Clinical spectrum of enterovirus 71 infection in children in southern Taiwan, with an emphasis on neurological complications

Factors associated with fatal outcome of children with enterovirus A71 infection: a case series

Enterovirus A-71 (EV-A71) may be fatal, but the natural history, symptoms, and signs are poorly understood. This study aimed to examine the natural history of fatal EV-A71 infection and to identify the symptoms and signs of early warning of deterioration. This was a clinical observational study of fatal cases of EV-A71 infection treated at five Chinese hospitals between 1 January 2010 and 31 December 2012. We recorded and analysed 91 manifestations of EV-A71 infection in order to identify early prognosis indicators. There were 54 fatal cases. Median age was 21.5 months (Q1−Q3: 12–36). The median duration from onset to death was 78.5 h (range, 6 to 432). The multilayer perceptron analysis showed that ataxia respiratory, ultrahyperpyrexia, excessive tachycardia, refractory shock, absent pharyngeal reflex, irregular respiratory rhythm, hyperventilation, deep coma, pulmonary oedema and/or haemorrhage, excessive hypertension, tachycardia, somnolence, CRT extension, fatigue or sleepiness and age were associated with death. Autopsy findings (n = 2) showed neuronal necrosis, softening, perivascular cuffing, colloid and neuronophagia phenomenon in the brainstem. The fatal cases of enterovirus A71 had neurologic involvement, even at the early stage. Direct virus invasion through the neural pathway and subsequent brainstem damage might explain the rapid progression to death.

Severity and burden of hand, foot and mouth disease in Asia: a modelling study

Background

Hand, foot and mouth disease (HFMD) affects millions of children across Asia annually, leading to an increase in implemented control policies such as surveillance, isolation and social distancing in affected jurisdictions. However, limited knowledge of disease burden and severity causes difficulty in policy optimisation as the associated economic cost cannot be easily estimated. We use a data synthesis approach to provide a comprehensive picture of HFMD disease burden, estimating infection risk, symptomatic rates, the risk of complications and death, and overall disability-adjusted life-year (DALY) losses, along with associated uncertainties.

Methods

Complementary data from a variety of sources were synthesised with mathematical models to obtain estimates of severity of HFMD. This includes serological and other data extracted through a systematic review of HFMD epidemiology previously published by the authors, and laboratory investigations and sentinel reports from Singapore's surveillance system.

Results

HFMD is estimated to cause 96 900 (95% CI 40 600 to 259 000) age-weighted DALYs per annum in eight high-burden countries in East and Southeast Asia, with the majority of DALYs attributed to years of life lost. The symptomatic case hospitalisation rate of HFMD is 6% (2.8%-14.9%), of which 18.7% (6.7%-31.5%) are expected to develop complications. 5% (2.9%-7.4%) of such cases are fatal, bringing the overall case fatality ratio to be 52.3 (24.4-92.7) per 100 000 symptomatic infections. In contrast, the EV-A71 case fatality ratio is estimated to be at least 229.7 (75.4-672.1) per 100 000 symptomatic cases. Asymptomatic rate for EV-A71 is 71.4% (68.3%-74.3%) for ages 1-4, the years of greatest incidence.

Conclusion

Despite the high incidence rate of HFMD, total DALY due to HFMD is limited in comparison to other endemic diseases in the region, such as dengue and upper respiratory tract infection. With the majority of DALY caused by years of life lost, it is possible to mitigate most with increased EV-A71 vaccine coverage.

The association between acute flaccid myelitis (AFM) and Enterovirus D68 (EV-D68) - what is the evidence for causation?

BackgroundEnterovirus D68 (EV-D68) has historically been a sporadic disease, causing occasional small outbreaks of generally mild infection. In recent years, there has been evidence of an increase in EV-D68 infections globally. Large outbreaks of EV-D68, with thousands of cases, occurred in the United States, Canada and Europe in 2014. The outbreaks were associated temporally and geographically with an increase in clusters of acute flaccid myelitis (AFM).
Aims: We aimed to evaluate a causal association between EV-D68 and AFM. 
Methods: Using data from the published and grey literature, we applied the Bradford Hill criteria, a set of nine principles applied to examine causality, to evaluate the relationship between EV-D68 and AFM. Based on available evidence, we defined the Bradford Hill Criteria as being not met, or met minimally, partially or fully. 
Results: Available evidence applied to EV-D68 and AFM showed that six of the Bradford Hill criteria were fully met and two were partially met. The criterion of biological gradient was minimally met. The incidence of EV-D68 infections is increasing world-wide. Phylogenetic epidemiology showed diversification from the original Fermon and Rhyne strains since the year 2000, with evolution of a genetically distinct outbreak strain, clade B1. Clade B1, but not older strains, is associated with AFM and is neuropathic in animal models. 
Conclusion: While more research is needed on dose-response relationship, application of the Bradford Hill criteria supported a causal relationship between EV-D68 and AFM.

Neuro-Magnetic Resonance Imaging in Hand, Foot, and Mouth Disease: Finding in 412 Patients and Prognostic Features

Purpose

The aims of this study were to describe the neuroimaging findings in hand, foot, and mouth disease and determine those who may provide prognosis.

Material and Methods

Magnetic resonance imaging scans in 412 severe hand, foot, and mouth disease between 2009 and 2014 were retrospectively evaluated. The patients who had the neurological signs were followed for 6 months to 1 year. According to the good or poor prognosis, 2 groups were categorized. The incidence of lesions in different sites between the 2 groups was compared, and multivariate analysis was used to look for risk factors.

Results

The major sites of involvement for all patients with percentages were the medulla oblongata (16.1%), spinal anterior nerve roots (12.4%), thoracic segments (11.1%), brain or spinal meninges (8.3%), and so on. There were 347 patients (84.2%) with good prognosis and 65 (15.8%) with poor prognosis in the follow-up. There was a significantly higher rate of lesions involving the cerebral white substance, thalamus, medulla oblongata, pons, midbrain, and spinal cord in the group with poor prognosis. Multivariate analysis showed 2 independent risk factors associated with poor prognosis: lesions located in the medulla oblongata (P < 0.015) and spinal cord (P < 0.001) on magnetic resonance imaging; the latter was the most significant prognostic factor (odds ratio, 29.11; P < 0.001).

Conclusions

We found that the distribution patterns for all patients mainly involved the medulla oblongata, spinal anterior nerve roots, thoracic segments, and brain or spinal meninges. Our findings suggested that patients with lesions located in the medulla oblongata and spinal cord may be closely monitored for early intervention and meticulous management. For children with the symptom of nervous system, they are strongly recommended for magnetic resonance examination.

Risk factors for death in children with critical and severe hand-foot-and-mouth disease in Chongqing, China: An observational study

Hand-foot-and-mouth disease (HFMD) is a common childhood infection that may lead to serious complications and even death. Globally, epidemics of HFMD are increasing each year, especially in China. This study aimed to identify risk factors for death in children with critical and severe HFMD in Chongqing, China.We performed an observational study involving patients with critical and severe HFMD admitted to the Children's Hospital of Chongqing Medical University from January 2009 to December 2016. Overall, 179 patients aged 2 months to 16 years, were included; 127 died (non-survival group) and 52 survived (survival group); the case-fatality rate was 70.94%. Data comprising demographic characteristics, clinical symptoms and signs, and laboratory findings were collected. Non-conditional logistic regression analysis was performed to determine the risk factors for death.Univariate analysis showed that sex, coma, light-reflex insensitivity, pulmonary rales, pulmonary edema or hemorrhage, cold extremities, tachycardia, hypotension, white blood cell count, blood glucose concentration, serum lactate level, creatine kinase-MB isoenzyme level, and acidosis were associated with death (P < .05). Logistic regression analysis identified female sex (odds ratio [OR] 9.6, 95% confidence interval [CI] 3.0-30.2), light-reflex insensitivity (OR 4.4, 95% CI 1.4-13.1), tachycardia (OR 1.05, 95% CI 1.03-1.07), and higher serum lactate levels (OR 1.14, 95% CI 1.19-1.69) as independent risk factors; and longer onset-to-hospitalization time (OR 0.43, 95% CI 0.28-0.66) as an independent protective factor for death in children with critical and severe HFMD.Female sex, light-reflex insensitivity, tachycardia, and higher serum lactate level are potential independent risk factors; and longer onset-to-hospitalization time is possibly an independent protective factor for death in patients with critical and severe HFMD.

Immunopathogenesis and Virus-Host Interactions of Enterovirus 71 in Patients with Hand, Foot and Mouth Disease

Enterovirus 71 (EV71) is a global infectious disease that affects millions of people. The virus is the main etiological agent for hand, foot, and mouth disease with outbreaks and epidemics being reported globally. Infection can cause severe neurological, cardiac, and respiratory problems in children under the age of 5. Despite on-going efforts, little is known about the pathogenesis of EV71, how the host immune system responds to the virus and the molecular mechanisms behind these responses. Moreover, current animal models remain limited, because they do not recapitulate similar disease patterns and symptoms observed in humans. In this review the role of the host-viral interactions of EV71 are discussed together with the various models available to examine: how EV71 utilizes its proteins to cleave host factors and proteins, aiding virus replication; how EV71 uses its own viral proteins to disrupt host immune responses and aid in its immune evasion. These discoveries along with others, such as the EV71 crystal structure, have provided possible targets for treatment and drug interventions.

Neurotropism In Vitro and Mouse Models of Severe and Mild Infection with Clinical Strains of Enterovirus 71

Enterovirus 71 (EV71) is a common etiological agent of hand, foot, and mouth disease and fatal neurological diseases in children. The neuropathogenicity of severe EV71 infection has been documented, but studies comparing mouse models of severe and mild EV71 infection are lacking. The aim of the study was to investigate the neurovirulence of EV71 strains and the differences in serum cytokine and chemokine levels in mouse models of severe and mild EV71 infection. Nine EV71 isolates belonging to the C4 subgenogroup (proposed as genotype D) displayed infectivity in human neuroblastoma SK-N-SH cells; moreover, ultrastructural observation confirmed viral particle replication. The survival rate of the severe model was 71.43% (5/7), and 60% (3/5) of the surviving severe model mice displayed sequelae of paralysis, whereas the only symptom in mild model mice was ruffled fur. Dynamic detection of serum cytokine and chemokine levels demonstrated that interleukin (IL)-5, IL-13, IL-6, monocyte chemotactic protein 1 (MCP-1), and chemokine (C-C motif) ligand 5 (also called Regulated upon Activation, Normal T-cell Expressed, and Secreted (CCL5/RANTES) were significantly up-regulated at the early period of infection, indicating that these factors might herald a severe outcome. Our findings suggest that elevated cytokines and chemokines may have potential value as prognostic markers in mouse models.

Alanine scanning mutagenesis of SP70 epitope in characterizing species‑specific antibodies induced by enterovirus 71‑based antigens

The enterovirus 71 (EV71) SP70 epitope, derived from amino acids 208‑222 of VP1, is a neutralizing epitope. The present study aimed to assess the inter‑species differences of the antibodies induced by EV71‑based antigens in responses to SP70 mutant peptides. BALB/c mice and Lou/C rats were immunized with EV71 SP70. Monoclonal antibodies (Mabs) were produced by hybridoma clones. Serum polyclonal antibodies (Pabs) were produced from BALB/c mice and New Zealand white rabbits immunized with recombinant EV71 VP1 (rEV71‑VP1) protein or inactivated EV71. Micro‑neutralization and immunofluorescence assays were used to evaluate the capacity of the antibodies to bind to EV71. Reactivity of Mabs and Pabs to mutated SP70 were determined by alanine scanning mutagenesis. Furthermore, serums from EV71‑infected patients were collected to examine the affinity of SP70 antibody in the serum to mutated SP70, using competitive ELISA. The binding affinity of mouse Mabs to the SP70 epitope was increased by alanine substitution at sites of 210, 212, 213, 214, and 221. The binding affinity of rat Mabs to the SP70 epitope was increased by alanine substitution at sites 210, 217, 219, and 221. Mouse serum Pabs elicited by inactivated EV71 bound wild‑type SP70, but lost affinity for mutated peptides. Conversely, rabbit serum Pabs elicited by inactivated EV71 robustly recognized SP70 mutants. Mouse serum Pabs elicited by rEV71‑VP1 presented the same trend as mouse Mabs. Mutations at sites 214, 215, and 217 led to loss of recognition by rabbit Pabs elicited by rEV71‑VP1, while most mutations did not influence antibody binding. Compared with the wild‑type, mutations at the sites 209, 219 and 221 of SP70 lead to increased affinity with the serum antibodies produced by the EV71‑infected patients. Antibody responses triggered by inactivated EV71, rEV71‑VP1 and EV71 SP70 differed among species in neutralizing capacity and affinity for SP70 mutant peptides.

Development of single-step multiplex real-time RT-PCR assays for rapid diagnosis of enterovirus 71, coxsackievirus A6, and A16 in patients with hand, foot, and mouth disease

Real-time reverse-transcription polymerase chain reaction (rRT-PCR) to detect enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) has facilitated the rapid and accurate identification of the two most common etiological agents underlying hand, foot, and mouth disease (HFMD). However, the worldwide emergence of CV-A6 infection in HFMD necessitates development of an improved multiplex rRT-PCR method. To rapidly determine the etiology of HFMD, two rRT-PCR assays using TaqMan probes were developed to differentiate among three selected common enteroviruses (EV-A71, CV-A16 and CV-A6) and to enable broad detection of enteroviruses (pan-enterovirus assay). No cross-reactions were observed with other RNA viruses examined. The detection limits of both assays were 10 copies per microliter for EV-A71, CV-A6 and CV-A16, and pan-enterovirus. The methods showed high accuracy (EV-A71, 90.6%; CV-A6, 92.0%; CV-A16, 100%), sensitivity (EV-A71, 96.5%; CV-A6, 95.8%; CV-A16, 99.0%), and specificity (EV-A71, 100%; CV-A6, 99.9%; CV-A16, 99.9%) in testing clinical specimens (n=1049) during 2014-2016, superior to those of conventional RT-PCR. Overall, the multiplex rRT-PCR assays enabled highly sensitive detection and rapid simultaneous typing of EV-A71, CV-A6 and CV-A16, and enteroviruses, rendering them feasible and attractive methods for large-scale surveillance of enteroviruses associated with HFMD outbreaks.

Exosome-mediated miR-146a transfer suppresses type I interferon response and facilitates EV71 infection

Exosomes can transfer genetic materials between cells. Their roles in viral infections are beginning to be appreciated. Researches have shown that exosomes released from virus-infected cells contain a variety of viral and host cellular factors that are able to modulate recipient’s cellular response and result in productive infection of the recipient host. Here, we showed that EV71 infection resulted in upregulated exosome secretion and differential packaging of the viral genomic RNA and miR-146a into exosomes. We provided evidence showing that miR-146a was preferentially enriched in exosomes while the viral RNA was not in infected cells. Moreover, the exosomes contained replication-competent EV71 RNA in complex with miR-146a, Ago2, and GW182 and could mediate EV71 transmission independent of virus-specific receptor. The exosomal viral RNA could be transferred to and replicate in a new target cell while the exosomal miR-146a suppressed type I interferon response in the target cell, thus facilitating the viral replication. Additionally, we found that the IFN-stimulated gene factors (ISGs), BST-2/tetherin, were involved in regulating EV71-induced upregulation of exosome secretion. Importantly, in vivo study showed that exosomal viral RNA exhibited differential tissue accumulation as compared to the free virus particles. Together, our findings provide evidence that exosomes secreted by EV71-infected cells selectively packaged high level miR-146a that can be functionally transferred to and facilitate exosomal EV71 RNA to replicate in the recipient cells by suppressing type I interferon response.

Exosomes are small membrane-encapsulated vesicles that secrete into the extracellular environment. Various proteins and RNA molecules have been identified in exosomes whose content reflects the physiological or pathological state of the host cells. Researches have shown that exosomes released from virus-infected cells contain a variety of viral and host cellular factors that are able to modulate recipient’s cellular responses and result in productive infection of the recipient host. Here, we showed that Enterovirus 71 (EV71), a non-enveloped, single-strand positive sense RNA virus that belongs to the family Picornaviridae and is a major etiologic agent of hand-foot and-mouth disease (HFMD), could stimulate exosome secretion and differential packaging of the viral genomic RNA and miR-146a into exosomes. The exosomal viral RNA could be transferred to and replicate in a new target cell while the exosomal miR-146a suppressed type I interferon response in the target cell, thus facilitating the viral replication. Importantly, in vivo study showed that exosomal viral RNA exhibited differential tissue accumulation as compared to the free virus particles. We postulate that the preferential packaging of miRNA-146a into exosome is a viral strategy of suppressing host innate immunity upon infection and the exosomal EV 71 RNA may play an important pathogenic role in the infection.

Cost-effectiveness of a national enterovirus 71 vaccination program in China

BACKGROUND AND AIMS

Enterovirus 71 (EV71) has caused great morbidity, mortality, and use of health service in children younger than five years in China. Vaccines against EV71 have been proved effective and safe by recent phase 3 trials and are now available in China. The purpose of this study was to evaluate the health impact and cost-effectiveness of a national EV71 vaccination program in China.

METHODS

Using Microsoft Excel, a decision model was built to calculate the net clinical and economic outcomes of EV71 vaccination compared with no EV71 vaccination in a birth cohort of 1,000,000 Chinese children followed for five years. Model parameters came from published epidemiology, clinical and cost data.

RESULTS

In the base-case, vaccination would annually avert 37,872 cases of hand, foot and mouth disease (HFMD), 2,629 herpangina cases, 72,900 outpatient visits, 6,363 admissions to hospital, 29 deaths, and 945 disability adjusted life years. The break-even price of the vaccine was $5.2/dose. When the price was less than $8.3 or $14.6/dose, the vaccination program would be highly cost-effective or cost-effective, respectively (incremental cost-effectiveness ratio less than or between one to three times China GDP per capita, respectively). In one-way sensitivity analyses, the HFMD incidence was the only influential parameter at the price of $5/dose.

CONCLUSIONS

Within the price range of current routine vaccines paid by the government, a national EV71 vaccination program would be cost-saving or highly cost-effective to prevent EV71 related morbidity, mortality, and use of health service among children younger than five years in China. Policy makers should consider including EV71 vaccination as part of China's routine childhood immunization schedule.

Sophocarpine against enterovirus 71 in vitro

Sophocarpine (SCA) is a bioactive alkaloid present in Sophoraflavescens Ait. The present study demonstrated that SCA inhibited enterovirus 71 (EV71) infection in Vero cells. The results indicated that the 50% cytotoxicity concentration of SCA for Vero cells was 1,346 µg/ml, and the 50% inhibition concentration of SCA against EV71 was 350 µg/ml. SCA produced a marked inhibitory effect against EV71 when the Vero cells were treated with SCA prior to infection with the virus. Additionally, SCA was effective against EV71 when the Vero cells were infected with EV71 (100xTCID₅₀) that had been treated with SCA for 2 h, and was effective when the Vero cells were infected with EV71 (100xTCID₅₀) at 37°C under 5% CO₂ for 2 h prior to treatment with SCA for 2 h. SCA was demonstrated to inhibit the attachment and penetration of EV71 and was more effective at inhibiting attachment. The assay additionally verified that SCA suppressed the replication of viral genomic RNA and indicated that SCA may inhibit EV71 infection in vitro.

Flos Farfarae Inhibits Enterovirus 71-Induced Cell Injury by Preventing Viral Replication and Structural Protein Expression

Enterovirus 71 (EV71) infection can cause airway symptoms, brainstem encephalitis, neurogenic shock, and neurogenic pulmonary edema with high morbidity and mortality. There is no proven therapeutic modality. Flos Farfarae is the dried flower bud of Tussilago farfara L. that has been used to manage airway illnesses for thousands of years. It has neuro-protective activity and has been used to manage neuro-inflammatory diseases. However, it is unknown whether Flos Farfarae has activity against EV71-induced neuropathy. The current study used both human foreskin fibroblast (CCFS-1/KMC) and human rhabdomyosarcoma (RD) cell lines to test the hypothesis that a hot water extract of Flos Farfarae could effectively inhibit EV71 infection. The authenticity of Flos Farfarae was confirmed by HPLC-UV fingerprint. Through plaque reduction assays and flow cytometry, Flos Farfarae was found to inhibit EV71 infection ([Formula: see text]). Inhibition of viral replication and protein expression were further confirmed by reverse transcription polymerase chain reaction (RT-PCR) and quantitative RT-PCR (qRT-PCR), and western blot, respectively. The estimated IC[Formula: see text]s were 106.3[Formula: see text][Formula: see text]g/mL in CCFS-1/KMC, and 15.0[Formula: see text][Formula: see text]g/mL in RD cells. Therefore, Flos Farfarae could be beneficial to inhibit EV71 infection by preventing viral replication and structural protein expression.

Enterovirus 71 induces apoptosis by directly modulating the conformational activation of pro-apoptotic protein Bax

Enterovirus 71 (EVA71), a virus of the genus Enterovirus in the family Picornaviridae, is one of the main causative agents of hand, foot and mouth disease in infected infants and young children. In this study, we report that cells with EVA71 infection exhibit increased levels of cytochrome c release and caspase-3 activation. EVA71 infection induces the conformational activation of pro-apoptotic protein Bax and the subsequent formation of oligomers of Bax in mitochondria. Inhibitors that block caspase-8 activation cannot inhibit apoptosis induced by EVA71 infection. Importantly, cells with Bax but not Bak or caspase-8 knockdown show resistance to apoptosis induced by EVA71 infection. Mitochondria isolated from EVA71-infected cells display clear Bax-binding ability and the subsequent release of cytochrome c. Therefore, these results indicate that EVA71 infection directly impacts the mitochondrial apoptotic pathway by modulating the recruitment and activation of Bax.

The Preferential Infection of Astrocytes by Enterovirus 71 Plays a Key Role in the Viral Neurogenic Pathogenesis

The pathological manifestations of fatal cases of human hand, foot, and mouth disease (HFMD) caused by enterovirus 71 (EV71) are characterized by inflammatory damage to the central nervous system (CNS). Here, the dynamic distribution of EV71 in the CNS and the subsequent pathological characteristics within different regions of neonatal rhesus macaque brain tissue were studied using a chimeric EV71 expressing green fluorescence protein. The results were compared with brain tissue obtained from the autopsies of deceased EV71-infected HFMD patients. These observations suggested that the virus was prevalent in areas around the blood vessels and nerve nuclei in the brain stem and showed a preference for astrocytes in the CNS. Interestingly, infected astrocytes within the in vivo and in vitro human and macaque systems exhibited increased expression of excitatory neurotransmitters and cytokines that also stimulated the neuronal secretion of the excitatory neurotransmitters noradrenalin and adrenalin, and this process most likely plays a role in the pathophysiological events that occur during EV71 infection.

Neurogenic pulmonary edema combined with febrile seizures in early childhood-A report of two cases

Neurogenic pulmonary edema (NPE) is a clinical entity that can occur following central nervous system disorders. However, NPE occurs quite rarely in early childhood, and there has only been one report about pediatric NPE associated with febrile seizures. Two cases are reported here. One case involved a 2-year-old girl who presented with febrile seizures, which rapidly progressed to severe NPE. Since the NPE occurred in the emergency department room, the patient was able to be resuscitated via immediate endotracheal intubation. The other case involved an 11-month-old boy who developed respiratory distress following a 50-min episode of febrile status epilepticus. Both patients required respiratory management in the intensive care unit. However their conditions were dramatically improved within several days and fully recovered without any sequelae.

Enterovirus 71 infection and neurological complications

Since the outbreak of the enterovirus 71 (EV71) infection in Malaysia in 1997, large epidemics of EV71 have occurred in the Asia-Pacific region. Many children and infants have died from serious neurological complications during these epidemics, and EV71 infection has become a serious public health problem in these areas. EV71 infection causes hand, foot and mouth disease (HFMD) in children, and usually resolves spontaneously. However, EV71 occasionally involves the central nervous system (CNS), and induces diverse neurological complications such as brainstem encephalitis, aseptic meningitis, and acute flaccid paralysis. Among those complications, brainstem encephalitis is the most critical neurological manifestation because it can cause neurogenic pulmonary hemorrhage/edema leading to death. The characteristic clinical symptoms such as myoclonus and ataxia, cerebrospinal fluid (CSF) pleocytosis, and brainstem lesions on magnetic resonance imaging, in conjunction with the skin rash of HFMD and the isolation of EV71 from a stool, throat-swab, or CSF sample are typical findings indicating CNS involvement of EV71 infection. Treatment with intravenous immunoglobulin and milrinone are recommended in cases with severe neurological complications from EV71 infection, such as brainstem encephalitis. Despite the recent discovery of receptors for EV71 in human cells, such as the scavenger receptor B2 and P-selection glycoprotein ligand 1, it is not known why EV71 infection predominantly involves the brainstem. Recently, 3 companies in China have completed phase III clinical trials of EV71 vaccines. However, the promotion and approval of these vaccines in various countries are problems yet to be resolved.

The Current Status of the Disease Caused by Enterovirus 71 Infections: Epidemiology, Pathogenesis, Molecular Epidemiology, and Vaccine Development

Enterovirus 71 (EV71) infections have a major public health impact in the Asia-Pacific region. We reviewed the epidemiology, pathogenesis, and molecular epidemiology of EV71 infection as well as EV71 vaccine development. Previous studies were found using the search terms "enterovirus 71" and "epidemiology" or "pathogenesis" or "molecular epidemiology" or "vaccine" in Medline and PubMed. Articles that were not published in the English language, manuscripts without an abstract, and opinion articles were excluded from the review. The reported epidemiology of cases caused by EV71 infection varied from country to country; seasonal variations in incidence were observed. Most cases of EV71 infection that resulted in hospitalization for complications occurred in children less than five years old. The brainstem was the most likely major target of EV71 infection. The emergence of the EV71 epidemic in the Asia-Pacific region has been associated with the circulation of different genetic lineages (genotypes B3, B4, C1, C2, and C4) that appear to be undergoing rapid evolutionary changes. The relationship between the gene structure of the EV71 virus and the factors that ensure its survival, circulation, and evasion of immunity is still unknown. EV71 infection has emerged as an important global public health problem. Vaccine development, including the development of inactivated whole-virus live attenuated, subviral particles, and DNA vaccines, has been progressing.

Changes in enterovirus serotype constituent ratios altered the clinical features of infected children in Guangdong Province, China, from 2010 to 2013

Background

Enterovirus (EV)-related hand, foot, and mouth disease/herpangina (HFMD/HA) has been prevalent in Guangdong Province, China, since 2010.

Methods

Clinical data for EV-related HFMD/HA inpatients admitted to the Department of Paediatrics of Zhujiang Hospital from 2010 to 2013 were retrospectively reviewed. The corresponding EV serotypes were also determined by reverse transcription-polymerase chain reaction or BLAST analysis of the sequenced partial lengths of the viral protein1/5′-untranslated region.

Results

A total of 867 eligible inpatients admitted during 2010–2013 were included in the study. Of these, the serotype of the responsible EV was successfully identified in 824 cases. The incidence of enterovirus 71 (EV71) infection amongst pediatric HFMD/HA inpatients decreased dramatically from 55.5 % in 2010 to 8.1 % in 2013, with a similar decrease recorded for coxsackievirus A16 (CVA16). However, the incidence of non-EV71/CVA16 infection increased from 30.0 % in 2010 to 83.8 % in 2013. We noted that the types of infection caused by different EV serotypes varied: EV71 was responsible for 100 % of the paralysis cases (26/26), 84.6 % of the deaths (11/13), and 84.1 % of cases with severe central nervous system involvement (SCNSI) (74/88); echovirus contributed to 16.4 % of the deaths (2/13) and 4.4 % of the SCNSI cases; and coxsackievirus accounted for only 2.2 % of the SCNSI cases (2/90). The clinical features of HFMD/HA cases varied greatly during the time period examined, with drastic changes in the hospitalization rates (45.1, 63.7, 36.4, and 19.1 % for 2010, 2011, 2012, and 21013, respectively), mortality rates (2.3, 0.9, 2.5, and 0.0 %, respectively), paralysis (5.1, 1.2, 5.4, and 0.0 %, respectively), SCNSI (16.8, 7.1, 12.7, and 2.2 %, respectively), and acute respiratory infection (21.1, 22.0, 45.9, and 59.0 %, respectively).

Conclusions

The incidences of infection caused by different EV serotypes, along with the clinical features of HFMD/HA cases, changed drastically in Guangdong Province, China, from 2010 to 2013, with the biggest changes observed in 2013. The changed constituent ratios of the different EV serotypes might therefore be responsible for the differences in the observed clinical features of HFMD/HA during this period.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1690-0) contains supplementary material, which is available to authorized users.

Interactome analysis of the EV71 5' untranslated region in differentiated neuronal cells SH-SY5Y and regulatory role of FBP3 in viral replication

Enterovirus 71 (EV71), a single-stranded RNA virus, is one of the most serious neurotropic pathogens in the Asia-Pacific region. Through interactions with host proteins, the 5' untranslated region (5'UTR) of EV71 is important for viral replication. To gain a protein profile that interact with the EV71 5'UTR in neuronal cells, we performed a biotinylated RNA-protein pull-down assay in conjunction with LC-MS/MS analysis. A total of 109 proteins were detected and subjected to Database for Annotation, Visualization and Integrated Discovery (DAVID) analyses. These proteins were found to be highly correlated with biological processes including RNA processing/splicing, epidermal cell differentiation, and protein folding. A protein-protein interaction network was constructed using the STRING online database to illustrate the interactions of those proteins that are mainly involved in RNA processing/splicing or protein folding. Moreover, we confirmed that the far-upstream element binding protein 3 (FBP3) was able to bind to the EV71 5'UTR. The redistribution of FBP3 in subcellular compartments was observed after EV71 infection, and the decreased expression of FBP3 in host neuronal cells markedly inhibited viral replication. Our results reveal various host proteins that potentially interact with the EV71 5'UTR in neuronal cells, and we found that FBP3 could serve as a positive regulator in host cells.

Atypical Forms of Hand, Foot, and Mouth Disease: A Prospective Study of 47 Italian Children

BACKGROUND

Atypical forms of hand, foot, and mouth disease (HFMD) caused by coxsackievirus A6 have been reported in recent years. High fever and severe cutaneous lesions are common, whereas neurologic complications are rare. Eczematous areas of patients with atopic dermatitis show more lesions. The goal of the current study was to describe the clinical characteristics of children with atypical HFMD and to investigate the involvement of the different enterovirus serotypes associated.

METHODS

All patients referred to our service for atypical HFMD from January 2012 to February 2014 were enrolled and classified as having the diffuse form (lesions extended to the trunk), the acral form (lesions with a mainly acral distribution), or eczema coxsackium (lesions on preexisting eczematous areas).

RESULTS

Data from 47 patients were analyzed (median age 22 months [range 4-84 mos]); viral genotyping was performed in 11 cases. Sixty-two percent of the subjects developed the acral form, 23% eczema coxsackium, and 15% the diffuse form. Most patients had a nonclassical vesicular eruption and moderate to severe extent of cutaneous involvement. Approximately 80% of patients had palmoplantar purpuric macules. Most children younger than 2 years old had the acral form, most patients with eczema coxsackium were age 2 years and older, and the diffuse form was similarly distributed between the two age groups. Coxsackievirus A6 was detected in 9 of 11 genotyped cases.

CONCLUSION

Our prospective study allowed the identification of three HFMD phenotypes differing from the classical form. Clinical care of these patients should include symptomatic treatment of extracutaneous features and, if necessary, hospitalization for complications.

A clinically authentic mouse model of enterovirus 71 (EV-A71)-induced neurogenic pulmonary oedema

Enterovirus 71 (EV-A71) is a neurotropic virus that sporadically causes fatal neurologic illness among infected children. Animal models of EV-A71 infection exist, but they do not recapitulate in animals the spectrum of disease and pathology observed in fatal human cases. Specifically, neurogenic pulmonary oedema (NPE)—the main cause of EV-A71 infection-related mortality—is not observed in any of these models. This limits their utility in understanding viral pathogenesis of neurologic infections. We report the development of a mouse model of EV-A71 infection displaying NPE in severely affected animals. We inoculated one-week-old BALB/c mice with an adapted EV-A71 strain and identified clinical signs consistent with observations in human cases and other animal models. We also observed respiratory distress in some mice. At necropsy, we found their lungs to be heavier and incompletely collapsed compared to other mice. Serum levels of catecholamines and histopathology of lung and brain tissues of these mice strongly indicated onset of NPE. The localization of virally-induced brain lesions also suggested a potential pathogenic mechanism for EV-A71-induced NPE. This novel mouse model of virally-induced NPE represents a valuable resource for studying viral mechanisms of neuro-pathogenesis and pre-clinical testing of potential therapeutics and prophylactics against EV-A71-related neurologic complications.

Acute Flaccid Myelitis in the United States, August-December 2014: Results of Nationwide Surveillance

BACKGROUND

During late summer/fall 2014, pediatric cases of acute flaccid myelitis (AFM) occurred in the United States, coincident with a national outbreak of enterovirus D68 (EV-D68)-associated severe respiratory illness.

METHODS

Clinicians and health departments reported standardized clinical, epidemiologic, and radiologic information on AFM cases to the Centers for Disease Control and Prevention (CDC), and submitted biological samples for testing. Cases were ≤21 years old, with acute onset of limb weakness 1 August-31 December 2014 and spinal magnetic resonance imaging (MRI) showing lesions predominantly restricted to gray matter.

RESULTS

From August through December 2014, 120 AFM cases were reported from 34 states. Median age was 7.1 years (interquartile range, 4.8-12.1 years); 59% were male. Most experienced respiratory (81%) or febrile (64%) illness before limb weakness onset. MRI abnormalities were predominantly in the cervical spinal cord (103/118). All but 1 case was hospitalized; none died. Cerebrospinal fluid (CSF) pleocytosis (>5 white blood cells/µL) was common (81%). At CDC, 1 CSF specimen was positive for EV-D68 and Epstein-Barr virus by real-time polymerase chain reaction, although the specimen had >3000 red blood cells/µL. The most common virus detected in upper respiratory tract specimens was EV-D68 (from 20%, and 47% with specimen collected ≤7 days from respiratory illness/fever onset). Continued surveillance in 2015 identified 16 AFM cases reported from 13 states.

CONCLUSIONS

Epidemiologic data suggest this AFM cluster was likely associated with the large outbreak of EV-D68-associated respiratory illness, although direct laboratory evidence linking AFM with EV-D68 remains inconclusive. Continued surveillance will help define the incidence, epidemiology, and etiology of AFM.

Neurologic Manifestations of Enterovirus 71 Infection in Korea

Enterovirus 71 frequently involves the central nervous system and may present with a variety of neurologic manifestations. Here, we aimed to describe the clinical features, magnetic resonance imaging (MRI) findings, and cerebrospinal fluid (CSF) profiles of patients presenting with neurologic complications of enterovirus 71 infection. We retrospectively reviewed the records of 31 pediatric patients hospitalized with acute neurologic manifestations accompanied by confirmed enterovirus 71 infection at Ulsan University Hospital between 2010 and 2014. The patients' mean age was 2.9 ± 5.5 years (range, 18 days to 12 years), and 80.6% of patients were less than 4 years old. Based on their clinical features, the patients were classified into 4 clinical groups: brainstem encephalitis (n = 21), meningitis (n = 7), encephalitis (n = 2), and acute flaccid paralysis (n = 1). The common neurologic symptoms included myoclonus (58.1%), lethargy (54.8%), irritability (54.8%), vomiting (48.4%), ataxia (38.7%), and tremor (35.5%). Twenty-five patients underwent an MRI scan; of these, 14 (56.0%) revealed the characteristic increased T2 signal intensity in the posterior region of the brainstem and bilateral cerebellar dentate nuclei. Twenty-six of 30 patients (86.7%) showed CSF pleocytosis. Thirty patients (96.8%) recovered completely without any neurologic deficits; one patient (3.2%) died due to pulmonary hemorrhage and shock. In the present study, brainstem encephalitis was the most common neurologic manifestation of enterovirus 71 infection. The characteristic clinical symptoms such as myoclonus, ataxia, and tremor in conjunction with CSF pleocytosis and brainstem lesions on MR images are pathognomonic for diagnosis of neurologic involvement by enterovirus 71 infection.

Milrinone in Enterovirus 71 Brain Stem Encephalitis

Enterovirus 71 (EV71) was implicated in a widespread outbreak of hand-foot-and-mouth disease (HFMD) across the Asia Pacific area since 1997 and has also been reported sporadically in patients with brain stem encephalitis. Neurogenic shock with pulmonary edema (PE) is a fatal complication of EV71 infection. Among inotropic agents, milrinone is selected as a therapeutic agent for EV71- induced PE due to its immunopathogenesis. Milrinone is a type III phosphodiesterase inhibitor that has both inotropic and vasodilator effects. Its clinical efficacy has been shown by modulating inflammation, reducing sympathetic over-activity, and improving survival in patients with EV71-associated PE. Milrinone exhibits immunoregulatory and anti-inflammatory effects in the management of systemic inflammatory responses in severe EV71 infection.

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.

Pulmonary and central nervous system pathology in fatal cases of hand foot and mouth disease caused by enterovirus A71 infection

In the past 17 years, neurological disease associated with enterovirus A71 (EV-A71) has increased dramatically in the Asia-Pacific region with a high fatality rate in young infants, often due to pulmonary oedema, however the mechanism of this oedema remains obscure. We analysed the brainstem, heart and lungs of 15 fatal cases of confirmed EV-A71 infection in order to understand the pathophysiological mechanism of death and pulmonary oedema. In keeping with other case studies, the main cause of death was neurogenic pulmonary oedema. In the brainstem, 11 cases showed inflammation and all cases showed parenchymal inflammation with seven cases showing moderate or severe clasmatodendrosis. No viral antigen was detected in sections of the brainstem in any of the cases. All fatal cases showed evidence of pulmonary oedema; however, there was absence of direct pulmonary viral damage or myocarditis-induced damage and EV-A71 viral antigen staining was negative. Though there was no increase in staining for Na/K-ATPase, 11 of the 15 cases showed a marked reduction in aquaporin-4 staining in the lung, and this reduction may contribute to the development of fatal pulmonary oedema.

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.

A functional polymorphism in IFNAR1 gene is associated with susceptibility and severity of HFMD with EV71 infection

Enterovirus 71 (EV71), one of the major pathogens of Hand, foot and mouth disease (HFMD), results in millions of infections and hundreds of deaths each year in Southeast Asia. Biased infection and variable clinical manifestations of EV71 HFMD indicated that host genetic background played an important role in the occurrence and development of the disease. We identified the mRNA profiles of EV71 HFMD patients, which type I interferon (IFN) pathway related genes were down-regulated. Four single nucleotide polymorphisms (SNPs) of type I IFN receptor 1 (IFNAR1) were chosen to analyze their relationships to EV71 infection. We found that genotype GG of promoter variant rs2843710 was associated with the susceptibility and severity to EV71 HFMD. In addition, we assessed the regulatory effects of rs2843710 to IFN stimulated genes (ISGs), and found that the expressions of IFNAR1, OAS1 and MX1 were significantly lower in patients with rs2843710 genotype GG. And rs2843710 allele G showed weaker transcriptional activity compared with allele C. Our study indicated that rs2843710 of IFNAR1 was associated with the susceptibility and severity of EV71 HFMD in Chinese Han populations, acting as a functional polymorphism by regulating ISGs expression, such as OAS1 and MX1.

Risk factors for severe hand foot mouth disease in Singapore: a case control study

Background

Hand foot mouth disease (HFMD) is a common childhood infection that can potentially lead to serious complications. The aim of this study is to identify risk factors of acquiring severe HFMD in our population.

Methods

We performed a case control study using patients admitted to our hospital from August 2004 to July 2014. Cases were patients with severe HFMD disease while controls were age-matched patients obtained from the same year, in a 2:1 ratio. Data comprising demographic characteristics, clinical symptoms and signs, and lab findings were collected. Conditional univariable logistic regression was performed to determine risk factors for severe disease.

Results

A total of 24 cases of severe HFMD were identified and matched with 48 controls. Seventeen (70.8 %) cases had central nervous system complications. Seven (29.2 %) had cardiovascular complications without evidence of myocarditis. One patient died of encephalitis. The overall mortality of severe disease is 4 %. Evidence of hypoperfusion, seizure, altered mentation, meningeal irritation, tachycardia, tachypnea, raised absolute neutrophil count and EV-A71 (Enterovirus A71) positivity were significantly associated with a severe course of HFMD.

Conclusion

In managing children with HFMD, physicians should consider these factors to help identify patients at risk for severe disease.

Immunologic Characterization of Cytokine Responses to Enterovirus 71 and Coxsackievirus A16 Infection in Children

Viral encephalitis is a serious complication of hand, foot, and mouth disease (HFMD), but characteristics of cytokines response in enterovirus 71 (EV-71) and/or coxsackievirus A16 (CV-A16) associated HFMD with or without viral encephalitis remained unclear.We performed a multigroup retrospective study and compared the serum cytokines concentrations among 16 encephalitis patients infected with EV-71 and CV-A16, 24 encephalitis patients with single EV-71 infection, 34 mild HFMD patients with EV-71 infection, 18 mild HFMD patients with CV-A16 infection, and 39 healthy control subjects.Serum levels of interleukin (IL)-4, IL-5, IL-22, and IL-23 were significantly higher in encephalitis patients than in HFMD-alone patients when adjusting for age and sex; IL-2, tumor necrosis factor (TNF)-α, IL-4, IL-22, and IL-1β were significantly higher in HFMD-alone patients of EV-71 infection than in CV-A16 infected HFMD patients; cerebrospinal fluid level of IL-6 was lower in the EV-71/CV-A16 associated encephalitis than that in the EV-71 alone associated encephalitis patients.Over or low expression of the cytokines cascade in HFMD patients appears to play an important role in the elicitation of the immune response to EV-71 and CV-A16. These data will be used to define a cytokine profile, which might help to recognize HFMD patients with the high risk of developing encephalitis.

Molecular epidemiology of an outbreak of hand, foot, and mouth disease associated with subgenotype C4a of enterovirus A71 in Nanchang, China in 2014

An outbreak of hand, foot, and mouth disease was reported through hospital-based surveillance in Nanchang, China in 2014. A total of 244 cases were reported, 176 (72.1%) cases were tested positive for enteroviruses by direct reverse transcription-polymerase chain reaction, in which enterovirus A71 (EV-A71), coxsackievirus A16 (CV-A16), and untyped enteroviruses (UEV) accounted for 84.1%, 3.4%, and 12.5%, respectively. In this outbreak, children under 5 years old constituted more than 98% of the positive cases, and the ratio of male to female cases was 2.6 to 1 (P < 0.01). Phylogenetic analysis indicated that the Nanchang EV-A71 strains belonged to subgenotype C4a undergoing continuously evolutionary changes.

Yakammaoto inhibits enterovirus 71 infection by reducing viral attachment, internalization, replication, and translation

Enterovirus 71 (EV71) can cause central nervous system infections with mortality and neurologic sequelae. At present, there is no effective therapeutic modality for EV71 infection. The infection is more common in families with poor socioeconomic status. Therefore, finding a readily available, cost-effective therapeutic modality would be very helpful to these socioeconomically disadvantaged families. Yakammaoto is a cheap and readily available traditional prescription that is proven to have antiviral activity against coxsackievirus B4 (CVB4). CVB4 and EV71 are enteroviruses. In this study, we evaluated the antiviral activity of hot water extract of yakammaoto against EV71. The results of plaque reduction assay and flow cytometry demonstrated that yakammaoto dose dependently inhibited EV71 infection. In addition, reverse transcription-polymerase chain reaction (RT-PCR) and quantitative RT-PCR results showed that yakammaoto reduced viral replication. Western blotting analysis showed that yakammaoto can inhibit viral protein production. Thus, our results suggest that yakammaoto should be considered to manage EV71 infection in the future.

Recombinant adeno-vaccine expressing enterovirus 71-like particles against hand, foot, and mouth disease

Enterovirus 71 (EV71) and coxsackieviruses (CV) are the major causative agents of hand, foot and mouth disease (HFMD). There is not currently a vaccine available against HFMD, even though a newly developed formalin-inactivated EV71 (FI-EV71) vaccine has been tested in clinical trial and has shown efficacy against EV71. We have designed and genetically engineered a recombinant adenovirus Ad-EVVLP with the EV71 P1 and 3CD genes inserted into the E1/E3-deleted adenoviral genome. Ad-EVVLP were produced in HEK-293A cells. In addition to Ad-EVVLP particles, virus-like particles (VLPs) formed from the physical association of EV71 capsid proteins, VP0, VP1, and VP3 expressed from P1 gene products. They were digested by 3CD protease and confirmed to be produced by Ad-EVVLP-producing cells, as determined using transmission electron microscopy and western blotting. Mouse immunogenicity studies showed that Ad-EVVLP-immunized antisera neutralized the EV71 B4 and C2 genotypes. Activation of VLP-specific CD4+ and CD8+/IFN-γ T cells associated with Th1/Th2-balanced IFN-ɣ, IL-17, IL-4, and IL-13 was induced; in contrast, FI-EV71 induced only Th2-mediated neutralizing antibody against EV71 and low VLP-specific CD4+ and CD8+ T cell responses. The antiviral immunity against EV71 was clearly demonstrated in mice vaccinated with Ad-EVVLP in a hSCARB2 transgenic (hSCARB2-Tg) mouse challenge model. Ad-EVVLP-vaccinated mice were 100% protected and demonstrated reduced viral load in both the CNS and muscle tissues. Ad-EVVLP successfully induced anti-CVA16 immunities. Although antisera had no neutralizing activity against CVA16, the 3C-specific CD4+ and CD8+/IFN-γ T cells were identified, which could mediate protection against CVA16 challenge. FI-EV71 did not induce 3C-mediated immunity and had no efficacy against the CVA16 challenge. These results suggest that Ad-EVVLP can enhance neutralizing antibody and protective cellular immune responses to prevent EV71 infection and cellular immune responses against CV infection.

Enterovirus 71 virion-associated galectin-1 facilitates viral replication and stability

Enterovirus 71 (EV71) infection causes a myriad of diseases from mild hand-foot-and-mouth disease or herpangina to fatal brain stem encephalitis complicated with pulmonary edema. Several severe EV71 endemics have occurred in Asia-Pacific region, including Taiwan, and have become a serious threat to children’s health. EV71 infection is initiated by the attachment of the virion to the target cell surface. Although this process relies primarily upon interaction between viruses and cell surface receptors, soluble factors may also influence the binding of EV71 to host cells.Galectin-1 has been reported to participate in several virus infections, but is not addressed in EV71. In this study, we found that the serum levels of galectin-1 in EV71-infected children were higher than those in non-infected people. In EV71 infected cells, galectin-1 was found to be associated with the EV71 VP1 and VP3 via carbohydrate residues and subsequently released and bound to another cell surface along with the virus. EV71 propagated from galectin-1 knockdown SK-N-SH cells exhibited lower infectivity in cultured cells and less pathogenicity in mice than the virus propagated from parental cells. In addition, this galectin-1-free EV71 virus was sensitive to high temperature and lost its viability after long-term storage, which could be restored following supplement of recombinant galectin-1. Taken together, our findings uncover a new role of galectin-1 in facilitating EV71 virus infection.

Performance of reversed transcription loop-mediated isothermal amplification technique detecting EV71: a systematic review with meta-analysis

Human enterovirus 71 (EV71) is the major etiological agent of hand, foot and mouth disease (HFMD), which is a common infectious disease in young children. Studies in the past have shown that reversed transcription loop-mediated isothermal amplification (RT-LAMP) was a rapid approach for the detection of EV71 in HFMD. This meta-analysis study is to evaluate the diagnostic role of RT-LAMP in detecting EV71 infection. A comprehensive literature research of PubMed, Embase, Wan Fang Data, and Chinese National Knowledge Infrastructure databases was conducted on articles aiming at the diagnostic performance of RT-LAMP in EV71 detection published before February 10, 2014. Data from selected studies were pooled to yield the summary sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR), diagnostic odds ratio (DOR), and receiver operating characteristic (SROC) curve by using STATA VERSION 12.0 software. Ten studies including a total of 907 clinical samples were of high quality in this meta-analysis. Overall, the pooled sensitivity, specificity, PLR, NLR, DOR, and the area under the SROC curve was 0.99 (0.97, 1.00), 0.97 (0.94, 1.00), 5.90 (95% CI: 3.90-8.94), 0.20 (95% CI: 0.14-0.29), and 1.00 (95% CI: 0.99-1.00), respectively. The univariate analysis of potential variables showed some changes in the diagnostic performance, but none of the differences reached statistical significance. Despite inter-study variability, the test performance of RT-LAMP was consistent with real-time RT-PCR in detecting EV71. This meta-analysis suggests that RT-LAMP is a useful diagnostic tool with high sensitivity and specificity for detecting EV71.

MRI findings in children with acute flaccid paralysis and cranial nerve dysfunction occurring during the 2014 enterovirus D68 outbreak

BACKGROUND AND PURPOSE

Enterovirus D68 was responsible for widespread outbreaks of respiratory illness throughout the United States in August and September 2014. During this time, several patients presented to our institution with acute flaccid paralysis and cranial nerve dysfunction. The purpose of this report is to describe the unique imaging findings of this neurologic syndrome occurring during an enterovirus D68 outbreak.

MATERIALS AND METHODS

Patients meeting a specific case definition of acute flaccid paralysis and/or cranial nerve dysfunction and presenting to our institution during the study period were included. All patients underwent routine MR imaging of the brain and/or spinal cord, including multiplanar T1, T2, and contrast-enhanced T1-weighted imaging.

RESULTS

Eleven patients met the inclusion criteria and underwent MR imaging of the brain and/or spinal cord. Nine patients presented with brain stem lesions, most commonly involving the pontine tegmentum, with bilateral facial nerve enhancement in 1 patient. Ten patients had longitudinally extensive spinal cord lesions; those imaged acutely demonstrated involvement of the entire central gray matter, and those imaged subacutely showed lesions restricted to the anterior horn cells. Ventral cauda equina nerve roots enhanced in 4 patients, and ventral cervical nerve roots enhanced in 3, both only in the subacute setting.

CONCLUSIONS

Patients presenting with acute flaccid paralysis and/or cranial nerve dysfunction during the recent enterovirus D68 outbreak demonstrate unique imaging findings characterized by brain stem and gray matter spinal cord lesions, similar to the neuroimaging findings described in previous outbreaks of viral myelitis such as enterovirus 71 and poliomyelitis.

Serum inflammatory cytokine levels correlate with hand-foot-mouth disease severity: a nested serial case-control study

Background

Hand-food-mouth disease (HFMD) cases can be fatal. These cases develop rapidly, and it is important to predict the severity of HFMD from mild to fatal and to identify risk factors for mild HFMD. The objective of this study was to correlate the levels of serum inflammatory cytokines with HFMD severity.

Methods

This study was designed as a nested serial case-control study. The data collected included general information, clinical symptoms and signs, laboratory findings and serum cytokine levels.

Results

The levels of IL-4, IL-6, IL-10, TNF-α and IFN-γ in patients with severe HFMD were significantly higher than in mild patients during the 2nd to 5th day after disease onset. The levels of IL-4, IL-6, IL-10 and IFN-γ increased from the 2nd day to the 4th day and later decreased. The levels of TNF-α were high on the first two days and subsequently decreased. The changes of IL-10, TNF-α and IFN-γ in the controls were similar for all cases. The levels of IL-4, IL-6 and IL-17 in the controls were not significantly different with the progression of HFMD.

Conclusions

Our findings indicate that the IL-4, IL-6, IL-10, TNF-α and IFN-γ levels correlate with HFMD severity.

Emerging and reemerging neurologic infections

The list of emerging and reemerging pathogens that cause neurologic disease is expanding. Various factors, including population growth and a rise in international travel, have contributed to the spread of pathogens to previously nonendemic regions. Recent advances in diagnostic methods have led to the identification of novel pathogens responsible for infections of the central nervous system. Furthermore, new issues have arisen surrounding established infections, particularly in an increasingly immunocompromised population due to advances in the treatment of rheumatologic disease and in transplant medicine.

Enterovirus 71 infects brain-derived neural progenitor cells

Neural progenitor cells (NPCs) are stem cells that can differentiate into various neural lineage cells. The damage and loss of NPCs are associated with neurological conditions such as cognitive deficits and memory impairment. In a long-term study of patients with EV71, cognitive disorders were observed. Therefore, we hypothesized that NPCs may be permissive to EV71 infection. We demonstrated that NPCs are prone to EV71 infection and that these stem cells can support the active replication of this virus. Furthermore, EV71 infection triggers apoptosis, resulting in significant cell death in infected NPCs. However, EV71 did not replicate in the differentiated cell types that were tested. Our findings suggest that EV71 can infect NPCs and cause the depletion of these cells.

Enterovirus 71 infection-associated acute flaccid paralysis: a case series of long-term neurologic follow-up

The authors undertook long-term neurologic outcomes of 27 patients aged 0 to 15 years with enterovirus 71-related acute flaccid paralysis from June 1998 to July 2012. Motor function outcome was graded from class I (complete recovery) to class V (permanent paralytic limbs). Twelve of 20 patients (60%) who received intravenous immunoglobulin for treatment of acute flaccid paralysis had motor function outcomes in classes III to V. The median duration of follow-up was 6 months, during which time 7 of 13 patients (54%) with central nervous system infection, 3 of 6 patients (50%) with autonomic nervous system dysregulation, and 3 of 8 patients (37%) with heart failure showed motor function outcomes in classes III to V. These findings suggested that the usage of intravenous immunoglobulin and the severity of disease staging at disease onset might not be able to predict long-term motor function outcomes.

Immunodeficient mouse models with different disease profiles by in vivo infection with the same clinical isolate of enterovirus 71

Like poliovirus infection, severe infection with enterovirus 71 (EV71) can cause neuropathology. Unlike poliovirus, EV71 is often associated with hand-foot-and-mouth disease (HFMD). Here we established three mouse models for experimental infection with the same clinical isolate of EV71. The NOD/SCID mouse model is unique for the development of skin rash, an HFMD-like symptom. While the NOD/SCID mice developed limb paralysis and death at near-100% efficiency, the gamma interferon receptor knockout (ifngr KO) and stat-1 knockout mice exhibited paralysis and death rates near 78% and 30%, respectively. Productive infection with EV71 depends on the viral dose, host age, and inoculation route. Levels of infectious EV71, and levels of VP1-specific RNA and protein in muscle, brain, and spinal cord, were compared side by side between the NOD/SCID and stat-1 knockout models before, during, and after disease onset. Spleen fibrosis and muscle degeneration are common in the NOD/SCID and stat-1 knockout models. The main differences between these two models include their disease manifestations and cytokine/chemokine profiles. The pathology of the NOD/SCID model includes (i) inflammation and expression of viral VP1 antigen in muscle, (ii) increased neutrophil levels and decreased eosinophil and lymphocyte levels, and (iii) hair loss and skin rash. The characteristic pathology of the stat-1 knockout model includes (i) a strong tropism of EV71 for the central nervous system, (ii) detection of VP1 protein in the Purkinje layer of cerebellar cortex, pons, brain stem, and spinal cord, (iii) amplification of microglial cells, and (iv) dystrophy of intestinal villi. Our comparative studies on these new models with oral or intraperitoneal (i.p.) infection underscored the contribution of host immunity, including the gamma interferon receptor, to EV71 pathogenesis.

IMPORTANCE

In the past decade, enterovirus 71 (EV71) has emerged as a major threat to public health in the Asia-Pacific region. Disease manifestations include subclinical infection, common-cold-like syndromes, hand-foot-and-mouth disease (HFMD), uncomplicated brain stem encephalitis, severe dysregulation of the autonomic nerve system, fatal pulmonary edema, and cardiopulmonary collapse. To date, no effective vaccine or treatment is available. A user-friendly and widely accessible animal model for researching EV71 infection and pathogenesis is urgently needed by the global community, both in academia and in industry.

Early dexamethasone treatment exacerbates enterovirus 71 infection in mice

Enterovirus 71 (EV71) infection can induce encephalitis. Overt immune responses is suspected to cause severe symptoms, so anti-inflammatory agents, corticosteroids have been recommended for treatment. However, one clinical study reported that treatment with glucocorticoids, dexamethasone (Dex) exacerbates disease severity. Here we investigated Dex treatment on EV71 infection using the murine model and found that both long-term (14-day) and short-term (4-day) Dex treatment starting from 1 or 3 days postinfection increased the mortality and disease severity of infected mice. Dex treatment starting from 4 or 8 days postinfection did not affect mouse mortality and disease severity. Early Dex treatment starting from 1 day postinfection caused atrophy and enhanced apoptosis in lymphoid organs to decrease the numbers of lymphocytes (CD4(+) T cells, CD8(+) T cells, and CD19(+) B cells) and to increase viral loads in infected tissues of mice. Our results demonstrate that Dex treatment has no beneficial effect on EV71 infection.

The correlation between the presence of viremia and clinical severity in patients with enterovirus 71 infection: a multi-center cohort study

BACKGROUND

Enterovirus 71 (EV71) is a great disease burden across the whole world, particularly in Southeast Asia. However, in recent decades, the pathogenesis of severe EV71 infection was not well understood. This study was aimed to investigate the correlation between the presence of viremia and the clinical severity of EV71 infection.

METHODS

We organized a prospective cohort study and enrolled laboratory-confirmed EV71 cases in six tertiary care hospitals in Taiwan during the EV71 epidemic from 2011 to 2012. Blood samples were collected once in the acute stage, on the first day of admission. We used real-time RT-PCR to detect EV71 viremia. Demographical and clinical data were collected and the clinical severity was categorized into four grades. Data analysis was performed to identify the risk factors of viremia and the correlation between viremia and clinical severity of EV71 infection.

RESULTS

Of the total 224 enrolled patients, 59 (26%) patients were confirmed to have viremia. Two-thirds (68%) of viremic cases were detected within the first three days of infection. Viremia occurred more frequently in children under the age of one year old (odds ratios [OR] 4.82, p < 0.001) but the association between the presence of viremia and complicated EV71 infection was not found (OR 1.02, p = 0.96). In the viremia group, patients had significantly more severe complications if viremia was detected after the third day of disease onset (26% vs. 5%, p = 0.03).

CONCLUSIONS

Viremia occurred more frequently in children under the age of one year and viremia detected beyond three days after the onset of disease correlated with more severe disease in EV71 patients.