RSAD2 and AIM2 Modulate Coxsackievirus A16 and Enterovirus A71 Replication in Neuronal Cells in Different Ways That May Be Associated with Their 5' Nontranslated Regions

RSAD2 suppresses viral replication by interacting with the Senecavirus A 2 C protein

Senecavirus A (SVA), an emerging virus that causes blisters on the nose and hooves, reduces the production performance of pigs. RSAD2 is a radical S-adenosylmethionine (SAM) enzyme, and its expression can suppress various viruses due to its broad antiviral activity. However, the regulatory relationship between SVA and RSAD2 and the mechanism of action remain unclear. Here, we demonstrated that SVA infection increased RSAD2 mRNA levels, whereas RSAD2 expression negatively regulated viral replication, as evidenced by decreased viral VP1 protein expression, viral titres, and infected cell numbers. Viral proteins that interact with RSAD2 were screened, and the interaction between the 2 C protein and RSAD2 was found to be stronger than that between other proteins. Additionally, amino acids (aa) 43-70 of RSAD2 were crucial for interacting with the 2 C protein and played an important role in its anti-SVA activity. RSAD2 was induced by type I interferon (IFN-I) via Janus kinase signal transducer and activator of transcription (JAK-STAT), and had antiviral activity. Ruxolitinib, a JAK-STAT pathway inhibitor, and the knockdown of JAK1 expression substantially reduced RSAD2 expression levels and antiviral activity. Taken together, these results revealed that RSAD2 blocked SVA infection by interacting with the viral 2 C protein and provide a strategy for preventing and controlling SVA infection.

The key mechanisms of multi-system responses triggered by central nervous system damage in hand, foot, and mouth disease severity

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.

Transcriptomics explores potential mechanisms for the development of Primary Sjogren's syndrome to diffuse large B-cell lymphoma in B cells

PURPOSE

Primary Sjogren's syndrome (pSS) is a prevalent autoimmune disease. The immune dysregulation it causes often leads to the development of diffuse large B-cell lymphoma (DLBCL) in clinical practice. However, how it contributes to these two disorders at the molecular level is not yet known. This study explored the potential molecular mechanisms associated with the differences between DLBCL and pSS.

PATIENTS AND METHODS

Gene expression matrices from discovery cohort 1, discovery cohort 2, and the validation cohort were downloaded from the GEO and TCGA databases. Weighted gene coexpression network analysis (WGCNA) was performed to identify the coexpression modules of DLBCL and pSS in discovery cohort 1 and obtain shared genes. GO and KEGG enrichment analyses and PPI network analysis were performed on the shared genes. Immune-related genes (IRGs) were intersected with shared genes to obtain common genes. Afterward, common genes were identified via machine learning methods. The immune infiltration analysis, miRNA-TF-hub gene regulatory chart, gene interactions of the hub genes, and gene‒drug target analysis were performed. Finally, STAT1 was identified as a possible essential gene by the above analysis, and immune infiltration and GSEA pathway analyses were performed in the high- and low-expression groups in discovery cohort 2. The diagnostic efficacy of the hub genes was assessed in the validation cohort, and clinical samples were collected for validation.

RESULTS

By WGCNA, one modular gene in each group was considered highly associated with the disease, and we obtained 28 shared genes. Enrichment analysis revealed shared genes involved in the viral response and regulation. We obtained four hub genes (ISG20, STAT1, TLR7, and RSAD2) via the algorithm. Hub genes and similar genes are primarily involved in regulating type I IFNs. The construction of a miRNA-TF-hub gene regulatory chart revealed that hsa-mir-155-5p, hsa-mir-146b-5p, hsa-mir-21-3p, and hsa-mir-126-3p play essential roles in both diseases. Hub genes were differentially expressed in B-cell memory according to immune infiltration analysis. Hub genes had a strong diagnostic effect on both diseases. STAT1 plays an essential role in immune cells in both diseases.

CONCLUSION

We identified hub susceptibility genes for DLBCL and pSS and identified hub genes and potential therapeutic targets that may act as biomarkers.

Construction of Infectious Clones for Human Enteroviruses

The infectious clone has been constructed for years via various mechanisms using reverse genetics of viral RNA into cDNA. The mechanism of construction has evolved to DNA-launch plasmids which simplify infectious clone manipulation and expression in mammalian cells. Infectious clones have enormously allowed manipulation of the enterovirus genome to discover antivirals, viral replication mechanisms, and functions of essential viral proteins. Here we will be discussing methods for the production of DNA-launch human enterovirus infectious clones and viral genome engineered with a fluorescent reporter gene.

The internal ribosome entry site determines the neurotropic potential of enterovirus A71

The mechanisms underlying tissue-specific replication of enteroviruses are currently unclear. Although enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are both common pathogens that cause hand-foot-mouth disease, they display quite different neurotropic properties. Herein, we characterized the role of the internal ribosomal entry site (IRES) in determining neurovirulence using an oral inoculation model of EV-A71. The receptor transgenic (hSCARB2-Tg) mice developed neurological symptoms after being infected with a mouse-adapted EV-A71 strain (MP4) via different administrative routes. Intragastric administration of the MP4 strain caused pathological changes such as neuronal loss and neuropil vacuolation, whereas replacing EV-A71 IRES with CV-A16 abolished the neuropathological phenotypes. The attenuated neurotropic potential of IRES-swapped EV-A71 was observed even in mice that received intraperitoneal and intracerebral inoculations. Fewer chimeric MP4 viral RNAs and proteins were detected in the mouse tissues, regardless of the inoculation route. Tissue-specific replication can be reflected in cell-based characterization. While chimeric MP4 virus replicated poorly in human intestinal C2BBe1 and neuroblastoma SH-SY5Y cells, its replication in susceptible rhabdomyosarcoma cells was not affected. Overall, our results demonstrated that the IRES determined the neurotropic potential of EV-A71 and CV-A16, emphasizing the importance of the IRES in tissue tropism, along with the host receptors.

Recent advances in anti-coxsackievirus A16 viral drug research

Hand, foot and mouth disease, a childhood disorder caused by enteroviruses, is intermittently endemic in the Asia-Pacific region and endangers the lives of many infants and young children. Coxsackievirus A16 (CV-A16) is one of the major pathogens causing hand, foot, and mouth disease on occasion, resulting in catastrophic neurological sequelae and patient death. Currently, no clinical interventions are available that completely block the CV-A16 infection. Therefore, research on anti-CV-A16 treatment continues to be a significant focus of interest. This report provides a detailed background on and an introduction to CV-A16; a description of the viral gene and protein structures and a summary of the current advances in pharmaceutical targets, drug research and other related areas.

Porcine epidemic diarrhea virus strain FJzz1 infection induces type I/III IFNs production through RLRs and TLRs-mediated signaling

Interferons (IFNs) including type I/III IFNs are the major components of the host innate immune response against porcine epidemic diarrhea virus (PEDV) infection, and several viral proteins have been identified to antagonize type I/III IFNs productions through diverse strategies. However, the modulation of PEDV infection upon the activation of the host’s innate immune response has not been fully characterized. In this study, we observed that various IFN-stimulated genes (ISGs) were upregulated significantly in a time- and dose-dependent manner in LLC-PK1 cells infected with the PEDV G2 strain FJzz1. The transcriptions of IRF9 and STAT1 were increased markedly in the late stage of FJzz1 infection and the promotion of the phosphorylation and nuclear translocation of STAT1, implicating the activation of the JAK-STAT signaling pathway during FJzz1 infection. In addition, abundant type I/III IFNs were produced after FJzz1 infection. However, type I/III IFNs and ISGs decreased greatly in FJzz1-infected LLC-PK1 cells following the silencing of the RIG-I-like receptors (RLRs), including RIG-I and MDA5, and the Toll-like receptors (TLRs) adaptors, MyD88 and TRIF. Altogether, FJzz1 infection induces the production of type-I/III IFNs in LLC-PK1 cells, in which RLRs and TLRs signaling pathways are involved, followed by the activation of the JAK-STAT signaling cascade, triggering the production of numerous ISGs to exert antiviral effects of innate immunity.

Immune-Related Protein Interaction Network in Severe COVID-19 Patients toward the Identification of Key Proteins and Drug Repurposing

Coronavirus disease 2019 (COVID-19) is still an active global public health issue. Although vaccines and therapeutic options are available, some patients experience severe conditions and need critical care support. Hence, identifying key genes or proteins involved in immune-related severe COVID-19 is necessary to find or develop the targeted therapies. This study proposed a novel construction of an immune-related protein interaction network (IPIN) in severe cases with the use of a network diffusion technique on a human interactome network and transcriptomic data. Enrichment analysis revealed that the IPIN was mainly associated with antiviral, innate immune, apoptosis, cell division, and cell cycle regulation signaling pathways. Twenty-three proteins were identified as key proteins to find associated drugs. Finally, poly (I:C), mitomycin C, decitabine, gemcitabine, hydroxyurea, tamoxifen, and curcumin were the potential drugs interacting with the key proteins to heal severe COVID-19. In conclusion, IPIN can be a good representative network for the immune system that integrates the protein interaction network and transcriptomic data. Thus, the key proteins and target drugs in IPIN help to find a new treatment with the use of existing drugs to treat the disease apart from vaccination and conventional antiviral therapy.

Molecular Pathogenicity of Enteroviruses Causing Neurological Disease

Enteroviruses are single-stranded positive-sense RNA viruses that primarily cause self-limiting gastrointestinal or respiratory illness. In some cases, these viruses can invade the central nervous system, causing life-threatening neurological diseases including encephalitis, meningitis and acute flaccid paralysis (AFP). As we near the global eradication of poliovirus, formerly the major cause of AFP, the number of AFP cases have not diminished implying a non-poliovirus etiology. As the number of enteroviruses linked with neurological disease is expanding, of which many had previously little clinical significance, these viruses are becoming increasingly important to public health. Our current understanding of these non-polio enteroviruses is limited, especially with regards to their neurovirulence. Elucidating the molecular pathogenesis of these viruses is paramount for the development of effective therapeutic strategies. This review summarizes the clinical diseases associated with neurotropic enteroviruses and discusses recent advances in the understanding of viral invasion of the central nervous system, cell tropism and molecular pathogenesis as it correlates with host responses.

Recent advances on the role of host factors during non-poliovirus enteroviral infections

Non-polio enteroviruses are emerging viruses known to cause outbreaks of polio-like infections in different parts of the world with several cases already reported in Asia Pacific, Europe and in United States of America. These outbreaks normally result in overstretching of health facilities as well as death in children under the age of five. Most of these infections are usually self-limiting except for the neurological complications associated with human enterovirus A 71 (EV-A71). The infection dynamics of these viruses have not been fully understood, with most inferences made from previous studies conducted with poliovirus.Non-poliovirus enteroviral infections are responsible for major outbreaks of hand, foot and mouth disease (HFMD) often associated with neurological complications and severe respiratory diseases. The myriad of disease presentations observed so far in children calls for an urgent need to fully elucidate the replication processes of these viruses. There are concerted efforts from different research groups to fully map out the role of human host factors in the replication cycle of these viral infections. Understanding the interaction between viral proteins and human host factors will unravel important insights on the lifecycle of this groups of viruses.This review provides the latest update on the interplay between human host factors/processes and non-polio enteroviruses (NPEV). We focus on the interactions involved in viral attachment, entry, internalization, uncoating, replication, virion assembly and eventual egress of the NPEV from the infected cells. We emphasize on the virus- human host interplay and highlight existing knowledge gaps that needs further studies. Understanding the NPEV-human host factors interactions will be key in the design and development of vaccines as well as antivirals against enteroviral infections. Dissecting the role of human host factors during NPEV infection cycle will provide a clear picture of how NPEVs usurp the human cellular processes to establish an efficient infection. This will be a boost to the drug and vaccine development against enteroviruses which will be key in control and eventual elimination of the viral infections.

Viperin Inhibits Enterovirus A71 Replication by Interacting with Viral 2C Protein

Enterovirus A71 (EVA71) is a human enterovirus belonging to the Picornaviridae family and mostly causes hand-foot-and-mouth disease in infants. Viperin is an important interferon-stimulated gene with a broad antiviral activity against various viruses. However, the effect of viperin on human enteroviruses and the interaction mechanism between EVA71 and viperin remains elusive. Here, we confirmed the EVA71-induced expression of viperin in a mouse model and cell lines and showed that viperin upregulation by EVA71 infection occurred on both the mRNA and protein level. Viperin knockdown and overexpression in EVA71-infected cells indicated that this protein can markedly inhibit EVA71 infection. Interestingly, immunofluorescent confocal microscopy and co-immunoprecipitation assays indicated that viperin interacts and colocalizes with the EVA71 protein 2C in the endoplasmic reticulum. Furthermore, amino acids 50⁻60 in the N-terminal domain of viperin were the key residues responsible for viperin interaction with 2C. More importantly, the N-terminal domain of viperin was found responsible for inhibiting EVA71 replication. Our findings can potentially aid future research on the prevention and treatment of nervous system damage caused by EVA71 and may provide a potential target for antiviral therapy.

Common Differences: The Ability of Inflammasomes to Distinguish Between Self and Pathogen Nucleic Acids During Infection

The innate immune system detects the presence of pathogens based on detection of non-self. In other words, most pathogens possess intrinsic differences that can distinguish them from host cells. For example, bacteria and fungi have cell walls comprised of peptidoglycan and carbohydrates (like mannans), respectively. Germline encoded pattern recognition receptors (PRRs) of the Toll-like receptor (TLR) and C-type lectin receptor (CLR) family have the ability to detect such unique pathogen associated features. However, some TLRs and members of the RIG-I-like receptor (RLR), NOD-like receptor (NLR), or AIM2-like receptor (ALR) family can sense pathogen invasion based on pathogen nucleic acids. Nucleic acids are not unique to pathogens, thus raising the question of how such PRRs evolved to detect pathogens but not self. In this chapter, we will examine the PRRs that sense pathogen nucleic acids and subsequently activate the inflammasome signaling pathway. We will examine the selective mechanisms by which these receptors distinguish pathogens from "self" and discuss the importance of such pathways in disease development in animal models and human patients.