Search Results (111)

Background/Objectives: Hand, foot and mouth disease (HFMD) has recently emerged as a serious health threat, as certain serotypes can cause severe illness. Serotype distribution vary by region, and seroprevalence studies helps in developing preventive strategies. This study aimed to determine the seroprevalence of enterovirus type 71 (EV-A71), Coxsackievirus A16 (CV-A16), Coxsackievirus A10 (CV-A10), and Coxsackievirus A6 (CV-A6), the main causative agents of HFMD and to investigate risk factors for seropositivity. Methods: This multicenter, cross-sectional study was conducted across five major cities in Türkiye. Children (6 months–17 years) who presented to outpatient clinics for any reason were included between May 2024 and January 2025. Neutralizing antibodies were measured using a microneutralization assay. Statistical analyses included descriptive methods, appropriate group comparisons (Chi-square/Fisher’s Exact), and backward logistic regression to identify factors associated with HFMD seropositivity. Results: The study included 998 participants (mean age: 8.6 ± 5.2 years; 51.3% male). CV-A6 antibodies were detected in 68.5%, EV-A71 in 66.5%, CV-A10 in 60.2%, and CV-A16 in 46.0% of samples. No viral antibodies were detected in 5.3% of serum samples (All-Negative group); antibodies against at least one HFMD agent were detected in 94.7% (Any-Positive group). HFMD seropositivity increased significantly with age. Handwashing habits did not differ between the groups. The any-positive group more often had a household member aged 12–18 years, a mother with lower education, and higher kindergarten attendance. In logistic regression analysis, age, average monthly household income, and mother’s education level were the factors influencing seropositivity. Conclusions: The seroprevalence of HFMD-causing viruses in Türkiye is high from six months of age onward. Beyond promoting personal protective measures, the implementation of a vaccination program should also be considered. Full article

LL-37, a 37-amino acid human-derived antimicrobial peptide, was shown in our earlier clinical study to shorten the negative conversion time of the Omicron BA.5.1.3 variant of SARS-CoV-2. In this work, we investigated the broad mechanism of LL-37 by examining its inhibitory effect on non-enveloped virus Enterovirus 71 (EV71). LL-37 treatment dose-dependently reduced EV71 viral RNA abundance, suppressed virus-encoded protein expression, and decreased infectious titers, acting predominantly at a post-entry stage of the viral life cycle. Transcriptomic analysis revealed that the SH3 and cysteine-rich domain protein (Stac) was uniquely upregulated by LL-37 irrespective of EV71 infection. Short hairpin RNA (shRNA)-mediated Stac silencing significantly enhanced EV71 infection, while Stac overexpression markedly reduced it. Furthermore, we found that LL-37 activates the EGFR–ERK signaling pathway, leading to time-dependent upregulation of Stac expression. These findings uncover a novel host-directed mechanism by which LL-37 combats EV71 infection and suggests a potential therapeutic use of LL-37 against non-enveloped viral disease. 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

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

Background: Numerous studies have reported on the epidemiology of hand, foot and mouth disease (HFMD) reinfection and its potential influencing factors; however, findings regarding reinfection rates as well as determinants such as gender, age, residence, and pathogens remain inconsistent. Due to this heterogeneity in reported outcomes, a comprehensive systematic review and meta-analysis are warranted to consolidate existing evidence. Methods: Effect estimates were expressed as reinfection rates, odds ratio (OR)/hazard ratio (HR) and 95% confidence intervals (CI). When necessary, data were converted to ensure consistency across comparison groups. Results: A thorough search was carried out using the predetermined literature retrieval approach across the PubMed, Web of Science, and Embase databases. Finally, 9 articles met the inclusion criteria and were included in this study. The results indicated that the overall reinfection rate for HFMD was 4.1% (95% CI: 2.0–6.2%). Males compared to females (overall effect = 1.256, 95% CI: 1.176–1.341), younger compared to older children (overall effect = 2.972, 95% CI: 1.512–5.843), scattered children compared to students (overall effect: 4.017, 95% CI: 1.560–10.344), and enterovirus 71 (EV71) compared to non-EV71 enteroviruses (overall effect = 0.71, 95% CI: 0.59–0.86) were associated with the HFMD reinfection. Conclusions: The overall HFMD reinfection rate was 4.1% (95% CI: 2.0–6.2%). Male, younger age, kindergarten children, and infection with non-EV71 enteroviruses (compared to EV71), were identified as significant risk factors for recurrent HFMD. Targeted intervention strategies should be developed for these high-risk populations to effectively reduce the incidence of reinfection. Full article

Objective: To explore the problems with non-National Immunization Program vaccinations in Hubei Province and to provide the basis for follow-up vaccination and management. Methods: Vaccination data on non-NIP/NIP vaccine doses were extracted from the Hubei Provincial Immunization Planning Information Management System. Descriptive epidemiological analyses were conducted to examine dose administration, vaccine-type composition, regional distribution, and substitution patterns. The trend χ² test was used to assess temporal significance. Multistage regression analysis was performed using Joinpoint software. Results: From 2011 to 2024, a total of 91,009,259 doses (annual average: 6,500,661) with 35 types of non-NIP vaccines were administered in Hubei Province, China. The top five vaccines by doses administered were influenza vaccine, rabies vaccine, Hemophilus influenzae type b conjugate vaccine, varicella attenuated live vaccine, and enterovirus 71 inactivated vaccine. Before 2024 (2011–2023), vaccine utilization showed a long-term upward trend: per 10,000, population usage rose from 657.07 (2011) to a peak of 2393.21 (2023) (Increase: 264.22%, χ² = 138.62, p < 0.05) (AAPC = 10.92%, p < 0.05) and non-NIP’s share of total vaccines increased from 25.52% (2011) to 65.95% (2023), (Increase: 154.33%, χ² = 89.47, p < 0.05) (AAPC = 8.74%, p < 0.05). A notable reversal occurred in 2024. Non-NIP doses dropped from 13,971,544 (2023) to 10,238,861 (2024) with population usage falling from 2393.21 (2023) to 1755.03 (2024) (decrease: 26.66%) per 10,000, with the top three declines being in inactivated polio vaccine (IPV) (decrease: 49.53%), influenza vaccine (decrease: 44.21%), and oral rotavirus attenuated live vaccine (decrease: 43.50%). The total number of substitutive non-National Immunization Program (non-NIP) vaccine doses administered reached 16,618,755, with an overall substitution rate of 10.10%. This rate showed a steady upward trend from 5.57% in 2011 to 24.74% in 2023 (trend χ² = 15.11, p < 0.05), yet it increased to 28.03% in 2024. Conclusions: Non-NIP vaccines and NIP-substitute use grew steadily for over a decade, then contracted sharply in 2024. Decision-makers should investigate the sudden dip, differentiate discretionary from replacement demand, and reallocate funds to sustain equity and prevent further erosion of coverage. Full article

Background: Inactivated enterovirus 71 (EV71) vaccines play a vital role in preventing severe cases of hand, foot, and mouth disease, with their quality and stability determined by the degree of viral particle aggregation. Objective: This study aimed to use dynamic light scattering (DLS) for monitoring EV71 particle size, comprehensively evaluate the effects of environmental stresses on viral aggregation, and identify suitable stabilizing agents. Methods: The DLS technique was validated. Using this method, the effects of pH, ionic strength, freeze–thaw cycles, temperature, and mechanical stresses on viral particle size were assessed. Additionally, the ability of different buffer salts and stabilizers to inhibit stress-induced aggregation was systematically evaluated. Results: The DLS method exhibited robust performance. EV71 particles were stable at pH 7.0–7.5. Exposure to 47 °C and magnetic stirring promoted viral aggregation. Phosphate buffer and citrate buffer exhibited the highest inhibitory effects on heat-induced aggregation and stirring-induced aggregation, respectively. M199 and Tween 80 efficiently mitigated heat-induced particle aggregation and shear stress-induced particle aggregation, respectively. Conclusions: This study demonstrated the performance of DLS in viral aggregation monitoring. Additionally, this study revealed tailored stabilization strategies, providing key insights for vaccine formulation and quality control. Full article

RNA interference (RNAi) is a powerful mechanism of post-transcriptional gene regulation in which small interfering RNA (siRNA) is utilized to target and degrade specific RNA sequences. In this study, experiments were conducted to evaluate the efficacy of combination siRNA therapy against enterovirus 71 (EV71) and the potential of this therapy to delay or prevent the emergence of resistance in vitro. siRNAs targeting multiple genes of EV71 were designed, and the effects of a cocktail of siRNAs on viral replication were assessed compared to those of single-siRNA treatment. Cotransfection of multiple siRNAs targeting different protein-coding genes of the EV71 genome effectively suppressed escape mutants resistant to RNAi. Combination therapy with siRNAs targeting multiple viral genes successfully prevented viral escape mutations over five passages. By contrast, serial passaging with a single siRNA led to the rapid emergence of resistance, with mutations identified in the siRNA target sites. The combination of siRNAs specifically targeting different regions demonstrated an additive effect and was more effective than individual siRNAs at inhibiting EV71 replication. This study supports the effectiveness of combination therapy using siRNAs targeting multiple genes of EV71 to inhibit viral replication and prevent the emergence of resistant escape mutants. Overall, the findings identify RNAi targeting multiple viral genes as a potential strategy for therapeutic development against viral diseases and for preventing the emergence of escape mutants resistant to antiviral RNAi. Full article

Background: The three commercial Enterovirus 71 (EV71) inactivated vaccines which have effectively controlled the EV71 pandemic currently rely on inherent variable in vivo potency methods for batch release. To align with 3R (Replacement, Reduction, Refinement) principles and enhance quality control, this study referred to WHO guidelines and the European Pharmacopoeia to develop in vitro relative potency (IVRP) methods. Methods: Working standards tracing to phase 3 clinical vaccines were established. Manufacture-specific IVRP methods were developed and validated per ICH Q14/Q2(R2), utilizing conformational epitope-targeting neutralizing monoclonal antibodies (MAbs). One of the MAbs (CT11F9) recognition sites was clarified with Cryo-EM. Subsequently, the performance of IVRP was assessed using varied concentrations and heat-treated vaccines. The correlation between IVRP and in vivo methods was analyzed, followed by setting IVRP specifications. Results: The manufacturer-specific working standard exhibited ED50 values comparable to those of related phase 3 clinical vaccines. All IVRP methods achieved a relative bias/precision/total error ≤ 15%. The IVRP methods correlated with in vivo methods (p < 0.05, r > 0.9) can discriminate EV71 antigen concentrations (p < 0.01, r > 0.99) and indicate the stability of the vaccines. Cryo-EM was adopted to identify the epitopes recognized by CT11F9, revealing that this neutralizing antibody recognizes a conformational epitope spanning VP1-3 of the same protomer. Using 31–47 batches of commercial vaccines, IVRP specifications were proposed as 0.56–1.35, 0.58–1.40, and 0.54–1.50. Conclusions: Based on conformational epitope-targeting neutralizing MAbs, manufacturer-specific IVRP methods, which were sensitive to process variations and correlated with in vivo results, have been established. IVRP methods provide a reliable, animal-free alternative for EV71 vaccine batch release. Full article

Enterovirus 71 (EV71) is the major causative agent of hand, foot, and mouth disease (HFMD), leading to a serious health threat to young children. Probiotics are effective at treating or preventing gastrointestinal infections, especially viral infections. Probiotics against EV71 are mainly traditional lactic acid-producing bacteria, and most of them have been proven to be effective only in vitro. Here, we report that the marine bacterium Paraliobacillus zengyii X-1125 (P. zengyii) has promising anti-EV71 activity. The antiviral effect of P. zengyii against EV71 was assessed in different cell lines, and the viral RNA levels and titers were obviously reduced after treatment with P. zengyii. Furthermore, we established an EV71-infected mouse model to evaluate its antiviral efficacy in vivo. The oral administration of P. zengyii significantly decreased the viral loads in the hindlimb muscles, spleens, and ileums. Further research revealed that P. zengyii enhances the expression of type I interferon (IFN-I) in EV71-infected cells. Similarly, transcriptome analysis indicated that the expression of interferon-stimulated genes (ISGs) in EV71-infected mice significantly increased after P. zengyii treatment. Taken together, the results of this study indicated that P. zengyii markedly reduces EV71 infection by regulating the IFN response both in vivo and in vitro, providing a potential means to work against EV71 infection. Full article

Background/Objectives: Enterovirus 71 (EV71) and coxsackieviruses A16 (CA16), A10 (CA10), and A6 (CA6) are the primary pathogens that cause hand, foot, and mouth disease (HFMD). Currently, many manufacturers are developing bivalent, trivalent, and tetravalent vaccines that target these antigens. Cell-based neutralization assay (CBNA), the gold standard for detecting neutralizing antibodies (NtAbs), which are used as indicators of HFMD vaccine efficacy, has several limitations. We aimed to develop a novel assay for detecting NtAbs against a quadrivalent HFMD vaccine. Methods: We developed a four-color pseudovirus-based neutralization assay (PBNA), utilizing fluorescent reporter genes, to rapidly evaluate neutralizing antibodies against EV71, CA16, CA10, and CA6 in multivalent vaccines and compared it with CBNA. Results: PBNA could rapidly and simultaneously detect NtAbs against the four serotypes and required lesser amounts of sera compared to CBNA. A good consistency in determining NtAb titers was observed for PBNA and CBNA. Conclusions: PBNA provides a robust tool for evaluating the efficacy of multivalent HFMD vaccines and conducting seroepidemiological studies. Full article

Hand, Foot, and Mouth Disease (HFMD) is a viral illness caused by enterovirus infections. While the introduction of the enterovirus 71 (EV71) vaccine has significantly reduced the number of EV71-related cases, the continued spread of Coxsackievirus A16 (CVA16) remains a major public health threat. Previous studies have shown that human SCARB2 (hSCARB2) knock-in (KI) mice, generated using embryonic stem cell (ESC) technology, are susceptible to CVA16. However, these models have failed to reproduce the clinical pathology and neurotoxicity after CVA16 infection. Therefore, there is an urgent need for a more reliable and effective animal model to study CVA16. In this study, we successfully created a hSCARB2 KI mouse model targeting the ROSA26 locus using CRISPR/Cas9 gene editing technology. The application of CRISPR/Cas9 enabled stable and widespread expression of hSCARB2 in the model. After infection, the KI mice exhibited a clinical pathology that closely mimics human infection, with prominent limb weakness and paralysis. The virus was detectable in multiple major organs of the mice, with peak viral load observed on day 7 post-infection, gradually clearing thereafter. Further analysis revealed widespread neuronal necrosis and infiltration of inflammatory cells in the brain and spinal cord of the KI mice. Additionally, significant activation of astrocytes (GFAP-positive) and microglia (IBA1-positive) was observed in the brain, suggesting that CVA16 infection may induce limb paralysis by attacking neuronal cells. Overall, this model effectively replicates the neuropathological changes induced by CVA16 infection and provides a potential experimental platform for studying CVA16-associated pathogenesis and neurotoxicity. Full article

Hand-foot-and-mouth disease (HFMD) caused by Enterovirus 71 (EV71) is highly infectious and can lead to serious neurological complications. This study proposed to evaluate the seroprevalence of EV71 in children of two states of western India by estimating neutralizing antibodies (nAbs) to EV71 genotypes D, G, and C isolated in India, using micro-neutralization assay. Among the serum samples of 612 children tested, 213 (34.80%, 95% CI: 31.00–38.73) and 312 (51.00%, 95% CI: 47.00–55.00) were positive for nAbs to EV71 BrCr and indigenous genotype D, respectively, with a significant rise with age for genotype D. However, compared to other age groups, only 23.2% of children aged 1–5 years showed nAbs to EV71 genotype D with a considerably lower Geometric Mean Titer, indicating the susceptibility of this age group to EV71 infection. Our study confirms the circulation of EV71 in India with relatively high susceptibility of children up to 5 years to EV71 infections. Full article

Enterovirus 71 (EV71) is a common pathogen responsible for hand, foot, and mouth disease (HFMD), leading to severe neurological complications and even death. However, the mechanisms underlying severe EV71-induced disease remain unclear, and no effective specific treatments are available. In this study, we successfully infected mice of different ages using a mouse-adapted EV71 strain, resulting in disease and mortality. We compared immune system responses between infected and uninfected mice of different ages to identify key pathogenic targets during EV71 infection. Our findings revealed that the level of Group 3 Innate Lymphoid Cells (ILC3s) in mice negatively correlated with the severity of disease induced by EV71 infection. We conducted anti-ILC3 cytokine injections and cytokine neutralizing antibody experiments on 14-day-old EV71-infected mice. The results showed that the cytokine IL-17 secreted by ILC3 cells had a mild protective effect, while IL-22 promoted inflammatory responses. Our research demonstrates that ILC3 cells play a dual role in EV71 infection. These findings not only clarify key immune factors in the progression of EV71-induced disease but also provide a promising approach for the early diagnosis and treatment of severe EV71 infections. Full article

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