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Background: Enterovirus is a well-known cause of infection in all age groups, with particular importance for neonates with both vertically and horizontally transmission. Neonatal clinical manifestations are highly variable and mostly is asymptomatic, but severe infections are described such as myocarditis, meningitis, encephalitis, hepatitis, coagulopathy, pneumonia and viral sepsis. Since 2022, The World Health Organization has recently reported an increasing number of severe neonatal infection associated with a new variant of Echovirus-11 (E-11). Many of the infants described with E-11 infections in a case reports series were preterm, male and twins. Despite the criticality of neonatal disease, the clinical management remains primarily supportive and therapeutic options are unfortunately few., Case Presentation: We present the case of male dichorionic diamniotic late-preterm twins, born in December 2023 at Filippo del Ponte Hospital in Varese (Northen Italy) with early Echovirus-11 infection. They had two dramatically different clinical scenarios and one of them developed a severe and fatal hemorrhage-hepatitis syndrome., Conclusions: Our experience has the purpose to emphasize public health attention to Echovirus-11 neonatal infections and their rare dramatically neonatal clinical presentations. Prematurity, host genetic predisposition and vertical transmission seem to be strong risk factors for severe infections, but it still need to be elucidated. According to previous Italian report, a surveillance protocols in all cases with unexpected clinical presentations and sequencing complete genome in order to better understand typing and molecular characterization of emerging and re-emerging pathogenic variants and new strains are strongly recommend in Italy., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Written informed consent was obtained from the patients’ parents for the publication of this case report and accompanying images. Competing interests: The authors declare that they have no competing interests., (© 2025. The Author(s).)

Fulminant myocarditis (FM) is a severe inflammatory condition of the myocardium that often results in sudden death, particularly in young individuals. In this study, we employed single-nucleus and spatial transcriptomics to perform a comprehensive analysis of coxsackievirus B3 (CVB3)-induced FM in A/J mice, spanning seven distinct time points pre- and post-treatment. Our findings reveal that mesothelial cells play a critical role in the early stage of myocarditis by acting as primary targets for CVB3 infection. This triggers the activation of macrophages, initiating a cascade of inflammation. Subsequently, pro-inflammatory Inflammatory_Mac and T cells infiltrate the myocardium, driving tissue damage. We also identified Cd8 + effector T cells as key mediators of cardiomyocyte injury. These cells release cytotoxic molecules, particularly IFN-γ, which modulates the expression of Spi1, a factor implicated in exacerbating cardiomyocyte death and amplifying disease progression. Therapeutic interventions targeting the IFN-γ/Spi1 axis demonstrated significant efficacy in FM models. Notably, intravenous immunoglobulin (IVIG) treatment reduced mortality, suppressed viral proliferation, and mitigated the hyperinflammatory state of FM. IVIG therapy also downregulated IFN-γ and Spi1 expression, underscoring its immunomodulatory and therapeutic potential. This comprehensive spatiotemporal transcriptomic analysis provides profound insights into the pathogenesis of FM and highlights actionable therapeutic targets, paving the way for more effective management strategies for this life-threatening condition., Competing Interests: Competing interests: Daowen Wang is the editorial board member of Signal Transduction and Targeted Therapy, but he has not been involved in the process of manuscript handling. Other authors declare no conflict of interest. Ethics: Animal experiments in this study were approved by the Institutional Animal Research Committee of Tongji Medical College (permit No. TJH-202311007) and the Ethics Committee of BGI (permit No. BGI-IRB A22019). All animal experiments were performed according to the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. Studies involving human participants were reviewed and approved by the Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (permit No. TJ-IRB20221265). Written informed consent was obtained from the legal representatives of the deceased individuals prior to sample collection. All procedures adhered to ethical standards and regulations for the use of human biological materials., (© 2025. The Author(s).)

In 2022-23, several European countries reported paediatric acute liver failure (ALF) with enterovirus infection. In August-November 2024, three neonatal cases of ALF with echovirus 11 (E11) were reported in Tokyo, Japan. All neonates developed irreversible multiple-organ failure and died. The E11 strain belonged to the new lineage 1, which was the same as strains isolated from neonatal ALF cases in Europe in 2022-23.

Recently, we demonstrated that the oncolytic Coxsackievirus B3 (CVB3) strain PD-H can be efficiently adapted to resistant colorectal cancer cells through dose-dependent passaging in colorectal cancer cells. However, the method is time-consuming, which limits its clinical applicability. Here, we investigated whether the manufacturing time of the adapted virus can be reduced by replacing the dose-based passaging with volume-based passaging. For this purpose, the murine colorectal carcinoma cell line MC38, resistant to PD-H-induced lysis, was initially infected with PD-H at 0.1 multiplicity of infection (MOI). For subsequent passages, 15-30 µL of a 1:10 dilution of the cell culture supernatant was transferred to fresh MC38 cells early after virus-induced cell lysis became visible. By virus passage 10, complete cell lysis of MC38 cells was achieved. Sequencing of the passage 10 virus (P-10) revealed two nucleotide substitutions in the 5' UTR and six amino acid changes in the viral polyprotein compared to the PD-H founder. P-10, however, consisted of a heterogeneous virus population. Therefore, the detected mutations were introduced into the cDNA of PD-H, from which the recombinant virus PD-MC38 was generated. PD-MC38 exhibited significantly enhanced replication and lytic activity in MC38 cells compared to PD-H, whereas its oncolytic activity in other colorectal cancer cell lines was comparable to or even lower than that of PD-H. These findings demonstrate that volume-based passaging is suitable to generate tumor cell-specific adapted PD-H. Moreover, compared to the dose-dependent passaging, volume-based passaging significantly reduced the time required to generate the adapted virus.

The development of pancreatic cancer requires both, acquisition of an oncogenic mutation in KRAS as well as an inflammatory insult. However, the physiological causes for pancreatic inflammation are less defined. We show here that oncogenic KRas-expressing pre-neoplastic lesion cells upregulate coxsackievirus (CVB) and adenovirus receptor (CAR). This facilitates infections from enteroviruses such as CVB3, which can be detected in approximately 50% of pancreatic cancer patients. Moreover, using an animal model we show that a one-time pancreatic infection with CVB3 in control mice is transient, but in the presence of oncogenic KRas drives chronic inflammation and rapid development of pancreatic cancer. We further demonstrate that a knockout of CAR in pancreatic lesion cells blocks these CVB3-induced effects. Our data demonstrate that KRas-caused lesions promote the development of pancreatic cancer by enabling certain viral infections., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Echovirus 11 (E11) has gained attention owing to its association with severe neonatal infections. From 2018 to 2023, a surge in severe neonatal cases and fatalities linked to a novel variant of genotype D5 was documented in China, France, and Italy. However, the prevention and control of E11 variants have been hampered by limited background data on the virus circulation and genetic variance. Therefore, the present study investigated the circulating dynamics of E11 and the genetic variation and molecular evolution of genotype D5 through the collection of strains from the national acute flaccid paralysis (AFP) and hand, foot, and mouth disease (HFMD) surveillance system in China during 2000-2022 and genetic sequences published in the GenBank database. The results of this study revealed a prevalent dynamic of E11 circulation, with D5 being the predominant genotype worldwide. Further phylogenetic analysis of genotype D5 indicated that it could be subdivided into three important geographic clusters (D5-CHN1: 2014-2019, D5-CHN2: 2016-2022, and D5-EUR: 2022-2023). Additionally, variant-specific (144) amino acid mutation sites and positive-selection pressure sites (132, 262) were identified in the VP1 region. Cluster-specific recombination patterns were also identified, with CVB5, E6, and CVB4 as the major recombinant viruses. These findings provide a preliminary landscape of E11 circulation worldwide and basic scientific data for further study of the pathogenicity of E11 variants.

Coxsackievirus B5 (CVB5) is a major pathogen responsible for hand-foot-mouth disease, herpangina, and even severe death. The mechanisms underlying CVB5-induced diseases are not fully elucidated, and no specific antiviral treatments are currently available. Circular RNAs (circRNAs), a closed-loop molecular structure, have been reported to be involved in virus infectious diseases. However, their roles and mechanisms in CVB5 infection remain largely unknown. In this study, we identify that CircPTPN11 is significantly upregulated following CVB5 infection in RD cells. Characteristic analysis reveals that the expression of CircPTPN11 is both time- and dose-dependent upon CVB5 infection and is specific to intestinal tissue. Moreover, CircPTPN11 inhibits CVB5 replication by activating IRF3 in the type-I interferon (IFN-I) pathway. Further underneath mechanism shows that CircPTPN11 indirectly regulates CVB5 replication by sponging miR-152-3p, and miR-152-3p influences CVB5 replication by interacting with the gene coding for signal regulatory protein alpha (SIRPA). In conclusion, this study suggests that CircPTPN11 targets SIRPA by sponging miR-152-3p, thereby inhibiting the replication and proliferation of CVB5. These findings provide a molecular target for the diagnosis and treatment of CVB5 infection., Competing Interests: Declaration of competing interest All authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Background: Enteroviruses (EV) are common and can cause severe diseases, particularly in young children. However, the information of EV infection in infants in China is limited due to the vast population size and extensive geographical area of the country. Here, we conducted a retrospective multicenter analysis of available EV data to assess the current epidemiological situation in the infant population in southern China., Methods: The study enrolled infants with suspected EV infection from 34 hospitals across 12 cities in southern China between 2019 to 2022, and the confirmation of EV was done using RT-PCR and VP1 gene sequencing., Results: Out of 1221 infants enrolled, 330 (27.03%) were confirmed as EV-infected. Of these, 260 (78.79%) were newborns aged 0-28 days. The EV belonged to three species: EV-B (80.61%), EV-A (11.82%), and human rhinovirus (7.58%). Newborns were more susceptible to EV-B than older infants ( p  < 0.001). Within EV-B, we identified 15 types, with coxsackievirus (CV) B3 (20.91%), echovirus (E) 11 (19.70%), and E18 (16.97%) being the most common. The predominant EV types changed across different years. EV infection in infants followed a seasonal pattern, with a higher incidence from May to August. Furthermore, perinatal mother-to-child EV transmission in 12 mother-newborn pairs were observed., Conclusion: Our study is the first to demonstrate the emergence and widespread circulation of EV-B species, mainly CVB3, E11, and E18, in southern China, primarily affecting young infants. This research provides valuable insights for future epidemic assessment, prediction, as well as the elimination of mother-to-child transmission.

Echovirus 11 has emerged as a major public health concern, causing sepsis in neonates in many European countries in recent years. In Africa, especially West Africa, where resources and diagnostic capacities are limited, only sporadic cases have been reported. To better understand the recent molecular epidemiology of E11 in West Africa, we characterized twenty-three echovirus 11 strains isolated through the acute flaccid paralysis and environmental surveillance systems for polio from 2013 to 2023, using high-throughput sequencing. Our data are noteworthy due to identifying for the first time a recombinant strain from an acute flaccid paralysis case and represent the first focus to date on molecular characterization of echovirus 11 in West Africa. Moreover, our data show that echovirus 11 diverged from 1970 (95% HPD range, 1961-1979) and evolved into four distinct clades, with the virus spread from West Africa to Europe, exhibiting two introductions in France around 2017, from Senegal and Guinea. Furthermore, the in silico analysis reveals four non-conservative amino acid substitutions in the VP1 sequences of the European strains associated with neonatal sepsis in newborns and a conserved amino acid motif in the VP1 protein toward enterovirus genotypes. Our data provide new insights into the epidemiology of echovirus 11 and point to the crucial need to implement specific surveillance programs targeting non-polio enteroviruses for the rapid identification of emerging or re-emerging enterovirus species, particularly in Africa.

Enteroviruses contain conserved RNA structures at the extreme 5' end of their genomes that recruit essential proteins 3CD and PCBP2 to promote genome replication. However, the high-resolution structures and mechanisms of these replication-linked RNAs (REPLRs) are limited. Here, we determined the crystal structures of the coxsackievirus B3 and rhinoviruses B14 and C15 REPLRs at 1.54, 2.2 and 2.54 Å resolution, revealing a highly conserved H-type four-way junction fold with co-axially stacked sA-sD and sB-sC helices that are stabilized by a long-range A•C•U base-triple. Such conserved features observed in the crystal structures also allowed us to predict the models of several other enteroviral REPLRs using homology modeling, which generated models almost identical to the experimentally determined structures. Moreover, our structure-guided binding studies with recombinantly purified full-length human PCBP2 showed that two previously proposed binding sites, the sB-loop and 3' spacer, reside proximally and bind a single PCBP2. Additionally, the DNA oligos complementary to the 3' spacer, the high-affinity PCBP2 binding site, abrogated its interactions with enteroviral REPLRs, suggesting the critical roles of this single-stranded region in recruiting PCBP2 for enteroviral genome replication and illuminating the promising prospects of developing therapeutics against enteroviral infections targeting this replication platform., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)

BackgroundIn 2023, a European alert was issued regarding an increase in severe enterovirus (EV) neonatal infections associated with echovirus 11 (E11) new lineage 1.AimTo analyse E11-positive cases between 2019 and 2023 to investigate whether the new lineage 1 circulated in Spain causing severe neonatal infections.MethodsEV-positive samples from hospitalised cases are sent for typing to the National Reference Enterovirus Laboratory. Available samples from 2022-23 were subjected to metagenomic next-generation sequencing.ResultsOf 1,288 samples genotyped, 103 were E11-positive (98 patients: 6 adults, 33 neonates, 89 children under 6 years; male to female ratio 1.9). E11 detection rate was similar before and after detection of the new lineage 1 in Spain in June 2022 (9.7% in 2019 vs 10.6% in 2023). The proportion of E11-infected ICU-admitted neonates in 2019-2022 (2/7) vs 2022-2023 (5/12) did not significantly differ (p = 0.65). In severe neonatal infections, 4/7 E11 strains were not linked to the new lineage 1. The three novel E11 recombinant genomes were associated with severe (n = 2) and non-severe (n = 1) cases from 2022-2023 and clustered outside the new lineage 1. Coinfecting pathogenic viruses were present in four of 10 E11-positive samples.ConclusionThe emergence of the new lineage 1 is not linked with an increase in incidence or severity of neonatal E11 infections in Spain. The detection of two novel E11 recombinants associated with severe disease warrants enhancing genomic and clinical surveillance.

Enteroviruses such as coxsackievirus B3 are identified as a common cause of viral myocarditis, but the potential mechanism of its replication and pathogenesis are largely unknown. The genomes of a variety of viruses contain N6-methyladenosine (m 6 A), which plays important roles in virus replication. Here, by using the online bioinformatics tools SRAMP and indirect immunofluorescence assay (IFA), we predict that the CVB3 genome contains m 6 A sites and found that CVB3 infection could alter the expression and cellular localization of m 6 A-related proteins. Moreover, we found that 3-deazaadenosine (3-DAA), an m 6 A modification inhibitor, significantly decreased CVB3 replication. We also observed that the m 6 A methyltransferases methyltransferase-like protein 3 (METTL3) and METTL14 play positive roles in CVB3 replication, whereas m 6 A demethylases fat mass and obesity-associated protein (FTO) or AlkB homolog 5 (ALKBH5) have opposite effects. Knockdown of the m 6 A binding proteins YTH domain family protein 1 (YTHDF1), YTHDF2 and YTHDF3 strikingly decreased CVB3 replication. Finally, the m 6 A site mutation in the CVB3 genome decreased the replication of CVB3 compared with that in the CVB3 wild-type (WT) strain. Taken together, our results demonstrated that CVB3 could exploit m 6 A modification to promote viral replication, which provides new insights into the mechanism of the interaction between CVB3 and the host.

Objectives: A new variant of echovirus 11 (E11) infection is a major health concern in neonates. Here, we describe the clinical and virological characteristics of enterovirus (EV) infections in children hospitalized with acute respiratory infection in Southern Italy., Methods: Between July 2022 and August 2023, 173 EV infections were identified. Demographic and clinical characteristics, comorbidities, and coinfections were analyzed. Genotypes were identified by sequencing of VP1. Whole-genome sequencing of five E11 strains was performed., Results: Case numbers peaked in July 2022, November-December 2022, and June-July 2023. Coxsackievirus A2 was identified in 36.7%, coxsackievirus B5 in 13.8%, echovirus E11 in 9.2%, and EV-D68 in 6.4% of cases. No child had critical symptoms or a severe infection. The only neonate infected by E11 recovered fully after 5 days in hospital. Phylogenetic analysis revealed that four E11 strains were closely related to divergent lineage I E11 strains identified in France and Italy., Conclusions: The new variant of E11 was identified in children in Southern Italy. Although the cases were mild, the data suggest that transmission routes and host factors are likely to be main drivers for the development of potentially severe diseases. Systematic epidemiological/molecular surveillance will help us better understand the clinical impact of EV infections and develop preventive strategies., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Enteroviruses cause a wide range of disorders with varying presentations and severities, and some enteroviruses have emerged as serious public health concerns. These include Coxsackievirus B3 (CVB3), an active causative agent of viral myocarditis, and Coxsackievirus B4 (CVB4), which may accelerate the progression of type 1 diabetes. The 3C proteases from CVB3 and CVB4 play important roles in the propagation of these viruses. In this study, the 3C proteases from CVB3 and CVB4 were expressed in Escherichia coli and purified by affinity chromatography and gel-filtration chromatography. The crystals of the CVB3 and CVB4 3C proteases diffracted to 2.10 and 2.01 Å resolution, respectively. The crystal structures were solved by the molecular-replacement method and contained a typical chymotrypsin-like fold and a conserved His40-Glu71-Cys147 catalytic triad. Comparison with the structures of 3C proteases from other enteroviruses revealed high similarity with minor differences, which will guide the design of 3C-targeting inhibitors with broad-spectrum properties.

Self-amplifying RNAs (saRNAs) are versatile vaccine platforms that take advantage of a viral RNA-dependent RNA polymerase (RdRp) to amplify the messenger RNA (mRNA) of an antigen of interest encoded within the backbone of the viral genome once inside the target cell. In recent years, more saRNA vaccines have been clinically tested with the hope of reducing the vaccination dose compared to the conventional mRNA approach. The use of N1-methyl-pseudouridine (1mΨ), which enhances RNA stability and reduces the innate immune response triggered by RNAs, is among the improvements included in the current mRNA vaccines. In the present study, we evaluated the effects of this modified nucleoside on various saRNA platforms based on different viruses. The results showed that different stages of the replication process were affected depending on the backbone virus. For TNCL, an insect virus of the Alphanodavirus genus, replication was impaired by poor recognition of viral RNA by RdRp. In contrast, the translation step was severely abrogated in coxsackievirus B3 (CVB3), a member of the Picornaviridae family. Finally, the effects of 1mΨ on Semliki forest virus (SFV), were not detrimental in in vitro studies, but no advantages were observed when immunogenicity was tested in vivo., (© 2024. The Author(s).)

RNA viruses have notoriously high mutation rates due to error-prone replication by their RNA polymerase. However, natural selection concentrates variability in a few key viral proteins. To test whether this stems from different mutation tolerance profiles among viral proteins, we measured the effect of >40,000 non-synonymous mutations across the full proteome of coxsackievirus B3 as well as >97% of all possible codon deletions in the nonstructural proteins. We find significant variation in mutational tolerance within and between individual viral proteins, which correlated with both general and protein-specific structural and functional attributes. Furthermore, mutational fitness effects remained stable across cell lines, suggesting selection pressures are mostly conserved across environments. In addition to providing a rich dataset for understanding virus biology and evolution, our results illustrate that incorporation of mutational tolerance data into druggable pocket discovery can aid in selecting targets with high barriers to drug resistance., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Álvarez-Rodríguez et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

After the first phase of the COVID-19 pandemic in Europe, a new highly pathogenic variant of echovirus 11 (E11) was detected. The aim of this study was to analyze the genetic diversity of Polish E11 environmental and clinical strains circulating between 2017 and 2023 as well as compare them with E11 strains isolated from severe neonatal sepsis cases reported in Europe between 2022 and 2023. Additionally, the study explores the effectiveness of environmental monitoring in tracking the spread of new variants. For this purpose, the complete sequences of the VP1 capsid protein gene were determined for 266 E11 strains isolated in Poland from 2017 to 2023, and phylogenetic analysis was performed. In the years 2017-2023, a significant increase in the detection of E11 strains was observed in both environmental and clinical samples in Poland. The Polish E11 strains represented three different genotypes, C3, D5 and E, and were characterized by a high diversity. In Poland, the intensive circulation of the new variant E11, responsible for severe neonatal infections with a high mortality in Europe, was detected in the years 2022-2023. This investigation demonstrates the important role of environmental surveillance in the tracking of enteroviruses circulation, especially in settings with limited clinical surveillance.

Objectives: Following the alert of echovirus 11 (E-11) infection in neonates in EU/EEA Member States, we conducted an investigation of E-11 circulation by gathering data from community and hospital surveillance of enterovirus (EV) in northern Italy from 01 August 2021 to 30 June 2023., Methods: Virological results of EVs were obtained from the regional sentinel surveillance database for influenza-like illness (ILI) in outpatients, and from the laboratory database of ten hospitals for inpatients with either respiratory or neurological symptoms. Molecular characterization of EVs was performed by sequence analysis of the VP1 gene., Results: In our ILI series, the rate of EV-positive specimens showed an upward trend from the end of May 2023, culminating at the end of June, coinciding with an increase in EV-positive hospital cases. The E-11 identified belonged to the D5 genogroup and the majority (83%) were closely associated with the novel E-11 variant, first identified in severe neonatal infections in France since 2022. E-11 was identified sporadically in community cases until February 2023, when it was also found in hospitalized cases with a range of clinical manifestations. All E-11 cases were children, with 14 out of 24 cases identified through hospital surveillance. Of these cases, 60% were neonates, and 71% had severe clinical manifestations., Conclusion: Baseline epidemiological data collected since 2021 through EV laboratory-based surveillance have rapidly tracked the E-11 variant since November 2022, alongside its transmission during the late spring of 2023., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Coxsackievirus B3 (CVB3) is known to cause acute myocarditis and pancreatitis in humans. We investigated the microRNAs (miRNAs) that can potentially govern the viral life cycle by binding to the untranslated regions (UTRs) of CVB3 RNA. MicroRNA-22-3p was short-listed, as its potential binding site overlapped with the region crucial for recruiting internal ribosome entry site trans -acting factors (ITAFs) and ribosomes. We demonstrate that miR-22-3p binds CVB3 5' UTR, hinders recruitment of key ITAFs on viral mRNA, disrupts the spatial structure required for ribosome recruitment, and ultimately blocks translation. Likewise, cells lacking miR-22-3p exhibited heightened CVB3 infection compared to wild type, confirming its role in controlling infection. Interestingly, miR-22-3p level was found to be increased at 4 hours post-infection, potentially due to the accumulation of viral 2A protease in the early phase of infection. 2A pro enhances the miR-22-3p level to dislodge the ITAFs from the SD-like sequence, rendering the viral RNA accessible for binding of replication factors to switch to replication. Furthermore, one of the cellular targets of miR-22-3p, protocadherin-1 (PCDH1), was significantly downregulated during CVB3 infection. Partial silencing of PCDH1 reduced viral replication, demonstrating its proviral role. Interestingly, upon CVB3 infection in mice, miR-22-3p level was found to be downregulated only in the small intestine, the primary target organ, indicating its possible role in influencing tissue tropism. It appears miR-22-3p plays a dual role during infection by binding viral RNA to aid its life cycle as a viral strategy and by targeting a proviral protein to restrict viral replication as a host response.IMPORTANCECVB3 infection is associated with the development of end-stage heart diseases. Lack of effective anti-viral treatments and vaccines for CVB3 necessitates comprehensive understanding of the molecular players during CVB3 infection. miRNAs have emerged as promising targets for anti-viral strategies. Here, we demonstrate that miR-22-3p binds to 5' UTR and inhibits viral RNA translation at the later stage of infection to promote viral RNA replication. Conversely, as host response, it targets PCDH1, a proviral factor, to discourage viral propagation. miR-22-3p also influences CVB3 tissue tropism. Deciphering the multifaced role of miR-22-3p during CVB3 infection unravels the necessary molecular insights, which can be exploited for novel intervening strategies to curb infection and restrict viral pathogenesis., Competing Interests: The authors declare no conflict of interest.

Echovirus 25 (E25), a member of the Enterovirus B (EV-B) species, can cause aseptic meningitis (AM), viral meningitis (VM), and acute flaccid paralysis (AFP). However, systematic studies on the molecular epidemiology of E25, especially those concerning its evolution and recombination, are lacking. In this study, 18 strains of E25, isolated from seven provinces of China between 2009 and 2018, were collected based on the Chinese hand, foot, and mouth disease (HFMD) surveillance network, and 95 sequences downloaded from GenBank were also screened. Based on the phylogenetic analysis of 113 full-length VP1 sequences worldwide, globally occurring E25 strains were classified into 9 genotypes (A-I), and genotype F was the dominant genotype in the Chinese mainland. The average nucleotide substitution rate of E25 was 6.08 × 10 -3 substitutions/site/year, and six important transmission routes were identified worldwide. Seventeen recombination patterns were determined, of which genotype F can be divided into 9 recombination patterns. A positive selector site was found in the capsid protein region of genotype F. Recombination analysis and pressure selection analysis for genotype F showed multiple recombination patterns and evolution characteristics, which may be responsible for it being the dominant genotype in the Chinese mainland. This study provides a theoretical basis for the subsequent prevention and control of E25., (© 2024. The Author(s).)

Evidence is emerging on the roles of long noncoding RNAs (lncRNAs) as regulatory factors in a variety of viral infection processes, but the mechanisms underlying their functions in coxsackievirus group B type3 (CVB3)-induced acute viral myocarditis have not been explicitly delineated. We previously demonstrated that CVB3 infection decreases miRNA-21 expression; however, lncRNAs that regulate the miRNA-21-dependent CVB3 disease process have yet to be identified. To evaluate lncRNAs upstream of miRNA-21, differentially expressed lncRNAs in CVB3-infected mouse hearts were identified by microarray analysis and lncRNA/miRNA-21 interactions were predicted bioinformatically. MEG3 was identified as a candidate miRNA-21-interacting lncRNA upregulated in CVB3-infected mouse hearts. MEG3 expression was verified to be upregulated in HeLa cells 48 h post CVB3 infection and to act as a competitive endogenous RNA of miRNA-21. MEG3 knockdown resulted in the upregulation of miRNA-21, which inhibited CVB3 replication by attenuating P38-MAPK signaling in vitro and in vivo. Knockdown of MEG3 expression before CVB3 infection inhibited viral replication in mouse hearts and alleviated cardiac injury, which improved survival. Furthermore, the knockdown of CREB5, which was predicted bioinformatically to function upstream of MEG3, was demonstrated to decrease MEG3 expression and CVB3 viral replication. This study identifies the function of the lncRNA MEG3/miRNA-21/P38 MAPK axis in the process of CVB3 replication, for which CREB5 could serve as an upstream modulator., Competing Interests: Declaration of Competing Interest All authors declare that they have no competing interests., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Importance: This study is the first report of echovirus 5 (E5) associated with severe acute respiratory infection and obtained the first E5 whole-genome sequence in China. Combined with the sequences available in the GenBank database, the first genotyping, phylogenetic characteristics, recombination, and genetic evolutionary analysis of E5 was performed in this study. Our findings providing valuable information on global E5 molecular epidemiology., Competing Interests: The authors declare no conflict of interest.

Viral myocarditis is an inflammatory disease of the myocardium, often leads to cardiac dysfunction and death. PARKIN (PRKN) and PINK1, well known as Parkinson's disease-associated genes, have been reported to be involved in innate immunity and mitochondrial damage control. Therefore, we investigated the role of parkin and PINK1 in coxsackievirus B3 (CVB3)-induced viral myocarditis because the etiology of myocarditis is related to abnormal immune response to viral infection and mitochondrial damage. After viral infection, the survival was significantly lower and myocardial damage was more severe in parkin knockout (KO) and PINK1 KO mice compared to wild-type (WT) mice. Parkin KO and PINK1 KO showed defective immune cell recruitment and impaired production of antiviral cytokines such as interferon-gamma, allowing increased viral replication. In addition, parkin KO and PINK1 KO mice were more susceptible to CVB3-induced mitochondrial damage than WT mice, resulting in susceptibility to viral-induced cardiac damage. Finally, using publicly available RNA-seq data, we found that pathogenic mutants of the PRKN gene are more common in patients with dilated cardiomyopathy and myocarditis than in controls or the general population. This study will help elucidate the molecular mechanism of CVB3-induced viral myocarditis., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Long noncoding RNAs (lncRNAs) modulate many aspects of biological and pathological processes. Recent studies have shown that host lncRNAs participate in the antiviral immune response, but functional lncRNAs in coxsackievirus B5 (CVB5) infection remain unknown. Here, we identified a novel cytoplasmic lncRNA, LINC1392, which was highly inducible in CVB5 infected RD cells in a time- and dose-dependent manner, and also can be induced by the viral RNA and IFN-β. Further investigation showed that LINC1392 promoted several important interferon-stimulated genes (ISGs) expression, including IFIT1, IFIT2, and IFITM3 by activating MDA5, thereby inhibiting the replication of CVB5 in vitro. Mechanistically, LINC1392 bound to ELAV like RNA binding protein 1 (ELAVL1) and blocked ELAVL1 interaction with MDA5. Functional study revealed that the 245-835 ​nt locus of LINC1392 exerted the antiviral effect and was also an important site for ELAVL1 binding. In mice, LINC1392 could inhibit CVB5 replication and alleviated the histopathological lesions of intestinal and brain tissues induced by viral infection. Our findings collectively reveal that the novel LINC1392 acts as a positive regulator in the IFN-I signaling pathway against CVB5 infection. Elucidating the underlying mechanisms on how lncRNA regulats the host innate immunity response towards CVB5 infection will lay the foundation for antiviral drug research., (Copyright © 2023 The Authors. Publishing services by Elsevier B.V. All rights reserved.)

Appendix has a distinct abundance of lymphatic cells and serves as a reservoir of microbiota which helps to replenish the large intestine with healthy flora. And it is the primary site of IgA induction, which shapes the composition of the intestinal microbiota. Recent population-based cohort studies report that appendectomy is associated with an increased risk of acute myocardial infarction and ischemic heart disease. Here, whether appendectomy has an effect on the occurrence and development of coxsackievirus B3 (CVB3)-induced viral myocarditis is studied. 10 3 TCID 50 CVB3 was inoculated i.p. into appendectomized and sham-operated mice. RNA levels of viral load and pro-inflammatory cytokines in the hearts and the intestine were detected by RT-PCR. Compared to sham-operated mice, appendectomized mice exhibited attenuated cardiac inflammation and improved cardiac function, which is associated with a systemic reduced viral load. Appendectomized mice also displayed a reduction in cardiac neutrophil and macrophage infiltration and pro-inflammatory cytokine production. Mechanistically, we found that CVB3 induced an early and potent IL-10 production in the cecal patch at 2 days post infection. Appendectomy significantly decreased intestinal IL-10 and IL-10 + CD4 + Treg frequency which led to a marked increase in intestinal (primary entry site for CVB3) anti-viral IFN-γ + CD4 + T and IFN-γ + CD8 + T response and viral restriction, eventually resulting in improved myocarditis. Our results suggest that appendix modulates cardiac infection and inflammation through regulating intestinal IL-10 + Treg response.

Background: Echovirus 30 is prone to cause hand-foot-and-mouth disease in infants and children. However, molecular epidemiologic information on the spread of E30 in southwestern China remains limited. In this study, we determined and analyzed the whole genomic sequences of E30 strains isolated from the stools of patients with hand-foot-and-mouth disease in Yunnan Province, China, in 2019., Methods: E30 isolates were obtained from fecal samples of HFMD patients. The whole genomes were sequenced by segmented PCR and analyzed for phylogeny, mutation and recombination. MEGA and DNAStar were used to align the present isolates with the reference strains. The VP1 sequence of the isolates were analyzed for selection pressure using datamonkey server., Results: The complete genome sequences of four E30 were obtained from this virus isolation. Significant homologous recombination signals in the P2-3'UTR region were found in all four isolates with other serotypes. Phylogenetic analysis showed that the four E30 isolates belonged to lineage H. Comparison of the VP1 sequences of these four isolates with other E30 reference strains using three selection pressure analysis models FUBAR, FEL, and MEME, revealed a positive selection site at 133rd position., Conclusions: This study extends the whole genome sequence of E30 in GenBank, in which mutations and recombinations have driven the evolution of E30 and further improved and enriched the genetic characteristics of E30, providing fundamental data for the prevention and control of diseases caused by E30. Furthermore, we demonstrated the value of continuous and extensive surveillance of enterovirus serotypes other than the major HFMD-causing viruses., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Enteroviruses are a common cause of seasonal childhood infections. The vast majority of enterovirus infections are mild and self-limiting, although neonates can sometimes develop severe disease. Myocarditis is a rare complication of enterovirus infection. Between June 2022 and April 2023, twenty cases of severe neonatal enteroviral myocarditis caused by coxsackie B viruses were reported in the United Kingdom. Sixteen required critical care support and two died. Enterovirus PCR on whole blood was the most sensitive diagnostic test. We describe the initial public health investigation into this cluster and aim to raise awareness among paediatricians, laboratories and public health specialists.

Enterovirus B (EVB) is a common species of enterovirus, mainly consisting of Echovirus (Echo) and Coxsackievirus B (CVB). The population is generally susceptible to EVB, especially among children. Since the 21st century, EVB has been widely prevalent worldwide, and can cause serious diseases, such as viral meningitis, myocarditis, and neonatal sepsis. By using cryo-electron microscopy, the three-dimensional (3D) structures of EVB and their uncoating receptors (FcRn and CAR) have been determined, laying the foundation for the study of viral pathogenesis and therapeutic antibodies. A limited number of epitopes bound to neutralizing antibodies have also been determined. It is unclear whether additional epitopes are present or whether epitope mutations play a key role in molecular evolutionary history and epidemics, as in influenza and SARS-CoV-2. In the current study, the conformational epitopes of six representative EVB serotypes (E6, E11, E30, CVB1, CVB3 and CVB5) were systematically predicted by bioinformatics-based epitope prediction algorithm. We found that their epitopes were distributed into three clusters, where the VP1 BC loop, C-terminus and VP2 EF loop were the main regions of EVB epitopes. Among them, the VP1 BC loop and VP2 EF loop may be the key epitope regions that determined the use of the uncoating receptors. Further molecular evolution analysis based on the VP1 and genome sequences showed that the VP1 C-terminus and VP2 EF loop, as well as a potential "breathing epitope" VP1 N-terminus, were common mutation hotspot regions, suggesting that the emergence of evolutionary clades was driven by epitope mutations. Finally, footprints showed mutations were located on or near epitopes, while mutations on the receptor binding sites were rare. This suggested that EVB promotes viral epidemics by breaking the immune barrier through epitope mutations, but the mutations avoided the receptor binding sites. The bioinformatics study of EVB epitopes may provide important information for the monitoring and early warning of EVB epidemics and developing therapeutic antibodies., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Wang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Coxsackievirus belongs to the Picornaviridae family and is one of the major pathogens that cause hand, foot and mouth disease (HFMD) in infants and children with potential serious complications and even deaths. The pathogenesis of this virus is not fully elucidated and no vaccine or antiviral drug has been approved. In this study, a full-length infectious cDNA clone of coxsackievirus B5 virus was assembled and the recombinant virus displayed similar growth kinetics and ability to cause cytopathic effects as the parental virus. Luciferase reporter was then incorporated to generate both full-length and subgenomic replicon (SGR) reporter viruses. The full-length reporter virus is suitable for high-throughput antiviral screening, while the SGR is a useful tool to study viral-host interactions. More importantly, the full-length reporter virus has also been shown to infect the suckling mouse model and the reporter gene could be detected using an in vivo imaging system, thus providing a powerful tool to track viruses in vivo. In summary, we have generated coxsackievirus B5 reporter viruses and provided unique tools for studying virus-host interactions in vitro and in vivo as well as for high-throughput screenings (HTS) to identify novel antivirals., (Copyright © 2023 The Authors. Publishing services by Elsevier B.V. All rights reserved.)

Picornaviruses infect a wide variety of cell types in vitro , with rapid replication kinetics and pronounced cytopathic effect. Coxsackievirus B3 (CVB3) can also establish a persistent infection in vivo that can lead to pathology, including dilated cardiomyopathy and myocarditis. One model system to study persistent infection is the pancreatic ductal cell line PANC-1, which CVB3 infects and is maintained indefinitely. We have characterized this model for CVB3 infection to study persistent infection for over 6 months. We find that CVB3 rapidly replicates within PANC-1 cells without robust cytopathic effect, and after 1 month in culture, titers stabilize. We find that infection does not significantly affect cellular viability. Persistent virus reverts to lytic infection when transferred to Huh7 or Vero cells. We find that persistent CVB3 adapts to PANC-1 cells via mutation of its capsid proteins and, curiously, the viral polymerase (3Dpol) to generate a high-fidelity polymerase. Persistent infection is associated with reduced cleavage of eIF4G, reduced plaque size, and decreasing particle infectivity. We further find that polyamine metabolism is altered in persistently infected cells, with the rate-limiting enzyme ornithine decarboxylase (ODC1) reduced in translation. We further find that targeting polyamine synthesis reduces persistent infection without affecting the viability of the PANC-1 cells. Finally, we find that viral fidelity is essential to maintaining CVB3 infection, and targeting viral fidelity reduces persistent virus infection. Together, these data highlight a novel role for polyamines and fidelity in persistent CVB3 infection and suggest avenues for therapeutic development to target persistent infection. IMPORTANCE Enteroviruses are significant human pathogens that can cause severe disease, including cardiomyopathies. Viruses like coxsackievirus B3 (CVB3) can cause tissue damage by lytically infecting cells; however, CVB3 can also persistently infect, which has been associated with several pathologies. Studying persistent infection in vitro is challenging, as CVB3 lytically infects most cellular model systems. Here, we show that CVB3 establishes persistent infection in pancreatic ductal cells in vitro , similar to prior studies on other coxsackieviruses. We also show that this infection results in adaptation of the virus to these cells, as well as changes to cellular metabolism of polyamines., Competing Interests: The authors declare no conflict of interest.

We report nine severe neonatal infections caused by a new variant of echovirus 11. All were male, eight were twins. At illness onset, they were 3-5 days-old and had severe sepsis and liver failure. This new variant, detected in France since April 2022, is still circulating and has caused more fatal neonatal enterovirus infections in 2022 and 2023 (8/496; 1.6%, seven associated with echovirus 11) compared with 2016 to 2021 (7/1,774; 0.4%). National and international alerts are warranted.

Echovirus 11 (E11) has recently been associated with a series of nine neonatal cases of severe hepatitis in France. Here, we present severe hepatitis caused by E11 in a pair of twins. In one of the neonates, the clinical picture evolved to fulminant hepatitis. The E11 genome showed 99% nucleotide identity with E11 strains reported in the cases in France. Rapid genome characterisation using next generation sequencing is essential to identify new and more pathogenetic variants.

Coxsackievirus B3 (CVB3) is an enterovirus that causes diseases such as pancreatitis and myocarditis in humans. Approximately 10% of the CVB3 RNA genome consists of a highly structured 5' untranslated region (5' UTR) that is organized into six domains and contains a type I internal ribosome entry site (IRES). These features are common to all enteroviruses. Each RNA domain plays a vital role in translation and replication during the viral multiplication cycle. We used SHAPE-MaP chemistry to generate secondary structures of the 5' UTR from the avirulent strain CVB3/GA and the virulent strain CVB3/28. Our comparative models show how key nucleotide substitutions cause major restructuring of domains II and III of the 5' UTR in CVB3/GA. Despite these structural shifts, the molecule maintains several well-characterized RNA elements, which allows persistence of the unique avirulent strain. The results shed light on the 5' UTR regions serving as virulence determinants and those required for fundamental viral mechanisms. We used the SHAPE-MaP data to produce theoretical tertiary models using 3dRNA v2.0. These models suggest a compact conformation of the 5' UTR from the virulent strain CVB3/28 that brings critical domains into close contact. In contrast, the model of the 5' UTR from the avirulent strain CVB3/GA suggests a more extended conformation where the same critical domains are more separated. Our results suggest that the structure and orientation of RNA domains in the 5' UTR are responsible for low-efficiency translation, low viral titers, and absence of virulence observed during infection by CVB3/GA. IMPORTANCE Human enteroviruses, which include five different species and over 100 serotypes, are responsible for diseases ranging from mild respiratory infections to serious infections of pancreas, heart, and neural tissue. All enteroviral RNA genomes have a long and highly structured 5' untranslated region (5' UTR) containing an internal ribosome entry site (IRES). Major virulence determinants are located in the 5' UTR. We present RNA structure models that directly compare the 5' UTR derived from virulent and avirulent strains of the enterovirus coxsackievirus B3 (CVB3). The secondary-structure models show rearrangement of RNA domains known to be virulence determinants and conservation of structure in RNA elements known to be vital for translation and replication in the avirulent strain CVB3/GA. The tertiary-structure models reveal reorientation of RNA domains in CVB3/GA. Identifying the details of structure in these critical RNA domains will help direct antiviral approaches to this major human pathogen., Competing Interests: The authors declare no conflict of interest.

Background: CVB5 can cause respiratory infections. However, the molecular epidemiological information about CVB5 in respiratory tract samples is still limited. Here, we report five cases in which CVB5 was detected in sputum sample of pneumonia children patients from Kunming, Southwest China., Methods: CVB5 isolates were obtained from sputum samples of patients with pneumonia. Whole-genome sequencing of CVB5 isolates was performed using segmented PCR, and phylogenetic, mutation and recombination analysis. The effect of mutations in the VP1 protein on hydration were analyzed by Protscale. The tertiary models of VP1 proteins were established by Colabfold, and the effect of mutations in VP1 protein on volume modifications and binding affinity were analyzed by Pymol software and PROVEAN., Results: A total of five CVB5 complete genome sequences were obtained. No obvious homologous recombination signals comparing with other coxsackie B viruses were observed in the five isolates. Phylogenetic analysis showed that the five CVB5 sputum isolates were from an independent branch in genogroup E. Due to the mutation, the structure and spatial of the VP1 protein N-terminus have changed significantly. Comparing to the Faulkner (CVB5 prototype strain), PROVEAN revealed three deleterious substitutions: Y75F, N166T (KM35), T140I (KM41). The last two of the three deleterious substitutions significantly increased the hydrophobicity of the residues., Conclusions: We unexpectedly found five cases of CVB5 infection instead of rhinoviruses infection during our routine surveillance of rhinoviruses in respiratory tract samples. All five patients were hospitalized with pneumonia symptoms and were not tested for enterovirus during their hospitalization. This report suggests that enterovirus surveillance in patients with respiratory symptoms should be strengthened., (© 2023. The Author(s).)

Coxsackievirus A9 (CVA9), an enterovirus, is a common cause of pediatric aseptic meningitis and neonatal sepsis. During cell entry, enterovirus capsids undergo conformational changes leading to expansion, formation of large pores, externalization of VP1 N termini, and loss of the lipid factor from VP1. Factors such as receptor binding, heat, and acidic pH can trigger capsid expansion in some enteroviruses. Here, we show that fatty acid-free bovine serum albumin or neutral endosomal ionic conditions can independently prime CVA9 for expansion and genome release. Our results showed that CVA9 treatment with albumin or endosomal ions generated a heterogeneous population of virions, which could be physically separated by asymmetric flow field flow fractionation and computationally by cryo-electron microscopy (cryo-EM) and image processing. We report cryo-EM structures of CVA9 A-particles obtained by albumin or endosomal ion treatment and a control nonexpanded virion to 3.5, 3.3, and 2.9 Å resolution, respectively. Whereas albumin promoted stable expanded virions, the endosomal ionic concentrations induced unstable CVA9 virions which easily disintegrated, losing their genome. Loss of most of the VP4 molecules and exposure of negatively charged amino acid residues in the capsid's interior after expansion created a repulsive viral RNA-capsid interface, aiding genome release. IMPORTANCE Coxsackievirus A9 (CVA9) is a common cause of meningitis and neonatal sepsis. The triggers and mode of action of RNA release into the cell unusually do not require receptor interaction. Rather, a slow process in the endosome, independent of low pH, is required. Here, we show by biophysical separation, cryogenic electron microscopy, and image reconstruction that albumin and buffers mimicking the endosomal ion composition can separately and together expand and prime CVA9 for uncoating. Furthermore, we show in these expanded particles that VP4 is present at only ~10% of the occupancy found in the virion, VP1 is externalized, and the genome is repelled by the negatively charged, repulsive inner surface of the capsid that occurs due to the expansion. Thus, we can now link observations from cell biology of infection with the physical processes that occur in the capsid to promote genome uncoating.

Emergence of 5' terminally deleted coxsackievirus-B RNA forms (CVB-TD) have been associated with the development of human diseases. These CVB-TD RNA forms have been detected in mouse pancreas during acute or persistent experimental infections. To date, the impact of the replication activities of CVB-TD RNA forms on insulin metabolism remains unexplored. Using an immunocompetent mouse model of CVB3/28 infection, acute and persistent infections of major CVB-TD populations were evidenced in the pancreas. The inoculation of mice with homogenized pancreases containing major CVB-TD populations induced acute and chronic pancreatic infections with pancreatitis. In the mouse pancreas, viral capsid protein 1 (VP1) expression colocalized with a decrease in beta cells insulin content. Moreover, in infected mouse pancreases, we showed a decrease in pro-hormone convertase 2 (PCSK2) mRNA, associated with a decrease in insulin plasmatic concentration. Finally, transfection of synthetic CVB-TD50 RNA forms into cultured rodent pancreatic beta cells demonstrated that viral replication with protein synthesis activities decreased the PCSK2 mRNA expression levels, impairing insulin secretion. In conclusion, our results show that the emergence and maintenance of major CVB-TD RNA replicative forms in pancreatic beta cells can play a direct, key role in the pathophysiological mechanisms leading to the development of type 1 diabetes., Competing Interests: The authors declare no conflicts of interest.

We report an acute Coxsackievirus B3 (CVB3)-induced meningo-cerebellitis in an immunocompetent adult patient. CVB3 has a global distribution and is the most common Enteroviruses cause of myocarditis and sudden cardiac death. To our knowledge, CVB3 is exceedingly rare as causes of meningo-encephalitis in immunocompetent adults, whereas some cases have been reported in neonates due to perinatal acquired infections or in immunocompromised patients., (© 2022. Journal of NeuroVirology, Inc.)

Coxsackievirus B5 (CVB5) is an important enterovirus B species (EV-Bs) type. We used the full-length genomic sequences of 53 viral sequences from the national hand, foot, and mouth disease surveillance network in the Chinese mainland (2001-2021). Among them, 69 entire VP1 coding region nucleotide sequences were used for CVB5 genotyping and genetic evolution analysis. Phylogenetic analysis based on a data set of 448 complete VP1 sequences showed that CVB5 could be divided into four genotypes (A-D) worldwide. Sequences from this study belonged to genotypes B and D, which dominated transmission in the Chinese mainland. Two transmission lineages of CVB5 have been discovered in the Chinese mainland, lineage 2 was predominant. Markov chain Monte Carlo analysis indicated that the tMRCA of CVB5 in the Chinese mainland could be traced to 1955, while the global trend could be traced to 1862, 93 years earlier than China. The evolution rate of CVB5 was higher in the Chinese mainland than worldwide. The spatiotemporal dynamics analysis of CVB5 assessed that virus transportation events were relatively active in Central, Northeast, North and Northwest China. Recombination analysis revealed frequent intertypic recombination in the non-structural region of CVB5 genotypes B and D with the other EV-Bs, revealing eight recombination lineages. Our study showed the molecular evolution and phylogeography of CVB5 that could provide valuable information for disease prevention.

Coxsackievirus B3 (CVB3) is a principal causative agent of viral myocarditis, meningitis and pancreatitis. There is no vaccine available for clinical use. It has been demonstrated that the primary molecular determinant of virulence phenotype is located in the 5' UTR of the viral genome. Translation initiation of CVB3 RNA is directed by the IRES element situated in the 5'UTR. In the present study, we analyse the effects of single point mutations introduced in different positions in the domain V of the IRES RNA of CVB3 wild type. We characterize in vitro virus replicative capacitiy and translation efficiency and we test in vivo virulence of different CVB3 mutants produced by the introduction of different mutations in the domain V of IRES by site-directed mutagenesis to abolish its structure. Our results demonstrate that all RNA mutants display different levels of decreased replication and translation initiation efficiency in vitro. The translation defect was correlated with significant reduced viral titer of mutant particles in comparison with the wild type. When inoculated in mice, mutant viruses were checked for inflammation and necrosis.In vitro and in vivo Findings strongly suggest that the most attenuated mutant strain could be considered a candidate for live-attenuated CVB3 vaccine., Competing Interests: The authors declare no conflict of interest.

RNA-remodeling proteins, including RNA helicases and chaperones, play vital roles in the remodeling of structured RNAs. During viral replication, viruses require RNA-remodeling proteins to facilitate proper folding and/or re-folding the viral RNA elements. Coxsackieviruses B3 (CVB3) and Coxsackieviruses B5 (CVB5), belonging to the genus Enterovirus in the family Picornaviridae, have been reported to cause various infectious diseases such as hand-foot-and-mouth disease, aseptic meningitis, and viral myocarditis. However, little is known about whether CVB3 and CVB5 encode any RNA remodeling proteins. In this study, we showed that 2C proteins of CVB3 and CVB5 contained the conserved SF3 helicase A, B, and C motifs, and functioned not only as RNA helicase that unwound RNA helix bidirectionally in an NTP-dependent manner, but also as RNA chaperone that remodeled structured RNAs and facilitated RNA strand annealing independently of NTP. In addition, we determined that the NTPase activity and RNA helicase activity of 2C proteins of CVB3 and CVB5 were dependent on the presence of divalent metallic ions. Our findings demonstrate that 2C proteins of CVBs possess RNA-remodeling activity and underline the functional importance of 2C protein in the life cycle of CVBs., Competing Interests: Conflict of interest The authors declare that there are no conflicts of interest., (Copyright © 2022 The Authors. Publishing services by Elsevier B.V. All rights reserved.)

Enteroviruses (EVs) are medically important RNA viruses that cause a broad spectrum of human illnesses for which limited therapy exists. Although EVs have been shown to usurp the cellular recycling process of autophagy for pro-viral functions, the precise manner by which this is accomplished remains to be elucidated. In the current manuscript, we sought to address the mechanism by which EVs subvert the autophagy pathway using Coxsackievirus B3 (CVB3) as a model. We showed that CVB3 infection selectively degrades the autophagy cysteine protease ATG4A but not other isoforms. Exogenous expression of an N-terminally Flag-labeled ATG4A demonstrated the emergence of a 43-kDa cleavage fragment following CVB3 infection. Furthermore, bioinformatics analysis coupled with site-directed mutagenesis and in vitro cleavage assays revealed that CVB3 protease 2A cleaves ATG4A before glycine 374. Using a combination of genetic silencing and overexpression studies, we demonstrated a novel pro-viral function for the autophagy protease ATG4A. Additionally, cleavage of ATG4A was associated with a loss of autophagy function of the truncated cleavage fragment. Collectively, our study identified ATG4A as a novel substrate of CVB3 protease, leading to disrupted host cellular function and sheds further light on viral mechanisms of autophagy dysregulation.

Coxsackievirus B3 (CVB3) can cause viral myocarditis, pancreatitis, and aseptic meningitis. This study aimed to construct an engineered CVB3 harboring three different tissue-specific miRNA targets (CVB3-miR3*T) to decrease the virulence of CVB3 in muscles, pancreas, and brain. CVB3-miR3*T and CVB3-miR-CON (containing three sequences not found in the human genome) were engineered and replicated in HELA cells. A viral plaque assay was used to determine the titers in HELA cells and TE671 cells (high miRNA-206 expression), MIN-6 cells (high miRNA-29a-3p expression), and mouse astrocytes (high miRNA-124-3p expression). We found that engineered CVB3 showed attenuated replication and reduced cytotoxicity, the variability of each type of cell was also increased in the CVB3-miR3*T group. Male BALB/c mice were infected to determine the LD50 and examine heart, pancreas, and brain titers and injury. Viral replication of the engineered viruses was restricted in infected mouse heart, pancreas, and brain, and viral plaques were about 100 fold lower compared with the control group. Mice immunized using CVB3-miR3*T, UV-inactivated CVB3-WT, and CVB3-miR-CON were infected with 100 × LD50 of CVB3-WT to determine neutralization. CVB3-miRT*3-preimmunized mice exhibited complete protection and remained alive after lethal virus infection, while only 5/15 were alive in the UV-inactivated mice, and all 15 mice were dead in the PBS-immunized group. The results demonstrate that miR-206-, miRNA-29a-3p-, and miRNA-124-3p-mediated CVB3 detargeting from the pancreas, heart, and brain might be a highly effective strategy for viral vaccine development., (Copyright © 2022. Published by Elsevier B.V.)

Host-pathogen dynamics are constantly at play during enteroviral infection. Coxsackievirus B (CVB) is a common juvenile enterovirus that infects multiple organs and drives inflammatory diseases including acute pancreatitis and myocarditis. Much like other enteroviruses, CVB is capable of manipulating host machinery to hijack and subvert autophagy for its benefit. We have previously reported that CVB triggers the release of infectious extracellular vesicles (EVs) which originate from autophagosomes. These EVs facilitate efficient dissemination of infectious virus. Here, we report that TBK1 (Tank-binding kinase 1) suppresses release of CVB-induced EVs. TBK1 is a multimeric kinase that directly activates autophagy adaptors for efficient cargo recruitment and induces type-1 interferons during viral-mediated STING recruitment. Positioning itself at the nexus of pathogen elimination, we hypothesized that loss of TBK1 could exacerbate CVB infection due to its specific role in autophagosome trafficking. Here we report that infection with CVB during genetic TBK1 knockdown significantly increases viral load and potentiates the bulk release of viral EVs. Similarly, suppressing TBK1 with small interfering RNA (siRNA) caused a marked increase in intracellular virus and EV release, while treatment in vivo with the TBK1-inhibitor Amlexanox exacerbated viral pancreatitis and EV spread. We further demonstrated that viral EV release is mediated by the autophagy modifier proteins GABARAPL1 and GABARAPL2 which facilitate autophagic flux. We observe that CVB infection stimulates autophagy and increases the release of GABARAPL1/2-positive EVs. We conclude that TBK1 plays additional antiviral roles by inducing autophagic flux during CVB infection independent of interferon signaling, and the loss of TBK1 better allows CVB-laden autophagosomes to circumvent lysosomal degradation, increasing the release of virus-laden EVs. This discovery sheds new light on the mechanisms involved in viral spread and EV propagation during acute enteroviral infection and highlights novel intracellular trafficking protein targets for antiviral therapy., Competing Interests: The authors have declared that no competing interests exist.

Virus-receptor interactions determine viral host range and tissue tropism. CD55 and human neonatal Fc receptor (FcRn) were found to be the binding and uncoating receptors for some of the echovirus-related enterovirus species B serotypes in our previous study. Echovirus 18 (E18), as a member of enterovirus species B, is a significant causative agent of aseptic meningitis and viral encephalitis in children. However, it does not use CD55 as a critical host factor. We conducted CRISPR/Cas9 knockout screening to determine the receptors and entry mechanisms and identified FcRn working as a dual-function receptor for E18. Knockout of FCGRT and B2M , which encode the two subunits of FcRn, prevented infection by E18 and other echoviruses in the same physiological cluster. We then elucidated the underlying molecular mechanism of receptor recognition by E18 using cryogenic electron microscopy. The binding of the FCGRT subunit to the canyon region rotates the residues around the pocket, triggering the release of the pocket factor as observed for other enterovirus species B members. IMPORTANCE E18 is a member of enterovirus species B. As one of the most common enterovirus serotypes in nonpolio enterovirus detection, it easily infects children and causes various clinical symptoms. Aseptic meningitis and viral encephalitis are the most commonly reported syndromes associated with E18. No effective antiviral drugs or approved vaccines are available. Previous studies showed that CD55 and FcRn were the binding and uncoating receptors for some echoviruses. However, we found that CD55 is not the critical host factor for E18. Thus, we want to determine the receptors and elucidate the entry mechanism of E18. Our findings reveal that FcRn is a two-in-one attachment-uncoating receptor for E18.

Atrial dysfunction is a relatively common complication of acute myocarditis, although its pathophysiology is unclear. There is limited information on myocarditis-associated histological changes in the atria and how they develop in time. The aim of this study therefore was to investigate inflammation, fibrosis and viral genome in the atria in time after mild CVB3-induced viral myocarditis (VM) in mice. C3H mice (n = 68) were infected with 10 5 PFU of Coxsackievirus B3 (CVB3) and were compared with uninfected mice (n = 10). Atrial tissue was obtained at days 4, 7, 10, 21, 35 or 49 post-infection. Cellular infiltration of CD45+ lymphocytes, MAC3+ macrophages, Ly6G+ neutrophils and mast cells was quantified by (immuno)histochemical staining. The CVB3 RNA was determined by in situ hybridization, and fibrosis was evaluated by elastic van Gieson (EvG) staining. In the atria of VM mice, the numbers of lymphocytes on days 4 and 7 (p < .05) and days 10 (p < .01); macrophages on days 7 (p < .01) and 10 (p < .05); neutrophils on days 4 (p < .05); and mast cells on days 4 and 7 (p < .05) increased significantly compared with control mice and decreased thereafter to basal levels. No cardiomyocyte death was observed, and the CVB3 genome was detected in only one infected mouse on Day 4 post-infection. No significant changes in the amount of atrial fibrosis were found between VM and control mice. A temporary increase in inflammation is induced in the atria in the acute phase of CVB3-induced mild VM, which may facilitate the development of atrial arrhythmia and contractile dysfunction., (© 2022 The Authors. International Journal of Experimental Pathology published by John Wiley & Sons Ltd on behalf of Company of the International Journal of Experimental Pathology (CIJEP).)

RNA viruses in the Picornaviridae family express a large 250 kDa viral polyprotein that is processed by virus-encoded proteinases into mature functional proteins with specific functions for virus replication. One of these proteins is the highly conserved enteroviral transmembrane protein 3A that assists in reorganizing cellular membranes associated with the Golgi apparatus. Here, we studied the molecular properties of the Coxsackievirus B3 (CVB3) protein 3A with regard to its dimerization and its functional stability. By applying mutational analysis and biochemical characterization, we demonstrate that protein 3A forms DTT-sensitive disulfide-linked dimers via a conserved cytosolic cysteine residue at position 38 (Cys38). Homodimerization of CVB3 protein 3A via Cys38 leads to profound stabilization of the protein, whereas a C38A mutation promotes a rapid proteasome-dependent elimination of its monomeric form. The lysosomotropic agent chloroquine (CQ) exerted only minor stabilizing effects on the 3A monomer but resulted in enrichment of the homodimer. Our experimental data demonstrate that disulfide linkages via a highly conserved Cys-residue in enteroviral protein 3A have an important role in the dimerization of this viral protein, thereby preserving its stability and functional integrity., (© 2022 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Background: Echovirus 9 (E9) is associated with a wide variety of diseases and medical conditions, and the clinical symptoms of sporadic cases caused by E9 often are severe. With a high global prevalence, E9 has caused multiple outbreaks worldwide. However, little is known about the genetic and geographic population dynamics of E9., Method: A total of 131 VP1 gene sequences, including15 generated in this study and 116 obtained from GenBank, were used to coestimate time-resolved phylogenies to infer viral evolution and transmission in worldwide. Overlapping fragments representing whole genomes were amplified by reverse transcription polymerase chain reaction (RT-PCR) using specific primers. Then, we reported the genetic characteristics of fifteen E9 strains in the Chinese Mainland. Similarity plots and bootscanning analysis were used to determine recombination patterns of E9., Results: The estimated mean evolutionary rate of global E9 VP1 gene was 4.278 × 10 -3 substitutions per site per year (95% confidence interval [CI], 3.822 × 10 -3 /site/year to 4.710 × 10 -3 /site/year), and the common ancestor of E9 likely emerged around 1868 (95% CI, 1840 to 1892). The full-length genomic sequences of the fifteen E9 strains showed 76.9-79.6% nucleotide identity and 95.3-95.9% amino acid identity with E9 Barty strain. 11 of 15 E9 whole genome sequence present four recombination patterns, and E9 recombinants have extensive genetic exchanges in the 2C and P3 regions with other Enterovirus B (EV-B) circulated in China. Four of six E9 strains were temperature sensitive, and two were temperature resistant, and a comparative genomics analysis suggested that 411, 865 and 867 amino acid substitution in the P1 region was related to temperature sensitivity., Conclusion: This study highlights a persistent transmission network of E9 in worldwide, provides valuable information regarding the molecular epidemiology of E9., (© 2022. The Author(s).)

Coxsackie virus B5 (CVB5), a main serotype in human Enterovirus B (EVB), can cause severe viral encephalitis and aseptic meningitis among infants and children. Currently, there is no approved vaccine or antiviral therapy available against CVB5 infection. Here, we determined the atomic structures of CVB5 in three forms: mature full (F) particle (2.73 Å), intermediate altered (A) particle (2.81 Å), and procapsid empty (E) particle (2.95 Å). Structural analysis of F particle of CVB5 unveiled similar structures of "canyon," "puff," and "knob" as those other EV-Bs. We observed structural rearrangements that are alike during the transition from F to A particle, indicative of similar antigenicity, cell entry, and uncoating mechanisms shared by all EV-Bs. Further comparison of structures and sequences among all structure-known EV-Bs revealed that while the residues targeted by neutralizing MAbs are diversified and drive the evolution of EV-Bs, the relative conserved residues recognized by uncoating receptors could serve as the basis for the development of antiviral vaccines and therapeutics. IMPORTANCE As one of the main serotypes in Enterovirus B, CVB5 has been commonly reported in recent years. The atomic structures of CVB5 shown here revealed classical features found in EV-Bs and the structural rearrangement occurring during particle expansion and uncoating. Also, structure- and sequence-based comparison between CVB5 and other structure-known EV-Bs screened out key domains important for viral evolution and survival. All these provide insights into the development of vaccine and therapeutics for EV-Bs.