Detection of human enterovirus 71 and Coxsackievirus A16 in an outbreak of hand, foot, and mouth disease in Henan Province, China in 2009

Murine models of neonatal susceptibility to a clinical strain of enterovirus A71

Enterovirus A71 (EV-A71) is neurotropic and one of the primary enteric pathogens responsible for severe central nervous system infection in infants and young children. Neonatal mice are ideal models for studying the pathogenesis of infection caused by EV-A71. In this study, we assessed the susceptibility of neonatal BALB/c, C57BL/6, ICR, Kunming, and NIH mice to a clinically isolated EV-A71 strain. One-day-old mice were challenged with a clinical isolate of EV-A71 via intraperitoneal injection, then observed for 13 days for mortality, body-weight changes, and limb paralysis. RT-qPCR was performed to quantify viral RNA in the brain, spinal cord, skeletal muscle, and lungs of BALB/c and C57BL/6 mice. The expression of murine scavenger receptor class B member 2 (mSCARB2) was measured by western blotting. Finally, lesions were assessed by histological examination. We found that neonatal BALB/c and C57BL/6 mice were both susceptible to EV-A71, leading to decreased survival rate, greater body weight loss, and prominent hind-limb paralysis. Tissue viral loads of C57BL/6J mice were markedly higher than those of BALB/c mice, indicating that EV-A71 replicated more efficiently in C57BL/6 mice. Increased expression of mSCARB2 was observed 5 days after infection in C57BL/6 mice, which coincided with the peak in EV-A71 replication. Histological examination indicated that infection caused obvious pathogenic lesions. In conclusion, C57BL/6 are most susceptible to infection caused by EV-A71 and can be used as a model for studying its pathogenesis and test therapeutic options.

Regulation of host factor γ-H2AX level and location by enterovirus A71 for viral replication

Numerous viruses manipulate host factors for viral production. We demonstrated that human enterovirus A71 (EVA71), a primary causative agent for hand, foot, and mouth disease (HFMD), increased the level of the DNA damage response (DDR) marker γ-H2AX. DDR is primarily mediated by the ataxia telangiectasia mutated (ATM), ATM and Rad3-related (ATR), or DNA-dependent protein kinase (DNA-PK) pathways. Upregulation of γ-H2AX by EVA71 was dependent on the ATR but not the ATM or DNA-PK pathway. As a nuclear factor, there is no previous evidence of cytoplasmic distribution of γ-H2AX. However, the present findings demonstrated that EVA71 encouraged the localization of γ-H2AX to the cytoplasm. Of note, γ-H2AX formed a complex with structural protein VP3, non-structural protein 3D, and the viral genome. Treatment with an inhibitor or CRISPR/Cas9 technology to decrease or silence the expression of γ-H2AX decreased viral genome replication in host cells; this effect was accompanied by decreased viral protein expression and virions. In animal experiments, caffeine was used to inhibit DDR; the results revealed that caffeine protected neonatal mice from death after infection with EVA71, laying the foundation for new therapeutic applications of caffeine. More importantly, in children with HFMD, γ-H2AX was upregulated in peripheral blood lymphocytes. The consistent in vitro and in vivo data on γ-H2AX from this study suggested that caffeine or other inhibitors of DDR might be novel therapeutic agents for HFMD.

Seroprevalence of coxsackievirus A16 antibody among people of various age groups: a systematic review and meta-analysis

BACKGROUND

Coxsackie virus group A type 16 (CoxA16) is the main pathogen and usually an alternative to or joins in prevalence with enterovirus 71 (EV71) causing hand, foot and mouth disease (HFMD). The objective of this study was to estimate the seroprevalence of CoxA16 antibody among people of various age groups by a systematic review and meta-analysis.

METHODS

The literature of seroprevalence of CoxA16 antibody among people has been systematically searched through databases from the date of their establishment to Jan. 2021. Estimates of seroprevalence of CoxA16 antibody by gender and age groups have been summarized by using fixed- and random- effect models. All analyses have been conducted in STATA version 12.0 software.

RESULTS

A total of 14 publications with 9 in English and 5 in Chinese containing 9562 samples were finally included in the meta-analysis. The seroprevalence of CoxA16 antibody reported in different studies range from 24.85 to 76.92 %. Meta-analysis has revealed that the seroprevalence of CoxA16 antibody was 56.3 % (95 %CI: 47.7 %~64.9 %) in the overall population and 55.1 % (95 %CI: 44.1 %~66.1 %) in the Chinese population. Subgroup analysis by gender has revealed that the seroprevalence of CoxA16 antibody was 56.1 % (95 %CI: 45.2 %~67.1 %) in males and 60.0 % (95 %CI: 50.0 %~69.9 %) in females. Subgroup analysis by age groups has revealed that the seroprevalence of CoxA16 antibody was 49.1 % (95 %CI: 36.2 %~62.0 %) in the 0 ~ 5 age group and 63.9 % (95 %CI: 53.1 %~74.7 %) in the over 5 age group. Begg's funnel plots have suggested that there were no publication bias in all groups. Sensitive analysis has suggested that the result of the meta-analysis was stable.

CONCLUSIONS

The seroprevalence of CoxA16 antibody was closely related to age. Children under 5 years old were the main susceptible groups for CoxA16 and also the key groups for the prevention and control of HFMD.

A Bacillus-based Coxsackie virus A16 mucosal vaccine induces strong neutralizing antibody responses

The purpose of this study was to construct a Coxsackie virus A16 (CA16) mucosal vaccine and evaluate its ability to induce immune response. VP1 gene of CA16 was inserted into the genome of Bacillus subtilis via recombination and displayed on the surface of the spores. This Bacillus-based vaccine was used for intranasal immunization of mice and the serum antibody titer was determined by enzyme-linked immunosorbent assay (ELISA). Neutralization activity of the serum from immunized mice was analyzed by an in vitro neutralizing test. VP1 gene was successfully integrated into the genome of Bacillus subtilis and was expressed on the surface of Bacillus spores. Intranasal immunization of mice with this vaccine induced a higher level of VP1 specific IgA and IgG than in mice of the control group (p < 0.05). The neutralizing antibody titer in the spore immunization group was 1 : 169, which was higher than that in the control group (p < 0.05). We concluded that vaccine prepared by displaying CA16 VP1 protein on the surface of Bacillus subtilis spores can stimulate mice to produce protective neutralizing antibodies, which provides foundations for the development of CA16 mucosal vaccine.

Epidemiologic features of enterovirus associated with hand, foot and mouth disease in 2013 and 2014 in Shenzhen, China

Hand, foot and mouth disease (HFMD) is responsible for a heavy economic and social burden in the Asia-Pacific region. Previous studies have shown that coxsackievirus A6 (CVA6) and coxsackievirus A10 (CVA10) have become the predominant agents of HFMD in mainland China in recent years, replacing enterovirus 71 (EV71) and coxsackievirus A16 (CVA16), although it is unclear if this is consistent throughout China. In this study, samples from 253 HFMD cases were collected in Shenzhen, China, from May 2013 through April 2014 to identify the etiological agent of HFMD. In total, 64.8% (164/253) of HFMD cases were enterovirus positive, in which 81.1% (133/164) were determined to be CVA6. The phylogenetic tree of the partial viral protein 1 sequence showed that the CVA6 isolates were divided into four clusters (Clusters A to D), and cluster D was further divided into four sub-clusters (Clusters D1 to D4). The 133 CVA6 samples isolated in our study were classified into cluster D4, in which the first identified sequence was isolated in Shenzhen in 2008. This study demonstrated that the CVA6 cluster D4, which is predominantly circulating in HFMD in mainland China, may have originated from a local strain identified in 2008 in Shenzhen.

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.

Epidemiological and serological surveillance of hand-foot-and-mouth disease in Shanghai, China, 2012-2016

Aside from enterovirus 71 (EV71) and coxsackie virus A16 (CV-A16), viruses that are known to cause hand-foot-and-mouth disease (HFMD), epidemiological profiles of other enteroviruses that induce HFMD are limited. We collected 9949 laboratory surveillance HFMD cases and 1230 serum samples from infants and children in Shanghai from 2012–2016. Since 2013, CV-A6 has displaced EV71 and CV-A16 to become the predominant serotype. Interestingly, novel epidemiological patterns in EV71 and CV-A16 infections were observed, with one large peak in both 2012 and 2014, followed by two smaller peaks in the respective following years (2013 and 2015). Through sequencing, we found that C4a, B1b, D-Cluster-1 and B constituted the major subgenotypes of EV71, CV-A16, CV-A6 and CV-A10, respectively. Among healthy individuals, 50.49% and 54.23% had positive neutralising antibodies (NtAbs) against EV71 and CV-A16, respectively, indicating that EV71 and CV-A16 silent infections were common. These populations may be an important potential source of infection. The overall seropositive rate of EV71 NtAbs showed a fluctuating, markedly downward trend, indicating the potential risk of a future EV71 epidemic. High CV-A16 NtAb seroprevalence corroborated a documented CV-A16 ‘silent’ epidemic. Children aged 1–5 years had the lowest EV71 NtAb seropositive rate, whereas those aged 1–2 years exhibited the lowest CV-A16 NtAb seropositive rate. This is the first comprehensive investigation of the epidemiology and aetiology, as well as the seroprevalence, of HFMD in Shanghai between 2012 and 2016. This study provides the latest insights into developing a more efficient HMFD vaccination programme.

The binding of a monoclonal antibody to the apical region of SCARB2 blocks EV71 infection

Entero virus 71 (EV71) causes hand, foot, and mouth disease (HFMD) and occasionally leads to severe neurological complications and even death. Scavenger receptor class B member 2 (SCARB2) is a functional receptor for EV71, that mediates viral attachment, internalization, and uncoating. However, the exact binding site of EV71 on SCARB2 is unknown. In this study, we generated a monoclonal antibody (mAb) that binds to human but not mouse SCARB2. It is named JL2, and it can effectively inhibit EV71 infection of target cells. Using a set of chimeras of human and mouse SCARB2, we identified that the region containing residues 77-113 of human SCARB2 contributes significantly to JL2 binding. The structure of the SCARB2-JL2 complex revealed that JL2 binds to the apical region of SCARB2 involving α-helices 2, 5, and 14. Our results provide new insights into the potential binding sites for EV71 on SCARB2 and the molecular mechanism of EV71 entry.

Rheum emodin inhibits enterovirus 71 viral replication and affects the host cell cycle environment

Human enterovirus 71 (EV71) is the primary causative agent of recent large-scale outbreaks of hand, foot, and mouth disease (HFMD) in Asia. Currently, there are no drugs available for the prevention and treatment of HFMD. In this study, we compared the anti-EV71 activities of three natural compounds, rheum emodin, artemisinin and astragaloside extracted from Chinese herbs Chinese rhubarb, Artemisia carvifolia and Astragalus, respectively, which have been traditionally used for the treatment and prevention of epidemic diseases. Human lung fibroblast cell line MRC5 was mock-infected or infected with EV71, and treated with drugs. The cytotoxicity of the drugs was detected with MTT assay. The cytopathic effects such as cell death and condensed nuclei were morphologically observed. The VP1-coding sequence required for EV71 genome replication was assayed with qRT-PCR. Viral protein expression was analyzed with Western blotting. Viral TCID50 was determined to evaluate EV71 virulence. Flow cytometry analysis of propidium iodide staining was performed to analyze the cell cycle distribution of MRC5 cells. Rheum emodin (29.6 μmol/L) effectively protected MRC5 cells from EV71-induced cytopathic effects, which resulted from the inhibiting viral replication: rheum emodin treatment decreased viral genomic levels by 5.34-fold, viral protein expression by less than 30-fold and EV71 virulence by 0.33107-fold. The fact that inhibition of rheum emodin on viral virulence was much stronger than its effects on genomic levels and viral protein expression suggested that rheum emodin inhibited viral maturation. Furthermore, rheum emodin treatment markedly diminished cell cycle arrest at S phase in MRC5 cells, which was induced by EV71 infection and favored the viral replication. In contrast, neither astragaloside (50 μmol/L) nor artemisinin (50 μmol/L) showed similar anti-EV71 activities. Among the three natural compounds tested, rheum emodin effectively suppressed EV71 viral replication, thus is a candidate anti-HFMD drug.

Hand, Foot, and Mouth Disease in Hunan Province, China, 2009-2014: Epidemiology and Death Risk Factors

Hand, foot, and mouth disease (HFMD) is an arising public health problem in Asia, including China. Epidemiological data is necessary to enable judicious public health responses and interventions. We analyzed the epidemiological and laboratory data of 759,301 HFMD cases reported to the Hunan Provincial Center for Disease Control and Prevention from 1 January 2009 to 31 December 2014. Univariate and multivariable conditional logistic regression analyses were used to identify risk factors of fatality in HFMD. The incidence of HFMD was highest among children aged 1-3 years, compared with other age groups. Of the total HFMD cases, 7,222 (0.95%) were considered severe and 338 (0.04%) were fatal. Enterovirus-A71 was the major cause of severe and fatal cases (65.75% and 88.78%, respectively). For severe cases, the median time from symptom onset to diagnosis was 0.5 days (interquartile range [IQR] 0-1.5 days); the median time from diagnosis to severe illness was 2 days (IQR 1-3 days). For fatal cases, the median time from symptom onset to diagnosis was 0.5 days (IQR 0-1.5 days); the median time from diagnosis to death was 1.5 days (IQR 0.5-2.5 days). In multivariable analysis, the abuse of antibiotic, glucocorticoid and pyrazolone in village clinics at basic medical institutions were identified as independent risk factors for HFMD fatal cases. In conclusion, our results suggest that the future direction to control and respond to HFMD is intensive surveillance of enterovirus-A71 and improving the ability to diagnose disease and treat patients, especially in basic medical institutions.

Epidemiological and genetic analysis of hand-foot-mouth disease by enterovirus A71 in Taizhou, P. R. China, between 2010 and 2013

Out of a population of 1,098 enteroviruses (EVs)-positive hand, foot, and mouth disease (HFMD) specimens, 352 were screened positive for EV-A71-accounting for 32.1% of all EV-positive specimens. This percentage denotes EV-A71 as the second major serotype of enteroviruse among HFMD suffers in Taizhou. An epidemic outbreak of EV-A71 among HFMD children was found in Taizhou in the second quarter of 2012. Phylogeny analysis based on the VP1 complete sequences leads us to find a sub-clade (designated TZ1-1) of EV-A71 circulating in Taizhou, whose emergence might be correlated with the epidemic outbreak. This correlation was further supported by the followed two analyses (namely skyline plot of population history and birth-death SIR simulation of epidemic history). And more importantly, at a positively selected site of VP1 caspid, a mutation of N31D was found to be a synapomorphy of TZ1-1 and its occurrence might be correlated with the epidemic outbreak. J. Med. Virol. 89:782-790, 2017. © 2016 Wiley Periodicals, Inc.

Seroprevalence of Enterovirus A71 and Coxsackievirus A16 in Healthy People in Shandong Province, China

Background

Hand, foot, and mouth disease has become very common in mainland of China in recent years, and enterovirus A71 and coxsackievirus A16 are its major etiologic factors. Here we investigated the seroprevalence of enterovirus A71 and coxsackievirus A16 based on a large group of healthy individuals in Shandong province, China.

Methods

A total of 1378 healthy individuals were tested for serum neutralizing antibodies against enterovirus A71 and coxsackievirus A16 using a micro neutralization test.

Results

The overall seroprevalence of enterovirus A71 neutralizing antibodies was 74.75%. It increased significantly from 48.84% in children aged 0–1 years old to 88.64% in those aged 20–29 years (p < 0.01) and decreased to 85.71% in adults > 40 years old with a significant gender-specific difference (p < 0.01). The overall coxsackievirus A16 antibody prevalence was 71.77%. It increased significantly from 39.53% in children aged 0–1 years to 80.68% in those aged 10–19 years (p < 0.01) and decreased to 75.63% in adults >40 years without a gender-specific difference. Nearly 50% of the children <1 year were susceptible to enterovirus A71 infection versus 40% to coxsackievirus A16 infection. Sample collection time and place also played a role in the enterovirus A71 and coxsackievirus A16 positive rates. The overall rates in January were significantly lower than those in April and August (p < 0.01); enterovirus A71 positive rates in Jinan city (capital city of Shandong province) were lower than those in Jining city and Zibo city (p < 0.05); and oxsackievirus A16 positive rates in Jining city were significantly higher than those in Jinan city and Zibo city (p < 0.01).

Conclusion

There were significant differences among age groups, locations, and time points in the seroprevalence rates of enterovirus A71 and coxsackievirus A16 neutralizing antibodies in healthy people in Shandong province.

Effect of integrated Chinese and Western medicine therapy on severe hand, foot and mouth disease: A prospective, randomized, controlled trial

OBJECTIVE

To evaluate the efficacy and safety of Chinese medicine (CM) plus Western medicine (WM) in the treatment of pediatric patients with severe hand, foot and mouth disease (HFMD) by conducting a prospective, controlled, and randomized trial.

METHODS

A total of 451 pediatric patients with severe HFMD were randomly assigned to receive WM therapy alone (224 cases, WM therapy group) or CM [Reduning Injection ( ) or Xiyanping Injection ()] plus WM therapy (227 cases, CM plus WM therapy group) for 7-10 days, according to a web-based randomization system. The primary outcome was fever clearance time, which was presented as temperature decreased half-life time. The secondary outcomes included the rate of rash/herpes disappearance within 120 h, as well as the rate for cough, runny nose, lethargy and weakness, agitation or irritability, and vomiting clearance within 120 h. The drug-related adverse events were also recorded.

RESULTS

The temperature decreased half-life time was 40.4 h in the WM therapy group, significantly longer than 27.2 h in the CM plus WM therapy group (P<0.01). Moreover, the rate for rash/herpes disappearance within 120 h was 43.6% (99/227) in the CM plus WM therapy group, significantly higher than 29.5% (66/224) in the WM therapy group (P<0.01). In addition, the rate for cough, lethargy and weakness, agitation or irritability disappearance within 120 h was 32.6% (74/227) in the CM plus WM therapy group, significantly higher than 19.2% (43/224) in the WM therapy group (P<0.01). No drug-related adverse events were observed during the course of the study.

CONCLUSION

The combined CM and WM therapy achieved a better therapeutic efficacy in treating severe HFMD than the WM therapy alone. Reduning or Xiyanping Injections may become an important complementary therapy to WM for relieving the symptoms of severe HFMD. (Registration No. NCT01145664).

Study of the epidemiology and etiological characteristics of hand, foot, and mouth disease in Suzhou City, East China, 2011-2014

Hand, foot, and mouth disease (HFMD) is a common childhood illness that is caused by enteroviruses, and the prevalence of HFMD in China and around the world has resulted in a huge disease burden. Since 2010, the HFMD incidence has been the highest among infectious diseases in Suzhou, China. To investigate the epidemical, features, etiological characteristics, and clinical characteristics of HFMD in Suzhou City, East China, from 2011 to 2014. We retrospectively analyzed HFMD epidemiological data in Suzhou from 2011 to 2014. A total of 80,723 outpatients in the city of Suzhou were diagnosed with HFMD, including 1,846 severe cases. There were 2,387 (3.0 %) laboratory-confirmed cases, 807 of which exhibited severe symptoms. All analyses were stratified by age, disease severity, laboratory confirmation status, and enterovirus subtype. From 2011 to 2014, HFMD mainly affected children aged 1-3, and boys were more affected than girls. The highest peak incidences of HFMD occurred in May or June from 2011 to 2014, and lower peak incidences were observed from November to December and in districts with higher humidity. Enterovirus 71 and coxsackievirus A16 were the predominant viral genotypes in Suzhou in 2011 to 2012 and 2014, and the severe cases mainly correlated with EV71 subtypes. In 2013, other EVs were dominant. The proportion of patients with severe disease decreased significantly, and the VP1 capsid proteins of EV71 and CA16 from severe and mild cases were nearly identical. This study shows that it is time to start monitoring EVs in China and that we should accelerate vaccine research and develop public-health interventions for the control and prevention of HFMD, all of which will play an important role in the prevention of HFMD.

Genomic features of coxsackievirus A6 correlate with herpangina and hand, foot and mouth disease

Aim: To study the genomic factors of coxsackievirus A6 (CVA6) correlated with herpangina and hand, foot and mouth disease (HFMD). Materials & methods: Complete genome of CVA6 strains and HFMD causing enteroviruses were enrolled for genomic comparisons. Results: Recombinations in the nonstructural P2-P3 region appeared to correlate with HFMD causing pathogenicity. Among nonrecombinant CVA6 strains, a markedly nucleotide diversity in 3C-3UTR was observed between herpangina and HFMD causing CVA6. Synonymous mutations take an important role in the evolution of CVA6 3C-3UTR region, as limited amino acid variations were resulted from the high nucleotide diversity. Key amino acid mutations at positions 168–170 of 3D protein were correlated with the differences in viral pathogenicities. Conclusion: These findings provide insights into viral genomic features correlated with CVA6 pathogenicities.

Enterovirus 71 mediates cell cycle arrest in S phase through non-structural protein 3D

Many viruses disrupt the host cell cycle to facilitate their own growth. We assessed the mechanism and function of enterovirus 71 (EV71), a primary causative agent for recent hand, foot, and mouth disease outbreaks, in manipulating cell cycle progression. Our results suggest that EV71 infection induces S-phase arrest in diverse cell types by preventing the cell cycle transition from the S phase into the G2/M phase. Similar results were observed for an alternate picornavirus, Coxsackievirus A16. Synchronization in S phase, but not G0/G1 phase or G2/M phase, promotes viral replication. Consistent with its ability to arrest cells in S phase, the expression of cyclin A2, CDK 2, cyclin E1, and cyclin B1 was regulated by EV71 through increasing transcription of cyclin E1, promoting proteasome-mediated degradation of cyclin A2 and regulating the phosphorylation of CDK 2. Finally, a non-structural protein of EV71, the RNA-dependent RNA polymerase 3D, was demonstrated to mediate S-phase cell cycle arrest. These findings suggest that EV71 induces S-phase cell cycle arrest in infected cells via non-structural protein 3D, which may provide favorable conditions for virus production.

Characterization of VP1 gene of coxsackievirus A16 prevalent among hand foot mouth disease suffered children in Taizhou, P. R. China, between 2010 and 2013

A total of 453 strains of Coxsackievirus A16 (CV-A16) were screened out of 1,509 hand-foot-mouth disease (HFMD) samples collected in Taizhou during the period from 2010 to 2013. And between first quarter of 2011 and first quarter of 2013, an outbreak of CV-A16 was found among the HFMD sufferers in Taizhou. Phylogenic analysis of VP1 sequences indicated a major CV-A16 sub-group in Taizhou, whose change pattern of effective population sizes was found to be similar to the pattern of the actual percentage changes of CV-A16 during the outbreak over the same period. More importantly, the sub-group all displayed a Leu (L) to Met (M) mutation at site-23 of capsid VP1 which might be correlated with the outbreak of CV-A16 in Taizhou.

Is a multivalent hand, foot, and mouth disease vaccine feasible?

Enterovirus A infections are the primary cause of hand, foot and mouth disease (HFMD) in infants and young children. Although enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) are the predominant causes of HFMD epidemics worldwide, EV-A71 has emerged as a major neurovirulent virus responsible for severe neurological complications and fatal outcomes. HFMD is a serious health threat and economic burden across the Asia-Pacific region. Inactivated EV-A71 vaccines have elicited protection against EV-A71 but not against CV-A16 infections in large efficacy trials. The current development of a bivalent inactivated EV-A71/CV-A16 vaccine is the next step toward that of multivalent HFMD vaccines. These vaccines should ultimately include other prevalent pathogenic coxsackieviruses A (CV-A6 and CV-A10), coxsackieviruses B (B3 and B5) and echovirus 30 that often co-circulate during HFMD epidemics and can cause severe HFMD, aseptic meningitis and acute viral myocarditis. The prospect and challenges for the development of such multivalent vaccines are discussed.

Clinical Efficacy of Andrographolide Sulfonate in the Treatment of Severe Hand, Foot, and Mouth Disease (HFMD) is Dependent upon Inhibition of Neutrophil Activation

Andrographolide sulfonate treatment has been shown to improve clinical severe hand, foot, and mouth disease (HFMD) efficacies when combined with conventional therapy. However, the mechanisms for its therapeutic effects remain elusive. In this study, we aimed to investigate whether andrographolide sulfonate exerts its efficacy by acting on neutrophil activation. We obtained serial plasma samples at two time points (before and after 5 days of therapy) from 28 HFMD patients who received conventional therapy and 18 patients who received combination therapy (andrographolide sulfonate plus conventional therapy). Then, we measured plasma myeloperoxidase (MPO), S100A8/A9, histone, and inflammatory cytokine levels. Furthermore, we examined if andrographolide sulfonate had direct effects on neutrophil activation in vitro. We observed that MPO and S100A8/A9 levels were markedly elevated in the HFMD patients before clinical treatment. At 5 days post-medication, the MPO, S100A8/A9, histone, and interleukin-6 levels were markedly lower in the combination therapy group compared with the conventional therapy group. In vitro studies showed that andrographolide sulfonate inhibited lipopolysaccharide-stimulated neutrophil activation, demonstrated by the decreased production of reactive oxygen species and cytokines. These data indicate that neutrophil activation modulation by andrographolide sulfonate may be a critical determinant for its clinical HFMD treatment efficacy. Copyright © 2015 John Wiley & Sons, Ltd.

Epidemiology of childhood enterovirus infections in Hangzhou, China

Background

There are over 100 serotypes of enterovirus species A-D, which are the common cause of various symptoms in infants, such as meningitis, encephalitis and hand foot mouth disease (HFMD). This study aims to investigate the epidemiological characteristics of enteroviruses in Hangzhou, Zhejiang province, China, and to provide relevant information to guide public health responses and interventions.

Methods

Systematic surveillance was conducted on enterovirus infections. Samples were collected from children admitted to the inpatient wards and outpatient departments between January 2010 and December 2012 in the Children’s Hospital, Zhejiang University School of Medicine. Enteroviruses from all specimens were detected by RT-PCR using a commercialized detection kit.

Results

From 13026 samples collected and examined, 2673 (21.21%) were found positive for enteroviruses. The annual enterovirus-positive rate decreased from 32.78% in 2010 to 14.23% in 2012. Positivity rate for enteroviruses was highest among children aged less than 5 years. The monthly positivity rate for enterovirus infection ranged from 2.6% to 34.83%, with a peak in June and July. Serotypes causing severe symptoms such as HFMD including EV71 and CA16 were decreasing, while the proportion of unidentified EV serotypes causing herpangina and viral encephalitis were on the rise.

Conclusions

EV infection is highly prevalent among young children in Hangzhou, as it is in the most other parts of the world. Further surveillance using methods that can subtype all EVs is warranted to better monitor these infections and their etiology.

Spatio-temporal analysis of the relationship between climate and hand, foot, and mouth disease in Shandong province, China, 2008-2012

Background

Hand, foot, and mouth disease (HFMD) is the most common communicable disease in China. Shandong Province is one of the most seriously affected areas. The distribution of HFMD had spatial heterogeneity and seasonal characteristic in this setting. The aim of this study was to explore the associations between climate and HFMD by a Bayesian approach from spatio-temporal interactions perspective.

Methods

The HFMD data of Shandong Province during 2008–2012 were derived from the China National Disease Surveillance Reporting and Management System. And six climatic indicators were obtained from the Meteorological Bureau of Shandong Province. The global spatial autocorrelation statistic (Moran’s I) was used to detect the spatial autocorrelation of HFMD cases in each year. The optimal one among four Bayesian models was further adopted to estimate the relative risk of the occurrence of HFMD via Markov chain Monte Carlo.

Results

The annual average incidence rate of HFMD was 104.40 per 100,000 in Shandong Province. Positive spatial autocorrelation appeared at county level (Moran’s I ≥0.30, P < 0.001). The best fitting Spatio-temporal interactive model showed that annual average temperature, annual average pressure, annual average relative humidity, annual average wind speed and annual sunshine hours were significantly positive related to the occurrence of HFMD. The estimated relative risk of 36, 87, 91, 79, 65 out of 140 counties for 2008–2012 respectively were significantly more than 1.

Conclusions

There were obvious spatio-temporal heterogeneity of HFMD in Shandong Province, and the climatic indicators were associated with the epidemic of HFMD. Bayesian approach should be recommended to capture the spatial-temporal pattern of HFMD.

Reemergence of enterovirus 71 epidemic in northern Taiwan, 2012

BACKGROUND

Enterovirus 71 (EV71) belongs to picornavirus family and could be classified phylogenetically into three major genogroups (A, B and C) including 11 genotypes (A, B1-B5 and C1-C5). Since 1997, EV71 has caused large-scale of epidemics with neurological complications in Asian children. In Taiwan, nationwide EV71 epidemics with different predominant genotypes have occurred cyclically since 1998. A nationwide EV71 epidemic occurred again in 2012. We conducted genetic and antigenic characterizations of the 2012 epidemic.

METHODS

Chang Gung Memorial Hospital (CGMH) is a medical center in northern Taiwan. In CGMH, specimens were collected from pediatric inpatients with suspected enterovirus infections for virus isolation. Enterovirus isolates were serotyped and genotyped and sera from EV71 inpatients were collected for measuring neutralizing antibody titers.

RESULTS

There were 10, 16 and 99 EV71 inpatients identified in 2010, 2011 and 2012, respectively. There were 82 EV71 isolates genotyped, which identified 17 genotype C4a viruses and 65 genotype B5 viruses. The genotype B5 viruses were not detected until November 2011 and caused epidemics in 2012. Interestingly, the B5-2011 viruses were genetically distinguishable from the B5 viruses causing the 2008 epidemic and are likely introduced from China or Southeastern Asia. Based on antigenic analysis, minor antigenic variations were detected among the B5-2008, B5-2011, C4a-2008 and C4a-2012 viruses but these viruses antigenically differed from genotype A.

CONCLUSIONS

Genotype B5 and C4a viruses antigenically differ from genotype A viruses which have disappeared globally for 30 years but have been detected in China since 2008. Enterovirus surveillance should monitor genetic and antigenic variations of EV71.

Epidemiological and etiological characteristics of hand, foot, and mouth disease in Henan, China, 2008-2013

Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by enteroviruses. HFMD outbreaks and reported cases have sharply increased in China since 2008. Epidemiological and clinical data of HFMD cases reported in Henan Province were collected from 2008 to 2013. Clinical specimens were obtained from a subset of these cases. Descriptive epidemiological methods were used to analyze the time, region and population distribution. The VP1 gene from EV71 and CA16 isolates was amplified, and the sequences were analyzed. 400,264 cases of HFMD were reported in this study, including 22,309 severe and 141 fatal cases. Incidence peaked between April and May. Laboratory confirmation was obtained for 27,692 (6.9%) cases; EV71, CA16, and other enteroviruses accounted for 59.5%, 14.1%, 26.4%, respectively. Phylogenetic analysis revealed that EV71 belonged to the C4a evolution branch of C4 sub-genotype and CA16 belonged to subtype B1a or B1b. The occurrence of HFMD in Henan was closely related to season, age and region distribution. Children under five were the most affected population. The major pathogens causing HFMD and their genotypes have not notably changed in Henan. The data strongly support the importance of EV71 vaccination in a high population density area such as Henan, China.

The variations of VP1 protein might be associated with nervous system symptoms caused by enterovirus 71 infection

Background

The VP1 protein of enterovirus 71 (EV71) is an important immunodominant protein which is responsible for host-receptor binding. Nevertheless, the relationship between VP1 and neurovirulence is still poorly understood. In this study, we investigated the relationship between mutation of VP1 and neurovirulent phenotype of EV71 infection.

Methods

One hundred and eighty-seven strains from Genbank were included, with a clear clinical background. They were divided into two groups, one with nervous system symptoms and one with no nervous system symptoms. After alignment, the significance of amino acid variation was determined by using the χ² test and a phylogenetic tree was constructed with MEGA software (version 5.1).

Results

We showed no significant difference in neurovirulence between genotype B and C. Interestingly, we found that variations of E145G/Q, E164D/K and T292N/K were associated with nervous system infection in genotype B. In the case of genotype C, the N31D mutation increased the risk for nervous complications, whereas I262V mutation decreased the risk of nervous complications. We used a 3D model of VP1 to demonstrate the potential molecular basis for EV71 nervous system tropism.

Conclusions

Distinct variations are shown to be associated with neurovirulent phenotype in the different genotype. Detection of variation in genotypes and subtypes may be important for the prediction of clinical outcomes.

Mutations in the non-structural protein region contribute to intra-genotypic evolution of enterovirus 71

Background

Clinical manifestations of enterovirus 71 (EV71) range from herpangina, hand-foot-and-mouth disease (HFMD), to severe neurological complications. Unlike the situation of switching genotypes seen in EV71 outbreaks during 1998–2008 in Taiwan, genotype B5 was responsible for two large outbreaks in 2008 and 2012, respectively. In China, by contrast, EV71 often persists as a single genotype in the population and causes frequent outbreaks. To investigate genetic changes in viral evolution, complete EV71 genome sequences were used to analyze the intra-genotypic evolution pattern in Taiwan, China, and the Netherlands.

Results

Genotype B5 was predominant in Taiwan’s 2008 outbreak and was re-emergent in 2012. EV71 strains from both outbreaks were phylogenetically segregated into two lineages containing fourteen non-synonymous substitutions predominantly in the non-structural protein coding region. In China, genotype C4 was first seen in 1998 and caused the latest large outbreak in 2008. Unlike shifting genotypes in Taiwan, genotype C4 persisted with progressive drift through time. A majority of non-synonymous mutations occurred in residues located in the non-structural coding region, showing annual increases. Interestingly, genotype B1/B2 in the Netherlands showed another stepwise evolution with dramatic EV71 activity increase in 1986. Phylogeny of the VP1 coding region in 1971–1986 exhibited similar lineage turnover with genotype C4 in China; however, phylogeny of the 3D-encoding region indicated separate lineage appearing after 1983, suggesting that the 3D-encoding region of genotype B2 was derived from an unidentified ancestor that contributed to intra-genotypic evolution in the Netherlands.

Conclusions

Unlike VP1 coding sequences long used for phylogenetic study of enteroviruses due to expected host immune escape, our study emphasizes a dominant role of non-synonymous mutations in non-structural protein regions that contribute to (re-)emergent genotypes in continuous stepwise evolution. Dozens of amino acid substitutions, especially in non-structural proteins, were identified via genetic changes driven through intra-genotypic evolution worldwide. These identified substitutions appeared to increase viral fitness in the population, affording valuable insights not only for viral evolution but also for prevention, control, and vaccine against EV71 infection.

SYBR green real-time PCR for the detection of all enterovirus-A71 genogroups

Enterovirus A71 (EV-A71) has recently become an important public health threat, especially in South-East Asia, where it has caused massive outbreaks of Hand, Foot and Mouth disease every year, resulting in significant mortality. Rapid detection of EV-A71 early in outbreaks would facilitate implementation of prevention and control measures to limit spread. Real-time RT-PCR is the technique of choice for the rapid diagnosis of EV-A71 infection and several systems have been developed to detect circulating strains. Although eight genogroups have been described globally, none of these PCR techniques detect all eight. We describe, for the first time, a SYBR Green real-time RT-PCR system validated to detect all 8 EV-A71 genogroups. This tool could permit the early detection and shift in genogroup circulation and the standardization of HFMD virological diagnosis, facilitating networking of laboratories working on EV-A71 in different regions.

Comparison between Chinese Herbal Medicines and Conventional Therapy in the Treatment of Severe Hand, Foot, and Mouth Disease: A Randomized Controlled Trial

Background. This study was made to evaluate the efficacy of Chinese herbal medicines, Reduning injection, and a traditional Chinese medicine (TCM) granule, in patients with severe hand, foot, and mouth disease (HFMD) by conducting a prospective, controlled, and randomized trial. Methods. 355 severe HFMD patients were randomly assigned to receive conventional therapy alone, Reduning injection plus conventional therapy, or TCM enema plus conventional therapy for 7–10 days. Results. There was no significant difference in the incidence of major complications between the groups. Median time to fever clearance was 20 hours (95% CI: 6.0–25.0) for conventional therapy recipients, 18 hours (95% CI: 4.0–24.0) for Reduning combination-treated patients, and 6 hours (95% CI: 4.0–16.0) for TCM combination-treated patients. Only the difference in time to fever clearance between TCM combination group and conventional group reached statistical significance (P = 0.048). Reduning combination group showed a significant reduction in sedative administration compared with conventional therapy group (P = 0.008). No HFMD-related death and no important adverse events were observed. Conclusions. Reduning injection plus conventional therapy significantly reduced the concomitant use of sedatives, which may help decrease HFMD-related neurologic complications in children. TCM effectively reduced time to fever clearance and may become a complementary therapy for relieving the symptoms of severe HFMD.

Molecular epidemiology of human enterovirus associated with aseptic meningitis in Shandong Province, China, 2006-2012

Background

Human enteroviruses (HEVs) are common causes of acute meningitis. However, there is limited information about HEV associated with aseptic meningitis in mainland China because it has not been classified as a notifiable disease.

Objectives

To characterize the HEVs associated with sporadic aseptic meningitis in China and to analyze their genetic features.

Study Design

Cerebrospinal fluid, throat swab and feces specimens were collected from patients with aseptic meningitis in 5 sentinel hospitals in Shandong Province, China between 2006 and 2012. Virological investigation (viral isolation and molecular identification) and phylogenetic analysis were performed.

Results

A total of 437 hospitalized patients were reported, and enteroviruses were detected in the specimens from 84 patients (19.2%) and were identified into 17 serotypes. The nine main serotypes were echovirus (E) 30 (27.4%), EV71 (13.1%), coxsackievirus (CV) B1 (9.5%), CVB3 (7.1%), CVB5 (7.1%), E6 (7.1%), E9 (7.1%), CVA9 (6.0%), and CVA10 (3.6%). Monthly distribution of isolated enteroviruses revealed a major peak in summer-fall season and a small second peak in winter constituted totally by EV71. Sequence analysis on VP1 coding region suggested Shandong strains had great genetic divergence with isolates from other countries.

Conclusions

Multiple serotypes were responsible for enterovirus meningitis in mainland China. Aseptic meningitis caused by EV71 and coxsackie A viruses–the predominant pathogens for the hand, foot, and mouth disease–is currently an important concern in mainland China.

Seroprevalence of human enterovirus 71 and coxsackievirus A16 in Guangdong, China, in pre- and post-2010 HFMD epidemic period

BACKGROUND

Human Enterovirus 71 and Coxsackie A16 have caused many outbreaks in the last decade in mainland China, resulting in thousands of fatal cases. Seroepidemiology which provides important information to document population immunity is rare in China.

METHODOLOGY/PRINCIPAL FINDINGS

A cross sectional study of Enterovirus 71 (EV71) and Coxsackie A16 (CA16) seroprevalence was carried out in Guangdong, China, pre- and post- the 2010 hand, foot and mouth disease (HFMD) epidemic period. The levels of EV71 and CA16 specific antibodies were evaluated by a microneutralization test and the geometric mean titer (GMT) was calculated and compared. Our results indicated frequent infection by EV71 and CA16 in Guangdong before the 2010 epidemic. Only EV71 neutralizing antibody but not CA16 seroprevalence was significantly increased after the 2010 HFMD epidemic. Children less than 3 years old especially those aged 2 years showed the lowest positive rates for EV71 and CA16 NA before epidemic and the most significantly increased EV71 seroprevalence after epidemic. CA16 GMT values declined after the 2010 epidemic.

CONCLUSIONS

These results indicate EV71 was the major pathogen of HFMD in Guangdong during the 2010 epidemic. The infection occurs largely in children less than 3 years, who should have first priority to receive an EV71 vaccine.

Patterns of polymorphism and divergence in the VP1 gene of enterovirus 71 circulating in the Asia-Pacific region between 1994 and 2013

Enterovirus 71 has been implicated in several outbreaks of hand, foot and mouth disease in the Asia-Pacific region. The present study aimed to achieve comprehensive evolutionary dynamic aspects of EV71 during 1994-2013, based on phylogenetic analyses of the VP1 sequences. The results indicated that 4 genotypes, namely C4, C1, C2 and B4 are the predominant strains, especially in Southeast Asian countries. No common ancestor was shared in different countries. Fourteen sites of substitutions were detected in the VP1 gene sequences; including the most common sites related to neutralization at position V249I [47.1% (189/401)] and A289T [42.6% (171/401)]. However, the sites Q22H and Q22R associated with increased virulence were recognized only in 13.7% (55/401) and 18% (72/401), respectively. None of the above mutations seemed to become fixed because the ratio of Ka/Ks was greater than 1.0. Mutations K43E, A58T, S184T, and T240S could possibly change the spatial structure. Two mutations, G145E and T240S, could obviously affect the hydrophobicity of VP1 and thus alter the EV71 immunoreactivity. In conclusion, the VP1 gene of EV71 strains circulating in the Asia-Pacific region during 1994-2013, showed polymorphisms and divergence with very slow evolution rate, which may be one of the reasons for periodic outbreaks in this area.

Enterovirus 71 infection cleaves a negative regulator for viral internal ribosomal entry site-driven translation

Far-upstream element-binding protein 2 (FBP2) is an internal ribosomal entry site (IRES) trans-acting factor (ITAF) that negatively regulates enterovirus 71 (EV71) translation. This study shows that EV71 infection cleaved FBP2. Live EV71 and the EV71 replicon (but not UV-inactivated virus particles) induced FBP2 cleavage, suggesting that viral replication results in FBP2 cleavage. The results also showed that virus-induced proteasome, autophagy, and caspase activity co-contribute to EV71-induced FBP2 cleavage. Using FLAG-fused FBP2, we mapped the potential cleavage fragments of FBP2 in infected cells. We also found that FBP2 altered its function when its carboxyl terminus was cleaved. This study presents a mechanism for virus-induced cellular events to cleave a negative regulator for viral IRES-driven translation.