Neurotropic Enterovirus Infections in the Central Nervous System

Transcriptomic analysis of coxsackievirus B3 infection in induced pluripotent stem cell-derived brain-like endothelial cells

Viral aseptic meningitis is a neuroinflammatory condition that occurs when viruses gain access to the central nervous system (CNS) and induce inflammation. The blood-brain barrier (BBB) is comprised of brain endothelial cells (BECs) that stringently regulate the passage of molecules, toxins, and pathogens from the circulation into the CNS. Through their unique properties, such as complex tight junctions, reduced rates of endocytosis, expression of efflux transporters, and restricted expression of leukocyte adhesion molecules, the BBB is often able to limit pathogen entry into the brain; however, certain neurotropic pathogens, such as coxsackievirus B3 (CVB3) are able to infect the CNS. We have previously demonstrated that CVB3 can infect and disrupt induced pluripotent stem cell-derived brain-like endothelial cells (iBECs), but the host response to this infection remains unknown. Here, we investigate global host transcriptional changes during CVB3 infection of iBECs using RNA sequencing. We validated our data set by exploring pathways altered by CVB3 using quantitative real-time PCR (qPCR) and enzyme-linked immunosorbent assay of upregulated cytokines and interferon signaling molecules.

IMPORTANCE

Coxsackievirus B3 (CVB3) is a leading cause of viral aseptic meningitis that can produce severe disease in susceptible individuals. To gain access to the central nervous system, CVB3 must cross central nervous system barriers, such as the blood-brain barrier. Previously, we have shown that CVB3 infects a human stem cell-derived brain-like endothelial cell model. Here, we report the global transcriptome of stem cell-derived brain-like endothelial cells to CVB3 infection and provide proof-of-concept validation of the dataset using molecular biology techniques. These data could inform novel mechanisms of CVB3-mediated blood-brain barrier dysfunction.

Viral Infection and Ischemic Stroke: Emerging Trends and Mechanistic Insights

Population studies have suggested that viral infections may be contributing to risk of ischemic stroke, although the mechanisms for this are unclear. In this review, we examine the epidemiological evidence supporting the involvement of viral diseases, including influenza, COVID-19, chronic herpesvirus infections, and hepatitis C in current trends of stroke incidence. To support these associations, we highlight the virus-host interactions that are critical in the context of stroke, including direct effects of acute and persistent viral infections on vascular function, inflammation, and thrombosis. Additionally, we evaluate the systemic changes that occur during viral infection that can predispose individuals to ischemic stroke, including alterations in blood pressure regulation, coagulation, and lipid metabolism. Our review emphasizes the need to further elucidate precise mechanisms involved in viral infections and stroke risk. Future research will inform the development of targeted interventions for stroke prevention in the context of viral diseases.

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.

Correlations of PSGL-1 VNTR polymorphism with the susceptibility to severe HFMD associated with EV-71 and the immune status after infection

Enterovirus 71 (EV-71) has strong neurotropism, and it is the main pathogen causing severe hand, foot, and mouth disease (HFMD). In clinical observations, significant differences were observed in the severity and prognosis of HFMD among children who were also infected with EV-71. Genetic differences among individuals could be one of the important causes of differences in susceptibility to EV-71-induced HFMD. As P-selectin glycoprotein ligand-1 (PSGL-1) is an important receptor of EV-71, the correlation between single-nucleotide polymorphisms (SNPs) in PSGL-1 and the susceptibility to severe HFMD following EV-71 infection is worth studying. Given the role of PSGL-1 in immunity, the correlations between PSGL-1 SNPs and the immune status after EV-71 infection are also worth studying. Meanwhile, PSGL-1 variable number of tandem repeats (VNTR) represents a research hotspot in cardiovascular and cerebrovascular diseases, but PSGL-1 VNTR polymorphism has not been investigated in HFMD caused by EV-71 infection. In this study, specific gene fragments were amplified by polymerase chain reaction, and PSGL-1 VNTR sequences were genotyped using an automatic nucleic acid analyzer. The correlations of PSGL-1 VNTR polymorphism with the susceptibility to EV-71-associated severe HFMD and the post-infection immune status were analyzed. The PSGL-1 VNTR A allele was identified as a susceptible SNP for severe HFMD. The risk of severe HFMD was higher for AA + AB genotype carriers than for BB genotype carriers. The counts of peripheral blood lymphocyte subsets were lower in AA + AB genotype carries than in BB genotype carries. In conclusion, PSGL-1 VNTR polymorphism is associated with the susceptibility to EV-71-induced severe HFMD and the immune status after infection. PSGL-1 VNTR might play a certain role in the pathogenesis of severe cases.

Enteroviral meningitis in children: Clinical and laboratory features with and without pleocytosis

BACKGROUND

Enteroviruses (EV) are most common causes of the etiologically known aseptic meningitis in children. EV can be detected with polymerase chain reaction (PCR) in cerebrospinal fluid (CSF) samples. We aimed to evaluate the clinical and laboratory characteristics of children diagnosed with PCR-confirmed EV meningitis in CSF samples.

PATIENTS

Patients aged 1 month to 17 years who underwent lumbar puncture (LP) with suspected meningitis and had CSF viral PCR and culture results between September 2012 and January 2021 at a tertiary care hospital in Turkey were included.

METHODS

Patients with no virus detected in CSF samples by PCR was comprised PCR-negative group. The EV PCR-positive patients were divided into two groups based on CSF pleocytosis as enteroviral meningitis (EVM) with CSF pleocytosis and EVM without CSF pleocytosis, and compared in terms of clinical and laboratory features.

RESULTS

78 (38.2%) were EV PCR-positive, and 126 (61.8%) were PCR-negative. Pleocytosis was detected in 55 (70.5%) EV PCR-positive patients and 94 (74.6%) of PCR-negative patients. Convulsion was significantly frequent (p=0.017) in EV PCR-positive patients with no pleocytosis. Protein and lactate concentrations in CSF were significantly higher in EV PCR-positive patients with pleocytosis (p=0.048, p=0.001, respectively). Median hospital stay was significantly longer in PCR-negative group (p<0.001).

CONCLUSION

Diagnosing EVM with PCR prevents long-term hospitalization, unnecessary antibiotic use and healthcare-related complications.

First isolation, identification, and pathogenicity evaluation of an EV-G6 strain in China

Enterovirus G (EV-G) belongs to the Picornaviridae family and infects porcine populations worldwide. A total of 20 EV-G genotypes (EV-G1 to EV-G20) have been identified. In this study, we isolated and characterized an EV-G strain, named EV-G/YN29/2022, from the feces of diarrheic pigs. This was the first EV-G6 strain isolated in China. Comparison of the whole genome nucleotide and corresponding amino acid sequences showed that the isolate was more closely related to those of the EV-G6 genotype than other genotypes, with the complete genome sequence similarity ranging from 83.7% (Iba46442) to 84.4% (PEV-B-KOR), and corresponding amino acid homology ranged from 96% (Iba46442) to 96.8% (PEV-B-KOR). Similarly, the VP1 gene and corresponding amino acid sequences of EV-G/YN29/2022 were highly similar to those of the EV-G6 genotype (>82.9% and >94.3%, respectively). Thus, the isolated strain was classified as EV-G6 genotype. This was the first EV-G6 strain isolated in China. Pathogenicity analyses revealed that EV-G/YN29/2022 infection caused mild diarrhea, typical skin lesions, and weight reduction. The strain was mainly distributed to the intestinal tissue but was also found in the brain, mesenteric lymph nodes, spleen, and liver. Our results can be used as a reference to further elucidate the epidemiology, evolution, and pathogenicity of EV-G.

Modulation of plasmacytoid dendritic cell and CD4+ T cell differentiation accompanied by upregulation of the cholinergic anti-inflammatory pathway induced by enterovirus 71

Enterovirus 71 (EV71) is a neurotropic enterovirus associated with hand, foot, and mouth disease (HFMD) fatalities. In this study, we investigated the impact of EV71 on plasmacytoid dendritic cells (pDCs) and CD4+ T cells. The results showed that pDCs were promptly activated, secreting interferon (IFN)-α and inducing CD4+ T cell proliferation and differentiation during early EV71 infection. This initiated adaptive immune responses and promoted proinflammatory cytokine production by CD4+ T cells. Over time, viral nucleic acids and proteins were synthesized in pDCs and CD4+ T cells. Concurrently, the cholinergic anti-inflammatory pathway (CAP) was activated, exhibiting an anti-inflammatory role. With constant viral stimulation, pDCs and CD4+ T cells showed reduced differentiation and cytokine secretion. Defects in pDCs were identified as a key factor in CD4+ T cell tolerance. CAP had a more significant regulatory effect on CD4+ T cells than on pDCs and was capable of inhibiting inflammation in these cells.

SARS-CoV-2 and oncolytic EV-D68-encoded proteases differentially regulate pyroptosis

Pyroptosis, a pro-inflammatory programmed cell death, has been implicated in the pathogenesis of coronavirus disease 2019 and other viral diseases. Gasdermin family proteins (GSDMs), including GSDMD and GSDME, are key regulators of pyroptotic cell death. However, the mechanisms by which virus infection modulates pyroptosis remain unclear. Here, we employed a mCherry-GSDMD fluorescent reporter assay to screen for viral proteins that impede the localization and function of GSDMD in living cells. Our data indicated that the main protease NSP5 of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) blocked GSDMD-mediated pyroptosis via cleaving residues Q29 and Q193 of GSDMD. While another SARS-CoV-2 protease, NSP3, cleaved GSDME at residue G370 but activated GSDME-mediated pyroptosis. Interestingly, respiratory enterovirus EV-D68-encoded proteases 3C and 2A also exhibit similar differential regulation on the functions of GSDMs by inactivating GSDMD but initiating GSDME-mediated pyroptosis. EV-D68 infection exerted oncolytic effects on human cancer cells by inducing pyroptotic cell death. Our findings provide insights into how respiratory viruses manipulate host cell pyroptosis and suggest potential targets for antiviral therapy as well as cancer treatment.IMPORTANCEPyroptosis plays a crucial role in the pathogenesis of coronavirus disease 2019, and comprehending its function may facilitate the development of novel therapeutic strategies. This study aims to explore how viral-encoded proteases modulate pyroptosis. We investigated the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and respiratory enterovirus D68 (EV-D68) proteases on host cell pyroptosis. We found that SARS-CoV-2-encoded proteases NSP5 and NSP3 inactivate gasdermin D (GSDMD) but initiate gasdermin E (GSDME)-mediated pyroptosis, respectively. We also discovered that another respiratory virus EV-D68 encodes two distinct proteases 2A and 3C that selectively trigger GSDME-mediated pyroptosis while suppressing the function of GSDMD. Based on these findings, we further noted that EV-D68 infection triggers pyroptosis and produces oncolytic effects in human carcinoma cells. Our study provides new insights into the molecular mechanisms underlying virus-modulated pyroptosis and identifies potential targets for the development of antiviral and cancer therapeutics.

Enterovirus evolution reveals the mechanism of an RNA-targeted antiviral and determinants of viral replication

Selective pressures on viruses provide opportunities to establish target site specificity and mechanisms of antivirals. Enterovirus (EV)-A71 with resistant mutations in the stem loop (SL) II internal ribosome entry site (IRES) (SLIIresist) were selected at low doses of the antiviral dimethylamiloride (DMA)-135. The EV-A71 mutants were resistant to DMA-135 at concentrations that inhibit replication of wild-type virus. EV-A71 IRES structures harboring resistant mutations induced efficient expression of Luciferase messenger RNA in the presence of noncytotoxic doses of DMA-135. Nuclear magnetic resonance indicates that the mutations change the structure of SLII at the binding site of DMA-135 and at the surface recognized by the host protein AU-rich element/poly(U)-binding/degradation factor 1 (AUF1). Biophysical studies of complexes formed between AUF1, DMA-135, and either SLII or SLIIresist show that DMA-135 stabilizes a ternary complex with AUF1-SLII but not AUF1-SLIIresist. This work demonstrates how viral evolution elucidates the (DMA-135)-RNA binding site specificity in cells and provides insights into the viral pathways inhibited by the antiviral.

Molecular Amplification and Cell Culturing Efficiency for Enteroviruses' Detection in Cerebrospinal Fluids of Algerian Patients Suffering from Meningitis

Enteroviruses (EVs) represent a major cause of viral meningitis, being responsible for nearly 1 billion infections each year worldwide. Several techniques were developed to obtain better diagnostic results of EV infections. Herein, we evaluated the efficiency of EV detection through isolation on both Rhabdomyosarcoma (RD) and Vero cell line cultures, conventional reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR. Thus, 50 cerebrospinal fluid (CSF) samples belonging to patients suspected to have viral meningitis in northern Algeria were collected, anonymously numbered from 1 to 50 and subjected to the above-mentioned techniques for EV detection. Using real-time RT-PCR, 34 CSF samples were revealed to be positive for viral origin of meningitis (68%). Thirteen of them were positive when the conventional RT-PCR was used (26%), and only three samples gave positive results when the cell culture technique was used (6%). Surprisingly, two cell culture-positive CSF samples, namely, 31 and 39, were negative using RT-PCR directly on the original samples. However, they turned to be positive when amplification was carried out on their corresponding cell culture supernatant. The cell-cultured viral isolates were then identified by sequencing their viral genome's VP1 regions. All of them were revealed to belong to the echovirus 27 strain. This investigation demonstrates that RT-PCR techniques are often more sensitive, accurate and much faster, providing reliable results within a clinically acceptable timeframe. However, viral isolation on cell cultures remains crucial to obtain enough viral load for serological tests or even to avoid the rare, but existing, false negative PCR.

Development of Zika Virus E Variants for Pseudotyping Retroviral Vectors Targeting Glioblastoma Cells

A fundamental idea for targeting glioblastoma cells is to exploit the neurotropic properties of Zika virus (ZIKV) through its two outer envelope proteins, prM and E. This study aimed to develop envelope glycoproteins for pseudotyping retroviral vectors that can be used for efficient tumor cell infection. Firstly, the retroviral vector pNLlucAM was packaged using wild-type ZIKV E to generate an E-HIVluc pseudotype. E-HIVluc infection rates for tumor cells were higher than those of normal prME pseudotyped particles and the traditionally used vesicular stomatitis virus G (VSV-G) pseudotypes, indicating that protein E alone was sufficient for the formation of infectious pseudotyped particles. Secondly, two envelope chimeras, E41.1 and E41.2, with the E wild-type transmembrane domain replaced by the gp41 transmembrane and cytoplasmic domains, were constructed; pNLlucAM or pNLgfpAM packaged with E41.1 or E41.2 constructs showed infectivity for tumor cells, with the highest rates observed for E41.2. This envelope construct can be used not only as a tool to further develop oncolytic pseudotyped viruses for therapy, but also as a new research tool to study changes in tumor cells after the transfer of genes that might have therapeutic potential.

Systematic Surveillance of an Emerging Picornavirus among Cattle and Sheep in China

Emerging viruses are a constant threat to human and animal health. Boosepivirus is a novel picornavirus considered a gastrointestinal pathogen and has broken out in recent years. In 2020, we identified a strain of boosepivirus NX20-1 from Chinese calf feces and performed genetic characterization and evolutionary analysis. NX20-1 was closely related to the Japanese strain Bo-12-38/2009/JPN and belonged to Boosepivirus B. We found that 64 of 603 samples (10.6%) from 20 different provinces across the country were positive for boosepivirus by reverse transcription (RT)-PCR. Further, coinfection with other diarrheal pathogens was also present in 35 of these positive samples. Importantly, we found the prevalence of boosepivirus in sheep as well, indicating that Boosepivirus can infect different domestic animals. Our data suggest that boosepivirus is a potential diarrheal pathogen, but the pathogenicity and the mechanism of pathogenesis need further study. IMPORTANCE We identified a novel picornavirus, boosepivirus, for the first time in China. Genetic evolutionary analysis revealed that NX20-1 strain was closely related to the Japanese strain Bo-12-38/2009/JPN and belonged to Boosepivirus B. In addition, we found that the virus was prevalent in China with an overall positivity rate of 10.6% (64 of 603 samples), and there was significant coinfection with other pathogens. Importantly, we found the prevalence of boosepivirus in sheep as well, suggesting that boosepivirus has a risk of spillover and can be transmitted across species.

Case report: Clinical and virological characteristics of aseptic meningitis caused by a recombinant echovirus 18 in an immunocompetent adult

Echovirus 18 has been recognized as an important causative pathogen of aseptic meningitis in young children worldwide, and echovirus 18-induced meningitis is rarely found in adults with immunocompetence. In this case study, we report the clinical and virological characteristics of aseptic meningitis caused by recombinant echovirus 18 in an adult with immunocompetence. A 31-year-old woman with immunocompetence was admitted to our hospital with fever, dizziness, severe headache, nausea, and vomiting for the past 1 day and was diagnosed with viral meningitis based on the clinical manifestations and laboratory results from cerebrospinal fluid (CSF). The patient received antiviral treatment with ribavirin and interferon as soon as the enterovirus infection was identified using qRT-PCR and was cured after 4 days. From the oropharyngeal swab and CSF samples, two echovirus 18 strains were isolated with a single nucleotide difference located at the 5' UTR. Phylogenetic analyses based on the VP1 gene showed that the two strains belonged to the subgenotype C2 and were clustered with sequences obtained from China after 2015, while the results from the 3D polymerase region showed that the two strains were closely related to the E30 strains. Bootscanning results using the 5' UTR to 2A region and the 2B to 3' UTR region showed that potential intertypic recombination had occurred in the 2B gene. Recombination analyses further confirmed that the two strains (echovirus 18) presented genome recombination with echovirus 30 in the nucleotide regions of the 2B gene. To the best of our knowledge, this is the first report of echovirus 18-induced meningitis in an adult with immunocompetence from mainland China, highlighting the need for close surveillance of echovirus 18 both in children and adults in the future.

Neuromuscular Complications of SARS-CoV-2 and Other Viral Infections

In this article we review complications to the peripheral nervous system that occur as a consequence of viral infections, with a special focus on complications of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We discuss neuromuscular complications in three broad categories; the direct consequences of viral infection, autoimmune neuromuscular disorders provoked by viral infections, and chronic neurodegenerative conditions which have been associated with viral infections. We also include discussion of neuromuscular disorders that are treated by immunomodulatory therapies, and how this affects patient susceptibility in the current context of the coronavirus disease 2019 (COVID-19) pandemic. COVID-19 is associated with direct consequences to the peripheral nervous system via presumed direct viral injury (dysgeusia/anosmia, myalgias/rhabdomyolysis, and potentially mononeuritis multiplex) and autoimmunity (Guillain Barré syndrome and variants). It has important implications for people receiving immunomodulatory therapies who may be at greater risk of severe outcomes from COVID-19. Thus far, chronic post-COVID syndromes (a.k.a: long COVID) also include possible involvement of the neuromuscular system. Whether we may observe neuromuscular degenerative conditions in the longer term will be an important question to monitor in future studies.

Neurology of Acute Viral Infections

As specialists in acute neurology, neurohospitalists are often called upon to diagnose and manage acute viral infections affecting the nervous system. In this broad review covering the neurology of several acute viral infections, our aim is to provide key diagnostic and therapeutic pearls of practical use to the busy neurohospitalist. We will review acute presentations, diagnosis, and treatment of human herpesviruses, arboviruses, enteroviruses, and some vaccine-preventable viruses. The neurological effects of coronaviruses, including COVID-19, are not covered in this review.

Molecular Mechanisms in the Genesis of Seizures and Epilepsy Associated With Viral Infection

Seizures are a common presenting symptom during viral infections of the central nervous system (CNS) and can occur during the initial phase of infection ("early" or acute symptomatic seizures), after recovery ("late" or spontaneous seizures, indicating the development of acquired epilepsy), or both. The development of acute and delayed seizures may have shared as well as unique pathogenic mechanisms and prognostic implications. Based on an extensive review of the literature, we present an overview of viruses that are associated with early and late seizures in humans. We then describe potential pathophysiologic mechanisms underlying ictogenesis and epileptogenesis, including routes of neuroinvasion, viral control and clearance, systemic inflammation, alterations of the blood-brain barrier, neuroinflammation, and inflammation-induced molecular reorganization of synapses and neural circuits. We provide clinical and animal model findings to highlight commonalities and differences in these processes across various neurotropic or neuropathogenic viruses, including herpesviruses, SARS-CoV-2, flaviviruses, and picornaviruses. In addition, we extensively review the literature regarding Theiler's murine encephalomyelitis virus (TMEV). This picornavirus, although not pathogenic for humans, is possibly the best-characterized model for understanding the molecular mechanisms that drive seizures, epilepsy, and hippocampal damage during viral infection. An enhanced understanding of these mechanisms derived from the TMEV model may lead to novel therapeutic interventions that interfere with ictogenesis and epileptogenesis, even within non-infectious contexts.

Role of Non-Coding RNA in Neurological Complications Associated With Enterovirus 71

Enterovirus 71 (EV71) is the main pathogenic virus that causes hand, foot, and mouth disease (HFMD). Studies have reported that EV71-induced infections including aseptic meningitis, acute flaccid paralysis, and even neurogenic pulmonary edema, can progress to severe neurological complications in infants, young children, and the immunosuppressed population. However, the mechanisms through which EV71 causes neurological diseases have not been fully explored. Non-coding RNAs (ncRNAs), are RNAs that do not code for proteins, play a key role in biological processes and disease development associated with EV71. In this review, we summarized recent advances concerning the impacts of ncRNAs on neurological diseases caused by interaction between EV71 and host, revealing the potential role of ncRNAs in pathogenesis, diagnosis and treatment of EV71-induced neurological complications.

Enterovirus A71 antivirals: Past, present, and future

Enterovirus A71 (EV-A71) is a significant human pathogen, especially in children. EV-A71 infection is one of the leading causes of hand, foot, and mouth diseases (HFMD), and can lead to neurological complications such as acute flaccid myelitis (AFM) in severe cases. Although three EV-A71 vaccines are available in China, they are not broadly protective and have reduced efficacy against emerging strains. There is currently no approved antiviral for EV-A71. Significant progress has been made in developing antivirals against EV-A71 by targeting both viral proteins and host factors. However, viral capsid inhibitors and protease inhibitors failed in clinical trials of human rhinovirus infection due to limited efficacy or side effects. This review discusses major discoveries in EV-A71 antiviral development, analyzes the advantages and limitations of each drug target, and highlights the knowledge gaps that need to be addressed to advance the field forward.

Molecular characterization of enterovirus detected in cerebrospinal fluid and wastewater samples in Monastir, Tunisia, 2014-2017

Background

Enteroviruses (EVs) are considered the main causative agents responsible for aseptic meningitis worldwide. This study was conducted in the Monastir region of Tunisia in order to know the prevalence of EV infections in children with meningitis symptoms. Detected EV types were compared to those identified in wastewater samples.

Methods

Two hundred CSF samples collected from hospitalized patients suspected of having aseptic meningitis for an EV infection between May 2014 and May 2017 and 80 wastewater samples collected in the same time-period were analyzed. EV detection and genotyping were performed using PCR methods followed by sequencing. Phylogenetic analyses in the 3′-VP1 region were also carried-out.

Results

EVs were detected in 12% (24/200) CSF and in 35% (28/80) wastewater samples. EV genotyping was reached in 50% (12/24) CSF-positive samples and in 64% (18/28) sewage. Most frequent types detected in CSF were CVB3, E-30 and E-9 (25% each). In wastewater samples, the same EVs were identified, but also other types non-detected in CSF samples, such as E-17,CVA9 and CVB1 from EV species B, and EV-A71 and CVA8 from EV-A, suggesting their likely lower pathogenicity. Phylogenetic analysis showed that within the same type, different strains circulate in Tunisia. For some of the EV types such as E-9, E-11 or CVB3, the same strains were detected in CSF and wastewater samples.

Conclusions

Epidemiological studies are important for the surveillance of the EV infections and to better understand the emergence of certain types and variants.

Epidemiology of Echovirus 30 Infections Detected in a University Hospital in Catalonia, Spain, in 1995–2020

There is a growing interest in echovirus 30 (E30), an enterovirus responsible for neurological disease and hospitalization. There are multiple studies of outbreaks, but few that study the epidemiology over long periods of time. Our study aims to describe the clinical, epidemiological and microbiological characteristics of a series of E30 infections detected over 26 years. Data were retrospectively collected from a database of all enterovirus infections identified in our laboratory. They were detected by viral isolation or nucleic acid detection in patients presenting with respiratory or neurological infections, rash, sepsis-like syndrome, or gastroenteritis. Enterovirus genotyping was performed by amplification of the VP1 gene using RT-nested PCR, followed by sequencing and BLAST analysis. Of the 2402 enterovirus infections detected, 1619 were linked to at least one genotype and 173 were caused by E30. Clinical information was available for 158 (91.3%) patients. E30 was associated with neurological infection in 107 (67.8%) cases and it was detected almost every year. Phylogenetic analysis was performed with 67 sequences. We observed that E30 strains circulating in Catalonia from 1996 to 2016 belong to two lineages (E and F), although the majority cluster was in F. In 2018, lineage I emerged as the dominant lineage.

Enterovirus Infections in Solid Organ Transplant Recipients: a Clinical Comparison from a Regional University Hospital in the Netherlands

Enterovirus infections are known to cause a diverse range of illnesses, even in healthy individuals. However, information detailing enterovirus infections and their severity in immunocompromised patients, such as transplant recipients, is limited. We compared enterovirus infections in terms of genotypes, clinical presentation, and severity between transplant and nontransplant patients. A total of 264 patients (38 transplant recipients) with 283 enterovirus infection episodes were identified in our hospital between 2014 and 2018. We explored the following factors associated with enterovirus infections: clinical presentation and diagnosis on discharge, length of hospital stay, symptom persistence, and infection episodes in both children and adults. We observed some differences in genotypes between patients, with enterovirus group C occurring mainly in transplant recipients (P < 0.05). EV-associated gastrointestinal infections were more common in patients with a transplant (children [71%] and adults [46%]), compared to nontransplant patients (P < 0.05). Additionally, nontransplant patients had a higher number of hospital stays (P < 0.05), potentially reflecting more severe disease. However, transplant patients were more likely to have symptom persistence after discharge (P < 0.05). Finally, children and adults with a transplant were more likely to have additional enterovirus infection episodes (P < 0.05). In our cohort, enterovirus infections did not seem to be more severe after transplantation; however, patients tended to present with different clinical symptoms and had genotypes rarely found in nontransplant recipients.

IMPORTANCE Despite the high prevalence of enteroviruses in the community and the increasing demand for transplants from an aging population, knowledge on enteroviruses in solid organ transplant recipients is currently limited. Transplant recipients represent a significant patient population and require additional considerations in patient management, particularly as they have an increased risk of disease severity. Enteroviruses are known to cause significant morbidity, with a diverse range of clinical presentation from over 100 different genotypes. In this study, we aimed to provide a more comprehensive overview of enteroviral infections in transplant recipients, compared to nontransplant patients, and to bridge some gaps in our current knowledge. Identifying potential clinical manifestation patterns can help improve patient management following enterovirus infections.

Transcriptome of human neuroblastoma SH-SY5Y cells in response to 2B protein of enterovirus-A71

Infection with enterovirus-A71 (EV-A71) can cause hand-foot-mouth disease associated with fatal neurological complications. The host response to EV-A71 has not yet been fully elucidated, thus, hampering the development of a precise therapeutic approach. A nonstructural 2B protein of EV-A71 has been reported to involve with calcium dysregulation and apoptosis induction in human neuroblastoma SH-SY5Y cells. However, the molecular mechanism has not been delineated. To address this, comprehensive study of the gene expression from SH-SY5Y cells transfected with EV-A71 2B was carried out by RNA sequencing and transcriptomic analysis. It was found that the signature of the upregulated genes of SH-SY5Y cells expressing EV-A71 2B involved the Ca²⁺-related signaling pathways participating gene expression, inflammatory response, apoptosis, and long-term potentiation of the neuron. Protein-protein interaction network analysis revealed that the products encoded by CCL2, RELB, BIRC3, and TNFRSF9 were the most significant hub proteins in the network. It indicated that EV-A71 2B protein might play a role in immunopathogenesis of the central nervous system (CNS) which probably associated with the non-canonical NF-κB pathway. The data suggest that transcriptomic profiling can provide novel information source for studying the neuropathogenesis of EV-A71 infection leading to development of an effective therapeutic measure for CNS complications.

Infectious Agents as Potential Drivers of α-Synucleinopathies

α-synucleinopathies, encompassing Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, are devastating neurodegenerative diseases for which available therapeutic options are scarce, mostly because of our limited understanding of their pathophysiology. Although these pathologies are attributed to an intracellular accumulation of the α-synuclein protein in the nervous system with subsequent neuronal loss, the trigger(s) of this accumulation is/are not clearly identified. Among the existing hypotheses, interest in the hypothesis advocating the involvement of infectious agents in the onset of these diseases is renewed. In this article, we aimed to review the ongoing relevant factors favoring and opposing this hypothesis, focusing on (1) the potential antimicrobial role of α-synuclein, (2) potential entry points of pathogens in regard to early symptoms of diverse α-synucleinopathies, (3) pre-existing literature reviews assessing potential associations between infectious agents and Parkinson's disease, (4) original studies assessing these associations for dementia with Lewy bodies and multiple system atrophy (identified through a systematic literature review), and finally (5) potential susceptibility factors modulating the effects of infectious agents on the nervous system. © 2022 International Parkinson and Movement Disorder Society.

Sublethal enteroviral infection exacerbates disease progression in an ALS mouse model

Background

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of the motor neuron system associated with both genetic and environmental risk factors. Infection with enteroviruses, including poliovirus and coxsackievirus, such as coxsackievirus B3 (CVB3), has been proposed as a possible causal/risk factor for ALS due to the evidence that enteroviruses can target motor neurons and establish a persistent infection in the central nervous system (CNS), and recent findings that enteroviral infection-induced molecular and pathological phenotypes closely resemble ALS. However, a causal relationship has not yet been affirmed.

Methods

Wild-type C57BL/6J and G85R mutant superoxide dismutase 1 (SOD1^G85R) ALS mice were intracerebroventricularly infected with a sublethal dose of CVB3 or sham-infected. For a subset of mice, ribavirin (a broad-spectrum anti-RNA viral drug) was given subcutaneously during the acute or chronic stage of infection. Following viral infection, general activity and survival were monitored daily for up to week 60. Starting at week 20 post-infection (PI), motor functions were measured weekly. Mouse brains and/or spinal cords were harvested at day 10, week 20 and week 60 PI for histopathological evaluation of neurotoxicity, immunohistochemical staining of viral protein, neuroinflammatory/immune and ALS pathology markers, and NanoString and RT-qPCR analysis of inflammatory gene expression.

Results

We found that sublethal infection (mimicking chronic infection) of SOD1^G85R ALS mice with CVB3 resulted in early onset and progressive motor dysfunction, and shortened lifespan, while similar viral infection in C57BL/6J, the background strain of SOD1^G85R mice, did not significantly affect motor function and mortality as compared to mock infection within the timeframe of the current study (60 weeks PI). Furthermore, we showed that CVB3 infection led to a significant increase in proinflammatory gene expression and immune cell infiltration and induced ALS-related pathologies (i.e., TAR DNA-binding protein 43 (TDP-43) pathology and neuronal damage) in the CNS of both SOD1^G85R and C57BL/6J mice. Finally, we discovered that early (day 1) but not late (day 15) administration of ribavirin could rescue ALS-like neuropathology and symptoms induced by CVB3 infection.

Conclusions

Our study identifies a new risk factor that contributes to early onset and accelerated progression of ALS and offers opportunities for the development of novel targeted therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02380-7.

Does enterovirus 71 urge for effective vaccine control strategies? Challenges and current opinion

Enterovirus 71 (EV71) is an infectious virus affecting all age groups of people around the world. It is one of the major aetiologic agents for HFMD (hand, foot and mouth disease) identified globally. It has led to many outbreaks and epidemics in Asian countries. Infection caused by this virus that can lead to serious psychological problems, heart diseases and respiratory issues in children younger than 10 years of age. Many studies are being carried out on the pathogenesis of the virus, but little is known. The host immune response and other molecular responses against the virus are also not clearly determined. This review deals with the interaction between the host and the EV71 virus. We discuss how the virus makes use of its proteins to affect the host's immunity and how the viral proteins help their replication. Additionally, we describe other useful resources that enable the virus to evade the host's immune responses. The knowledge of the viral structure and its interactions with host cells has led to the discovery of various drug targets for the treatment of the virus. Additionally, this review focusses on the antiviral drugs and vaccines developed by targeting various viral surface molecules during their infectious period. Furthermore, it is asserted that the improvement of prevailing vaccines will be the simplest method to manage EV71 infection swiftly. Therefore, we summarise numerous vaccines candidate for the EV71, such as the use of an inactivated complete virus, recombinant VP1 protein, artificial peptides, VLPs (viral-like particles) and live attenuated vaccines for combating the viral outbreaks promptly.

The Causes and Long-Term Consequences of Viral Encephalitis

Reports regarding brain inflammation, known as encephalitis, have shown an increasing frequency during the past years. Encephalitis is a relevant concern to public health due to its high morbidity and mortality. Infectious or autoimmune diseases are the most common cause of encephalitis. The clinical symptoms of this pathology can vary depending on the brain zone affected, with mild ones such as fever, headache, confusion, and stiff neck, or severe ones, such as seizures, weakness, hallucinations, and coma, among others. Encephalitis can affect individuals of all ages, but it is frequently observed in pediatric and elderly populations, and the most common causes are viral infections. Several viral agents have been described to induce encephalitis, such as arboviruses, rhabdoviruses, enteroviruses, herpesviruses, retroviruses, orthomyxoviruses, orthopneumovirus, and coronaviruses, among others. Once a neurotropic virus reaches the brain parenchyma, the resident cells such as neurons, astrocytes, and microglia, can be infected, promoting the secretion of pro-inflammatory molecules and the subsequent immune cell infiltration that leads to brain damage. After resolving the viral infection, the local immune response can remain active, contributing to long-term neuropsychiatric disorders, neurocognitive impairment, and degenerative diseases. In this article, we will discuss how viruses can reach the brain, the impact of viral encephalitis on brain function, and we will focus especially on the neurocognitive sequelae reported even after viral clearance.

Isolation, Identification, and Evaluation of the Pathogenicity of a Porcine Enterovirus G Isolated From China

Enterovirus G (EV-G) infects porcine populations worldwide and the infections are generally asymptomatic, with the insertion of the papain-like cysteine protease gene (PLCP) increasing the potential public health threats. However, the genetic and pathogenic characteristics of EV-G itself are not fully understood as yet. In the present study, one EV-G strain, named CH/17GXQZ/2017, was isolated and purified from piglets with diarrheic symptoms from the Guangxi Province, China. This strain produced stable cytopathic effects on Marc-145 cells with a titer of 5 × 10⁶ PFU/mL. The spherical enterovirus particles with diameters of 25–30 nm were observed by using transmission electron microscopy. The whole genome sequence of the CH/17GXQZ/2017 strain consists of 7,364 nucleotides, and the phylogenetic tree based on the amino acid sequences of VP1 indicated this strain was clustered to the G1 genotype. Seven-day-old piglets were inoculated orally with the CH/17GXQZ/2017 strain in order to evaluate its pathogenicity. Although none of the infected piglets died during the experiment, clinical neurological symptoms were observed manifesting as mild hyperemia and Nissl bodies vacuolization in the cerebrum. In addition, the infection with the CH/17GXQZ/2017 strain decelerated the weight gain of suckling piglets significantly. This study demonstrates that CH/17GXQZ/2017 is pathogenic to neonatal piglets and advance knowledge on the biological characteristics, evolution and pathogenicity of EV-G.

Long COVID or Post-acute Sequelae of COVID-19 (PASC): An Overview of Biological Factors That May Contribute to Persistent Symptoms

The novel virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a pandemic of coronavirus disease 2019 (COVID-19). Across the globe, a subset of patients who sustain an acute SARS-CoV-2 infection are developing a wide range of persistent symptoms that do not resolve over the course of many months. These patients are being given the diagnosis Long COVID or Post-acute sequelae of COVID-19 (PASC). It is likely that individual patients with a PASC diagnosis have different underlying biological factors driving their symptoms, none of which are mutually exclusive. This paper details mechanisms by which RNA viruses beyond just SARS-CoV-2 have be connected to long-term health consequences. It also reviews literature on acute COVID-19 and other virus-initiated chronic syndromes such as post-Ebola syndrome or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) to discuss different scenarios for PASC symptom development. Potential contributors to PASC symptoms include consequences from acute SARS-CoV-2 injury to one or multiple organs, persistent reservoirs of SARS-CoV-2 in certain tissues, re-activation of neurotrophic pathogens such as herpesviruses under conditions of COVID-19 immune dysregulation, SARS-CoV-2 interactions with host microbiome/virome communities, clotting/coagulation issues, dysfunctional brainstem/vagus nerve signaling, ongoing activity of primed immune cells, and autoimmunity due to molecular mimicry between pathogen and host proteins. The individualized nature of PASC symptoms suggests that different therapeutic approaches may be required to best manage care for specific patients with the diagnosis.

Development of Group B Coxsackievirus as an Oncolytic Virus: Opportunities and Challenges

Oncolytic viruses have emerged as a promising strategy for cancer therapy due to their dual ability to selectively infect and lyse tumor cells and to induce systemic anti-tumor immunity. Among various candidate viruses, coxsackievirus group B (CVBs) have attracted increasing attention in recent years. CVBs are a group of small, non-enveloped, single-stranded, positive-sense RNA viruses, belonging to species human Enterovirus B in the genus Enterovirus of the family Picornaviridae. Preclinical studies have demonstrated potent anti-tumor activities for CVBs, particularly type 3, against multiple cancer types, including lung, breast, and colorectal cancer. Various approaches have been proposed or applied to enhance the safety and specificity of CVBs towards tumor cells and to further increase their anti-tumor efficacy. This review summarizes current knowledge and strategies for developing CVBs as oncolytic viruses for cancer virotherapy. The challenges arising from these studies and future prospects are also discussed in this review.

Potential Virus Involvement in Alzheimer's Disease: Results from a Phase IIa Trial Evaluating Apovir, an Antiviral Drug Combination

Background:

Accumulating data suggest infectious agents are involved in Alzheimer’s disease (AD). The two primary aims of this trial were to assess safety and efficacy of an antiviral drug combination on AD progression.

Objective:

The trial evaluated whether Apovir, a combination of two antiviral agents, pleconaril (active on enteroviruses) and ribavirin (active on several viruses), could slow AD progression.

Methods:

Sixty-nine patients 60–85 years were treated with Apovir or placebo for 9 months and followed until 12 months after end of treatment. Cognitive tests, safety, biomarkers, drug plasma, and cerebrospinal fluid concentrations were assessed.

Results:

The tolerability of Apovir was compromised as demonstrated by the large drop-out rate and increased frequency and severity of adverse events. The primary endpoint, demonstrating a difference in change from baseline to 9 months between groups in ADAS-cog total score, was not met (p = 0.1809). However, there were observations indicating potential effects on both ADAS-cog and CDR-SB but these effects need to be verified. Also, there was a decrease in cerebrospinal fluid amyloid-β in Apovir at 9 months (p = 0.0330) but no change in placebo.

Conclusion:

This was the first randomized, placebo controlled clinical trial exploring antiviral treatment on AD progression. The trial is considered inconclusive due to the large drop-out rate. New trials are needed to verify if the indications of effect observed can be confirmed and which component(s) in Apovir contributed to such effects. Pleconaril alone may be studied to improve the tolerability and to verify if enterovirus is involved in the disease process.

Back to the future: lessons from past viral infections and the link with Parkinson's disease

During the current coronavirus disease 2019 (COVID-19) pandemic, there has been noticeable increase in the reporting of neurological symptoms in patients. There is still uncertainty around the significance and long-term consequence of these symptoms. There are also many outstanding questions on whether the causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) can directly infect the central nervous system (CNS). Given the long association between viral infections with neurodegenerative conditions such as Parkinson's disease (PD), it seems timely to review this literature again in the context of the COVID-19 pandemic and to glean some useful information from studies on similar viruses. In this commentary, we will consider the current knowledge on viral infections in the brain. In addition, we review the link between viral infection and neurodegeneration in PD, and review the recent literature on SARS infections, the potential link with PD and the potential areas of study in the future.

Pathogenesis Study of Enterovirus 71 Using a Novel Human SCARB2 Knock-In Mouse Model

Enterovirus 71 (EV71) can cause a severe hand-foot-mouth disease in children. However, the precise mechanism of EV71-associated disease, particularly the neuropathogenesis and pulmonary disorder, is still not fully understood because no suitable animal models are available. The human scavenger receptor class B, member 2 (hSCARB2), is a cellular receptor for EV71. Here, we generated a novel knock-in (KI) mouse model using the CRISPR/Cas9 system to insert the hSCARB2 gene into the mouse Rosa26 locus to study the pathogenesis of EV71. The hSCARB2 KI mice infected with clinical isolates of EV71 showed neurological symptoms, such as ataxia, paralysis, and death. Viral replication was detected in mainly astrocytes and a limited number of neurons and microglia, accompanied by gliosis. Vascular leakage and alveoli filled with erythrocytes were detected, suggesting that edema and hemorrhage, which are observed in human patients, also occurred in EV71-infected KI mice. In addition, proinflammatory cytokines and chemokines were significantly increased in the serum of infected KI mice. These pathological features of the KI mice after infection resembled those of EV71 encephalomyelitis in humans. Therefore, our KI mouse model is suitable to study the pathogenesis of EV71 and is of great significance for development of antiviral drugs and vaccines to treat or prevent EV71 infection.IMPORTANCE Enterovirus 71 (EV71) is associated with severe hand-foot-mouth disease. Recently, outbreaks of EV71 infection with high mortality have been reported in the Asia-Pacific region, posing a great challenge for global public health. To date, the precise mechanism of EV71-induced disease, particularly the neuropathogenesis and respiratory disorders, is still not fully understood because no suitable animal models are available. Human scavenger receptor class B, member 2 (hSCARB2), has been identified as a cellular receptor for EV71. Here, we introduce a novel CRISPR/Cas9-mediated hSCARB2 knock-in (KI) mouse model for the study of EV71 pathogenesis, which is of great significance for the development of antiviral drugs and vaccines.

Innate Immune Responses in Serum and Cerebrospinal Fluid From Neonates and Infants Infected With Parechovirus-A3 or Enteroviruses

BACKGROUND

Parechovirus (PeV)-A3 and enteroviruses (EV) are the most common viruses causing sepsis and meningoencephalitis in neonates and young infants. Clinical manifestations of PeV-A3 infection are more severe than those of EV infection, and no pleocytosis with a positive polymerase chain reaction (PCR) result for PeV-A3 in cerebrospinal fluid (CSF) are characteristic findings. We hypothesized that innate immune responses to PeV-A3 and EV are distinct in serum and CSF.

METHODS

We evaluated 22 cytokines/chemokines in serum and CSF from PeV-A3- or EV-infected patients younger than 4 months in Niigata, Japan, from 2015 through 2018. Infection was diagnosed with real-time PCR followed by sequencing. Febrile neonates and infants with sepsis-like syndrome who had negative bacterial culture and viral PCR for both PeV-A and EV were also included (non-PeV-A/EV patients).

RESULTS

Among 192 febrile patients, we evaluated 16 PeV-A3-infected, 15 EV-infected, and 8 non-PeV-A/EV patients. Serum pro-/anti-inflammatory cytokine/chemokine levels were higher in PeV-A3-infected patients than in EV-infected patients (P < .02). Although most cytokine/chemokine were elevated in CSF from EV-infected patients, levels were low or undetectable in PeV-A3-infected and non-PeV-A/EV patients (P < .001).

CONCLUSIONS

Distinct cytokine/chemokine patterns in serum and CSF may explain the different clinical manifestations of PeV-A3-infected and EV-infected neonates and young infants.

Long-Term Survival, Health, Social Functioning, and Education in Patients With an Enterovirus Central Nervous System Infection, Denmark, 1997-2016

BACKGROUND

The long-term clinical course of patients with an enterovirus central nervous system infection (ECI) is poorly understood.

METHODS

We performed a nationwide population-based cohort study of all Danish patients with ECI diagnosed 1997-2016 (n = 1745) and a comparison cohort from the general population individually matched on date of birth and sex (n = 17 450). Outcomes were categorized into mortality and risk of cancer and likely measures of neurological sequelae: neuropsychiatric morbidities, educational landmarks, use of hospital services, employment, receipt of disability pension, income, number of sick leave days, and nursing home residency.

RESULTS

Mortality in the first year was higher among patients with ECI (mortality rate ratio [MRR] = 10.0; 95% confidence interval [CI], 4.17-24.1), but thereafter mortality was not higher (MMR = 0.94; 95% CI, 0.47-1.86). Long-term outcomes for patients with ECI were not inferior to those of the comparison cohort for risk of cancer, epilepsy, mental and behavioral disorders, dementia, depression, school start, school marks, high school education, use of hospital services, employment, receipt of disability pension, income, days of sick leave, or nursing home residency.

CONCLUSIONS

Diagnosis of an ECI had no substantial impact on long-term survival, health, or social/educational functioning.

A potential new recombinant echovirus 18 strain detected in a 4-year-old child with encephalitis in China in 2019

The species Enterovirus B includes diverse serotypes that can cause a wide spectrum of human diseases, such as aseptic encephalitis, myocarditis, and paralysis. In this study, a 4-year-old child was diagnosed with viral encephalitis, but the causative agent could not be identified using routine immunological tests. Using metagenomic RNA sequencing, a novel strain of enterovirus B, strain PC06, was identified, and its genome sequence was determined by RT-PCR and Sanger sequencing. The viral genome sequence was most similar to that of echovirus E18 strain E18-HeB15-54498/HeB/CHN/2015 (GenBank accession MG720261), with 87.73% nucleotide sequence identity, while the viral proteins shared 96.98% amino acid sequence identity with those of E18 strain Jena/AN1365/10 (GenBank accession no. KX139452). Phylogenetic analysis based on the VP1 and 3D genes revealed discrepant placement of PC06 in the two trees. In the 3D tree, PC06 formed a separate branch together with other recombinant E18 strains. Further recombination tests revealed that PC06 had possibly undergone recombination at a site between the structural and non-structural regions during its evolutionary history. Based on the analysis of VP1 phylogeny and using online genotyping tools, this potential recombinant is tentatively considered a strain of echovirus 18. This information might contribute to the diagnosis and prevention of related diseases.

Inhibition of Enterovirus A71 by a Novel 2-Phenyl-Benzimidazole Derivative

Enterovirus A71 (EV-A71) infection has emerged as a significant public health concern at the global level. Epidemic events of EV-A71 have been reported worldwide, and this succession of outbreaks has heightened concern that EV-A71 may become a public health threat. In recent years, widespread A71 enterovirus also occurred in European countries. EV-A71 infection causes hand-foot-mouth disease (HFMD), herpangina, and fever. However, it can sometimes induce a variety of neurological complications, including encephalitis, aseptic meningitis, pulmonary edema, and acute flaccid paralysis. We identified new benzimidazole derivatives and described theirin vitrocytotoxicity and broad-spectrum anti-enterovirus activity. Among them, derivative 2b resulted in interesting activity against EV-A71, and therefore it was selected for further investigations. Compound 2b proved to be able to protect cell monolayers from EV-A71-induced cytopathogenicity, with an EC₅₀ of 3 µM. Moreover, Vero-76 cells resulted in being significantly protected from necrosis and apoptosis when treated with 2b at 20 and 80 µM. Compound 2b reduced viral adsorption to Vero-76 cells, and when evaluated in a time-of-addition assay, the derivative had the highest effect when added during the infection period. Moreover, derivative 2b reduced viral penetration into host cells. Besides, 2b did not affect intestinal monolayers permeability, showing no toxic effects. A detailed insight into the efficacy of compound 2b against EV-A71 showed a dose-dependent reduction in the viral titer, also at low concentrations. Mechanism of action investigations suggested that our derivative can inhibit viral endocytosis by reducing viral attachment to and penetration into host cells. Pharmacokinetic and toxicity predictions validated compound 2b as a good candidate for furtherin vivoassays.

Viral meningitis: an overview

Meningitis is a serious condition that affects the central nervous system. It is an inflammation of the meninges, which is the membrane that surrounds both the brain and the spinal cord. Meningitis can be caused by bacterial, viral, or fungal infections. Many viruses, such as enteroviruses, herpesviruses, and influenza viruses, can cause this neurological disorder. However, enteroviruses have been found to be the underlying cause of most viral meningitis cases worldwide. With few exceptions, the clinical manifestations and symptoms associated with viral meningitis are similar for the different causative agents, which makes it difficult to diagnose the disease at early stages. The pathogenesis of viral meningitis is not clearly defined, and more studies are needed to improve the health care of patients in terms of early diagnosis and management. This review article discusses the most common causative agents, epidemiology, clinical features, diagnosis, and pathogenesis of viral meningitis.

Inhibition of viral RNA-dependent RNA polymerases with clinically relevant nucleotide analogs

The treatment of viral infections remains challenging, in particular in the face of emerging pathogens. Broad-spectrum antiviral drugs could potentially be used as a first line of defense. The RNA-dependent RNA polymerase (RdRp) of RNA viruses serves as a logical target for drug discovery and development efforts. Herein we discuss compounds that target RdRp of poliovirus, hepatitis C virus, influenza viruses, respiratory syncytial virus, and the growing data on coronaviruses. We focus on nucleotide analogs and mechanisms of action and resistance.

Echovirus-30 Infection Alters Host Proteins in Lipid Rafts at the Cerebrospinal Fluid Barrier In Vitro

Echovirus-30 (E-30) is a non-polio enterovirus responsible for meningitis outbreaks in children worldwide. To gain access to the central nervous system (CNS), E-30 first has to cross the blood-brain barrier (BBB) or the blood-cerebrospinal fluid barrier (BCSFB). E-30 may use lipid rafts of the host cells to interact with and to invade the BCSFB. To study enteroviral infection of the BCSFB, an established in vitro model based on human immortalized brain choroid plexus papilloma (HIBCPP) cells has been used. Here, we investigated the impact of E-30 infection on the protein content of the lipid rafts at the BCSFB in vitro. Mass spectrometry analysis following E-30 infection versus uninfected conditions revealed differential abundancy in proteins implicated in cellular adhesion, cytoskeleton remodeling, and endocytosis/vesicle budding. Further, we evaluated the blocking of endocytosis via clathrin/dynamin blocking and its consequences for E-30 induced barrier disruption. Interestingly, blocking of endocytosis had no impact on the capacity of E-30 to induce loss of barrier properties in HIBCPP cells. Altogether, these data highlight the impact of E-30 on HIBCPP cells microdomain as an important factor for host cell alteration.

Type B coxsackieviruses and central nervous system disorders: critical review of reported associations

Type B coxsackieviruses (CV-B) frequently infect the central nervous system (CNS) causing neurological diseases notably meningitis and encephalitis. These infections occur principally among newborns and children. Epidemiological studies of patients with nervous system disorders demonstrate the presence of infectious virus, its components, or anti-CV-B antibodies. Some experimental studies conducted in vitro and in vivo support the potential association between CV-B and idiopathic neurodegenerative diseases such as amyotrophic lateral sclerosis and psychiatric illness such as schizophrenia. However, mechanisms explaining how CV-B infections may contribute to the genesis of CNS disorders remain unclear. The proposed mechanisms focus on the immune response following the viral infection as a contributor to pathogenesis. This review describes these epidemiological and experimental studies, the modes of transmission of CV-B with an emphasis on congenital transmission, the routes used by CV-B to reach the brain parenchyma, and plausible mechanisms by which CV-B may induce CNS diseases, with a focus on potential immunopathogenesis.

Integrated approaches to reveal mechanisms by which RNA viruses reprogram the cellular environment

RNA viruses are major threats to global society and mass outbreaks can cause long-lasting damage to international economies. RNA and related retro viruses represent a large and diverse family that contribute to the onset of human diseases such as AIDS; certain cancers like T cell lymphoma; severe acute respiratory illnesses as seen with COVID-19; and others. The hallmark of this viral family is the storage of genetic material in the form of RNA, and upon infecting host cells, their RNA genomes reprogram the cellular environment to favor productive viral replication. RNA is a multifunctional biomolecule that not only stores and transmits heritable information, but it also has the capacity to catalyze complex biochemical reactions. It is therefore no surprise that RNA viruses use this functional diversity to their advantage to sustain chronic or lifelong infections. Efforts to subvert RNA viruses therefore requires a deep understanding of the mechanisms by which these pathogens usurp cellular machinery. Here, we briefly summarize several experimental techniques that individually inform on key physicochemical features of viral RNA genomes and their interactions with proteins. Each of these techniques provide important vantage points to understand the complexities of virus-host interactions, but we attempt to make the case that by integrating these and similar methods, more vivid descriptions of how viruses reprogram the cellular environment emerges. These vivid descriptions should expedite the identification of novel therapeutic targets.

Viral Infections of the Central Nervous System in Children: A Systematic Review

Viral infections of the central nervous system such as meningitis, encephalitis or meningoencephalitis, are important causes of significant morbidities and mortality worldwide. Early diagnosis and prompt treatment will lead to better outcomes, but any delay may results in high fatality with serious neurologic sequelae among survivors. We conducted a systematic review of published literature on the clinical presentation, diagnosis, treatment and complications of viral infections of the central nervous system from 1980 to 2019 on four databases comprising of PubMed, PubMed Central, Google Scholar and Medline to give the current understanding for better patient management. This systematic review demonstrates the management approach of viral infections of the central nervous system in children from the point of clinical presentation, diagnosis, treatment and complications. Definitive treatment remained unknown; however, certain antiviral drugs were proved to be effective. Therefore, prevention through childhood vaccination is the best management option.

Effective Antiviral Medicinal Plants and Biological Compounds Against Central Nervous System Infections: A Mechanistic Review

BACKGROUND AND OBJECTIVE

Infectious diseases are amongst the leading causes of death in the world and central nervous system infections produced by viruses may either be fatal or generate a wide range of symptoms that affect global human health. Most antiviral plants contain active phytoconstituents such as alkaloids, flavonoids, and polyphenols, some of which play an important antiviral role. Herein, we present a background to viral central nervous system (CNS) infections, followed by a review of medicinal plants and bioactive compounds that are effective against viral pathogens in CNS infections.

METHODS

A comprehensive literature search was conducted on scientific databases including: PubMed, Scopus, Google Scholar, and Web of Science. The relevant keywords used as search terms were: "myelitis", "encephalitis", "meningitis", "meningoencephalitis", "encephalomyelitis", "central nervous system", "brain", "spinal cord", "infection", "virus", "medicinal plants", and "biological compounds".

RESULTS

The most significant viruses involved in central nervous system infections are: Herpes Simplex Virus (HSV), Varicella Zoster Virus (VZV), West Nile Virus (WNV), Enterovirus 71 (EV71), Japanese Encephalitis Virus (JEV), and Dengue Virus (DENV). The inhibitory activity of medicinal plants against CNS viruses is mostly active through prevention of viral binding to cell membranes, blocking viral genome replication, prevention of viral protein expression, scavenging reactive Oxygen Species (ROS), and reduction of plaque formation.

CONCLUSION

Due to the increased resistance of microorganisms (bacteria, viruses, and parasites) to antimicrobial therapies, alternative treatments, especially using plant sources and their bioactive constituents, appear to be more fruitful.

Linking Virus Discovery to Immune Responses Visualized during Zebrafish Infections

The discovery of new viruses currently outpaces our capacity for experimental examination of infection biology. To better couple virus discovery with immunology, we genetically modified zebrafish to visually report on virus infections. After generating a strain that expresses green fluorescent protein (GFP) under an interferon-stimulated gene promoter, we repeatedly observed transgenic larvae spontaneously expressing GFP days after hatching. RNA sequencing comparisons of co-housed GFP-positive and GFP-negative zebrafish revealed a naturally occurring picornavirus that induced a canonical interferon-mediated response and hundreds of antiviral defense genes not observed following immunostimulatory treatments or experimental infections with other viruses. Among the many genes induced by picornavirus infection was a large set encoding guanosine triphosphatase (GTPase) of immunity-associated proteins (GIMAPs). The GIMAP gene family is massively expanded in fish genomes and may also play a crucial role in antiviral responses in mammals, including humans. We subsequently detected zebrafish picornavirus in publicly available sequencing data from seemingly asymptomatic zebrafish in many research institutes and found that it altered gene expression in a previous study of zebrafish development. Experiments revealed a horizontal mode of virus transmission, highlighting a system for studying the spread of picornavirus infections within and between individuals. Our study describes a naturally occurring picornavirus that elicits strong antiviral responses in zebrafish and provides new strategies for simultaneously discovering viruses and their impact on vertebrate hosts.

Protective and causative killer Ig-like receptor (KIR) and metalloproteinase genetic patterns associated with Herpes simplex virus 1 (HSV-1) encephalitis occurrence

BACKGROUND

The cerebral innate immune system has a critical role in control processes of viral replication in the brain after primary infactivo and immunologic disregulation and inflammation has been reported as a primary determinant of pathogenesis and prognosis of subsequent HSV-1 related encephalitis (HSE). Interaction linking LTR3-activated DCs is also represented by the killer Ig-like receptor (KIR) + pathways on NK cells. Only a few studies analyzed the role of of MMP-9 activity regulating genetic polymorphism on clinical outcome of viral infections. Susceptibility to symptomatic encephalitis depends on SNC viral invasion and BBB disruption. We hypothesize that certain KIR genes and MMP allele may help to characterize a risk profile of developing an acute encephalitis due to HSV 1.

AIM OF THE STUDY

Analyze the frequency of KIR genes and the C(-1562)T MMP-9 allels in subjects with HSV-1 encephalitis and to analyze their interaction with regard of the risk of occurrence of a symptomatic encephalitis.

MATERIALS AND METHODS

Between November 2014 and January 2019, all consecutive patients with symptomatic acute encephalitis were recruited from three wards (Internal Medicine, Neurology, and Infectious Diseases) of "P. Giaccone" University Hospital, Palermo.

RESULTS

Patients with acute viral encephalitis in comparison to controls showed a higher frequency AA KIR haplotype, HLA-C2 and of HLA-A-Bw4 alleles. With regard of HLA allele frequency patients with acute viral encephalitis In comparison to controls also showed a higher frequency of HLA-C2 and of HLA-A-Bw4 alleles. With regard of MMP-9 alleles, subjects with acute viral encephalitis were more likely to have the TT genotype. The multiple logistic regression analysis considering variables predictive of the occurrence of acute viral encephalitis showed the detrimental effect of AA KIR, HLAC1, HLA-A-BW4 and HLA-B-BW4T and of TT aplotype of MMP-9 genotype.

CONCLUSIONS

Our study shows that in immunocompetent adult subjects there is an association between some KIR genes, MMP-9 alleles and HLA-ligand alleles and susceptibility to develop a symptomatic acute viral encephalitis. Definition of the genetic and immunological background of acute viral encephalitis can play a key role to determine personalized medicine.