Neurologic complications in children with enterovirus 71 infection

Enterovirus 71 targets the cardiopulmonary system in a robust oral infection mouse model

Severe infection with the re-emerging enterovirus 71 (EV71 or EV-A71) can cause cardiopulmonary failure. However, in patients' heart and lung, viral protein has not been detected. In mouse models, heart disease has not been reported. EV71-infected brainstem is generally believed to be responsible for the cardiopulmonary collapse. One major limitation in EV71 research is the lack of an efficient oral infection system using non-mouse-adapted clinical isolates. In a robust oral infection NOD/SCID mouse model, we detected EV71 protein at multiple organs, including heart and lung, in 100% of moribund mice with limb paralysis. Infiltrating leukocytes were always detected in heart and muscle, and VP1-positive M2 macrophages were abundant in the lung. Functional dissection on the pathogenesis mechanism revealed severe apoptosis, inflammatory cytokines, and abnormal electrocardiogram (EKG) in orally infected hearts. Therefore, cardiopulmonary disease could be one plausible cause of death in this mouse model. Inoculation of EV71 through an oral route resulted in viral infection in the intestine, viremia, and EV71 appeared to spread to peripheral tissues via blood circulation. Infectious virus was no longer detected in the blood on day 5 post-infection by the plaque formation assay. We demonstrated that both EV71 clinical isolate and cloned virus can target the cardiopulmonary system via a natural infection-like oral route.

An inactivated enterovirus 71 vaccine is safe and immunogenic in healthy adults: A phase I, double blind, randomized, placebo-controlled, study of two dosages

BACKGROUND

Hand, foot and mouth disease (HFMD), especially that caused by enterovirus 71 (EV71) infection, is a public health concern in the Asia-Pacific region. We report a phase I clinical trial of an EV71 candidate vaccine (INV21) based on a binary ethylenimine inactivated B2 sub-genotype formulated with aluminum hydroxide.

METHODS

In this double-blind, placebo-controlled, randomized, dose escalation study adult volunteers received two vaccinations 28 days apart of low or high dose formulations of the candidate vaccine and were then monitored for safety and reactogenicity for four weeks after each dose, and for their immune responses up to 28 weeks.

RESULTS

Of 36 adults enrolled, 35 completed the study as planned. Either no or mild adverse events were observed, mainly injection site pain and tiredness. Seroconversion was 100% after two vaccinations. High geometric mean neutralizing antibody titers (GMT) were observed 14 days post first dose, peaking 14 days post second dose (at Day 42) in both high and low dose groups; GMTs on days 14, 28, 42, and 56 were 128, 81, 323, 203 and 144, 100, 451, 351 in low- and high-dose groups, respectively. Titers for both doses declined gradually to Day 196 but remained higher than baseline and the placebo groups, which had low GMTs throughout the duration of the study. Cross-neutralizing antibody activity against heterologous sub-genotypes was demonstrated.

CONCLUSION

These data show that the EV71 candidate vaccine is safe and immunogenic in adults and supports further clinical development as a potential pediatric vaccine by initiating a dose-escalation study for determining the dose-dependent safety and immunogenicity of the vaccine in young naïve children.

Recent advances on the role of host factors during non-poliovirus enteroviral infections

Non-polio enteroviruses are emerging viruses known to cause outbreaks of polio-like infections in different parts of the world with several cases already reported in Asia Pacific, Europe and in United States of America. These outbreaks normally result in overstretching of health facilities as well as death in children under the age of five. Most of these infections are usually self-limiting except for the neurological complications associated with human enterovirus A 71 (EV-A71). The infection dynamics of these viruses have not been fully understood, with most inferences made from previous studies conducted with poliovirus.Non-poliovirus enteroviral infections are responsible for major outbreaks of hand, foot and mouth disease (HFMD) often associated with neurological complications and severe respiratory diseases. The myriad of disease presentations observed so far in children calls for an urgent need to fully elucidate the replication processes of these viruses. There are concerted efforts from different research groups to fully map out the role of human host factors in the replication cycle of these viral infections. Understanding the interaction between viral proteins and human host factors will unravel important insights on the lifecycle of this groups of viruses.This review provides the latest update on the interplay between human host factors/processes and non-polio enteroviruses (NPEV). We focus on the interactions involved in viral attachment, entry, internalization, uncoating, replication, virion assembly and eventual egress of the NPEV from the infected cells. We emphasize on the virus- human host interplay and highlight existing knowledge gaps that needs further studies. Understanding the NPEV-human host factors interactions will be key in the design and development of vaccines as well as antivirals against enteroviral infections. Dissecting the role of human host factors during NPEV infection cycle will provide a clear picture of how NPEVs usurp the human cellular processes to establish an efficient infection. This will be a boost to the drug and vaccine development against enteroviruses which will be key in control and eventual elimination of the viral infections.

Economic Burden Attributed to Children Presenting to Hospitals With Hand, Foot, and Mouth Disease in Vietnam

Background

Hand, foot, and mouth disease (HFMD) has become a major public health concern in the Asia-Pacific region. Knowledge of its economic burden is essential for policy makers in prioritizing the development and implementation of interventions.

Methods

A multi-hospital-based study was prospectively conducted at 3 major hospitals in Ho Chi Minh City, Vietnam, during 2016–2017. Data on direct and productivity costs were collected alongside clinical information and samples and demographic information from study participants.

Results

A total of 466 patients were enrolled. Two hundred three of 466 (43.6%) patients lived in Ho Chi Minh City, and 72/466 (15.5%) had severe HFMD. An enterovirus was identified in 74% of 466 patients, with EV-A71, CV-A6, CV-A10, and CV-A16 being the most common viruses identified (236/466, 50.6%). The mean economic burden per case was estimated at US$400.80 (95% confidence interval [CI], $353.80–$448.90), of which the total direct (medical) costs accounted for 69.7%. There were considerable differences in direct medical costs between groups of patients with different clinical severities and pathogens (ie, EV-A71 vs non-EV-A71). In Vietnam, during 2016–2017, the economic burden posed by HFMD was US$90 761 749 (95% CI, $79 033 973–$103 009 756).

Conclusions

Our findings are of public health significance because for the first time we demonstrate that HFMD causes a substantial economic burden in Vietnam, and although multivalent vaccines are required to control HFMD, effective EV-A71 vaccine could substantially reduce the burden posed by severe HFMD. The results will be helpful for health policy makers in prioritizing resources for the development and implementation of intervention strategies to reduce the burden of HFMD.

Mitochondria Redistribution in Enterovirus A71 Infected Cells and Its Effect on Virus Replication

Enterovirus A71 (EV-A71) is one of the main causative agents of hand, foot and mouth disease (HFMD) and it also causes severe neurologic complications in infected children. The interactions between some viruses and the host mitochondria are crucial for virus replication and pathogenicity. In this study, it was observed that EV-A71 infection resulted in a perinuclear redistribution of the mitochondria. The mitochondria rearrangement was found to require the microtubule network, the dynein complex and a low cytosolic calcium concentration. Subsequently, the EV-A71 non-structural protein 2BC was identified as the viral protein capable of inducing mitochondria clustering. The protein was found localized on mitochondria and interacted with the mitochondrial Rho GTPase 1 (RHOT1) that is a key protein required for attachment between the mitochondria and the motor proteins, which are responsible for the control of mitochondria movement. Additionally, suppressing mitochondria clustering by treating cells with nocodazole, EHNA, thapsigargin or A23187 consistently inhibited EV-A71 replication, indicating that mitochondria recruitment played a crucial role in the EV-A71 life cycle. This study identified a novel function of the EV-A71 2BC protein and provided a potential model for the regulation of mitochondrial motility in EV-A71 infection.

Serial MRI findings of acute flaccid myelitis during an outbreak of enterovirus D68 infection in Japan

OBJECIVE

To clarify the neuroimaging findings of children with acute flaccid myelitis during an outbreak of EV-D68 infection.

METHODS

We performed a detailed review of the spinal and cranial MRI results of 54 children with acute flaccid myelitis. We focused on the range of longitudinal lesions, the localization and appearance of lesions within a horizontal section, Gadolinium-enhancement, and changes over time.

RESULTS

All children had longitudinal spinal lesions involving central gray matter. Twenty-six children had lesions spanning the entire spine. Six of them had weakness in all limbs, whereas seven had weakness of only one limb. Thirty-eight children had lesions in both gray and white matter and limb weakness tended to be more severe in these children. During the acute period, spinal lesions showed bilateral ill-defined widespread T2 hyperintensity. During the subacute period, lesions were well defined and confined to the anterior horn. The distribution of limb weakness was correlated with the appearance of lesions during the subacute period. Gadolinium enhancement was performed in 37 children, and enhancement was seen in the cauda equina in 29 children. Enhancement was infrequent within 2 days after onset but was seen in almost all children thereafter. Twenty-two children had brainstem lesions continuous with spinal lesions.

CONCLUSION

Extensive longitudinal spinal lesions were characteristic in children with acute flaccid myelitis. Lesions were usually bilateral and widespread during the acute period, whereas localization to the anterior horn could become obvious. Although enhancement of the cauda equina was often observed, its appearance was sometimes delayed.

Hsp27 Responds to and Facilitates Enterovirus A71 Replication by Enhancing Viral Internal Ribosome Entry Site-Mediated Translation

Outbreaks of infections with EV-A71, which causes hand, foot, and mouth disease, severe neurological disorders, and even death, have been repeatedly reported worldwide in recent decades and are a great public health problem for which no approved treatments are available. We show that Hsp27, a heat shock protein, supports EV-A71 infection in two distinct ways to promote viral IRES-dependent translation. A small-molecule Hsp27 inhibitor isolated from a traditional Chinese medicinal herb effectively reduces virus yields. Together, our findings demonstrate that Hsp27 plays an important role in EV-A71 infection and may serve as an antiviral target.

Enterovirus 71 (EV-A71) is a human pathogen that causes hand, foot, and mouth disease (HFMD) and fatal neurological diseases, and no effective treatment is available. Characterization of key host factors is important for understanding its pathogenesis and developing antiviral drugs. Here we report that Hsp27 is one of the most upregulated proteins in response to EV-A71 infection, as revealed by two-dimensional gel electrophoresis-based proteomics studies. Depletion of Hsp27 by small interfering RNA or CRISPR/Cas9-mediated knockout significantly inhibited viral replication, protein expression, and reproduction, while restoration of Hsp27 restored such virus activities. Furthermore, we show that Hsp27 plays a crucial role in regulating viral internal ribosome entry site (IRES) activities by two different mechanisms. Hsp27 markedly promoted 2A^pro-mediated eukaryotic initiation factor 4G cleavage, an important process for selecting and initiating IRES-mediated translation. hnRNP A1 is a key IRES trans-acting factor (ITAF) for enhancing IRES-mediated translation. Surprisingly, knockout of Hsp27 differentially blocked hnRNP A1 but not FBP1 translocation from the nucleus to the cytoplasm and therefore abolished the hnRNP A1 interaction with IRES. Most importantly, the Hsp27 inhibitor 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran [7,6-b] xanthone (TDP), a compound isolated from a traditional Chinese herb, significantly protected against cytopathic effects and inhibited EV-A71 infection. Collectively, our results demonstrate new functions of Hsp27 in facilitating virus infection and provide novel options for combating EV-A71 infection by targeting Hsp27.

IMPORTANCE Outbreaks of infections with EV-A71, which causes hand, foot, and mouth disease, severe neurological disorders, and even death, have been repeatedly reported worldwide in recent decades and are a great public health problem for which no approved treatments are available. We show that Hsp27, a heat shock protein, supports EV-A71 infection in two distinct ways to promote viral IRES-dependent translation. A small-molecule Hsp27 inhibitor isolated from a traditional Chinese medicinal herb effectively reduces virus yields. Together, our findings demonstrate that Hsp27 plays an important role in EV-A71 infection and may serve as an antiviral target.

Association of polymorphisms in the vitamin D receptor gene with severity of hand, foot, and mouth disease caused by enterovirus 71

Severe hand, foot, and mouth disease (HFMD) is sometimes associated with critical complications that can cause substantial child mortality. Activity of the vitamin D receptor (VDR) may influence the outcomes of enterovirus 71 (EV71) infection. This case-control study aimed to assess the association of single-nucleotide polymorphisms (SNPs) in the gene encoding the VDR with the severity of EV71-associated HFMD. We selected four VDR SNPs based on linkage disequilibrium and functional prediction, and we tested them using the SNPscan multiple SNP typing method for potential association with severity of EV71-associated HFMD. We found a significant association in the case of rs11574129 (G vs A: odds ratio (OR), 0.3439; 95% confidence intervals (CI), 0.1778-0.6653) and rs739837 (T vs G: OR, 0.5580; 95%CI, 0.3352-0.9291). Our results suggest that these two SNPs may influence the severity of EV71-associated HFMD.

Autophagy induced by enterovirus 71 regulates the production of IL-6 through the p38MAPK and ERK signaling pathways

Enterovirus 71 (EV71) is the main causative agent of hand, foot, and mouth disease (HFMD), which has high morbidity and mortality. It mainly threatens children under six years of age. Because of a poor understanding of its pathogenesis, there are no effective drugs to control EV71 infection. Previous studies showed that EV71 infection induced autophagy and the production of cytokine IL-6. However, the underlying mechanisms between autophagy and the production of IL-6 induced by EV71 remain unclear. This study aimed to reveal the regulatory mechanisms between autophagy and the expression of IL-6 induced by EV71 infection. Our results showed that the proliferation of human gastric epithelial (GES-1) cells was inhibited by EV71 in a time- and dose-dependent manner. In addition, EV71 induced autophagy in GES-1 cells. EV71 infection promoted the expression and the release of IL-6 to the extracellular space, although the expression and release were inhibited by autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) in GES-1 cells. The phosphorylated levels of p38MAPK and ERK proteins in GES-1 cells also increased after infection with EV71, and these changes were also reversed by 3-MA and CQ treatment. Our findings suggested that EV71-induced autophagy regulated the production of IL-6 through the p38MAPK and ERK signaling pathways.

Outcome of paediatric acute flaccid myelitis associated with enterovirus D68: a case series

Enterovirus D68 (EV-D68) is an emerging infection associated with acute flaccid myelitis (AFM). Cases of AFM associated with EV-D68 infection have increased in recent years and the evidence for a causal link is growing. However, our understanding of the epidemiology, clinical features, prognosis, and neurological sequelae of EV-D68 requires ongoing surveillance and investigation. We report five cases of AFM in previously typically developing children (2-6y) from South East Scotland during September and October 2016 after infection with EV-D68 (all detected in the nasopharyngeal aspirates). All cases presented with significant neurological symptoms, which were severe in two cases requiring intensive care support because of respiratory paralysis. At 18-month follow-up, two cases remain ventilator-dependent with other cases requiring ongoing community rehabilitation. These cases represent one of the largest reported paediatric cluster of AFM associated with EV-D68 in Europe. The epidemiology and clinical information add to the knowledge base and the 18-month outcome will help clinicians to counsel families. WHAT THIS PAPER ADDS: Nasopharyngeal aspirate is more sensitive for viral isolation and isolated in all cases. Clinical outcome at 18 months after enterovirus D68 with acute flaccid myelitis provides information on extent of recovery and level of disability.

Short-term effects of extreme meteorological factors on childhood hand, foot, and mouth disease reinfection in Hefei, China: A distributed lag non-linear analysis

BACKGROUND

Hand, foot, and mouth disease (HFMD) is a major public health issue in China with a high burden of reinfection. Previous studies presented evidence of the relationship between meteorological factors and HFMD incidence, but no study examined the effects of extreme meteorological factors on HFMD reinfection.

METHODS

Daily HFMD reinfection counts and meteorological data of Hefei city were collected from 2011 to 2016. A distributed lag non-linear model was used to quantify the effects of extreme weather (wind speed, sunshine duration, and precipitation) on HFMD reinfection. All effects were presented as relative risk (RR), with 90th or 10th percentiles of meteorological variables compare with their median values. Confounding factors, such as mean temperature, relative humidity, day of week, and long-term trend were controlled.

RESULTS

A total of 4873 HFMD reinfection cases aged 0-11 years were reported. Extremely high precipitation, low wind speed, and low sunshine duration increased HFMD reinfection risk. The effect of extremely high precipitation was greatest at 8 days lag (RR = 1.01, 95%CI: 1.00-1.02). Extremely low wind speed and low sunshine increased 19% (RR = 1.19, 95%CI: 1.09-1.32) and 12% (RR = 1.12, 95%CI: 1.00-1.26) risk at lag 0-12 days, respectively. By contrast, extremely high wind speed and high sunshine duration exerted certain protective effects on HFMD reinfection at lag 0-12 days (RR = 0.76, 95%CI: 0.66-0.88; RR = 0.88, 95%CI: 0.79-0.99, respectively). Subgroup analyses showed that nursery children were the most sensitive people to the extreme wind speed and sunshine duration. Children aged 4-11 years appeared to be more susceptible to extreme sunshine duration than children aged <3 years.

CONCLUSION

The present study provides evidence that extreme meteorological factors exert delayed effects on HFMD reinfection. Developing an early warning system is necessary for the protection of children from harm due to extreme meteorological factors.

Interactions Between Enteroviruses and the Inflammasome: New Insights Into Viral Pathogenesis

Enteroviruses (EVs) have emerged a substantial threat to public health. EVs infection range from mild to severe disease, including mild respiratory illness, diarrhea, poliomyelitis, hand, foot, and mouth disease, aseptic meningitis, and encephalitis. In the Asia-Pacific region, for example, one of the best studied enterovirus 71 (EV71) has been associated with pandemics of hand, foot, and mouth disease (HFMD) in children, particularly those under the age of five. Serious HFMD cases are associated with neurological complications, such as aseptic meningitis, acute flaccid paralysis, brainstem encephalitis, and have been associated with as many as 1000s of deaths in children and infants from 2008 to 2017, in China. More than 90% of laboratory confirmed deaths due to HMFD are associated with EV71. However, little is known about the pathogenesis of EVs. Studies have reported that EVs-infected patients with severe complications show elevated serum concentrations of IL-1β. The secretion of IL-1β is mediated by NLRP3 inflammasome during EV71 and CVB3 infection. Enteroviruses 2B and 3D proteins play an important role in activation of NLRP3 inflammasome, while 3C and 2A play important roles in antagonizing the activation of NLRP3 and the secretion of IL-1β. In this review, we summarize current knowledge regarding the molecular mechanisms that underlie the activation and regulation of the NLRP3 inflammasome, particularly how viral proteins regulate NLRP3 inflammasome activation. These insights into the relationship between the NLRP3 inflammasome and the pathogenesis of EVs infection may ultimately inform the development of novel antiviral drugs.

Immunogenicity, safety, cross-reaction, and immune persistence of an inactivated enterovirus A71 vaccine in children aged from two months to 11 years in Taiwan

BACKGROUND

To fight against enterovirus A71 (EV-A71)-associated diseases, vaccine development was initiated in Taiwan focusing on two-month-old infants.

METHODS

We conducted a phase II, double-blind, randomised, placebo-controlled study on infants and children aged two months to 11 years. This study was conducted in 4 parts (2a, 2b, 2c, and 2d) with age de-escalation sequentially. Two doses were administered with a 28-day or 56-day interval. Participants aged two months to <two years received a booster dose at one year after the first dose. During the surveillance period, solicited adverse events (AEs) and unsolicited AEs were recorded for safety evaluation. Blood samples were collected for neutralising antibody assay at various times. Immune persistence and booster effects were also assessed.

RESULTS

A total of 363 children completed the study. Most AEs were mild and unrelated to treatment. No vaccine-related serious adverse events (SAEs) were reported. Geometric mean titres (GMTs) of serum neutralising antibody titres increased profoundly. Most participants in the vaccine groups achieved defined seroprotection (neutralization titre ≥ 1:32) after the second vaccination and persisted for two years. Furthermore, the EV-A71 vaccine could provide a cross-reaction against other EV-A71 strain genotypes: B5, C4a, C4b, and C5.

CONCLUSIONS

The mid dose of the EV-A71 vaccine elicited high immune response and were tolerable in participants aged between two months and 11 years in all dosing groups.

Clinical Value of Dorsal Medulla Oblongata Involvement Detected With Conventional Magnetic Resonance Imaging for Prediction of Outcome in Children With Enterovirus 71-Related Brainstem Encephalitis

BACKGROUND

Brainstem encephalitis is the most common neurologic complication after enterovirus 71 infection. The involvement of brainstem, especially the dorsal medulla oblongata, can cause severe sequelae or death in children with enterovirus 71 infection. We aimed to determine the prevalence of dorsal medulla oblongata involvement in children with enterovirus 71-related brainstem encephalitis (EBE) by using conventional magnetic resonance imaging (MRI) and to evaluate the value of dorsal medulla oblongata involvement in outcome prediction.

METHODS

Forty-six children with EBE were enrolled in the study. All subjects underwent a 1.5 Tesla MRI examination of the brain. The disease distribution and clinical data were collected. Dichotomized outcomes (good vs. poor) at longer than 6 months were available for 28 patients. Logistic regression was used to determine whether the MRI-confirmed dorsal medulla oblongata involvement resulted in improved clinical outcome prediction when compared with other location involvement.

RESULTS

Of the 46 patients, 35 had MRI evidence of dorsal medulla oblongata involvement, 32 had pons involvement, 10 had midbrain involvement and 7 had dentate nuclei involvement. Patients with dorsal medulla oblongata involvement or multiple area involvement were significantly more often in the poor outcome group than in the good outcome group. Logistic regression analysis showed that dorsal medulla oblongata involvement was the most significant single variable in outcome prediction (predictive accuracy, 90.5%), followed by multiple area involvement, age and initial Glasgow Coma Scale score.

CONCLUSIONS

Dorsal medulla oblongata involvement on conventional MRI correlated significantly with poor outcomes in EBE children, improved outcome prediction when compared with other clinical and disease location variables, and was most predictive when combined with multiple area involvement, Glasgow Coma Scale score and age.

Surveillance for severe hand, foot, and mouth disease from 2009 to 2015 in Jiangsu province: epidemiology, etiology, and disease burden

Background

Severe hand, foot, and mouth disease (HFMD) is a common childhood illness caused by various enteroviruses. The disease has imposed increased burden on children younger than 5 years old. We aimed to determine the epidemiology, CNS complication, and etiology among severe HFMD patients, in Jiangsu, China.

Methods

Epidemiological, clinical, and laboratory data of severe HFMD cases were extracted from 2009 to 2015. The CNS complication, annually severe illness rates, mortality rates, severity-PICU admission rates, severity-hospitalization rates, and so on were analyzed to assess the disease burden of severe HFMD. All analyses were stratified by time, region, population, CNS involvement and serotypes. The VP1 gene from EV-A71, CV-A16, CV-A6, CV-A10 and other enteroviruses isolates was amplified. Phylogenetic analysis was performed using MEGA5.0.

Results

Seven thousand nine hundred ninety-four severe HFMD cases were reported, of them, 7224 cases were inpatients, 611 were PICU inpatients, and 68 were fatal. The average severe illness rate, mortality rate, severity−fatality rate, severity-PICU admission rate, and severity-hospitalization rate were 14.54, 0.12,8506, 76,430, and 903,700 per 1 million, respectively. The severe illness rate was the highest in the 12–23 months age group, and the greatest mortality rate was in the 6–11 months age group. Geographical difference in severe illness rate and mortality were found. Patients infected with EV-A71 were at a higher proportion in different CNS involvement even death. EV-A71, CV-A16 and other enteroviruses accounted for 79.14, 6.49, and 14.47%, respectively. A total of 14 non-EV-A71/ CV-A16 genotypes including CV-A2, CV-A4, CV-A 6, CV-A9, CV-A10, CV-B1, CV-B2, CV-B3, CV-B4, CV-B5, E-6, E-7, E-18, and EV-C96 were identified. Phylogentic analyses demonstrated that EV-A71 strains belonged to subgenotype C4a, while CV-A16 strains belonged to sub-genotype B1a and sub-genotype B1b of genotype B1. CV-A6 strains were assigned to genogroup F, and CV-A10 strains belonged to genogroup D.

Conclusions

Future mitigation policies should take into account the age, region heterogeneities, CNS conditions and serotype of disease. Additional a more rigorous study between the mild and severe HFMD should be warranted to elucidate the difference epidemiology, pathogen spectrum and immunity patterns and to optimize interventions in the following study.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3659-7) contains supplementary material, which is available to authorized users.

Enterovirus A71 Infection Activates Human Immune Responses and Induces Pathological Changes in Humanized Mice

Since the discovery of enterovirus A71 (EV-A71) half a century ago, it has been recognized as the cause of large-scale outbreaks of hand-foot-and-mouth disease worldwide, particularly in the Asia-Pacific region, causing great concern for public health and economic burdens. Detailed mechanisms on the modulation of immune responses after EV-A71 infection have not been fully known, and the lack of appropriate models hinders the development of promising vaccines and drugs. In the present study, NOD-scid IL2Rγ^-/- (NSG) mice with a human immune system (humanized mice) at the age of 4 weeks were found to be susceptible to a human isolate of EV-A71 infection. After infection, humanized mice displayed limb weakness, which is similar to the clinical features found in some of the EV-A71-infected patients. Histopathological examination indicated the presence of vacuolation, gliosis, or meningomyelitis in brain stem and spinal cord, which were accompanied by high viral loads detected in these organs. The numbers of activated human CD4⁺ and CD8⁺ T cells were upregulated after EV-A71 infection, and EV-A71-specific human T cell responses were found. Furthermore, the secretion of several proinflammatory cytokines, such as human gamma interferon (IFN-γ), interleukin-8 (IL-8), and IL-17A, was elevated in the EV-A71-infected humanized mice. Taken together, our results suggested that the humanized mouse model permits insights into the human immune responses and the pathogenesis of EV-A71 infection, which may provide a platform for the evaluation of anti-EV-A71 drug candidates in the future.IMPORTANCE Despite causing self-limited hand-food-and-mouth disease in younger children, EV-A71 is consistently associated with severe forms of neurological complications and pulmonary edema. Nevertheless, only limited vaccines and drugs have been developed over the years, which is possibly due to a lack of models that can more accurately recapitulate human specificity, since human is the only natural host for wild-type EV-A71 infection. Our humanized mouse model not only mimics histological symptoms in patients but also allows us to investigate the function of the human immune system during infection. It was found that human T cell responses were activated, accompanied by an increase in the production of proinflammatory cytokines in EV-A71-infected humanized mice, which might contribute to the exacerbation of disease pathogenesis. Collectively, this model allows us to delineate the modulation of human immune responses during EV-A71 infection and may provide a platform to evaluate anti-EV-A71 drug candidates in the future.

Epidemiology of Recurrent Hand, Foot and Mouth Disease, China, 2008-2015

Children who have received the enterovirus A71 vaccine are still at risk for disease with infections of enteroviruses of other serotypes.

Using China’s national surveillance data on hand, foot and mouth disease (HFMD) for 2008–2015, we described the epidemiologic and virologic features of recurrent HFMD. A total of 398,010 patients had HFMD recurrence; 1,767 patients had 1,814 cases of recurrent laboratory-confirmed HFMD: 99 reinfections of enterovirus A71 (EV-A71) with EV-A71, 45 of coxsackievirus A16 (CV-A16) with CV-A16, 364 of other enteroviruses with other enteroviruses, 383 of EV-A71 with CV-A16 and CV-A16 with EV-A71, and 923 of EV-A71 or CV-A16 with other enteroviruses and other enteroviruses with EV-A71 or CV-A16. The probability of HFMD recurrence was 1.9% at 12 months, 3.3% at 24 months, 3.9% at 36 months, and 4.0% at 38.8 months after the primary episode. HFMD severity was not associated with recurrent episodes or time interval between episodes. Elucidation of the mechanism underlying HFMD recurrence with the same enterovirus serotype and confirmation that HFMD recurrence is not associated with disease severity is needed.

Magnetic Resonance Imaging Features of Pediatric Coxsackievirus Encephalitis

Coxsackievirus, a common pathogen causing pediatric infection, typically causes a mild, nonspecific illness with low-grade fever, but can cause severe illness on rare occasions. Encephalitis is an uncommon but important complication of coxsackievirus infection. The magnetic resonance imaging (MRI) findings of coxsackievirus B3 (CVB3) encephalitis have not been reported in the literature, and there are few descriptions of MRI findings of encephalitis induced by coxsackieviruses of other serotypes. We report the MRI findings of CVB3 encephalitis in a two-year-old girl, review the MRI findings in previously reported cases of pediatric coxsackievirus encephalitis, and present the MRI characteristics of coxsackievirus encephalitis.

Acute flaccid myelitis: Rehabilitation challenges and outcomes in a pediatric cohort

PURPOSE

To describe one institution's experience in the rehabilitation of children with acute flaccid myelitis (AFM). This study reviews the medical and rehabilitative course and functional outcomes of a cohort of children who underwent Activity Based Restorative Therapy (ABRT) at a single center.

METHODS

Children with AFM presenting for rehabilitation between March 2005 and January 2017 were identified and a retrospective chart review was conducted. Changes in medical and functional status were assessed using multiple standardized instruments, as well as a chart review of medical progress.

RESULTS

Thirty-one children with AFM treated at our institution in the study time period were identified. Of these, seventeen received inpatient treatment, and fourteen received solely outpatient interventions. Their medical and functional outcomes are described with use of standardized measures when available.

CONCLUSIONS

Children with flaccid paralysis due to AFM undergoing structured, comprehensive rehabilitation interventions, even when these are initiated long after paralysis onset, can make significant neurologic and functional gains. Recovery of function and prevention of comorbidities are the main therapeutic targets for interventions in this population.

Acute flaccid myelitis and enterovirus D68: lessons from the past and present

Acute flaccid myelitis is characterized by the combination of acute flaccid paralysis and a spinal cord lesion largely restricted to the gray matter on magnetic resonance imaging. The term acute flaccid myelitis was introduced in 2014 after the upsurge of pediatric cases in the USA with enterovirus D68 infection. Since then, an increasing number of cases have been reported worldwide. Whereas the terminology is new, the clinical syndrome has been recognized in the past in association with several other neurotropic viruses such as poliovirus.Conclusion: This review presents the current knowledge on acute flaccid myelitis with respect to the clinical presentation and its differential diagnosis with Guillain-Barré syndrome and acute transverse myelitis. We also discuss the association with enterovirus D68 and the presumed pathophysiological mechanism of this infection causing anterior horn cell damage. Sharing clinical knowledge and insights from basic research is needed to make progress in diagnosis, treatment, and prevention of this new polio-like disease. What is Known: • Acute flaccid myelitis (AFM) is a polio-like condition characterized by rapid progressive asymmetric weakness, together with specific findings on MRI • AFM has been related to different viral agents, but recent outbreaks are predominantly associated with enterovirus D68. What is New: • Improving knowledge on AFM must increase early recognition and adequate diagnostic procedures by clinicians. • The increasing incidence of AFM urges cooperation between pediatricians, neurologists, and microbiologists for the development of treatment and preventive options.

Spiramycin and azithromycin, safe for administration to children, exert antiviral activity against enterovirus A71 in vitro and in vivo

Hand-foot-mouth disease (HFMD) is a common viral disease in young children, mainly caused by enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). Specific antiviral agents are not commercially available yet. Here we report that the macrolide antibiotics spiramycin (SPM) and azithromycin (AZM) possess antiviral activities against EV-A71 and CV-A16. SPM significantly reduced EV-A71 RNA and protein levels, most likely through interfering with viral RNA replication. The SPM-resistant EV-A71 variants showed similar resistance to AZM, indicating a similar anti-EV-A71 mechanism by which these two drugs exert their functions. The mutations of these variants were reproducibly mapped to VP1 and 2A, which were confirmed to confer resistance to SPM. Animal experiments showed that AZM possesses stronger anti-infection efficacy than SPM, greatly alleviated the disease symptoms and increased the survival rate in a mouse model severely infected with EV-A71. In all, our work suggests that AZM is a potential treatment option for EV-A71-induced HFMD, whose proved safety for infants and children makes it even more promising.

Clinical and aetiological study of hand, foot and mouth disease in southern Vietnam, 2013-2015: Inpatients and outpatients

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Multiple serotypes of enterovirus A cause hand, foot and mouth disease in southern Vietnam.

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Clinical characteristics differed slightly between the different pathogen groups.

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CV-A6 and CV-A10 emerged in Vietnam in 2013–2015.

•

An unexpected dominance of EV-A71 was found among both inpatients and outpatients.

Background

Hand, foot and mouth disease (HFMD) has been associated with large outbreaks among young children in the Asia-Pacific Region since 1997, including cases of severe illness and death. Severe illness is often associated with enterovirus A71 (EV-A71). Vietnam experienced a large sustained outbreak of 200 000 hospitalized cases and over 200 deaths in 2011–12, the large majority occurring in southern Vietnam.

Methods

A prospective observational study was conducted in the outpatient clinics, infectious diseases wards, and paediatric intensive care units of the three main referral centres for the treatment of HFMD in southern Vietnam. Demographic data, basic laboratory parameters, and clinical data were recorded, and molecular diagnostic tests were performed.

Results

Between July 2013 and July 2015, a total of 1547 children were enrolled. Four serotypes of enterovirus A (EV-A71, Coxsackievirus (CV) A6, A10, and A16) were responsible for 1005 of 1327 diagnosed cases (75.7%). An unexpected dominance of EV-A71 was found among both inpatients and outpatients, as well as a strong association with severe illness. CV-A6 and CV-A10 emerged in Vietnam during the study period and replaced CV-A16. CV-A10 was associated with different clinical and laboratory characteristics. During admission, 119 children developed a more severe illness. It was found that children with a skin rash showed less progression of severity, but when a rash was present, a macular rash was significantly associated with an increased risk of progression.

Conclusions

This study represents the most comprehensive descriptive HFMD study from Vietnam to date. Co-circulation and replacement of different serotypes has implications for vaccine development and implementation. These findings from a severely affected country add to our understanding of the presentation, progression, and aetiology of HFMD.

Urine catecholamines in children with severe Enterovirus A71 infection: comparison with paediatric septic shock

Purpose: Hypercatecholaminemia-related heart failure has been proposed as the main cause of enterovirus A71-related (EV-A71) early mortality. The purpose of this study was to measure urine catecholamine concentrations in severe EV-A71-infected children. Methods: A total of 35 children, aged 2.5 ± 2.1 years, were divided into three groups. Group I: 15 septic shock patients, group II: 17 EV-A71-stage-2 patients, and group III: 3 EV-A71-stage-4 patients. The laboratory results, cardiac biomarkers and urine catecholamine concentrations were statistically analysed. Results: Group I had the highest C-reactive protein (CRP) levels and group II had the lowest B-type natriuretic peptide (BNP) and its N-terminal prohormone among the groups (p = 0.039, <0.01 and <0.01, respectively). Group III patients had significantly higher urine catecholamine and troponin-I values among the groups. If urine epinephrine (Epi) >134 ug/gCr, norepinephrine (NE) >176 ug/gCr and vanillylmandelic acid (VMA) >11.7 mg/gCr were used as the cutoff points to differentiate groups II and III, the sensitivities and specificity were all 100%. Conclusions: The significantly elevated urine catecholamine concentrations in EV-A71-stage-4 patients support the hypothesis that hypercatecholaminemia-related heart failure is involved in severe EV-A71 infection. Urine catecholamines could be used as reliable biomarkers for differentiation of severe EV-A71 infection with or without heart failure and septic shock.

Enterovirus and parechovirus infections in children: differences in clinical presentation, mechanisms for meningitis without pleocytosis and mechanisms involved in the neurological outcome

Enterovirus (EV) and Parechovirus (HPeV) are a frequent cause of infection in children. This review gives an overview of possible causes for differences in clinical presentation. EV and HPeV can cause a meningitis with or without pleocytosis. Different possible mechanisms for meningitis without pleocytosis are given. Little is known about the prognosis and long-term effects of EV and HPeV meningitis in children. Only some studies with a small number of children with EV or HPeV meningitis are reported. The different possible mechanisms involved in the neurological outcome after EV or HPeV meningitis will be discussed.

Seroprevalence of antibodies to enterovirus 71 and coxsackievirus A16 among people of various age groups in a northeast province of Thailand

BACKGROUND

Hand, foot and mouth disease (HFMD) is endemic among population of young children in Thailand. The disease is mostly caused by enterovirus 71 (EV71) and coxsackievirus A16 (CA16).

METHODS

This study conducted serosurveillance for neutralizing (NT) antibodies to EV71 subgenotypes B5 and C4a, and to CA16 subgenotypes B1a and B1b, in 579 subjects of various ages using a microneutralization assay in human rhabdomyosarcoma (RD) cells. These test viruses were the major circulating subgenotypes associated with HFMD in Thailand during the study period.

RESULTS

We found that the levels of seropositivity against all 4 study viruses were lowest in the age group of 6-11 months, i.e., 5.5% had antibody to both EV71 subgenotypes, while 14.5% and 16.4% had antibody to CA16 subgenotypes B1a and B1b, respectively. The percentages of subjects with antibodies to these 4 viruses gradually increased with age, but were still less than 50% in children younger than 3 years. These laboratory data were consistent with the epidemiological data collected by the Ministry of Public Health which showed repeatedly that the highest number of HFMD cases was in children aged 1 year. Analyses of amino acid sequences of the test viruses showed 97% identity between the two subgenotypes of EV71, and 99% between the two subgenotypes of CA16. Nevertheless, the levels of seropositivity and antibody titer against the two subgenotypes of EV71 and of CA16 were not significantly different.

CONCLUSIONS

This study clearly demonstrated NT antibody activity across EV71-B5 and EV71-C4a subgenotypes, and also across CA16-B1a and CA16-B1b subgenotypes. Moreover, there were no significant differences by gender in the seropositive rates and antibody levels to any of the 4 virus subgenotypes.

Viral Encephalitis

Viruses are a frequent cause of encephalitis. Common or important viruses causing encephalitis include herpesviruses, arboviruses, enteroviruses, parechoviruses, mumps, measles, rabies, Ebola, lymphocytic choriomeningitis virus, and henipaviruses. Other viruses may cause an encephalopathy. Host factors and clinical features of infection are important to consider in identifying the cause for encephalitis. Cerebrospinal fluid evaluation, serologic/polymerase chain reaction studies, and neuroimaging are cornerstones of diagnostic evaluation in encephalitis. Treatable forms of encephalitis are important to consider in all cases. Central nervous system inflammation may also occur because of postinfectious autoimmunity, such as acute disseminated encephalomyelitis or antibody-mediated encephalitis after herpes simplex virus encephalitis.

Acute-Onset Flaccid Hemiparesis in a 9-Year-Old Boy With Presumed Enteroviral Infection

In the summer and autumn of 2014, a cluster of cases of flaccid paralysis were seen in the United States related to patients infected with enterovirus D68 (EV-D68). We present here a case of acute-onset flaccid hemiparesis in a previously healthy boy with altered mental status, hypothermia, and bowel incontinence.

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 hand hygiene intervention to decrease hand, foot and mouth disease and absence due to sickness among kindergarteners in China: A cluster-randomized controlled trial

OBJECTIVES

To evaluate the effect of the "Clean Hands, Happy Life" intervention on the incidence of hand, food and mouth disease (HFMD) and on school absences due to sickness in kindergarten students.

METHODS

The intervention consisted of four hand hygiene (HH) promotion components and was evaluated in a cluster-randomized controlled trial among 8275 children and 18 kindergartens from May to October, 2015 in Shenzhen, China. We compared two intervention arms - received the intervention in kindergartens only and in both kindergartens and families, respectively - to the control arm in multilevel analyses.

RESULTS

During the follow-up, the incidence of HFMD in both intervention arms was significantly lower than in the control arm (IRR₁: 0.39, 95%CI: 0.26-0.59; IRR₂: 0.30, 95%CI: 0.19-0.49); the duration of absence due to sickness (in days) in both intervention arms was significantly shorter than in the control arm (β₁ = 0.58, 95%CI: 0.41-0.74; β₂ = 0.34, 95%CI: 0.17-0.50), controlling for the area type of kindergarten and grade level of children. Furthermore, during the follow-up we found that there were fewer episodes of absence due to respiratory, skin and eye infections (P < 0.05).

CONCLUSIONS

Our intervention is effective at reducing HFMD infections and absence due to sickness in children attending kindergartens in China.

Flt3 ligand treatment reduces enterovirus A71 lethality in mice with enhanced B cell responses

Enterovirus A71 (EV-A71) infection can induce encephalitis, which causes death or long-term neurological sequelae, especially in young children. Using a murine infection model, we searched for anti-EV-A71 agents, because effective therapies are not available to control fatal infection. In EV-A71-infected mice, treatment with the hematopoietic growth factor, Fms-like tyrosine-kinase 3 ligand (Flt3 ligand) before infection reduced the lethality and tissue viral loads. Flt3 ligand failed to enhance the production of type I interferons. Instead, Flt3 ligand boosted the numbers of dendritic cells and, particularly lymphocytes in infected organs with an expansion of spleen B cells, and resulted in an increased titer of virus-specific antibody with neutralizing activity in the serum. The protective effect of Flt3 ligand was abolished in B cell-deficient mice. Our findings revealed that Flt3 ligand administration promotes resistance to EV-A71 infection with enhanced B cell response in a mechanism rarely reported before.

Enterovirus D68 and acute flaccid myelitis-evaluating the evidence for causality

Increased circulation of enterovirus D68 in 2014 and 2016 temporally and geographically coincided with increases in cases of acute flaccid myelitis, an uncommon condition of paralysis due to lesions in the anterior horn of the spinal cord. The identification of enterovirus D68 in respiratory specimens from cases of acute flaccid myelitis worldwide further supports an association, yet the absence of direct virus isolation from affected tissues, infrequent detection in cerebrospinal fluid, and the absence, until recently, of an animal model has left the causal nature of the relationship unproven. In this Personal View we evaluate epidemiological and biological evidence linking enterovirus D68 and acute flaccid myelitis. We applied the Bradford Hill criteria to investigate the evidence for a causal relationship and highlight the importance of comprehensive surveillance and research to further characterise the role of enterovirus D68 in acute flaccid myelitis and pursue effective therapies and prevention strategies.

Acute Flaccid Paralysis and Enteroviral Infections

PURPOSE OF REVIEW

The focus of this review is on enterovirus (EV)-associated acute flaccid paralysis (AFP) due to spinal cord anterior horn cell disease. Emphasis is placed on the epidemiology, pathogenesis, diagnosis, treatment, and outcome of AFP caused by polioviruses, vaccine-derived polioviruses, EV-D68, and EV-A71.

RECENT FINDINGS

Since the launch of The Global Polio Eradication Initiative in 1988, the worldwide incidence of polio has been reduced by 99.9%, with small numbers of poliomyelitis cases being reported only in Afghanistan, Pakistan, and Nigeria. With the planned phaseout of oral polio vaccine, vaccine-associated poliomyelitis is also expected to be eliminated. In their place, other EVs, chiefly EV-D68 and EV-A71, have emerged as the principal causes of AFP. There is evidence that the emergence of EV-D68 as a cause of severe respiratory disease and AFP was due to recent genetic virus evolution. Antiviral medications targeting EV-D68, EV-A71, and other EVs will likely be available in the near future. An effective EV-A71 vaccine has been developed, and preliminary investigations suggest an EV-D68 vaccine could be on the horizon. The eradication of poliomyelitis and vaccine-associated poliomyelitis is near, after which other EVs, presently EV-D68 and EV-A71, will be the principle viral causes of AFP. Moving forward, it is essential that EV outbreaks, in particular those associated with neurologic complications, be investigated carefully and the causal strains identified, so that treatment and prevention efforts can be rapidly developed and implemented.

Changes in the EV-A71 Genome through Recombination and Spontaneous Mutations: Impact on Virulence

Enterovirus 71 (EV-A71) is a major etiological agent of hand, foot and mouth disease (HFMD) that mainly affects young children less than five years old. The onset of severe HFMD is due to neurological complications bringing about acute flaccid paralysis and pulmonary oedema. In this review, we address how genetic events such as recombination and spontaneous mutations could change the genomic organization of EV-A71, leading to an impact on viral virulence. An understanding of the recombination mechanism of the poliovirus and non-polio enteroviruses will provide further evidence of the emergence of novel strains responsible for fatal HFMD outbreaks. We aim to see if the virulence of EV-A71 is contributed solely by the presence of fatal strains or is due to the co-operation of quasispecies within a viral population. The phenomenon of quasispecies within the poliovirus is discussed to reflect viral fitness, virulence and its implications for EV-A71. Ultimately, this review gives an insight into the evolution patterns of EV-A71 by looking into its recombination history and how spontaneous mutations would affect its virulence.

A virus-like particle-based tetravalent vaccine for hand, foot, and mouth disease elicits broad and balanced protective immunity

Hand, foot, and mouth disease (HFMD) is an infectious disease that mainly affects infants and children, causing considerable morbidity and mortality worldwide. HFMD is commonly caused by enterovirus 71 (EV71) and coxsackieviruses A16 (CVA16), A6 (CVA6), and A10 (CVA10). Formalin-inactivated EV71 vaccines are currently available in China; however, these vaccines fail to confer cross-protection against infections by other HFMD-causing enteroviruses, highlighting the necessity of developing a multivalent HFMD vaccine. Our previous studies demonstrated that recombinant virus-like particles (VLP) of EV71, CVA16, and CVA6 are capable of inducing protective immunity against homologous virus challenges in mice. In this study, we generated CVA10-VLP using a baculovirus-insect cell expression system and then combined CVA10-VLP with EV71-VLP, CVA16-VLP, and CVA6-VLP to formulate a tetravalent VLP vaccine. Immunogenicity and protective efficacy of tetravalent VLP vaccine was compared with that of monovalent VLP vaccines. Mouse immunization studies revealed that the tetravalent vaccine elicited antigen-specific and long-lasting serum antibody responses comparable to those elicited by its corresponding monovalent vaccines. Moreover, tetravalent vaccine immune sera strongly neutralized EV71, CVA16, CVA10, and CVA6 strains with neutralization titers similar to those of their monovalent counterparts, indicating a good compatibility among the four antigens in the combination vaccine. Importantly, passively transferred tetravalent vaccine-immunized sera conferred efficient protection against single or mixed infections with EV71, CVA16, CVA10, and CVA6 viruses in mice, whereas the monovalent vaccines could only protect mice against homotypic virus infections but not heterotypic challenges. These results demonstrate that the tetravalent VLP vaccine represents a promising broad-spectrum HFMD vaccine candidate.

Clinical and biological features of enteroviral meningitis among adults and children and factors associated with severity and length of stay

BACKGROUND

Enterovirus (EV) meningitis is the most common form of meningitis. Clinical and biological manifestations may be non-specific, leading to prolonged and costly investigations.

OBJECTIVES

To determine the different aspects of EV meningitis and the variables associated with length of stay (LOS) in hospital independently of patients' age.

STUDY DESIGN

Single center retrospective study of all EV PCR positive CSF samples during 3.5 years in Bordeaux University Hospital, France.

RESULTS

172 patients were included. 65 were under 3 years old and 49 over 18 years old. 10% of patients had severe forms of the disease. 47 patients (27.3%) had normal CSF count and in 63 patients (36.6%) polynuclear cells predominated in CSF. Procalcitonin, Hoens' score or PCR in stool samples appeared as good markers for enteroviral diagnosis. Time elapsed before PCR results was associated with LOS (p = .002) and should help in limiting investigations in case of aseptic meningitis.

CONCLUSION

Rapid availability of EV PCR reduces LOS for patients and contributes to diminish unnecessary procedures and further tests.

Mutations in VP1 and 5'-UTR affect enterovirus 71 virulence

Enterovirus 71 (EV71) is a major cause of hand, foot and mouth disease (HFMD). The current EV71 propagating in Vero (EV-V) or sub-passaged in RD (EV-R) cells was used as a pathogen. Interestingly, EV-R exhibited differential virulence; challenging human scavenger receptor class B2-expressing (hSCARB2-Tg) mice with EV71 revealed that EV-V was more virulent than EV-R: 100% of mice that received lethal amounts of EV-V died, while all the mice that received EV-R survived. Severe pathogenesis correlated with viral burdens and proinflammatory cytokine levels were observed in EV-V-challenged mice, but controversy in EV-R-challenged mice. Consensus sequence analysis revealed EV-R rapidly acquired complete mutations at E145G and S241L and partial mutations at V146I of VP1, and acquired a T to C substitution at nucleotide 494 of the 5'-UTR. EV-R exhibited higher binding affinity for another EV71 receptor, human P-selectin glycoprotein ligand-1 (hPSGL-1), than EV-V. Both EV71s exhibited no significant difference in binding to hSCARB2. The molecular modelling indicate that these mutations might influence EV71 engagement with PSGL-1 and in vivo virulence.

Association of gene polymorphisms of pattern-recognition receptor signaling pathway with the risk and severity of hand, foot, and mouth disease caused by enterovirus 71 in Chinese Han population

Hand, foot, and mouth disease (HFMD) caused by enterovirus 71 (EV71) presents with a wide variety of clinical manifestations. Host immune response is a factor that influences disease susceptibility and severity. We investigated the potential association of gene polymorphisms in the pattern recognition receptor (PRR) pathway with the risk and severity of EV71 infection. A total of 180 EV71 HFMD cases (108 severe case; 72 mild cases) were enrolled. A group of 201 sex- and age-matched children was included as a control. All subjects were genotyped for the most common single-nucleotide polymorphisms (SNPs) in the PRR and the PRR signaling pathway using the SNPscan multiple SNP typing method. Binary logistic regression analysis revealed statistically significant differences in polymorphism of RIG-1 between patients and controls (rs3739674 G vs C: OR = 1.502, 95%CI: 1.120-2.014; rs9695310 G vs C: OR = 1.782, 95%CI: 1.312-2.419). Polymorphisms of RIG-1 rs3739674 (G vs C: OR = 2.047, 95%CI: 1.307-3.205) and TLR3 rs5743305 (A vs T: OR = 0.346, 95%CI: 0.212-0.566) were found to be associated with disease severity. The results indicated that RIG-1 (rs3739674 and rs9695310) polymorphisms are associated with an increased risk of EV71-induced HFMD in Chinese children, whereas RIG-1 rs3739674 and TLR3 rs5743305 polymorphisms are associated with disease severity. These findings support an important role of innate immune mechanism in EV71 infection.

Enteroviruses: Classification, Diseases They Cause, and Approaches to Development of Antiviral Drugs

The genus Enterovirus combines a portion of small (+)ssRNA-containing viruses and is divided into 10 species of true enteroviruses and three species of rhinoviruses. These viruses are causative agents of the widest spectrum of severe and deadly epidemic diseases of higher vertebrates, including humans. Their ubiquitous distribution and high pathogenici- ty motivate active search to counteract enterovirus infections. There are no sufficiently effective drugs targeted against enteroviral diseases, thus treatment is reduced to supportive and symptomatic measures. This makes it extremely urgent to develop drugs that directly affect enteroviruses and hinder their development and spread in infected organisms. In this review, we cover the classification of enteroviruses, mention the most common enterovirus infections and their clinical man- ifestations, and consider the current state of development of anti-enteroviral drugs. One of the most promising targets for such antiviral drugs is the viral Internal Ribosome Entry Site (IRES). The classification of these elements of the viral mRNA translation system is also examined.

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.

Complete Genome Sequence of an Enterovirus A71 Strain Isolated in 2006 from a Patient in Shenzhen, Southern China, with a Lethal Case of Enterovirus Infection

The whole-genome sequence of an enterovirus A71 strain (EV71/SHENZHEN001/2006) isolated in 2006 from a patient with a fatal case of enterovirus infection was determined. Phylogenetic analysis based on the complete VP1 gene classified this strain as subgenotype C4a.

Prognostic Value of B-Type Natriuretic Peptide, Leukocytosis, and Hyperglycemia in Children with Severe Hand, Foot, and Mouth Disease

OBJECTIVE

Our goal is to determine the prognostic value of serum N-terminal prohormone of brain natriuretic peptide (NT-proBNP), leukocytosis, and hyperglycemia in patients with severe hand, foot, and mouth disease (HFMD).

DESIGN

This is a prospective cohort study conducted from March 2011 through October 2012 at Hunan Children's Hospital.

SETTING

Hunan Children's Hospital, a large children's teaching hospital with 1,500-beds located in the Changsha region of Hunan Province in China.

PATIENTS

295 children who were presented with clinical manifestation of severe HFMD, and required hospitalization.

INTERVENTIONS

Standard supportive treatment for HFMD as recommended by the national guidelines.

MEASUREMENTS

Admission blood samples were analyzed for NT-proBNP, leukocyte count, and serum glucose. Independent prognostic value of NT-proBNP for predicting mortality was evaluated using the Cox proportional hazard model adjusting for various covariates.

MAIN RESULTS

Area under the curve of receiver operating characteristic (AUROC) analysis suggested that a serum concentration of NT-proBNP concentration more than 1,500 pg/mL is an optimal cutoff point. Twenty-four patients (8.1%) had an NT-proBNP more than 1,500 pg/mL, and a 3-day mortality of 46% (11/24). Adjusted for tachycardia, tachypnea, hypertension, hyperglycemia, leukocytosis, and conscious disturbance on presentation, elevated NT-proBNP was associated with a 22.5-fold (95% confidence interval, 3.56-142.66) increased risk of 3-day mortality. We have further improved the specificity and AUROC values by the HFMD laboratory score, which combines NT-proBNP, leukocytosis, and hyperglycemia.

CONCLUSIONS

Routine admission surveillance for NT-proBNP is useful for identifying patients with HFMD at risk for mortality. Further studies are needed to determine whether early intervention in patients with highly elevated NT-proBNP can improve outcome.

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.

The 3C protease of enterovirus A71 counteracts the activity of host zinc-finger antiviral protein (ZAP)

Enterovirus A71 (EV-A71) is a positive-strand RNA virus that causes hand-foot-mouth disease and neurological complications in children and infants. Although the underlying mechanisms remain to be further defined, impaired immunity is thought to play an important role. The host zinc-finger antiviral protein (ZAP), an IFN-stimulated gene product, has been reported to specifically inhibit the replication of certain viruses. However, whether ZAP restricts the infection of enteroviruses remains unknown. Here, we report that EV-A71 infection upregulates ZAP mRNA in RD and HeLa cells. Moreover, ZAP overexpression rendered 293 T cells resistant to EV-A71 infection, whereas siRNA-mediated depletion of endogenous ZAP enhanced EV-A71 infection. The EV-A71 infection stimulated site-specific proteolysis of two ZAP isoforms, leading to the accumulation of a 40 kDa N-terminal ZAP fragment in virus-infected cells. We further revealed that the 3C protease (3Cpro) of EV-A71 mediates ZAP cleavage, which requires protease activity. Furthermore, ZAP variants with single amino acid substitutions at Gln-369 were resistant to 3Cpro cleavage, implying that Gln-369 is the sole cleavage site in ZAP. Moreover, although ZAP overexpression inhibited EV-A71 replication, the cleaved fragments did not show this effect. Our results indicate that an equilibrium between ZAP and enterovirus 3Cpro controls viral infection. The findings in this study suggest that viral 3Cpro mediated ZAP cleavage may represent a mechanism to escape host antiviral responses.

Mortality in Children with Severe Hand, Foot and Mouth Disease in Guangxi, China

Objective

To analyze the clinical features of children with hand foot and mouth disease (HFMD) who died.

Methods

331 deaths due to HFMD between 2010 and 2014 were included in this retrospective study; 15 autopsies were performed.

Results

Most deaths were seen in children aged below 3 y, and with enterovirus 71 infection (91%). The mean (SD) duration of HFMD from onset to death was 3.7(2.9) d. The mean (SD) age of fast progressors (from onset to death less than 4 days) was 17.4 (9.2) mo. Most of them were diagnosed as stage 3 and stage 4 of HFMD. Various pathological changes were observed in brain after autopsy, especially in brain stem and medulla.

Conclusions

The brain stem encephalitis with the neurotropism of enteroviruses seems to be the main contributor to the death in HFMD.