Coxsackievirus A16 Research Articles

Enterovirus-like particles encapsidate RNA and exhibit decreased stability due to lack of maturation.

To counteract hand, foot, and mouth disease-causing viruses such as enterovirus A71 and coxsackievirus A6, virus-like particles (VLPs) have emerged as a leading contender for the development of a multivalent vaccine. However, VLPs have shown rapid conversion from a highly immunogenic state to a less immunogenic state and low particle integrity lifetimes compared to inactivated virus vaccines, thus raising concerns about their overall stability. Here, we produce VLPs to investigate capsid stability using cryogenic electron microscopy (cryo-EM), mass spectrometry (MS), biochemical assays, and atomic force microscopy (AFM). In contrast to prior studies and prevailing hypotheses, we show that insect-cell produced enterovirus VLPs include encapsidated RNA fragments with viral protein coding sequences. Our integrated approach reveals that CVA6 VLPs do not undergo viral maturation, in contrast to virions; that they can encapsidate RNA fragments, similarly to virions; and that despite the latter, they are more brittle than virions. Interestingly, this indicates that CVA6 VLP stability is more affected by lack of viral maturation than the presence of RNA. Our study highlights how the development of VLPs as vaccine candidates should encompass probing for unwanted (viral) RNA content and establishing control of their maturation to enhance stability.

The Emergence of Coxsackievirus A16 Subgenotype B1c: A Key Driver of the Hand, Foot, and Mouth Disease Epidemic in Guangdong, China

Background: In 2024, mainland China witnessed a significant upsurge in Hand, Foot, and Mouth Disease (HFMD) cases. Coxsackievirus A16 (CVA16) is one of the primary causative agents of HFMD. Long-term monitoring of theCVA16 infection rate and genotype changes is crucial for the prevention and control of HFMD. Methods: A total of 40,673 clinical specimens were collected from suspected HFMD cases in Guangdong province from 2018 to 2024, including rectal swabs (n = 27,954), throat swabs (n = 6791), stool (n = 5923), cerebrospinal fluid (n = 3), and herpes fluid (n = 2). A total of 24,410 samples were detected as EV-positive and further typed by RT-PCR. A total of 872 CVA16-positive samples were isolated and further sequenced to obtain the full-length VP1 sequence. Phylogenetic analysis was performed based on viral protein 1 gene (VP1). Results: In the first 25 weeks of 2024, reported cases of HFMD were 1.36 times higher than the mean rates of 2023. In 2024, CVA16 predominated at 75.42%, contrasting with the past etiological pattern in which the CVA6 was predominant with the detection rate ranging from 32.85 to 77.61% from 2019 to 2023. Phylogenetic analysis based on the VP1 gene revealed that the B1a and B1b subtypes co-circulated in Guangdong from 2018 to 2022. The B1c outbreak clade, detected in Guangdong in 2023, constituted 68.24% of the 148 strains of CVA16 collected in 2024, suggesting a subtype shift in the CVA16 virus. There were three specific amino acid variations (P3S, I235V, and T240A) in the VP1 sequence of B1c. Conclusions: The new emergence of the CVA16 B1c outbreak clade in Guangdong during 2023–2024 highlights the necessity for the enhanced surveillance of the virus evolution epidemiological dynamic in this region. Furthermore, it is imperative to closely monitor the etiological pattern changes in Hand, Foot, and Mouth Disease (HFMD) in other regions as well. Such vigilance will be instrumental in guiding future vaccination strategies for HFMD.

Optimization of Enterovirus-like Particle Production and Purification Using Design of Experiments

Hand, foot, and mouth disease (HFMD) represents an emerging health concern whose main causative agents are Coxsackievirus A6 (CVA6) and enterovirus A71 (EV71). The lack of a CVA6 vaccine and the rise of new HFMD-causing strains due to the containment of established HFMD-causing viruses necessitates the search for alternative vaccine technologies, including virus-like particle (VLP) vaccine candidates. While studies have demonstrated that production of enterovirus-like particles in various organisms can be achieved by expression of the viral P1 structural proteins and the 3CD protease, optimization based on the interplay between the three most commonly altered infection parameters (multiplicity of infection (MOI), viable cell density at the time of infection (VCD), and the infection period) is often not investigated. To address this challenge, we have performed Design of Experiments (DoE) to optimize the production of CVA6 and EV71 VLPs. Our results indicate that CVA6 VLP production peaks at high MOI, high VCD, and long infection periods. Our subsequent downstream purification processes yielded 38 mg and 158 mg of purified CVA6 and EV71 VLPs from 1 L crude harvest, respectively. This translates into thousands of potential vaccine doses and highlights the economic potential of enterovirus-like particles for vaccine purposes.

The Role of Disulfide Bridges in the Interaction of E. coli -Derived Recombinant SCARB2 and EV-A71's Capsid

Background: Hand, Foot, and Mouth disease is an acute infectious disease caused by a group of enteroviruses, including Coxsackievirus A16 and Enterovirus 71. EV-A71-causing disease can give rise to severe complications in children, leading to meningitis, encephalitis, and even death. A potential approach to prevent the virus spread is inhibiting the invasion of EV-A71 into target cells, thereby helping to prevent not only the spread of EV-A71 in the community but also lessen the risk of outbreaks. EV-A71 cell’s receptor, human scavenger receptor class B member 2, SCARB2, was used as a trap to gather the virus and limit its spreading. Methods: In this study, the recombinant receptor was expressed using Escherichia coli (E. coli) system. SCARB2 proteins expressed from E. coli BL21(DE3), and E. coli SHuffle® T7 Express were in inclusion bodies and subsequently refolded into soluble forms with recovery efficiencies of 57.57, and 82.2%, respectively. The presence of intramolecular disulfide bridges in the refolded SCARB2 was examined by SDS-PAGE in combination with Dithiothreitol (DTT). The two proteins were then utilized to evalu-ate the interaction with EV-A71 capsid by Indirect Enzyme-Linked Immunosorbent Assay (ELISA) at different pH levels to compare the adhesion efficiency. Results: The results showed that SCARB2 protein expressed from E. coli SHuffle® T7 Express with disulfide bond modifications had better adhesion to the viral capsid. Notably, when the medium pH was lowered to acidic levels, the binding efficiency of recombinant receptors to the viral capsid increased. Conclusion: To our knowledge, this study reported for the first time the activity of SCARB2 under extreme pH conditions and also revealed the crucial role of disulfide bridges in the interaction with EV-A71’s capsid. This finding contributed to the strategy using recombinant SCARB2 as a viral trap.

HIV-1 Vpu and SARS-CoV-2 ORF3a proteins disrupt STING-mediated activation of antiviral NF-κB signaling.

Activation of the stimulator of interferon genes (STING) pathway by cytosolic DNA leads to the activation of the transcription factors interferon regulatory factor 3 (IRF3) and nuclear factor κB (NF-κB). Although many viruses produce proteins that inhibit IRF3-dependent antiviral responses, some viruses produce proteins that inhibit STING-induced NF-κB activation without blocking IRF3 activation. Here, we found that STING-activated, NF-κB-dependent, and IRF3-independent innate immunity inhibited the replication of the DNA virus herpes simplex virus type 1 (HSV-1), the RNA virus coxsackievirus A16 (CV-A16), and the retrovirus HIV-1. The HIV-1 nonstructural protein Vpu bound to STING and prevented it from interacting with the upstream NF-κB pathway kinase inhibitor of NF-κB subunit β (IKKβ), thus blocking NF-κB signaling. This function of Vpu was conserved among Vpu proteins from diverse HIV-1 and simian immunodeficiency virus strains and was distinct from its action in disrupting other host antiviral pathways. Furthermore, the ORF3a protein from the coronavirus SARS-CoV-2 also promoted viral replication by interacting with STING and blocking STING-induced activity of NF-κB but not of IRF3. These findings demonstrate that diverse viral proteins have convergently evolved to selectively inhibit NF-κB-mediated innate immunity downstream of STING activation, suggesting that targeting this pathway may represent a promising antiviral strategy.

Construction of a Vero cell line expression human KREMEN1 for the development of CVA6 vaccines

Coxsackievirus A6 (CVA6) has emerged as a major pathogen causing hand, foot and mouth disease (HFMD) outbreaks worldwide. The CVA6 epidemic poses a new challenge in HFMD control since there is currently no vaccine available against CVA6 infections. The Vero cell line has been widely used in vaccine production, particularly in the preparation of viral vaccines, including poliovirus vaccines and EV71 vaccines. Unfortunately, most CVA6 strains failed to propagate effectively on Vero cells. The expression level of virus-specific receptors on the cell membrane significantly influences viral infection. Here, a Vero cell line with stable over-expressing of KREMEN1 (KRM1), a crucial receptor for CVA6, was constructed using the lentivirus system. The cloned cell line, called Vero-KRM1_#11, could efficiently support most CVA6 infections. The propagation of CVA6-TW00141 strain on Vero-KRM1_#11 was equal to that on RD cells. After four passages, the virus batch was obtained with a titer of about 107 TCID50/mL. Moreover, the purified CVA6 particles produced from Vero-KRM1_#11 or RD cells both could induce high and comparable levels of IgG and neutralizing antibodies. Importantly, passive transfer of the antisera from CVA6-vaccined mice showed 100% preventive efficacy against CVA6 infection in mice. Therefore, KRM1-expressing cells have the potential to serve as a valuable tool for the development and production of CVA6 or polyvalent HFMD vaccines.

Genome Analysis of Coxsackievirus A4 Identified from Herpangina Children in Northern China.

Sporadic epidemics of coxsackievirus A4 (CVA4) have been reported worldwide. However, the lack of the whole genome sequence has restricted the study of the gene characterization and evolution of CVA4. In this study, four whole genome sequences and 17 VP1 sequences of CVA4 identified from Linyi, northern China, in summer 2024 were used for genetic characterization and phylogenetic analysis. Four genotypes (A, B, C, and D) and five subgenotypes (C1-C5) were identified based on VP1 sequences. The Linyi CVA4 strains belong to subgenotype C2, which has also been the main prevalent subgenotype in China in recent years. The Linyi CVA4 strains exhibited high homology with the CVA4 prototype strain in the P1 region while exhibited higher homology with some non-CVA4 EV-A strains identified in China, including five CVA2 strains, three CVA5 strains, three CVA6 strains, one CVA8 strain, one CVA12 strain, and one CVA14 strain in the P2 and P3 regions. Recombination analysis of the whole genome sequences of the Linyi CV4 strains revealed that two Linyi CVA4 strains might be recombinants of one Shanghai CVA4 strain (KJ541163) and one Jiangsu CVA2 strain (OL519580). One Linyi CVA4 strain might be a recombinant of one Shandong CVA2 strain (MK967660) and one Shanghai CVA4 strain (KJ541163).

Targeted Enrichment Sequencing Utilizing a Respiratory Pathogen Panel for Genomic Wastewater-Based Viral Epidemiology in Uruguay.

Human respiratory and enteric viruses are responsible for substantial morbidity and mortality worldwide. Wastewater-based epidemiology utilizing next-generation sequencing serves as an effective tool for monitoring viral circulation dynamics at the community level. However, these complex environmental samples are often laden with other microorganisms and host genomic material, which can hinder the sensitivity of viral detection. To address this limitation, targeted enrichment sequencing is emerging as a preferred strategy, facilitating the acquisition of a more comprehensive understanding of specific pathogens. In this study, we evaluated the performance of a targeted enrichment sequencing panel for 42 excreted respiratory viruses (including Picornaviridae, Adenoviridae, Coronaviridae, Paramyxoviridae, Orthomyxoviridae, Orthoherpesviridae, Pneumoviridae, and Parvoviridae families), known as the Respiratory Pathogen ID/AMR enrichment panel (RPIP), coupled with Explify bioinformatics analysis in 3 sewage samples from Uruguay. RPIP panel successfully identified sequences from frequently circulating viruses, along with some that had not been documented previously. We identified and characterized various viruses, including human Enterovirus (Coxsackievirus A1 and A19), Influenza A-H1N1, and full-length sequences of SARS-CoV-2. Additionally, several other viral pathogens were detected, such as human Bocavirus, human Parechovirus, Enterovirus A71, and Enterovirus D68; however, for these viruses further analysis was limited due to the small genomic regions or low-read coverage obtained. While the RPIP panel necessitates substantial sequencing depth and may introduce bias towards the more predominant strains present in the samples, this approach suggests its viability as a genomic epidemiological tool for assessing respiratory and enteric viruses in wastewater.

Clinical, aetiological, and epidemiological studies of outpatient cases of hand, foot, and mouth disease in Chengdu, China, from 2019 to 2022: a retrospective study

BackgroundThe introduction of the Enterovirus A71 (EV-A71) vaccine in China in 2016 has led to a considerable decline in severe hand, foot, and mouth disease (HFMD) cases, with mild outpatient instances now representing the majority of HFMD cases in the country. Nevertheless, epidemiological investigations concerning mild outpatient cases remain scarce, resulting in inadequate descriptions of their clinical, etiological, and epidemiological characteristics. Our study aimed to analyze the clinical, etiological, and epidemiological characteristics of HFMD outpatients in Chengdu from 2019 to 2022 while identifying potential risk factors associated with the progression of outpatients requiring hospitalization.MethodsA retrospective study was conducted to summarize the clinical, etiological, and epidemiological characteristics of outpatient HFMD cases in Chengdu from 2019 to 2022. Risk factors associated with progression to hospitalization of HFMD outpatients were evaluated using binomial logistic regression analysis.ResultsThe study included 1,073 coxsackievirus A6 (CVA6), coxsackievirus A10 (CVA10), and coxsackievirus A16 (CVA16) HFMD nucleic acid test-positive outpatients. Among these, only 45 outpatients (4.19%) progressed to hospitalization. The median ages for CVA6, CVA10, and CVA16 infections were 25.23, 28.13, and 38.45 months, respectively (P < 0.001). CVA6 (76.51%, 821/1,073) has become the main serotype among outpatients in Chengdu, with the proportions from the second half of 2019 to 2022 being 45.59%, 95.17%, 77.67% and 80.71% respectively. EV-A71 cases even disappeared. Patients infected with CVA10 had a significantly higher likelihood of hospitalization (P < 0.05), while the presence of oral rash served as a protective factor (P < 0.05).ConclusionsOur study highlights the critical need for enhanced surveillance of multiple HFMD pathogens, predominantly caused by the prevalent serotype CVA6. Clinically, enhanced surveillance of CVA10 is imperative to mitigate the hospitalization rate associated with HFMD.

Onychomadesis and Beau’s Lines- Rare Complications of Hand- foot-and-mouth Disease

Hand-foot-and-mouth disease (HFMD) is a common self-limiting viral infection in children caused by Coxsackievirus A16 and human enterovirus 71, presenting with fever, erythematous papulovesicular eruptions/ blisters on the palms, soles, knees, buttocks, and oral mucosa. Although rare, complications may arise in nails e. g. onychomadesis (nail separation) and Beau’s lines (transverse lines on the nails). These typically appear within four to eight weeks of HFMD and persist for around 5-6 weeks. No active treatment is required and these nail changes resolve spontaneously within few weeks as the nail bed remain intact. We present here a boy of 4 years who presented with such nail changes after around 5 weeks of HFM disease and diagnosed as onychomadesis and Beau’s lines after ruling out other possible causes of nail changes. Bangladesh J Child Health 2023; Vol 47 (2) : 109-112

Epidemiological characteristics and trend of mortality on hand, foot and mouth disease in China, 2008-2022

Objective: To analyze the nationwide epidemiological characteristics and trend of hand, foot and mouth disease (HFMD) fatal cases from 2008 to 2022 and provide evidence for the prevention and control of HFMD. Methods: The information on HFMD fatal cases during 2008 to 2022 was collected from the National Notifiable Disease Surveillance Reporting System of China. Data of the epidemiological characteristics was analyzed by R 4.2.2 software and the changing trends for the case fatality rates, mortality rates and their age-adjusted rates were analyzed by Joinpoint 4.9.10 software. Results: From 2008 to 2022, a total of 3 704 fatal HFMD cases were reported in China. The fatal cases were primarily observed in children aged <3 years (83.42%, 3 090/3 704). The male and female gender ratio was 1.82 ∶1 (2 389 ∶1 315). Regarding the age-adjusted case fatality rates over time, there was a rapid increase from 2008 to 2010 [annual percentage change (APC) =41.97%, P<0.05]. From 2010 to 2016, a steady decline was observed (APC=-28.57%, P<0.05), and the decline accelerated (APC=-39.66%, P<0.05) from 2016 to 2022. Since 2020, less than 10 fatal cases were reported annually nationwide. Among the 2 566 laboratory-confirmed deaths from 2008 to 2022, Enterovirus A71 (EV71) was the predominant pathogen (91.62%,2 351/2 566). There have been noticeable changes in the pathogen composition since 2017, decreasing in EV71 and increasing in the proportion of fatalities caused by Coxsackievirus A16 (CV-A16) and other enteroviruses. Conclusions: From 2008 to 2022, the HFMD case fatality rates and mortality rates continuously declined, peaked in 2010. Since 2017, the decline of HFMD case fatality rates has been noticeably accelerated. Along with the decrease in the proportion of EV71 in HFMD fatal cases, the proportion of other enteroviruses appeared increasing. It is essential to continuously monitor the etiological spectrum of the fatal cases.

Analysis of the level of serum-neutralizing antibodies against Coxsackievirus A6 in a healthy population in Tianjin City from 2014 to 2020

Objective: To investigate the level of serum-neutralizing antibodies against Coxsackievirus A6 (CVA6) in a healthy population in Tianjin City from 2014 to 2020. Methods: From March 2014 to March 2020, 5 492 healthy volunteers were recruited in Tianjin City. The demographic information, personal hygiene habits, living environment hygiene, contact history with hand, foot and mouth disease cases within 6 months before the survey, history of upper respiratory tract infection, and medical history of the subjects were investigated using a self-designed questionnaire. Venous blood was collected from the volunteers, and the level of serum anti-CVA6 IgG neutralizing antibodies was determined by the micro-neutralization assay. The level of CVA6-neutralizing antibodies was compared in different years, regions, and age groups, and the influencing factors in healthy individuals were analyzed by an ordered logistic regression model. Results: The age of 5 492 healthy volunteers ranged from 0 to 77, with M (Q1, Q3) of age being 21 (7, 32) years old, and a male-to-female ratio of 1∶1.09. The high, medium and low levels of CVA6-neutralizing antibodies among the volunteers were 5.39% (296), 30.35% (1 667) and 64.26% (3 529). The proportion of volunteers with high levels of CVA6-neutralizing antibodies decreased from 54.63% (437/800) in 2014 to 30.01% (229/763) in 2020, and it also decreased with age (all P values <0.001). The results of the ordered logistic regression model analysis showed that compared with those aged >35 years, volunteers aged 0-5 years had higher levels of CVA6-neutralizing antibodies [OR (95%CI): 1.39 (1.16-1.67)]. Compared with those who did not wash their hands after going out and had poor living environments, volunteers who washed their hands after going out, had good and general living environments and had lower levels of CVA6-neutralizing antibodies [OR (95%CI): 0.80 (0.70-0.91), 0.52 (028-0.88) and 0.54 (0.31-0.96), respectively]. Conclusion: The level of CVA6-neutralizing antibodies in Tianjin City remains at a relatively high level from 2014 to 2020 and shows a decreasing trend over the years.

Overview of the Trending Enteric Viruses and Their Pathogenesis in Intestinal Epithelial Cell Infection.

Enteric virus infection is a major public health issue worldwide. Enteric viruses have become epidemic infectious diseases in several countries. Enteric viruses primarily infect the gastrointestinal tract and complete their life cycle in intestinal epithelial cells. These viruses are transmitted via the fecal-oral route through contaminated food, water, or person to person and cause similar common symptoms, including vomiting, abdominal pain, and diarrhea. Diarrheal disease is the third leading cause of death in children under five years of age, accounting for approximately 1.7 billion cases and 443,832 deaths annually in this age group. Additionally, some enteric viruses can invade other tissues, leading to severe conditions and even death. The pathogenic mechanisms of enteric viruses are also unclear. In this review, we organized the research on trending enteric virus infections, including rotavirus, norovirus, adenovirus, Enterovirus-A71, Coxsackievirus A6, and Echovirus 11. Furthermore, we discuss the gastrointestinal effects and pathogenic mechanisms of SARS-CoV-2 in intestinal epithelial cells, given the gastrointestinal symptoms observed during the COVID-19 pandemic. We conducted a literature review on their pathogenic mechanisms, which serves as a guide for formulating future treatment strategies for enteric virus infections.

Genetic Characteristics and Phylogenetic Analysis of Coxsackievirus A6 Isolated in Linyi, China, 2022–2023

Hand, foot, and mouth disease (HFMD) has become one of the most common infectious diseases in the past few decades. Since 2013, coxsackievirus A6 (CVA6) has replaced enterovirus A71 (EV-A71) and coxsackievirus A16 (CVA16), becoming the predominant pathogen responsible for HFMD in many areas of China. This study aimed to investigate the genetic characteristics and molecular epidemiology of CVA6 in Linyi between the years 2022 and 2023. In total, 965 patients with HFMD were enrolled in this study, and analyses based on VP1 nucleotide sequences were performed to determine the evolutionary trajectory of CVA6. In 2022, 281/386 (72.8%) patients were positive for enteroviruses (EVs) and 217/281 (77.2%) were CVA6 positive. In 2023, 398/579 (68.7%) samples were positive for EVs and 243/398 (61.1%) were CVA6 positive. Six sequences were selected each year for homology analysis. The results showed that the 12 strains isolated from Linyi were distant from the prototype strain (AY421764) and the first CVA6 strain reported in China (JQ364886). Phylogenetic analysis showed that the CVA6 strains isolated from Linyi belonged to the D3 sub-genotype. CVA6 is emerging as a common pathogen causing HFMD in Linyi and continuous surveillance of HFMD etiologies agents is necessary.

Coxsackievirus A6 U.K. Genetic and Clinical Epidemiology Pre- and Post-SARS-CoV-2 Emergence.

Coxsackievirus A6 (CVA6) has become increasingly clinically relevant as a cause of Hand, Foot and Mouth Disease (HFMD) globally since 2008. However, most laboratories do not routinely determine the enteroviral type of positive samples. The non-pharmaceutical measures introduced to curb transmission during the COVID-19 pandemic may also have perturbed CVA6 epidemiology. We thus aimed to determine the prevalence, clinical presentation and genetic relationship of CVA6 across three complete epidemic seasons: one pre-SARS-CoV-2 emergence and two post-SARS-CoV-2 emergence in our regional healthcare setting. Surplus diagnostic nucleic acid from diagnosed enteroviral positives diagnosed between September and December of 2018 and between May 2021 and April of 2023 was subject to VP1 gene sequencing to determine the CVA6 cases and interrogate their phylogenetic relationship. The confirmed CVA6 cases were also retrospectively clinically audited. CVA6 infections were identified in 33 and 69 individuals pre- and post-pandemic, respectively, with cases peaking in November of 2018 and 2022, but in October of 2021. HFMD was the primary diagnosis in 85.5% of the post-pandemic cases, but only 69.7% of the pre-pandemic cases, where respiratory and neurological symptoms (45.5% and 12.1%, respectively) were significantly elevated. A complete VP1 sequence was retrieved for 94% of the CVA6 cases, revealing that studied infections were genetically diverse and suggestive of multiple local and international transmission chains. CVA6 presented a significant clinical burden in our regional U.K. hospital setting both pre- and post-pandemic and was subject to dynamic clinical and genetic epidemiology.

Enterovirus A71 and coxsackievirus A6 circulation in England, UK, 2006-2017: A mathematical modelling study using cross-sectional seroprevalence data.

Enterovirus A71 (EV-A71) and coxsackievirus A6 (CVA6) primarily cause hand, foot and mouth disease and have emerged to cause potential fatal neurological and systemic manifestations. However, limited surveillance data collected through passive surveillance systems hampers characterization of their epidemiological dynamics. We fit a series of catalytic models to age-stratified seroprevalence data for EV-A71 and CVA6 collected in England at three time points (2006, 2011 and 2017) to estimate the force of infection (FOI) over time and assess possible changes in transmission. For both serotypes, model comparison does not support the occurrence of important changes in transmission over the study period, and we find that a declining risk of infection with age and / or seroreversion are needed to explain the seroprevalence data. Furthermore, we provide evidence that the increased number of reports of CVA6 during 2006-2017 is unlikely to be explained by changes in surveillance. Therefore, we hypothesize that the increased number of CVA6 cases observed since 2011 must be explained by increased virus pathogenicity. Further studies of seroprevalence data from other countries would allow to confirm this. Our results underscore the value of seroprevalence data to unravel changes in the circulation dynamics of pathogens with weak surveillance systems and large number of asymptomatic infections.

Trend of hand, foot and mouth disease before, during, and after China's COVID control policies in Zhejiang, China.

To describe the trends in the incidence of hand, foot and mouth disease (HFMD) before, during, and after China's Coronavirus Disease (COVID) control policies, and to interpret the influence on HFMD incidence at different control stages in Zhejiang Province. We collected data on HFMD cases in Zhejiang between 2014 and 2023. We compared the constituent ratios of cases at different COVID control stages by sex, age, child groups, and pathogens and weekly seasonal indices to observe seasonal variations in the incidence of HFMD. An interrupted time-series segmented regression analysis was applied to estimate the influence on HFMD incidence at different control stages. Stratified and sensitivity analyses were conducted to validate the findings. A considerable proportion of cases occurred among children living separately. The proportions of children in kindergartens or nurseries and children aged 2-4 years were relatively low at the strict control stage compared to the other three stages. Enteroviruses other than enterovirus 71 and coxsackie virus A16 were the dominant HFMD pathogens, and the proportion showed an increasing trend. The usual spring-summer peak in HMFD incidence did not occur in 2020, and the periodicity of the biennial peak was disrupted for a year. The summer peak in 2023 was higher than that in the other years, and was delayed by 3 weeks. The trend changes in weekly HFMD cases during the strict control and regular control stages were - 15% (IRR: 0.85, 95% CI: 0.81-0.89) and 17% (IRR: 1.17, 95% CI: 1.12-1.23), respectively. However, the change was not statistically significant during the reopening stage (IRR: 1.41, 95% CI: 0.34-5.88). The expected number of cases increased by 1.12 times (95% CI: 243.17, 53.45%) during the reopening stage compared to what would have occurred if the zero-COVID policy had continued in 2023. Non-pharmaceutical interventions (NPIs) for COVID-19 control can mitigate HFMD. However, after the dynamic zero-COVID policy ended, the HFMD incidence returned to historical levels. Strict NPIs such as traffic restrictions and kindergarten closures cannot be sustained long-term. NPIs such as improving personal hygiene for routine prevention are highly recommended.

Concurrent Coxsackievirus A6 Infection and Kawasaki Disease: A Case Report

Background and Clinical Significance: Kawasaki disease (KD) is an acute febrile vasculitis that primarily affects children and is associated with systemic inflammation, particularly in the coronary arteries. Coxsackievirus A6 (CVA6) has emerged as a significant agent in atypical presentations of hand, foot, and mouth disease (HFMD), raising the possibility of its involvement in KD. Case Presentation: This report presents the case of an 18-month-old Thai boy admitted with symptoms of high fever, sore throat, and ulcerative lesions, initially diagnosed with herpangina. As his condition progressed, additional KD symptoms developed, including conjunctival injection, rash, and elevated inflammatory markers, fulfilling the diagnostic criteria for KD. Notably, throat swab analysis confirmed CVA6 as the causative agent. Phylogenetic analysis revealed that the CVA6 strain closely aligned with Chinese strains from 2023, showing a high nucleotide sequence homology of 98.4%. Conclusions: In conclusion, this case highlights a possible association between CVA6-associated herpangina and KD, suggesting that CVA6 infection may act as a trigger for KD in genetically susceptible children. These findings highlight the need for increased awareness among healthcare providers to promptly identify and manage Kawasaki Disease during peak enterovirus seasons, reducing its impact on children.

Molecular epidemiology of herpangina in the subcenter of Beijing, China: a surveillance study during 2021-2022.

In this study, we analyzed the dynamic molecular epidemiology of herpangina based on pharyngeal swabs and demographic data collected from children with herpangina monitored in Tongzhou district in China from January 2021 to December 2022. A total of 1022 herpangina cases were diagnosed. Out of 225 samples collected, 56.4% (127/225) were positive for non-polio enterovirus, with seven genotypes identified: coxsackievirus A4 (CV-A4), CV-A6, CV-A10, CV-A2, CV-A16, CV-B3, and CV-A8. The predominant genotypes associated with herpangina changed during and after the COVID-19 pandemic, with the predominant genotypes being CV-A4 and CV-A6 in 2021 and CV-A10 and CV-A6 in 2022.

Genetic diversity and spread of recombinant coxsackievirus A4 in hand, foot, and mouth disease cases in Bangkok, Thailand: 2017–2023

Coxsackievirus A4 (CVA4) has recently become one of the most common causative agents of hand, foot, and mouth disease. The current study investigated the genetic diversity and spread of recombinant CVA4 by analyzing circulating genotypes and recombinant strains in Bangkok, Thailand, from 2017 to 2023. Partial VP1, 3Dpol, and whole genome sequencing of CVA4 samples collected from collaborating hospitals were conducted. Phylogenetic analysis of CVA4 VP1 and 3Dpol genome regions revealed discordance, indicating recombination. The predominant CVA4 genotype was C3, primarily observed in 2019. The predominant genotype in 2017 was C1. D2, commonly found in China, was occasionally observed. In nucleotide similarity analysis, intertypic recombination between CVA4 and EV-A during the evolutionary history of the virus was evident, particularly in the nonstructural region. The estimated emergence of genotypes C1 and C3 in Thailand occurred around 2014, with an evolutionary rate of 5.8 × 10− 3 nucleotide substitutions per site per year. Genotype D2 exhibited notable variability across both the entire genome and the structural protein region compared to genotype C. Monitoring the genetic diversity and circulation of recombinant CVA4 is crucial for identifying newly emerging virus strains, enabling prompt public health responses and containment efforts, and enhancing surveillance in Thailand.