms by which the host employs ubiquitination modifications to hinder EV71 infection remain unclear. The present study demonstrated that the nonstructural protein 2Apro, which is encoded by EV71, exhibits ubiquitination and degradation mediated by the host E3 ubiquitin ligase SPOP. In addition, it is the first report, to our knowledge, that SPOP is involved in the host antiviral response.

Small extracellular vesicles (exosomes) are important components of the tumor microenvironment. They are small membrane-bound vesicles derived from almost all cell types and play an important role in intercellular communication. Exosomes transmit biological molecules obtained from parent cells, such as proteins, lipids, and nucleic acids, and are involved in cancer development. MicroRNAs (miRNAs), the most abundant contents in exosomes, are selectively packaged into exosomes to carry out their biological functions. Recent studies have revealed that exosome-delivered miRNAs play crucial roles in the tumorigenesis, progression, and drug resistance of hepatocellular carcinoma (HCC). In addition, exosomes have great industrial prospects in the diagnosis, treatment, and prognosis of patients with HCC. This review summarized the composition and function of exosomal miRNAs of different cell origins in HCC and highlighted the association between exosomal miRNAs from stromal cells and immune cells in the tumor microenvironment and the progression of HCC. Finally, we described the potential applicability of exosomal miRNAs derived from mesenchymal stem cells in the treatment of HCC.

The oxidative stress induced by the accumulation of reactive oxygen species (ROS) can lead to cell aging and death. Equally, the skeletal muscle usually hosts enteroviral persistent infection in inflammatory muscle diseases. As excellent bioactive products, the exosomes derived from umbilical cord mesenchymal stem cells (ucMSCs) have been proven to be safe and have low immunogenicity with a potential cell-free therapeutic function. Here, exosomes derived from ucMSCs (ucMSC-EXO) were extracted and characterized. In a model of oxidative damage to skin fibroblasts (HSFs) under exposure to H2O2, ucMSC-EXO had an observable repairing effect for the HSFs suffering from oxidative damage. Furthermore, ucMSC-EXO inhibited mitogen-activated protein kinases (MAPK), c-Jun N-terminal kinase (JNK), and nuclear factor kappa-B (NF-κB) signaling pathways, thereby promoting p21 protein expression while decreasing lamin B1 protein expression, and finally alleviated oxidative stress-induced cell damage and aging. In a model of rhabdomyosarcoma (RD) cells being infected by enterovirus 71 (EV71) and coxsackievirus B3 (CVB3), the ucMSC-EXO enhanced the expression of interferon-stimulated gene 15 (ISG15) and ISG56 to inhibit enteroviral replication, whereafter reducing the virus-induced proinflammatory factor production. This study provides a promising therapeutic strategy for ucMSC-EXO in anti-oxidative stress and antiviral effects, which provides insight into extending the function of ucMSC-EXO in cell-free therapy.