Comparison of clinical features between coxsackievirus A2 and enterovirus 71 during the enterovirus outbreak in Taiwan, 2008: a children's hospital experience

Epidemiology of Enterovirus Genotypes in Association with Human Diseases

Enteroviruses (EVs) are well-known causes of a wide range of infectious diseases in infants and young children, ranging from mild illnesses to severe conditions, depending on the virus genotypes and the host's immunity. Recent advances in molecular surveillance and genotyping tools have identified over 116 different human EV genotypes from various types of clinical samples. However, the current knowledge about most of these genotypes, except for those of well-known genotypes like EV-A71 and EV-D68, is still limited due to a lack of comprehensive EV surveillance systems. This limited information makes it difficult to understand the true burden of EV-related diseases globally. Furthermore, the specific EV genotype associated with diseases varies according to country, population group, and study period. The same genotype can exhibit different epidemiological features in different areas. By integrating the data from established EV surveillance systems in the USA, Europe, Japan, and China, in combination with other EV infection studies, we can elaborate a better understanding of the distribution of prevalent EV genotypes and the diseases associated with EV. This review analyzed the data from various EV surveillance databases and explored the EV seroprevalence and the association of specific EV genotypes with human diseases.

Chemoproteomics enables identification of coatomer subunit zeta-1 targeted by a small molecule for enterovirus A71 inhibition

Human enterovirus A71 (EV-A71) is a significant etiological agent responsible for epidemics of hand, foot, and mouth disease (HFMD) in Asia-Pacific regions. There are presently no licensed antivirals against EV-A71, and the druggable target for EV-A71 remains very limited. The phenotypic hit 10,10'-bis(trifluoromethyl) marinopyrrole A derivative, herein termed MPA-CF3, is a novel potent small-molecule inhibitor against EV-A71, but its pharmacological target(s) and antiviral mechanisms are not defined. Here, quantitative chemoproteomics deciphered the antiviral target of MAP-CF3 as host factor coatomer subunit zeta-1 (COPZ1). Mechanistically, MPA-CF3 disrupts the interaction of COPZ1 with the EV-A71 nonstructural protein 2C by destabilizing COPZ1 upon binding. The destruction of this interaction blocks the coatomer-mediated transport of 2C to endoplasmic reticulum, and ultimately inhibits EV-A71 replication. Taken together, our study disclosed that MPA-CF3 can be a structurally novel host-targeting anti-EV-A71 agent, providing a structural basis for developing the COPZ1-targeting broad-spectrum antivirals against enteroviruses. The mechanistic elucidation of MPA-CF3 against EV-A71 may offer an alternative COPZ1-involved therapeutic pathway for enterovirus infection.

Emerging concerns of blood-brain barrier dysfunction caused by neurotropic enteroviral infections

Enteroviruses (EVs), comprise a genus in the Picornaviridae family, which have been shown to be neurotropic and can cause various neurological disorders or long-term neurological condition, placing a huge burden on society and families. The blood-brain barrier (BBB) is a protective barrier that prevents dangerous substances from entering the central nervous system (CNS). Recently, numerous EVs have been demonstrated to have the ability to disrupt BBB, and further lead to severe neurological damage. However, the precise mechanisms of BBB disruption associated with these EVs remain largely unknown. In this Review, we focus on the molecular mechanisms of BBB dysfunction caused by EVs, emphasizing the invasiveness of enterovirus A71 (EVA71), which will provide a research direction for further treatment and prevention of CNS disorders.

Genetic characterization and molecular epidemiology of Coxsackievirus A12 from mainland China during 2010-2019

Coxsackievirus A12 (CVA12) is an enterovirus that has been isolated in many countries in recent years. However, studies on CVA12 are limited, and its effective population size, evolutionary dynamics and recombination patterns have not been clarified now. In this study, we described the phylogenetic characteristics of 16 CVA12 strains isolated from pediatric HFMD patients in mainland China from 2010 to 2019. Comparison of the nucleotide sequences and amino acid sequences with the CVA12 prototype strain revealed that the 16 CVA12 strains are identical in 78.8-79% and 94-94.2%, respectively. A phylodynamic analysis based on the 16 full-length VP1 sequences from this study and 21 sequences obtained from GenBank revealed a mean substitution rate of 6.61 × 10^-3 substitutions/site/year (95% HPD: 5.16-8.20 × 10^-3), dating the time to most recent common ancestor (tMRCA) of CVA12 back to 1946 (95% HPD: 1942-1947). The Bayesian skyline plot showed that the effective population size has experienced twice dynamic fluctuations since 2007. Phylogeographic analysis identified two significant migration pathways, indicating the existence of cross-provincial transmission of CVA12 in mainland China. Recombination analysis revealed two recombination patterns between 16 CVA12 strains and other EV-A, suggesting that there may be extensive genetic exchange between CVA12 and other enteroviruses. In summary, a total of 16 full-length CVA12 strains were reported in this study, providing valuable references for further studies of CVA12 worldwide.

Efficacy of Coxsackievirus A2 vaccine candidates correlating to humoral immunity in mice challenged with a mouse-adapted strain

BACKGROUND

In recent years, Coxsackievirus A2 (CV-A2) has become one of the main serotypes of enterovirus species A associated with hand, foot and mouth disease (HFMD) in China. It has also caused HFMD epidemics in many countries all over the world. Currently, there are no effective, preventive vaccines against it.

METHODS

A CV-A2 strain was isolated in RD cells and then adapted to grow in Vero cells. This is in compliance with guidelines for cell substrates allowed for human vaccines by the Chinese regulatory authority. Groups of newborn Kunming mice were inoculated on day 3 and day 9 using two formulations of candidate vaccines, empty particles and full particles. They were then challenged on day 14 at a lethal dose with a mouse-adapted strain.

RESULTS

The mice in the control group all died within 14 days post-challenge whereas most of the mice in the candidate vaccine groups survived. It was found that the titers of neutralizing antibodies was dose-dependent in sera of immunized mice. The results also showed that the vaccine candidates stimulated a strong humoral immune response and protected the mice from disease and death. The virus loads in tissues or organs were significantly reduced and pathological changes were either weak or not observed in the immunized groups compared with those in Al(OH)₃ control group. Preliminary mapping of the nucleotide and amino acid residues potentially related to cell tropism of the vaccine strain and virulence of the challenge strain was performed.

CONCLUSION

The results showed that the RD cell-isolated and Vero cell-adapted CV-A2 strain is a promising vaccine candidate. This active immunization-challenge mouse model mimics the vaccination and then exposure to wildtype viruses, compared with passive immunization-challenge model, and is invaluable for efficacy evaluation in studies on multivalent vaccines containing CV-A2 against HFMD.

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

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

Cases of Acute Flaccid Paralysis Associated with Coxsackievirus A2: Findings of a 20-Year Surveillance in the Russian Federation

Surveillance for acute flaccid paralysis syndrome (AFP) in children under 15 is the backbone of the Global Polio Eradication Initiative. Laboratory examination of stool samples from AFP cases allows the detection of, along with polioviruses, a variety of non-polio enteroviruses (NPEV). The etiological significance of these viruses in the occurrence of AFP cases has been definitively established only for enteroviruses A71 and D68. Enterovirus Coxsackie A2 (CVA2) is most often associated with vesicular pharyngitis and hand, foot and mouth disease. Among 7280 AFP cases registered in Russia over 20 years (2001–2020), CVA2 was isolated only from five cases. However, these included three children aged 3 to 4 years, without overt immune deficiency, immunized with 4–5 doses of poliovirus vaccine in accordance with the National Vaccination Schedule. The disease resulted in persistent residual paralysis. Clinical and laboratory data corresponded to poliomyelitis developing during poliovirus infection. These findings are compatible with CVA2 being the cause of AFP. Molecular analysis of CVA2 from these patients and a number of AFP cases in other countries did not reveal association with a specific phylogenetic group, suggesting that virus genetics is unlikely to explain the pathogenic profile. The overall results highlight the value of AFP surveillance not just for polio control but for studies of uncommon AFP agents.

A fatal case of acute encephalopathy in a child due to coxsackievirus A2 infection: a case report

Background

Certain types of enteroviruses, including coxsackieviruses, cause encephalitis, and other neurological complications. However, these pathogens rarely cause fatal infections, especially in immunocompetent infants. In this study, we present a rare case of acute encephalopathy caused by coxsackievirus A2 (CV-A2), which progressed rapidly in a previously healthy female child.

Case presentation

In June 2013, a 26-month-old female child from Kanagawa, Japan, was found unresponsive during sleep. She was healthy until that morning. Her temperature was 37 °C at 08:00. She was feeling fine and went to the nursery that same morning. However, her condition worsened around noon. Therefore, she went home and slept at around 13:00. Surprisingly, after 2 h, her parents checked on her and found that she was lying on her back and was not breathing. Hence, she was immediately taken to a hospital by ambulance, but she was declared dead on arrival at the hospital. Subsequently, pathological autopsy and pathogenetic analysis, including multiple pathogen detection real-time PCR, were conducted to investigate the cause of death. The examination results revealed that she had an infectious respiratory disease and acute encephalopathy due to a CV-A2 infection.

Conclusions

Based on our findings, we concluded that a previously healthy girl who had no immediate history of underlying medical condition were susceptible to death by acute encephalopathy due to CV-A2 infections. We proposed this conclusion because the patient’s condition progressed rapidly in less than 2 h and eventually led to her death. This is the first report on an acute encephalitis-dependent death in a child due to CV-A2 infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06858-2.

Coxsackievirus A2 Leads to Heart Injury in a Neonatal Mouse Model

Coxsackievirus A2 (CVA2) has emerged as an active pathogen that has been implicated in hand, foot, and mouth disease (HFMD) and herpangina outbreaks worldwide. It has been reported that severe cases with CVA2 infection develop into heart injury, which may be one of the causes of death. However, the mechanisms of CVA2-induced heart injury have not been well understood. In this study, we used a neonatal mouse model of CVA2 to investigate the possible mechanisms of heart injury. We detected CVA2 replication and apoptosis in heart tissues from infected mice. The activity of total aspartate transaminase (AST) and lactate dehydrogenase (LDH) was notably increased in heart tissues from infected mice. CVA2 infection also led to the disruption of cell-matrix interactions in heart tissues, including the increases of matrix metalloproteinase (MMP)3, MMP8, MMP9, connective tissue growth factor (CTGF) and tissue inhibitors of metalloproteinases (TIMP)4. Infiltrating leukocytes (CD45⁺ and CD11b⁺ cells) were observed in heart tissues of infected mice. Correspondingly, the expression levels of inflammatory cytokines in tissue lysates of hearts, including tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β), IL6 and monocyte chemoattractant protein-1 (MCP-1) were significantly elevated in CVA2 infected mice. Inflammatory signal pathways in heart tissues, including phosphatidylinositol 3-kinase (PI3K)-AKT, mitogen-activated protein kinases (MAPK) and nuclear factor kappa B (NF-κB), were also activated after infection. In summary, CVA2 infection leads to heart injury in a neonatal mouse model, which might be related to viral replication, increased expression levels of MMP-related enzymes and excessive inflammatory responses.

Neonatal Murine Model of Coxsackievirus A2 Infection for the Evaluation of Antiviral Therapeutics and Vaccination

Coxsackievirus (CV) A2 has emerged as an important etiological agent in the pathogen spectrum of hand, foot, and mouth disease (HFMD). The symptoms of CVA2 infections are generally mild, but worsen rapidly in some people, posing a serious threat to children’s health. However, compared with enterovirus 71 detected frequently in fatal cases, limited attention has been paid to CVA2 infections because of its benign clinical course. In the present study, we identified three CVA2 strains from HFMD infections and used the cell-adapted CVA2 strain HN202009 to inoculate 5-day-old BALB/c mice intramuscularly. These mice developed remarkably neurological symptoms such as ataxia, hind-limb paralysis, and death. Histopathological determination showed neuronophagia, pulmonary hemorrhage, myofiberlysis and viral myocarditis. Viral replication was detected in multiple organs and tissues, and CVA2 exhibited strong tropism to muscle tissue. The severity of illness was associated with abnormally high levels of inflammatory cytokines, including interleukin (IL)-6, IL-10, tumor necrosis factor α, and monocyte chemotactic protein 1, although the blockade of these proinflammatory cytokines had no obvious protection. We also tested whether an experimental formaldehyde-inactivated CVA2 vaccine could induce protective immune response in adult mice. The CVA2 antisera from the vaccinated mice were effective against CVA2 infection. Moreover, the inactivated CVA2 vaccine could successfully generate immune protection in neonatal mice. Our results indicated that the neonatal mouse model could be a useful tool to study CVA2 infection and to develop CVA2 vaccines.

Epidemical and etiological study on hand, foot and mouth disease following EV-A71 vaccination in Xiangyang, China

Coxsackievirus A6 (CV-A6) and Coxsackievirus A10 (CV-A10) have been emerging as the prevailing serotypes and overtaking Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CV-A16) in most areas as main pathogens of hand, foot and mouth disease (HFMD) in China since 2013. To investigate whole etiological spectrum following EV-A71 vaccination of approximate 40,000 infants and young children in Xiangyang, enteroviruses were serotyped in 4415 HFMD cases from October 2016 to December 2017 using Real Time and conventional PCR and cell cultures. Of the typeable 3201 specimen, CV-A6 was the predominant serotype followed by CV-A16, CV-A10, CV-A5, CV-A2 and EV-A71 with proportions of 59.54%, 15.31%, 11.56%, 4.56%, 3.78% and 3.03%, respectively. Other 12 minor serotypes were also detected. The results demonstrated that six major serotypes of enteroviruses were co-circulating, including newly emerged CV-A2 and CV-A5. A dramatic decrease of EV-A71 cases was observed, whereas the total cases remained high. Multivalent vaccines against major serotypes are urgently needed for control of HFMD.

Epidemiology and Sequence-Based Evolutionary Analysis of Circulating Non-Polio Enteroviruses

Enteroviruses (EVs) are positive-sense RNA viruses, with over 50,000 nucleotide sequences publicly available. While most human infections are typically associated with mild respiratory symptoms, several different EV types have also been associated with severe human disease, especially acute flaccid paralysis (AFP), particularly with endemic members of the EV-B species and two pandemic types—EV-A71 and EV-D68—that appear to be responsible for recent widespread outbreaks. Here we review the recent literature on the prevalence, characteristics, and circulation dynamics of different enterovirus types and combine this with an analysis of the sequence coverage of different EV types in public databases (e.g., the Virus Pathogen Resource). This evaluation reveals temporal and geographic differences in EV circulation and sequence distribution, highlighting recent EV outbreaks and revealing gaps in sequence coverage. Phylogenetic analysis of the EV genus shows the relatedness of different EV types. Recombination analysis of the EV-A species provides evidence for recombination as a mechanism of genomic diversification. The absence of broadly protective vaccines and effective antivirals makes human enteroviruses important pathogens of public health concern.

Clinical features of gingivostomatitis due to primary infection of herpes simplex virus in children

Background

Primary herpetic gingivostomatitis (PHGS) in children, though usually self-limited, might mimic bacterial and enteroviral pharyngitis clinically. We conducted a study to define the clinical features of PHGS in children.

Methods

Between January 2012 and December 2016, 282 inpatients aged less than 19 years with cell culture-confirmed herpes simplex virus (HSV) infection in a medical center were identified from the virologic laboratory logbook. Clinical data were retrospectively collected.

Results

Among the 282 inpatients, 185 cases were considered as PHGS and were included for analysis. Fever was present in 99.5%. The mean duration of fever was 5.11 days (±2.24) with the longest being 17 days. Common oral manifestations included oral ulcers (84.3%), which equally resided in the anterior and posterior part of the oral cavity (65.4% vs. 63.2%), gum swelling and/or bleeding (67.6%), and exudate coated tonsils (16.8%). Leukocytosis (WBC count > 15,000/uL³) was noted in 52 patients (28.1%) and a serum C-reactive protein level > 40 mg/L in 55 patients (29.7%). Fixty-five patients (35%) were diagnosed with PHGS on admission and were significantly more likely to have ulcers over the anterior oral cavity (76.1% vs. 26.7%) and gum swelling/bleeding (76.2% vs. 7.5%, p-value all < 0.001) on admission and were significantly less likely to receive antibiotic treatment (16.9 vs. 36.7%, p-value < 0.01) than others. Forty-six patients (25%) undiagnosed as PHGS on discharge were significantly more likely to have exudate coated on the tonsils, to receive antibiotic treatment and significantly less likely to have gum swelling/bleeding and oral ulcers (all p-values < 0.01).

Conclusions

Meticulously identifying specific oral manifestations of gum swelling/bleeding and ulcers over the anterior oral cavity in children can help making the diagnosis of PHGS earlier and subsequently reduce unnecessary prescription of antibiotics.

Non-polio enterovirus infections in children with central nervous system disorders in Shanghai, 2016-2018: Serotypes and clinical characteristics

BACKGROUND

Non-polio enrerovirus causes a wide spectrum of neurologic syndromes. The epidemiological and clinical profiles of non-polio enrerovirus-associated central nervous system infections vary by regions and over year.

OBJECTIVES

This study aimed to understand the prevalence, serotypes and clinical characteristics of enterovirus-associated aseptic meningitis, encephalitis and meningo-encephalitis in children in Shanghai during 2016-2018.

METHODS

We collected the clinical data and the cerebrospinal fluid specimens from the pediatric patients with aseptic meningitis, encephalitis and meningo-encephalitis during 2016-2018. The nested RT-PCR and sequencing were performed to identify enterovirus and serotypes.

RESULTS

A total of 424 patients were included in this study and their non-duplicated cerebrospinal fluid specimens were collected during the acute stage of illness. Based on PCR assay, enterovirus was detected in 272 (64.15 %) patients, of whom, the ratio of male to female subjects was 1.99, and the mean age was 5.71 ± 3.55 years (range: 0.03-16 years). There were 17 serotypes identified. Echovirus 30 (24.63 %), Coxsackievirus A10 (20.96 %), Coxsackievirus A6 (18.01 %) accounted for 63.6 %, followed by Coxsackievirus B5 (7.72 %), Echovirus 6 (5.88 %), and other serotypes (22.8 %). Of the 10 (3.68 %) critically severe patients, all had refractory seizure, 8 required mechanical ventilation, 7 survivors had recurrent attacks of epilepsy and 3 abandoned treatment; Coxsackievirus A10, Echovirus 9, Coxsackievirus A2, Coxsackievirus A6 and Echovirus 6 were identified.

CONCLUSIONS

Non-polio enterovirus is the major pathogen causing aseptic meningitis, encephalitis and meningo-encephalitis in Chinese children and can cause life-threatening encephalitis and severe sequelae.

The Epidemiological and Clinical Characteristics of Hand, Foot, and Mouth Disease in Hangzhou, China, 2016 to 2018

Hand, foot, and mouth disease (HFMD) is most frequently caused by several serotypes of human enterovirus (EV) including Enterovirus 71 (EV-A71), coxsackievirus A16 (CV-A16), or other types of EV. The aim of this study was to determine the epidemiological characteristics of HFMD and to describe the epidemiologic characteristics of HFMD among severe and mild cases. We collected 4760 HFMD cases in Hangzhou from 2016 to 2018. Specimens from these cases were collected and tested for EV-A71, CV-A16, CV-A6, CV-A10, CV-A2, and CV-A5 by reverse transcriptase polymerase chain reaction. From 2016 to 2018, the prevalence of HFMD was seasonal each year. Among the 4760 probable HFMD cases, 3559 cases were confirmed (74.8%), including 426 cases of EV-A71 infections (8.9%), 249 cases of CV-A16 infections (5.2%), and 2884 cases of other EV infections (60.6%). The percentage of other EV infections was more than 80%, which increased year by year. Random selection of samples for detection of other EV infections in 2017 and 2018, among the 1297 cases, showed there were 835 (64.4%) cases of CV-A6 infections, 177 (13.6%) cases of CV-A10 infections, 100 (7.7%) cases of CV-A2 infections, 40 (3.1%) cases of CV-A5 infections, 3 (0.02 %) cases of mixed infections, and 11.0% untyped EV infections. Preschool children were still the primary population susceptible to HFMD. In severe cases, EV-A71 infection was the main cause. Characterizing the epidemiology and the relationship between severe and common cases of HFMD would provide relevant evidences for the prevention and treatment of HFMD.

The History of Enterovirus A71 Outbreaks and Molecular Epidemiology in the Asia-Pacific Region

Enterovirus A71 (EV-A71) is one of the common causative pathogens for hand foot and mouth disease (HFMD) affecting young children. HFMD outbreak can result in a substantial pediatric hospitalization and burden the healthcare services, especially in less-developed countries. Since the initial epidemic of predominantly EV-A71 in California in 1969, the high prevalence of HFMD in the Asia-pacific region and elsewhere around the world represents a significant morbidity in this age group. With the advent of rapid and accurate diagnostic tools, there has been a dramatic increase in the number of laboratory-confirmed EV-A71 infection over the past two decades. The population, cultural, and socioeconomic diversity among countries in the Asia-Pacific region all influence the transmission and morbidity associated with HFMD. This review summarizes the current state of epidemiology of EV-A71 in Asia-Pacific countries based on the most recent epidemiological data and available information on the prevalence and disease burden. This knowledge is important in guiding the prevention, control and future research on vaccine development of this highly contagious disease of significant socioeconomic implications in public health.

Two Coxsackievirus B3 outbreaks associated with hand, foot, and mouth disease in China and the evolutionary history worldwide

BACKGROUND

Coxsackievirus B3 (CV-B3) is usually associated with aseptic meningitis and myocarditis; however, the association between CV-B3 and hand, foot, and mouth disease (HFMD) has not been clearly demonstrated, and the phylogenetic dynamics and transmission history of CV-B3 have not been well summarized.

METHOD

Two HFMD outbreaks caused by CV-B3 were described in Hebei Province in 2012 and in Shandong Province in 2016 in China. To analyze the epidemiological features of two CV-B3 outbreaks, a retrospective analysis was conducted. All clinical specimens from CV-B3 outbreaks were collected and disposed according to the standard procedures supported by the WHO Global Poliovirus Specialized Laboratory. EV genotyping and phylogenetic analysis were performed to illustrate the genetic characteristics of CV-B3 in China and worldwide.

RESULTS

Two transmissible lineages (lineage 2 and 3) were observed in Northern China, which acted as an important "reservoir" for the transmission of CV-B3. Sporadic exporting and importing of cases were observed in almost all regions. In addition, the global sequences of CV-B3 showed a tendency of geographic-specific clustering, indicating that geographic-driven adaptation plays a major role in the diversification and evolution of CV-B3.

CONCLUSIONS

Overall, our study indicated that CV-B3 is a causative agent of HFMD outbreak and revealed the phylogenetic dynamics of CV-B3 worldwide, as well as provided an insight on CV-B3 outbreaks for effective intervention and countermeasures.

Persistent circulation of genotype D coxsackievirus A2 in mainland of China since 2008

Coxsackievirus A2 (CV-A2) has emerged as an important etiological agent in the hand, foot, and mouth disease and herpangina pathogen spectrum because of its high global prevalence. In the present study, we investigated the evolutionary dynamics of CV-A2 circulating in China. We analyzed a total of 163 entire VP1 sequences of CV-A2, including 74 sequences generated from the present study and 89 sequences collected from the GenBank database. Phylogenetic analysis based on the entire VP1 nucleotide sequences confirmed the persistent circulation of the predominant genotype D in mainland of China since 2008. Cluster analysis grouped the sequences into two distinct clusters, clusters 1 and 2, with most grouped under cluster 2. After 2012, cluster 1 was gradually replaced by cluster 2. Results of Bayesian Markov chain Monte Carlo analysis suggested that multiple lineages of genotype D were transmitted in mainland of China at an estimated evolutionary rate of 6.32×10⁻³ substitutions per site per year, which is consistent with the global evolutionary rate of CV-A2 (5.82×10⁻³ substitutions per site per year). Continuous transmission and evolution of CV-A2 resulted in the genetic polymorphism.

Understanding physician antibiotic prescribing behavior for children with enterovirus infection

Background

Our previous study demonstrated that pediatricians prescribe antibiotics without proper clinical justification to patients with enterovirus infection, although antibiotics are not effective in treating the infections caused by these viruses. To improve the quality of healthcare, we aim to evaluate the association of clinical and demographic characteristics of patients and further to identify the determining factors for prescribing antibiotics to children experiencing enterovirus infection.

Methods

We retrospectively reviewed the medical records of children who were hospitalized between January 2008 and December 2016 with a diagnosis of herpangina or hand-foot-mouth disease (HFMD). We identified those children who were prescribed antibiotics for at least 24 hours during admission. We conducted a retrospective descriptive study to analyze data in order to determine the factors associated with pediatrician antibiotics prescribing for enterovirus infection.

Results

In the nine years of study period, the rate of antibiotics use was about 13% in these patients. A total of 3659 patients were enrolled during 2008~2012 and analyzed in detail. Elevated levels of C-reactive protein (CRP) and presence of leukocytosis in blood (WBC) were both significantly associated with pediatrician antibiotic prescribing for enterovirus infection (p<0.001). Between different specialistic devisions, there was significantly different proportion of antibiotics utilization for patients. In further analysis of antibiotics prescribing by Receiver operating characteristic (ROC) curve method, the level of CRP significantly had more the area under curve (0.708) compared with the count of WBC (p<0.05).

Conclusions

The present study indicates that higher serum level of CRP is strongly associated with pediatricians prescribing antibiotics for children experiencing herpangina or HFMD. Antibiotic prescribing is a complex process. Pediatricians should be more judicious in decision-making time by their specialistics. Our findings would shed new light on process and allay the concern about inappropriate antibiotics.

Outcomes following severe hand foot and mouth disease: A systematic review and meta-analysis

BACKGROUND

Hand, foot and mouth disease (HFMD) caused by enterovirus A71 (EV-A71) is associated with acute neurological disease in children. This study aimed to estimate the burden of long-term sequelae and death following severe HFMD.

METHODS

This systematic review and meta-analysis pooled all reports from English and Chinese databases including MEDLINE and Wangfang on outbreaks of clinically diagnosed HFMD and/or laboratory-confirmed EV-A71 with at least 7 days' follow-up published between 1st January 1966 and 19th October 2015. Two independent reviewers assessed the literature. We used a random effects meta-analysis to estimate cumulative incidence of neurological sequelae or death. Studies were assessed for methodological and reporting quality. PROSPERO registration number: 10.15124/CRD42015021981.

FINDINGS

43 studies were included in the review, and 599 children from 9 studies were included in the primary analysis. Estimated cumulative incidence of death or neurological sequelae at maximum follow up was 19.8% (95% CI:10.2%, 31.3%). Heterogeneity (Iˆ2) was 88.57%, partly accounted for by year of data collection and reporting quality of studies. Incidence by acute disease severity was 0.00% (0.00, 0.00) for grade IIa; 17.0% (7.9, 28.2) for grade IIb/III; 81.6% (65.1, 94.5) for grade IV (p = 0.00) disease.

CONCLUSIONS

HFMD with neurological involvement is associated with a substantial burden of long-term neurological sequelae. Grade of acute disease severity was a strong predictor of outcome. Strengths of this study include its bilingual approach and clinical applicability. Future prospective and interventional studies must use rigorous methodology to assess long-term outcomes in survivors.

FUNDING

There was no specific funding for this study. See below for researcher funding.

A complex mosaic of enteroviruses shapes community-acquired hand, foot and mouth disease transmission and evolution within a single hospital

Human enteroviruses (EV) pose a major risk to public health. This is especially so in the Asia-Pacific region where increasing numbers of hand, foot and mouth disease (HFMD) cases and large outbreaks of severe neurological disease associated with EV-A71 have occurred. Despite their importance, key aspects of the emergence, epidemiology and evolution of EVs remain unclear, and most studies of EV evolution have focused on a limited number of genes. Here, we describe the genomic-scale evolution of EV-A viruses sampled from pediatric patients with mild disease attending a single hospital in western Sydney, Australia, over an 18-month period. This analysis revealed the presence of eight viral serotypes-Coxsackievirus (CV) A2, A4, A5, A6, A8, A10, A16 and EV-A71-with up to four different serotypes circulating in any 1 month. Despite an absence of large-scale outbreaks, high levels of geographical and temporal mixing of serotypes were identified. Phylogenetic analysis revealed that multiple strains of the same serotype were present in the community, and that this diversity was shaped by multiple introductions into the Sydney population, with only a single lineage of CV-A6 exhibiting in situ transmission over the entire study period. Genomic-scale analyses also revealed the presence of novel and historical EV recombinants. Notably, our analysis revealed no association between viral phylogeny, including serotype, and patient age, sex, nor disease severity (for uncomplicated disease). This study emphasizes the contribution of EV-A viruses other than EV-A71 to mild EV disease including HFMD in Australia and highlights the need for greater surveillance of these viruses to improve strategies for outbreak preparedness and vaccine design.

Hand, foot and mouth disease: current knowledge on clinical manifestations, epidemiology, aetiology and prevention

For a long time, hand, foot and mouth disease (HFMD) was seen as a mild viral infection characterized by typical clinical manifestations that spontaneously resolved in a few days without complications. In the past two decades, HFMD has received new attention because of evidence that this disease could have clinical, epidemiological and aetiological characteristics quite different from those initially thought. In contrast to previous beliefs, it has been clarified that HFMD can be associated with complications, leading to severe neurological sequelae and, rarely, to death. This finding has led to an enormous number of studies that have indicated that several viruses in addition to those known to be causes of HFMD could be associated with the development of disease. Moreover, it was found that if some viruses were more common in some geographic areas, frequent modification of the molecular epidemiology of the infecting strains could lead to outbreaks caused by infectious agents significantly different from those previously circulating. Vaccines able to confer protection against the most common aetiologic agents in a given country have been developed. However, simultaneous circulation of more than one causative virus and modification of the molecular epidemiology of infectious agents make preparations based on a single agent relatively inadequate. Vaccines with multiple components are a possible solution. However, several problems concerning their development must be solved before adequate prevention of severe cases of HFMD can be achieved.

Machine Learning Algorithms for Risk Prediction of Severe Hand-Foot-Mouth Disease in Children

The identification of indicators for severe HFMD is critical for early prevention and control of the disease. With this goal in mind, 185 severe and 345 mild HFMD cases were assessed. Patient demographics, clinical features, MRI findings, and laboratory test results were collected. Gradient boosting tree (GBT) was then used to determine the relative importance (RI) and interaction effects of the variables. Results indicated that elevated white blood cell (WBC) count > 15 × 10⁹/L (RI: 4⁹.47, p < 0.001) was the top predictor of severe HFMD, followed by spinal cord involvement (RI: 26.62, p < 0.001), spinal nerve roots involvement (RI: 10.34, p < 0.001), hyperglycemia (RI: 3.40, p < 0.001), and brain or spinal meninges involvement (RI: 2.45, p = 0.003). Interactions between elevated WBC count and hyperglycemia (H statistic: 0.231, 95% CI: 0-0.262, p = 0.031), between spinal cord involvement and duration of fever ≥3 days (H statistic: 0.291, 95% CI: 0.035-0.326, p = 0.035), and between brainstem involvement and body temperature (H statistic: 0.313, 95% CI: 0-0.273, p = 0.017) were observed. Therefore, GBT is capable to identify the predictors for severe HFMD and their interaction effects, outperforming conventional regression methods.

Derivation and Validation of a Mortality Risk Score for Severe Hand, Foot and Mouth Disease in China

Outbreaks of hand, foot and mouth disease (HFMD) have increased recently, as has the case fatality rate in severe cases. No scoring system currently exists to predict mortality risk for severe HFMD in previous study. We retrospectively collected laboratory parameters for 546 patients with severe HFMD (a derivation and a validation cohort) at Hunan Children’s Hospitals between January 2012 and December 2014. We developed a mortality risk score comprising four laboratory parameters: blood glucose (GLU), white blood cells (WBC), lactate (LAC), and N-terminal-probrain natriuretic peptide (NT-proBNP). Using an “optimal” cutoff score of 4, the sensitivity, specificity, positive predictive value and negative predictive value was 88.00%, 96.14%, 62.86% and 99.08%, respectively, in the derivation cohort. Among severe HFMD patients with low- and high-risk scores in the validation cohort, case fatality rates were 1.49% and 74.07%, respectively. According to the “optimal” cut-off in the derivation cohort, the sensitivity, specificity, positive predictive value, and negative predictive value were 80.95%, 93.83%, 62.96% and 97.44%, respectively, in the derivation cohort. The mortality risk score demonstrated good discrimination (AUC > 0.9) and calibration (P > 0.05) in both cohorts. The mortality risk score, comprising WBC, GLU, LAC and NT-proBNP, has been demonstrated good discrimination and calibration in the both cohorts.

Serotyping and Genetic Characterization of Hand, Foot, and Mouth Disease (HFMD)-Associated Enteroviruses of No-EV71 and Non-CVA16 Circulating in Fujian, China, 2011-2015

BACKGROUND Hand, foot, and mouth disease (HFMD) is a common contagious disease in infants; it is caused by multiple serotypes of human enterovirus (EV), which belongs to the enterovirus genus of the picornavirus family. According to sentinel surveillance, infection with EVs other than EV71 and CVA 16 have become increasingly common in recent years among HFMD patients, posing new challenges for HFMD control. This study aimed to explore the spectrum of serotypes in the other EVs (non-EV71 and non-CVA16) in Fujian province in southeastern China. MATERIAL AND METHODS We investigated 562 samples from EVs-infected HFMD patients with diagnosis confirmed by real-time RT-PCR with other EVs infection between 2011 and 2015. Nucleotide acid detection and the serotyping of the enteroviruses were also performed. The complete VP1 gene was amplified and sequenced. VP1-based phylogenetic analyses of CVA6, CVA10, CVA4, and CVA2 were also performed. RESULTS Among the samples, 22 serotypes of the other EVs, which belong to 4 species of human enterovirus A-D, were identified. Of the 22 serotypes, CVA6 (57.8%) and CVA10 (21.0%) were most common, followed by CVA4 (6.8%) and CVA2 (2.7%). The other 18 serotypes accounted for 11.7% of samples, none of which exceeded 2%. Among 47 (8.4%) samples from patients with severe HFMD, 10 serotypes were identified and most samples belonged to CVA6 (20/47), followed by CVA10 (11/47). Entire VP1 comparison revealed that overall genetic identities were 96.7%, 96.3%, 94.4%, and 94.9% among strains within CVA6, CVA10, CVA4, and CVA2, respectively. CONCLUSIONS VP1-based phylogenetic analysis for the 4 predominant serotypes indicated various clades or sub-clades, which suggests the complex transmissions of other enteroviruses in Fujian.

High prevalence of coxsackievirus A2 in children with herpangina in Thailand in 2015

Coxsackievirus (CV) is a member of the genus Enterovirus and the family Picornaviridae. CV infection can cause herpangina, a disease characterized by multiple ulcers on the tonsils and soft palate affecting mostly young children. CV strains are categorized by serotypes. Unfortunately, serotypes responsible for infections in patients are often undetermined. This knowledge gap partly contributes to the ineffective prevention and control of CV-associated herpangina in Southeast Asia. To characterize the viral etiology of children presented with herpangina, 295 throat swabs were tested for human enterovirus infection. Using RT-PCR specific for the viral 5'UTR/VP2 and the VP1 regions, two most frequent CV types found in these samples were CV-A2 (33.33%, 40/120) and CV-A4 (15.8%, 19/120). Phylogenetic analysis of the VP1 gene demonstrated that the CV-A2 strains in this study not only were closely related to those previously identified in Asia and Europe, but the majority clustered into a distinct group. Thus, infection predominantly by CV-A2 and CV-A4 caused herpangina in 2015 in Thailand.

Two Genotypes of Coxsackievirus A2 Associated with Hand, Foot, and Mouth Disease Circulating in China since 2008

Coxsackievirus A2 (CV-A2) has been frequently detected and commonly associated with hand, foot, and mouth disease (HFMD) in China since 2008. However, limited sequences of CV-A2 are currently available. As a result, we have been focusing on the genetic characteristics of CV-A2 in the mainland of China during 2008-2015 based on national HFMD surveillance. In this study, 20 CV-A2 strains were isolated and phylogenetic analyses of the VP1 sequences were performed. Full-length genome sequences of two representative CV-A2 isolates were acquired and similarity plot and bootscanning analyses were performed. The phylogenetic dendrogram indicated that all CV-A2 strains could be divided into four genotypes (Genotypes A-D). The CV-A2 prototype strain (Fleetwood) was the sole member of genotype A. From 2008 to 2015, the CV-A2 strains isolated in China dispersed into two different genotypes (B and D). And the genotype D became the dominant circulating strains in China. Strains isolated in Russia and India from 2005 to 2011 converged into genotype C. Intertypic recombination occurred between the Chinese CV-A2 strains and other enterovirus-A donor sequences. This result reconfirmed that recombination is a common phenomenon among enteroviruses. This study helps expand the numbers of whole virus genome sequence and entire VP1 sequence of CV-A2 in the GenBank database for further researcher.

Epidemiological and etiological characteristics of herpangina and hand foot mouth diseases in Jiangsu, China, 2013-2014

Herpangina (HA) and hand, foot, and mouth disease (HFMD) are common infectious diseases caused by human enteroviruses and frequently occurr in young children. Previous published studies have mainly focused on HFMD, while the HA epidemiological and etiological characteristics in mainland China have not been described. From June, 2013 to March, 2014, HA and HFMD patients were monitored in participants from clinical trial of EV-A71 vaccine conducted during 2012-2013. A total of 95 HA patients and 161 HFMD patients were defined. Enteroviruses of HA samples were differentiated into 17 serotypes (EV-A71, CV-A16, CV-A24, E6, CV-B5, CV-A22, CV-A6, CV-A10, CV-B3, E9, CV-A9, CV-B4, CV-B2, E1, E7, E21 and CV-A20), the most common serotypes were EV-A71(10/95,10.5%), CV-A16(4/95,4.2%) and CV-A24(4/95,4.2%); while enteroviruses detected from HFMD samples were classfied into 21 serotypes ( EV-A71, CV-A16, CV-A10, CV-A6, E6, CV-B3, CV-B5, CV-A9, E9, CV-B2, CV-B4, E3, E11, E15, E16, CV-A1, EV-A69, E5, CA22, CA24 and EV99), the most common serotypes were EV-A71(28/161,17.4%), CV-A16(7/161,4.4%) and CV-A10(5/161,3.1%). The first HA epidemic peak occurred in summer and a second smaller peak occurred in January. In HA patients, the body temperature (P < 0.0001) and the incidence of fever (P < 0.05) were significant higher than those in HFMD patients. Between HA and HFMD patients infected with EV-A71, no significant differences were found in age, sex, circulating season, and the viral genome diversity. In summary, we firstly reported the epidemiological and etiological characteristics of HA in mainland China. Developing a multivalent vaccine will be helpful for the control of the HA/HFMD epidemic.

The Epidemiology of Hand, Foot and Mouth Disease in Asia: A Systematic Review and Analysis

CONTEXT

Hand, foot and mouth disease (HFMD) is a widespread pediatric disease caused primarily by human enterovirus 71 (EV-A71) and Coxsackievirus A16 (CV-A16).

OBJECTIVE

This study reports a systematic review of the epidemiology of HFMD in Asia.

DATA SOURCES

PubMed, Web of Science and Google Scholar were searched up to December 2014.

STUDY SELECTION

Two reviewers independently assessed studies for epidemiologic and serologic information about prevalence and incidence of HFMD against predetermined inclusion/exclusion criteria.

DATA EXTRACTION

Two reviewers extracted answers for 8 specific research questions on HFMD epidemiology. The results are checked by 3 others.

RESULTS

HFMD is found to be seasonal in temperate Asia with a summer peak and in subtropical Asia with spring and fall peaks, but not in tropical Asia; evidence of a climatic role was identified for temperate Japan. Risk factors for HFMD include hygiene, age, gender and social contacts, but most studies were underpowered to adjust rigorously for confounding variables. Both community-level and school-level transmission have been implicated, but their relative importance for HFMD is inconclusive. Epidemiologic indices are poorly understood: No supporting quantitative evidence was found for the incubation period of EV-A71; the symptomatic rate of EV-A71/Coxsackievirus A16 infection was from 10% to 71% in 4 studies; while the basic reproduction number was between 1.1 and 5.5 in 3 studies. The uncertainty in these estimates inhibits their use for further analysis.

LIMITATIONS

Diversity of study designs complicates attempts to identify features of HFMD epidemiology.

CONCLUSIONS

Knowledge on HFMD remains insufficient to guide interventions such as the incorporation of an EV-A71 vaccine in pediatric vaccination schedules. Research is urgently needed to fill these gaps.

Molecular epidemiology of the enteroviruses associated with hand, foot and mouth disease/herpangina in Dongguan, China, 2015

Enteroviruses (EVs) are the etiological agents involved in most cases of hand, foot and mouth disease (HFMD) and herpangina (HA). Information on the epidemiology profiles of EVs in China is very limited, as the present surveillance system of China focuses on CAV16 and EV71, and no published data are available in Dongguan. The aim of this study is to determine the prevalence of EVs among patients with HFMD and HA in Dongguan, China, during 2015. A total of 271 clinical stool specimens that were clinically determined to be positive for enteroviruses were genotyped by semi-nested polymerase chain reaction (PCR) for the VP1 genes of EVs. The results showed that a total of 14 enterovirus genotypes were identified among HFMD and HA patients in this study. CVA6 was the most common genotype for HFMD, and CVA2 accounted for the majority of HA cases in this study. Sequence and phylogenetic analysis showed that all of the CVA6 and CVA2 strains identified in our study displayed a close genetic relationship to strains identified in other cities in China. This study also demonstrates that there are associations between particular causative enterovirus genotypes and some clinical symptoms, which may provide useful information for improving case prevention, diagnosis and treatment of HFMD and HA.

Enterovirus infections in Singaporean children: an assessment of neurological manifestations and clinical outcomes

INTRODUCTION

Enterovirus infections in childhood can be associated with significant neurological morbidity. This study aimed to describe the prevalence and range of neurological manifestations, determine the clinical characteristics and assess differences in clinical outcomes for Singaporean children diagnosed with enterovirus infections.

METHODS

In this single-centre, case-control study, clinical data was collected retrospectively from patients admitted to National University Hospital, Singapore, from August 2007 to October 2011 and diagnosed with enterovirus infection, based on the enterovirus polymerase chain reaction test, or cultures from throat and rectal swabs or cerebrospinal fluid samples. The occurrence of neurological manifestations was reviewed and clinical outcomes were assessed.

RESULTS

A total of 48 patients (age range: six days-17.8 years) were included in the study. Neurological manifestations were seen in 75.0% of patients, 63.9% of whom presented with aseptic meningitis. Other neurological manifestations included encephalitis, acute cerebellitis, transverse myelitis and autonomic dysfunction. The incidence of neurological manifestations was significantly higher in patients aged > 1 year as compared to younger patients (p = 0.043). In patients without neurological manifestations, a significantly higher proportion presented with hand, foot and mouth disease and poor feeding. Long-term neurological sequelae were seen in 16.7% of patients with neurological manifestations.

CONCLUSION

A wide spectrum of neurological manifestations resulting in a relatively low incidence of long-term neurological sequelae was observed in our study of Singaporean children with enterovirus infections. As some of these neurological morbidities were severe, careful evaluation of children with neurological involvement is therefore necessary.

Neurological complications and risk factors of cardiopulmonary failure of EV-A71-related hand, foot and mouth disease

From 2010 to 2012, large outbreaks of EV-A71-related- hand foot and mouth disease (HFMD) occurred annually in China. Some cases had neurological complications and were closely associated with fatal cardiopulmonary collapse, but not all children with central nervous system (CNS) involvement demonstrated a poor prognosis. To identify which patients and which neurological complications are more likely to progress to cardiopulmonary failure, we retrospectively studied 1,125 paediatric inpatients diagnosed with EV-A71-related HFMD in Hunan province, including 1,017 cases with CNS involvement. These patients were divided into cardiopulmonary failure (976 people) group and group without cardiopulmonary failure (149 people). A logistic regression analysis was used to compare the clinical symptoms, laboratory test results, and neurological complications between these two groups. The most significant risk factors included young age, fever duration ≥3 days, coma, limb weakness, drowsiness and ANS involvement. Patients with brainstem encephalitis and more CNS-involved regions were more likely to progress to cardiopulmonary failure. These findings can help front-line clinicians rapidly and accurately determine patient prognosis, thus rationally distributing the limited medical resources and implementing interventions as early as possible.

Carnitine palmitoyl transferase 2 polymorphism may be associated with enterovirus 71 severe infection in a Chinese population

Genetic polymorphism in the carnitine palmitoyl transferase 2 (CPT2) gene has been reported to be a susceptibility factor in a number of syndromes of acute encephalopathy with various infectious diseases, but evidence of its effect on enterovirus 71 (EV71) infection is lacking. The goal of this study was to examine the relationship between genetic polymorphism of CPT2 and severity of EV71 infection in a Chinese population. PCR of five exons of the CPT2 gene was carried out to identify single-nucleotide polymorphisms (SNPs) in EV71-infected subjects (n = 333), including mild cases (n = 271) and severe cases (n = 62) as well as healthy controls (n = 328). Blood ATP levels were measured within 24 h of admission. The frequency of the A allele of rs1799821 (P = 0.023) and the G allele of rs2229291 (P = 0.009) in the CPT2 gene was higher in patients with severe EV71 infection. The A-G haplotype of rs1799821and rs2229291 was directly linked to EV71 severe infection risk when compared to all other haplotypes (OR = 2.005, 95 % CI = 1.087-3.700, P = 0.024). The blood ATP levels of severe cases were significantly lower than in mild cases (P < 0.01) and controls (P < 0.01). A significant negative correlation was observed in haplotype A-G between ATP levels and physical findings in severe cases (P < 0.05). These findings suggest that CPT2 polymorphism may be associated with severity of EV71 infection and that the A-G haplotype of the CPT2 gene is involved in the inflammatory process of EV71 infection.

Polysaccharides from Angelica and Astragalus exert hepatoprotective effects against carbon-tetrachloride-induced intoxication in mice

This study aimed to investigate the effects of polysaccharide from Angelica and Astragalus (AAP) on carbon tetrachloride (CCl4) induced liver damage in mice. A total of 120 Kunming mice were randomly distributed among 6 groups comprising (i) the normal control mice, (ii) the CCl4 treatment group, (iii) the bifendate treatment group, (iv) the AAP treatment group, (v) the Angelica sinensis polysaccharide (ASP) treatment group, and (vi) the Astragalus membranaceus polysaccharide (AMP) treatment group. AAP, ASP and AMP were administered to mice treated with CCl4. The activities of alanine transaminase (ALT) and aspartate transaminase (AST) in the serum, and superoxide dismutase (SOD) and malondialdehyde (MDA) in the liver tissues were quantified, as well as the liver index. Hepatic histological changes were observed by staining liver sections with hematoxylin and eosin. Our results show that bifendate, AAP, ASP, and AMP significantly decreased the activities of MDA, AST, and ALT, and enhanced the activity of SOD in CCl4-treated mice. Bifendate, AAP, ASP, and AMP consistently ameliorated the liver injuries induced with CCl4. Notably, the hepatoprotective effect of AAP was stronger than that of bifendate, ASP, or AMP. In addition, AAP alleviated liver inflammation and decreased the liver indexes of mice induced with CCl4. These effects were at least partly due to the antioxidant properties of AAP in scavenging free radicals to ameliorate oxidative stress and to inhibit lipid peroxidation.

EV71 vaccine, a new tool to control outbreaks of hand, foot and mouth disease (HFMD)

On December 3rd 2015, the China Food and Drug Administration (CFDA) approved the first inactivated Enterovirus 71 (EV71) whole virus vaccine for preventing severe hand, foot and mouth disease (HFMD). As one of the few preventive vaccines for children's infectious diseases generated by the developing countries in recent years, EV71 vaccine is a blessing to children's health in China and worldwide. However, there are still a few challenges facing the worldwide use of EV71 vaccine, including the applicability against various EV71 pandemic strains in other countries, international requirements on vaccine production and quality control, standardization and harmonization on different pathogen monitoring and detecting methods, etc. In addition, the affordability of EV71 vaccine in other countries is a factor to be considered in HFMD prevention. Therefore, with EV71 vaccine commercially available, there is still a long way to go before reaching effective protection against severe HFMD after EV71 vaccines enter the market. In this paper, the bottlenecks and prospects for the wide use of EV71 vaccine after its approval are evaluated.

Pyrrolidine dithiocarbamate inhibits enterovirus 71 replication by down-regulating ubiquitin-proteasome system

Enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD). The severe neurological complications caused by EV71 infection and the lack of effective therapeutic medicine underline the importance of searching for antiviral substances. Pyrrolidine dithiocarbamate (PDTC), an antioxidant, has been reported to inhibit the replication of coxsackievirus B (CVB) through dysregulating ubiquitin-proteasome system (UPS). In this study, we demonstrated that PDTC exerted potent antiviral effect on EV71. Viral RNA synthesis, viral protein expression, and the production of viral progeny were significantly reduced by the treatment of PDTC in Vero cells infected with EV71. Similar to the previous report about the inhibitory effect of PDTC on UPS, we found that PDTC treatment led to decreased levels of polyubiquitinated proteins in EV71-infected cells. The inhibitory effect of PDTC on UPS was further confirmed by the increased accumulation of cell cycle regulatory proteins p21 and p53, which are normally degraded through UPS, while the expression levels of both proteins remained unchanged. We also showed that PDTC had no impact on the activity of proteasome. Thus, we demonstrated that the down-regulation of PDTC on UPS was the result of its inhibition on ubiquitination. More importantly, this study provides evidence that the inhibition on UPS was required for the antiviral activity of PDTC, since MG132, a potent proteasome inhibitor, significantly inhibited the cytopathic effect and viral protein synthesis in EV71-infected cells. We also found that the antioxidant property of PDTC did not contribute to its antiviral effect, since N-acetyl-l-cysteine, a potent antioxidant, could not inhibit viral replication. In addition, CPE and viral protein synthesis were not inhibited in the cells pretreated with PDTC 2h before viral infection and then cultured in the media with no PDTC supplement, while the antioxidant effect of PDTC was retained. PDTC also showed significant inhibition on apoptosis induced by EV71 infection when it was applied at the early stage of viral infection. Our results collectively suggest that PDTC could be a potential anti-EV71 compound which possesses both antiviral and anti-apoptotic capacity.

Monitoring antigenic variations of enterovirus 71: implications for virus surveillance and vaccine development

Enterovirus 71 (EV71) causes life-threatening epidemics in Asia and can be phylogenetically classified into three major genogroups (A ∼ C) including 11 genotypes (A, B1 ∼ B5, and C1 ∼ C5). Recently, EV71 epidemics occurred cyclically in Taiwan with different genotypes. In recent years, human studies using post-infection sera obtained from children have detected antigenic variations among different EV71 strains. Therefore, surveillance of enterovirus 71 should include phylogenetic and antigenic analysis. Due to limitation of sera available from children with EV71 primary infection, suitable animal models should be developed to generate a panel of antisera for monitoring EV71 antigenic variations. Twelve reference strains representing the 11 EV71 genotypes were grown in rhabdomyosarcoma cells. Infectious EV71 particles were purified and collected to immunize rabbits. The rabbit antisera were then employed to measure neutralizing antibody titers against the 12 reference strains and 5 recent strains. Rabbits immunized with genogroup B and C viruses consistently have a lower neutralizing antibody titers against genogroup A (≧ 8-fold difference) and antigenic variations between genogroup B and C viruses can be detected but did not have a clear pattern, which are consistent with previous human studies. Comparison between human and rabbit neutralizing antibody profiles, the results showed that ≧ 8-fold difference in rabbit cross-reactive antibody ratios could be used to screen EV71 isolates for identifying potential antigenic variants. In conclusion, a rabbit model was developed to monitor antigenic variations of EV71, which are critical to select vaccine strains and predict epidemics.

Are antibiotics beneficial to children suffering from enterovirus infection complicated with a high C-reactive protein level?

BACKGROUND

Enteroviruses are seasonally prevalent each year in Southeast Asia. Elevated C-reactive protein (CRP) levels have been noted in minor populations of patients, and antibiotics may be prescribed under the impression of a suspected bacterial infection. This prescription might be inappropriate, resulting in further bacterial resistance and medical expense. The aim of this study was to delineate how effective antibiotics are for children suffering from enterovirus infection complicated with a high CRP level.

METHODS

The medical records of children hospitalized between January 2008 and December 2012 with herpangina or hand, foot and mouth disease were reviewed retrospectively. The children enrolled were divided into three groups, A, B, and C, by CRP level, which were <40, 40-80, and ≥ 80 mg/l, respectively. A case-control study of group C divided into subgroups according to the prescription of antibiotics for at least 24h during the admission was conducted for further analysis.

RESULTS

A total 3566 cases were identified; 214 were in group C and 71.0% of them received a prescription for antibiotics. There was a linear trend between a relatively higher CRP level and a higher proportion of antibiotics prescribed in the three groups (p=0.001). In the case-control study, there were no significant differences in age, sex, mean CRP, or febrile days. However, a relatively longer stay of hospitalization was recorded in the subgroup with an antibiotic prescription (p=0.020).

CONCLUSIONS

The present study indicated that antibiotics might not be beneficial in treating these patients, even those with a high CRP level. Clinicians should be more prudent in antibiotic use when no obvious evidence of bacterial infection is found.

Co-circulation and genomic recombination of coxsackievirus A16 and enterovirus 71 during a large outbreak of hand, foot, and mouth disease in Central China

A total of 1844 patients with hand, foot, and mouth disease (HFMD), most of them were children of age 1–3-year-old, in Central China were hospitalized from 2011 to 2012. Among them, 422 were infected with coxsackievirus A16 (CVA16), 334 were infected with enterovirus 71 (EV71), 38 were co-infected with EV71 and CVA16, and 35 were infected with other enteroviruses. Molecular epidemiology analysis revealed that EV71 and CVA16 were detected year-round, but EV71 circulated mainly in July and CVA16 circulated predominantly in November, and incidence of HFMD was reduced in January and February and increased in March. Clinical data showed that hyperglycemia and neurologic complications were significantly higher in EV71-infected patients, while upper respiratory tract infection and C-reactive protein were significantly higher in CVA16-associated patients. 124 EV71 and 80 CVA16 strains were isolated, among them 56 and 68 EV71 strains were C4a and C4b, while 25 and 55 CVA16 strains were B1a and B1b, respectively. Similarity plots and bootscan analyses based on entire genomic sequences revealed that the three C4a sub-genotype EV71 strains were recombinant with C4b sub-genotype EV71 in 2B–2C region, and the three CVA16 strains were recombinant with EV71 in 2A–2B region. Thus, CVA16 and EV71 were the major causative agents in a large HFMD outbreak in Central China. HFMD incidence was high for children among household contact and was detected year-round, but outbreak was seasonal dependent. CVA16 B1b and EV71 C4b reemerged and caused a large epidemic in China after a quiet period of many years. Moreover, EV71 and CVA16 were co-circulated during the outbreak, which may have contributed to the genomic recombination between the pathogens. It should gain more attention as there may be an upward trend in co-circulation of the two pathogens globally and the new role recombination plays in the emergence of new enterovirus variants.

Epidemiology and seroepidemiology of human enterovirus 71 among Thai populations

Background

Human enterovirus 71 (EV71) is an important pathogen caused large outbreaks in Asian-Pacific region with severe neurological complications and may lead to death in young children. Understanding of the etiological spectrum and epidemic changes of enterovirus and population’s immunity against EV71 are crucial for the implementation of future therapeutic and prophylactic intervention.

Results

A total of 1,182 patients who presented with the symptoms of hand foot and mouth disease (67.3%) or herpangina (HA) (16.7%) and admitted to the hospitals during 2008-2013 were tested for enterovirus using pan-enterovirus PCR targeting 5′-untranslated region and specific PCR for viral capsid protein 1 gene. Overall, 59.7% were pan-enterovirus positive comprising 9.1% EV71 and 31.2% coxsackievirus species A (CV-A) including 70.5% CV-A6, 27.6% CV-A16, 1.1% CV-A10, and 0.8% CV-A5. HFMD and HA occurred endemically during 2008-2011. The number of cases increased dramatically in June 2012 with the percentage of the recently emerged CV-A6 significantly rose to 28.4%. Co-circulation between different EV71 genotypes was observed during the outbreak. Total of 161 sera obtained from healthy individuals were tested for neutralizing antibodies (NAb) against EV71 subgenotype B5 (EV71-B5) using microneutralization assay. The seropositive rate of EV71-B5 was 65.8%. The age-adjusted seroprevalence for individuals was found to be lowest in children aged >6 months to 2 years (42.5%). The seropositive rate remained relatively low in preschool children aged > 2 years to 6 years (48.3%) and thereafter increased sharply to more than 80% in individuals aged > 6 years.

Conclusions

This study describes longitudinal data reflecting changing patterns of enterovirus prevalence over 6 years and demonstrates high seroprevalences of EV71-B5 NAb among Thai individuals. The rate of EV71 seropositive increased with age but without gender-specific significant difference. We identified that relative lower EV71 seropositive rate in early 2012 may demonstrate widely presented of EV71-B5 in the population before account for a large outbreak scale epidemic occurred in 2012 with due to a relatively high susceptibility of the younger population.

Antiviral activity of GuiQi polysaccharides against enterovirus 71 in vitro

In this study, we have investigated the antiviral activity of GuiQi polysaccharides (GQP) upon enterovirus 71 (EV71) in vitro. An assay using methyl thiazolyl tetrazolium (MTT), and analyses of cytopathic effects (CPE) were used to examine the antiviral activity of GQP upon Vero cells infected with EV71. The results revealed that GQP at concentrations below 31.2 μg/mL exhibited significant antiviral effects upon EV71 when applied under three different experimental protocols. GQP was most strongly active in preventing the adsorption of EV71 to target cells and in this respect it was significantly more effective than ribavirin. In addition, it was clear that GQP could inhibit viral replication when added to cells 2 h after infection, but if added at the point of infection its effect was weak. GQP is considered to be less toxic than ribavirin, and may warrant further evaluation as a possible agent in the treatment of hand, foot and mouth disease (HFMD).

Association of functional polymorphisms in the MxA gene with susceptibility to enterovirus 71 infection

Myxovirus resistance A (MxA) is an antiviral protein induced by type I interferons α and β (IFN-α and IFN-β) that can inhibit virus replication. We examined whether the MxA polymorphisms were related to the risk and severity of enterovirus 71 (EV71) infection in Chinese populations. The MxA C-123A and G-88T polymorphisms were genotyped in two independent case–control populations in China by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analysis. Multivariate logistic regression analysis was used to calculate adjusted odds ratios (ORs) and 95 % confidence intervals (95 % CIs). MxA messenger RNA was quantified by real-time quantitative PCR in peripheral blood mononuclear cells (PBMCs) from 45 healthy children and 19 patients with EV71 infection. Significantly decreased susceptibility to EV71 infection was observed for the -123A allele and -88T allele carriers, with ORs (95 % CIs) estimated as 0.56 (0.39–0.81) and 0.64 (0.47–0.88), respectively, in the northern population. This association was confirmed in the southern population, with ORs (95 % CIs) estimated as 0.58 (0.38–0.89) and 0.67(0.47–0.95), respectively. The A_-123T_-88 haplotype was also significantly associated with lower risk of EV71 infection in both the northern (OR = 0.62; 95 % CI = 0.44–0.85) and the southern population (OR = 0.63; 95 % CI = 0.43–0.92). Furthermore, we observed higher MxA messenger RNA levels in IFNβ1a-stimulated PBMCs from the -123A or -88T allele carriers compared with that from nocarriers. Our findings suggest that polymorphisms in the MxA promoter may play a role in mediating the susceptibility to EV71 infection in Chinese population.

Inhibition of enterovirus 71 infections and viral IRES activity by Fructus gardeniae and geniposide

Fructus gardeniae has long been used by traditional Chinese medical practitioners for its anti-inflammatory, anti-oxidant, anti-tumor and anti-hyperlipidemic characteristics. Here we describe our finding that F. gardeniae greatly reduces anti-enterovirus 71 (EV71) activity, resulting in significant decreases in EV71 virus yields, EV71 infections, and internal ribosome entry site activity. We also found that geniposide, a primary F. gardeniae component, inhibited both EV71 replication and viral IRES activity. Our data suggest the presence of a mechanism that blocks viral protein translation. According to our findings, F. gardeniae and geniposide deserve a closer look as potential chemopreventive agents against EV71 infections.

Circulation of Coxsackievirus A10 and A6 in hand-foot-mouth disease in China, 2009-2011

Coxsackieviruses A10 (CV-A10) and A6 (CV-A6) have been associated with increasingly occurred sporadic hand-foot-mouth disease (HFMD) cases and outbreak events globally. However, our understanding of epidemiological and genetic characteristics of these new agents remains far from complete. This study was to explore the circulation of CV-A10 and CV-A6 in HFMD and their genetic characteristics in China. A hospital based surveillance was performed in three heavily inflicted regions with HFMD from March 2009 to August 2011. Feces samples were collected from children with clinical diagnosis of HFMD. The detection and genotyping of enteroviruses was performed by real-time PCR and sequencing of 5′UTR/VP1 regions. Phylogenetic analysis and selection pressure were performed based on the VP1 sequences. Logistic regression model was used to identify the effect of predominant enterovirus serotypes in causing severe HFMD. The results showed 92.0% of 1748 feces samples were detected positive for enterovirus, with the most frequently presented serotypes as EV-71 (944, 54.0%) and CV-A16 (451, 25.8%). CV-A10 and CV-A6 were detected as a sole pathogen in 82 (4.7%) and 44 (2.5%) cases, respectively. Infection with CV-A10 and EV-71 were independently associated with high risk of severe HFMD (OR = 2.66, 95% CI: 1.40–5.06; OR = 4.81, 95% CI: 3.07–7.53), when adjusted for age and sex. Phylogenetic analysis revealed that distinct geographic and temporal origins correlated with the gene clusters based on VP1 sequences. An overall ω value of the VP1 was 0.046 for CV-A10 and 0.047 for CV-A6, and no positively selected site was detected in VP1 of both CV-A10 and CV-A6, indicating that purifying selection shaped the evolution of CV-A10 and CV-A6. Our study demonstrates variety of enterovirus genotypes as viral pathogens in causing HFMD in China. CV-A10 and CV-A6 were co-circulating together with EV-71 and CV-A16 in recent years. CV-A10 infection might also be independently associated with severe HFMD.

Enteroviruses isolated from herpangina and hand-foot-and-mouth disease in Korean children

Hand-foot-and-mouth disease (HFMD) and herpangina are commonly prevalent illness in young children. They are similarly characterized by lesions on the skin and oral mucosa. Both diseases are associated with various enterovirus serotypes. In this study, enteroviruses from patients with these diseases in Korea in 2009 were isolated and analyzed. Demographic data for patients with HFMD and herpangina were compared and all enterovirus isolates were amplified in the VP1 region by reverse transcription-polymerase chain reaction and sequenced. Among the enterovirus isolates, prevalent agents were coxsackievirus A16 in HFMD and coxsackievirus A5 in herpangina. More prevalent months for HFMD were June (69.2%) and May (11.5%), and June (40.0%) and July (24.0%) for herpangina. Age prevalence of HFMD patients with enterovirus infection was 1 year (23.1%), 4 years (19.2%), and over 5 years (19.2%). However, the dominant age group of herpangina patients with enterovirus infection was 1 year (48.0%) followed by 2 years (28.0%). Comparison of pairwise VP1 nucleotide sequence alignment of all isolates within the same serotypes revealed high intra-type variation of CVA2 isolates (84.6–99.3% nucleotide identity). HFMD and herpangina showed differences in demographic data and serotypes of isolated enteroviruses, but there was no notable difference in amino acid sequences by clinical syndromes in multiple comparison of the partial VP1 gene sequence.