Search Results (570)

The coronavirus disease 19 pandemic disrupted pediatric respiratory infections through non-pharmaceutical interventions and altered contact patterns. Long-term comparisons across the pandemic timeline in children remain limited. In this study, we analyzed 15,657 respiratory specimens from patients ≤ 18 years at Dankook University Hospital (2007–2023) using multiplex polymerase chain reaction assays targeting 15 viruses. Age-stratified positivity rates were compared across pandemic phases. Children ≤ 6 years comprised 88.61% of the study population. Human rhinovirus showed the highest detection rate (24.06%), followed by adenovirus (12.33%), respiratory syncytial virus-subtypes A and B (RSV-A: 11.13%; RSV-B: 8.65%), human parainfluenza virus-type 3 (HPIV-3; 6.21%), human metapneumovirus (HMPV; 5.33%), and enterovirus (2018–2023; EV; 10.96%). Monthly distributions differed (p < 0.001). RSV peaked in late autumn and winter; influenza and seasonal coronaviruses in winter and spring; HMPV, HPIV-3, EV, and human bocavirus in summer and fall. Positivity declined during the pandemic, rebounding in 2023, most prominently among children aged 1–6 years (84.91%). HPIV-3 and EV increased (p < 0.001). RSV-A predominated pre-pandemic, whereas RSV-B showed a non-significant relative increase post-pandemic; no subtype differences occurred during the pandemic. Findings demonstrate pathogen-specific shifts in predominance and seasonality and support ongoing surveillance and pediatric care planning. Full article

Background/Objectives: Hand, foot, and mouth disease (HFMD) is a major public health concern primarily caused by human enterovirus A71 (EV-A71), coxsackievirus A16 (CVA16), coxsackievirus A6 (CVA6), and certain coxsackievirus B serotypes. Currently available EV-A71 vaccines lack cross-protective efficacy against other serotypes, highlighting the urgent need for multivalent and broadly effective enterovirus vaccines. Methods: Immunoinformatics approaches were used to predict highly immunogenic B-cell and T-cell epitopes, which were assembled to construct a novel multivalent epitope vaccine, rCV-A3V, followed by in silico validation. Recombinant protein expression was confirmed by Western blotting and immunofluorescence assays. The immunogenicity was evaluated in Balb/c mice following intranasal immunization. Results: A preliminary safety evaluation demonstrated that the rCV-A3V vaccine was well tolerated in the mouse model, with no abnormal changes in body weight observed after immunization. In addition, the target protein was successfully expressed. Intranasal immunization induced a strong Th1-biased immune response, robust serum neutralizing and IgG antibody responses, and pronounced mucosal immunity, including elevated sIgA and IgG levels in nasal lavage fluid, sIgA in feces, and substantial sIgA responses in milk. Dominant epitope peptides were also identified. Conclusions: The intranasal live attenuated rCV-A3V vaccine successfully induced humoral, mucosal, and cellular immune responses against EV-A71, CVA16, CVA6, and CVB3, demonstrating broad immunogenicity. These findings provide experimental evidence supporting its potential as a candidate vaccine for HFMD. Full article

Prior molecular docking and dynamics studies indicated a pyrazolopyridine–sulfonamide derivative (L87/PPS2, or simply PPS2) as a potential interactant with SARS-CoV-2 protein targets. The in vitro anti-SARS-CoV-2 activity and cytotoxicity profile of PPS2 were screened alongside a series of pyrazolopyrimidine (PZP) and triazolopyrimidine (TZP) derivatives. PPS2 demonstrated only partial inhibition of SARS-CoV-2 growth in Vero E6 cells at 100 µM. Crucially, however, four out of five PZPs and eight out of fourteen TZPs exhibited potent in vitro inhibitory activity against SARS-CoV-2 at 100 µM, with none of the tested compounds displaying cytotoxicity against Vero E6 cells at this concentration. Further characterization of one compound, PZP25, revealed an inhibitory concentration (IC50) of 8.2 µM, combined with low cytotoxicity (CC50 > 800 µM), yielding a selectivity index greater than 100. Time of addition assays indicated that PZP25’s antiviral effects were most pronounced when administered post-infection. While cellular pre-treatment provided a partial reduction in virus growth, modest virucidal activity was also observed at warmer temperatures (20 °C and 37 °C). Collectively, our findings demonstrate that PZP and TZP derivatives possess potent inhibitory activity of SARS-CoV-2 replication in vitro and highlight such compounds as promising chemical scaffolds for the development of novel antiviral agents targeting coronaviruses. Full article

Background/Objectives: Hand, foot and mouth disease (HFMD) caused by enterovirus 71 (EV71) may cause severe complications and death in children. It is also a common cause of outbreaks in the Asia-Pacific Region. Incidence among children 1 to <2 years was over 3000/100,000 population in China. A systematic review and meta-analysis was performed to review evidence on vaccine efficacy (VE), immunogenicity, and safety of two doses of EV71 vaccine in children. Methods: Randomized controlled trials (RCTs) comparing EV71 vaccine with placebo or with another EV71 vaccine in children and adolescents aged ≤18 years were searched on PubMed, Medline, Embase, CENTRAL, and CNKI (Chinese) in week 5 November 2024. The reference list of each study and the websites of vaccine manufacturers were also searched. The Cochrane Risk of Bias 2 tool (RoB2) was used to assess the risk of bias. VE, immunogenicity (including seropositive rate, seroconversion rate, geometric mean titer (GMT), Geometric Mean Fold Increase (GMFI)), and rate of adverse events were analyzed. Results: A total of 4199 articles were identified, and 25 studies were finally included. VE (%) against EV71 HFMD in children aged ≤5 years at 12 months was 94.8% (95%CI 87.2–97.9) for Sinovac and 90.9% (95%CI 70.4–97.2) for Wuhan Institute of Biological Products (WIBP), while the Chinese Academy of Medical Sciences (CAMS) reported 97.4% (95%CI 92.9–99.0) at 11 months. At 1 month after the second dose, 99.19% (95%CI 98.15–99.65) of children aged ≤5 years in the vaccine group were seropositive, and 96.30% (95%CI 92.71–98.17) achieved seroconversion. GMT at 1 month after the second dose in the vaccine group was 46.78 (95%CI 26.18–83.61) times that in the placebo group. GMFI at 1 month after the second dose in the vaccine group was 28.41 (95%CI 22.18–36.39) times that of the placebo group. The rate of serious adverse events (AEs) was lower in the vaccine group than the placebo group (1.23% (95%CI 0.58–2.69) vs. 1.34% (95%CI 0.58–3.07)) at 1 month after the second dose. There was no significant difference in other adverse events between the vaccine and placebo groups. Conclusions: EV71 vaccines were effective, immunogenic and safe. Areas with a high incidence of EV71 may consider introducing EV71 vaccines. Full article

Poliovirus (PV), a historically significant enterovirus responsible for severe paralytic diseases, has seen its incidence dramatically reduced through widespread vaccination efforts, propelling global eradication initiatives. Despite the success of traditional oral poliovirus vaccines (OPVs) and inactivated poliovirus vaccines (IPVs), challenges such as vaccine-derived virus reversion and biosafety concerns during vaccine production persist. Virus-like particle (VLP) vaccines, which mimic native viral structures without containing viral genomes, offer enhanced safety profiles and robust immunogenicity, positioning them as promising candidates for next-generation poliovirus vaccines, especially in the post-certification era. This review systematically summarizes current progress in poliovirus VLP vaccine research, including the diverse expression systems employed for VLP production, strategies for peptide assembly and stabilization, and evaluations of antigenicity and immunogenicity. Additionally, it highlights structural analyses utilizing cutting-edge cryo-electron microscopy. By integrating recent developments in genetic engineering, structural biology, and immunology, this article discusses the advantages and challenges associated with poliovirus VLP vaccines and explores future directions aimed at supporting the global goal of a poliovirus-free world. This comprehensive overview aims to provide a theoretical foundation and technical guidance to facilitate the development and deployment of safer and more effective poliovirus vaccines. Full article

Nirsevimab is a long-acting monoclonal antibody designed to prevent infections due to respiratory syncytial virus (RSV). Here we report on a retrospective, multicenter study encompassing a total of 19 Italian neonatal and pediatric centers evaluating the epidemiology of lower respiratory tract infection (LRTI)-related hospitalizations in infants younger than 2 years during the first RSV season following the introduction of nirsevimab prophylaxis. A total of 401 hospitalizations were reported, with 40.4% being in children with previous prophylaxis with nirsevimab. Respiratory syncytial virus was the most frequently identified pathogen (47.5%), followed by rhinovirus/enterovirus (20.2%) and human metapneumovirus (hMPV; 6.9%). In multivariable analyses adjusted for age, sex, and month of diagnosis, prior nirsevimab immunization was associated with a significantly reduced likelihood of RSV-related hospitalization (adjusted odds ratio [aOR], 0.259; 95% CI, 0.157–0.427), corresponding to an estimated effectiveness of 74.1% (95% CI, 57.3–84.3). Conversely, nirsevimab-immunized infants showed increased odds of hospitalization due to hMPV (aOR, 2.490; 95% CI, 1.019–6.085) and rhinovirus/enterovirus (aOR, 2.573; 95% CI, 1.424–4.650). Lower respiratory tract infections associated with hMPV predominantly occurred outside the typical RSV season, being associated with moderate-to-severe clinical presentations. These findings confirm the real-world effectiveness of nirsevimab against RSV hospitalizations, also highlighting the need for the continued surveillance of non-RSV respiratory pathogens in the context of universal RSV immunoprophylaxis. Full article

This study constructed a bioinformatics prediction algorithm for human enterovirus uncoating receptors based on amino acid sequences and physicochemical properties. Based on the availability of uncoating receptor information and three-dimensional (3D) structural data, human enterovirus serotypes were classified into training, validation, and prediction datasets. Using amino acid sequences of receptor-binding sites and their physicochemical properties as model features, a prediction model was constructed using the Naive Bayes algorithm and bioinformatic network analysis method. The results showed that both the training and validation datasets achieved a prediction accuracy of 100%. Among the 56 serotypes in the prediction dataset, the vast majority utilized seven known types of uncoating receptors (e.g., SCARB2, CAR, and ICAM-1), while a minority of serotypes may share the same novel, unknown receptor. This study indicates that uncoating receptors can be accurately predicted based on the amino acid sequences and physicochemical properties of human enteroviruses. Furthermore, the three-dimensional structural features at receptor-binding sites can be reflected through corresponding amino acid sequences and their physicochemical properties. This study facilitates a more in-depth investigations of enterovirus pathogenic mechanisms and provides important insights for the development of vaccines and antiviral drugs. Full article

Background/Objectives: Coxsackievirus B4 (CVB4), a member of the Enterovirus genus and the Picornaviridae family, is a significant pathogen causing several human diseases such as pancreatitis, myocarditis, cardiomyopathy and type 1 diabetes. Despite its clinical impact, no vaccines or specific antiviral therapies are currently available. This study investigates the attenuation of CVB4 virulence through targeted mutations in the domain V of the IRES (Internal Ribosome Entry Segment) sequence present in the 5′ UTR (Untranslated Region) of the viral genome. Materials and Methods: We engineered six CVB4E2 mutants by introducing single nucleotide mutations in domain V of the IRES sequence using PCR-based site-directed mutagenesis assays. Mutants were rigorously evaluated in vitro for their replicative capacities on HeLa cell culture and for their in vitro translation efficiencies in standard rabbit reticulocyte lysates supplemented with HeLa cell S10 extracts. Using different strategies of immunization and lethal challenges in a Balb/c mice model, we evaluated the immune responses elicited by the most attenuated C488A mutant strain. Results: The obtained results demonstrated that the live-attenuated C488A mutant with the single mutation C to A at nucleotide position 488 of the viral IRES sequence exhibited a significant reduction in vitro of both viral productivity and translation efficiency. The oral immunization with the live-attenuated C488A mutant induced a potent immune response and protected Balb/c mice against lethal infection challenge with a pathogenic strain. Conclusions: These findings underscored the critical role of IRES in CVB4 virulence and highlighted the use of the live-attenuated C488A mutant strain as a promising candidate for developing a live-attenuated vaccine against CVB4 infections. Full article

Enteroviruses (EVs) are major pathogens transmitted via direct and indirect contact, with children being particularly susceptible. As EVs persist on surfaces, environmental hygiene is critical in communal environments. We investigated EVs presence on environmental surfaces in daycare centers from April to July 2024. Environmental samples (300) were collected from floors, toys, and desks. Viral RNA was extracted and analyzed using real-time reverse transcription polymerase chain reaction (real-time RT-PCR) and ddPCR to detect pan-Enterovirus (pan-EVs) and Enterovirus D68 (EV-D68). EVs were detected in 45.3% of the samples. The detection rate refers to the combined results, including both ddPCR and real-time PCR. Specifically, pan-EVs were found in 88 samples (1.12–505 copies/20 μL) and EV-D68 in 104 samples (1.12–309 copies/20 μL). Floors (31%) were the most contaminated surfaces. Monthly analysis showed a gradual decrease in detection rates from 88.6% in April to 18.5% in July, appearing to align with the implementation of enhanced hygiene measures. However, this trend may also reflect multifaceted factors, including natural viral reduction, exclusion of symptomatic children, and increased hygiene awareness. Notably ddPCR (83.0%) exhibited nearly twice the detection rate of real-time RT-PCR (42.5%), identifying low-level viral persistence. These findings suggest that environmental surfaces serve as reservoirs for transmission, and integrating sensitive detection like ddPCR with proactive hygiene management may help mitigate EVs spread. Full article

Coxsackievirus A16 (CVA16), a major etiological agent of hand, foot, and mouth disease, is increasingly contributing to neurological complications, with no vaccines or virus-specific antivirals currently available. To identify CVA16-restricting host factors, we investigated the role of the interferon-stimulated gene shiftless (SHFL), previously implicated in the control of other RNA viruses. Using CRISPR–Cas 9, we generated SHFL knockout rhabdomyosarcoma cells and assessed viral replication, cytopathic effects, and replication stage dynamics. We evaluated disease progression and tissue injury in neonatal mice infected with a mouse-adapted CVA16 strain. SHFL expression was strongly induced during CVA16 infection and was inducible by exogenous interferon-β treatment, and its loss markedly increased infectious virus production, accelerated early replication, and exerted severe cytopathic effects. In vivo, SHFL deficiency led to rapid weight loss, pronounced neurological signs, increased viral burden across multiple tissues, and uniform mortality, together with high viral loads and extensive pathological damage in the central nervous system, lungs, and skeletal muscle. Transcriptomic analyses revealed SHFL-dependent modulation of adhesion- and mitogen-activated protein kinase-related pathways. Overall, our results suggest SHFL as a key determinant of host resistance to CVA16, acting mainly at the post-transcriptional stage to limit viral spread and tissue injury, and highlight SHFL-linked pathways as promising host-directed antiviral targets. Full article

Enteroviruses (EVs) are small, non-enveloped RNA viruses that can cause diverse clinical outcomes, particularly severe in patients with primary immunodeficiency (PID) due to their impaired ability to clear infections. This study aimed to characterize EV excretion among 138 Tunisian PID patients over a five-year period, to identify circulating EV serotypes and assess their genetic diversity. A total of 558 stool samples were collected and analyzed by virus isolation and intratypic differentiation using RT-qPCR. Molecular typing was performed through Sanger sequencing of the VP1 region and whole genome sequencing using Next-Generation Sequencing (NGS) technologies. Phylogenetic analysis was conducted using the Maximum Likelihood (ML) method. EVs were detected in 55 stool samples from 23 patients. The excretion kinetics of EVs ranged between 30 and 946 days. Thirteen serotypes were identified, including one Poliovirus (PV) and twelve Non-Polio Enteroviruses (NPEVs), predominantly belonging to species B. Two previously unreported serotypes in Tunisia were detected: Coxsackievirus A5 (CVA5) and Echovirus type 19 (E19). In addition, five patients presented enhanced susceptibility to the excretion of successive EV serotypes, and one patient exhibited a co-infection. A possible recombination event was identified in one patient involving Coxsackievirus B5 (CVB5), Coxsackievirus A9 (CVA9) and Coxsackievirus B1 (CVB1) sequences. Phylogenetic analysis showed close genetic relationships with European, American and Asian strains. These findings underscore the dynamic nature of EV circulation and the importance of ongoing molecular surveillance to detect emerging serotypes and guide public health strategies. Full article

Coxsackieviruses B are single-stranded RNA viruses belonging to the Enterovirus genus and are associated with various clinical outcomes, ranging from acute infections to chronic diseases, such as type 1 diabetes (T1D). It was previously shown that inoculation of Swiss albino mice with CVB4 by the intraperitoneal route induced both anti-CVB4 neutralizing and enhancing activities of serum. This study aimed to investigate the humoral immune response of mice inoculated with CVB4 by the mucosal route. Mice were inoculated orally or intranasally with CVB4, and the anti-CVB4 neutralizing activity of serum and saliva was assessed by a cell culture neutralization assay. Anti-enterovirus (EV) IgG and IgA antibodies were detected in serum and saliva, respectively, by ELISA. The serum-dependent enhancement of CVB4 infection in cultures of murine splenocytes was evaluated by detecting intracellular viral RNA using RT-qPCR. At day 45 post-inoculation, an anti-CVB4 neutralizing activity, the extent of which depends on the amount of inoculated infectious particles, was detected in the serum of mice exposed orally or intranasally. An increase in anti-CVB4 neutralizing activity was observed in the saliva of mice inoculated orally or intranasally during the follow-up. Oral or intranasal inoculation of CVB4 induced a systemic IgG and mucosal IgA response. In addition, serum from these mice harbored an anti-CVB4 enhancing activity in vitro. These data indicate that Swiss albino mice exposed to CVB4 via the mucosal route constitute a potentially useful model for testing strategies to promote the production of protective mucosal and systemic anti-CVB4 antibodies and for verifying whether or not enhanced antibodies are produced. Full article

During viral infection, NLR family CARD domain-containing protein 5 (NLRC5) participates in innate immunity through multiple mechanisms. These include regulating type I interferon and related immune factor expression, as well as modulating immune cell functions, such as cytotoxic T lymphocytes (CTLs) and macrophages, thereby promoting antiviral defence and maintaining immune homeostasis. Our study demonstrates that (1) Enterovirus 71 (EV71) infection upregulates NLRC5 expression through the RIG-I-IRF3-mediated IFN-β pathway, which in turn promotes MHC-I molecule expression and (2) NLRC5 suppresses EV71 replication and simultaneously restrains excessive inflammatory responses by fine-tuning IFN-β production through a negative feedback loop. This loop operates via two distinct mechanisms, namely, direct downregulation of key IFN-β pathway mediators (e.g., RIG-I and IRF3) and binding to the 5′UTR of the EV71 genome to inhibit viral replication, thereby indirectly dampening the IFN-β signal. Furthermore, we show that EV71 activates the NLRC5-dependent MHC-I response in an IFN-β-dependent manner. Collectively, these results elucidate the dual role of NLRC5 during EV71 infection, offering novel insights into viral pathogenesis and highlighting potential targets for antiviral drug development. Full article

Respiratory infections represent one of the leading causes of pediatric consultations and hospitalizations in Chile, where rapid etiological identification is essential for clinical decision-making. We evaluated the impact of implementing the BIOFIRE^® SPOTFIRE^® Respiratory (R) Panel in the pediatric Emergency Department of a public referral hospital in Santiago, using a pre–post cross-sectional design comparing two winter periods (July 2023 vs. July 2024). Clinical records, laboratory data, and operational indicators were analyzed to assess changes in diagnostic yield, turnaround time, hospitalizations, discharges, supplementary test requests, and antimicrobial use. A total of 470 patients were included (224 in 2023; 246 in 2024). The etiological detection rate increased from 58.0% to 87.8% after the implementation of Spotfire^® (p < 0.0001), with marked increases in the identification of adenovirus, RSV, rhinovirus/enterovirus, and seasonal coronaviruses. Rapid molecular testing was associated with a significant rise in emergency department discharges (23.7% vs. 57.3%; p < 0.0001) and a reduction in hospitalizations (76.3% vs. 42.7%; p < 0.0001) and readmissions (9.2% vs. 0.5%; p < 0.0001). Requests for complete blood counts, chest X-rays, and antimicrobial prescriptions at discharge also decreased significantly. These effects persisted in key subgroups, including infants and children with comorbidities. In this high-demand winter setting, the BIOFIRE^® SPOTFIRE^® R Panel improved diagnostic performance and supported more efficient and targeted clinical management. Full article