Seroprevalence and molecular epidemiology of enterovirus 71 in Germany

Enterovirus 71 (EV71) has emerged as a significant pathogen with potential to cause large outbreaks. Because little is known about its seroprevalence and molecular epidemiology in Germany, data for 1997–2007 are presented. Four hundred thirty-six sera from persons aging 10 months to 75 years were tested in a neutralisation test; 63.4% of pre-school children were seronegative, whereas about 75% of adults had antibodies to EV71. Phylogenetic analysis of 28 isolates associated with neurological or cutaneous manifestations showed that isolates belonging to genogroup C1 predominated in 2000–2005, followed by a change to genogroup C2 in 2006 and 2007. This shows the importance of monitoring the diversity of one of the most relevant neurotropic enteroviruses.     

广州地区健康儿童肠道病毒71型抗体水平调查

目的调查广州地区健康儿童肠道病毒71型抗体IgG（EV71-IgG）的水平,分析与EV71所致手足口病（HFMD）发病的关系。方法以来源于广州市妇女儿童医疗中心（我院）中心实验室分离到的EV71 C4亚型标本,制备EV71诊断抗原,建立EV71-IgG抗体诊断试剂盒方法,并进行实验室评价。收集2010年1~3月在我院儿保科抽血进行常规保健检测的标本,筛选出无发热、无HFMD症状的健康儿童血清标本,检测EV71-IgG抗体。选取我院2010年全年门诊及住院HFMD患儿的咽拭子标本进行EV71特异性核酸检测。结果①本研究建立的试剂盒EV71-IgG抗体检测临界值为0.148;与细胞中和实验方法阳性符合率为100%,阴性符合率为92%,与柯萨奇A16病毒抗体无交叉反应。②819名健康儿童血清标本中,男481名,女338名。〈1岁组（60%,60/100名）和~2岁组（39.3%,72/183名）EV71-IgG抗体阳性率显著高于其他各年龄组[~3岁、~4岁、~5岁和~14岁组分别为12.9%（15/116名）、27.1%（38/140名）、14.2%（16/113名）和22.8%（38/167名）]。EV71-IgG抗体阳性率无显著性别差异。③4 780例EV71阳性HFMD患儿中,男3 070例,女1 718例。〈1岁310例（6.5%）,~2岁1 157例（24.2%）,~3岁1 337例（28.0%）,~4岁1 094例（22.9%）,~5岁450例（9.4%）,~14岁432例（9.0%）。④各年龄组EV71-IgG抗体阳性率与EV71阳性年龄构成比呈相反趋势,〈1岁组EV71-IgG抗体阳性率最高,EV71阳性年龄构成比最低;~3岁组EV71-IgG抗体阳性率最低,EV71阳性年龄构成比最高。结论 〈1岁健康儿童EV71-IgG阳性率最高,EV71阳性年龄构成比与EV71-IgG阳性率呈相关现象。     

Characterization of a monoclonal antibody against the 3D polymerase of enterovirus 71 and its use for the detection of human enterovirus A infection

Over the last decade, frequent epidemic outbreaks of hand, foot and mouth disease have been observed in the Asia-Pacific region. Hand, foot and mouth disease is caused by different viruses from the enterovirus family, mainly coxsackievirus A16 and enterovirus 71 (EV71) from the human enterovirus A family. Severe disease and neurological complications are associated more often with EV71 infection, and can lead occasionally to fatal brain stem encephalitis in young children. The rapid progression and high mortality of severe hand, foot and mouth disease makes the direct detection of antigens early in infection essential. The best method for virus detection is the use of specific monoclonal antibodies. The generation and characterization of a monoclonal antibody specific for the 3D polymerase of human enterovirus A and the development of a virus detection dot blot assay are described. A recombinant 3CD protein from EV71 C4 strain was used as an immunogen to generate monoclonal antibodies (MAbs). Screening of hybridoma cells led to the isolation of monoclonal antibody 4B12 of the immunoglobulin IgG1 isotype. MAb 4B12 recognizes the linear epitope DFEQALFS close to the active site of the 3D polymerase, corresponding to amino acid positions 53-60 of 3D and 1784-1791 of enterovirus 71 polyprotein. The presence of 3D polymerase and its precursor 3CD proteinase in purified virus particles was confirmed. MAb 4B12 was used successfully to detect all enterovirus 71 subgenotypes in a denaturing dot blot assay with a sensitivity of 10 pg of 3D protein and 10(4) tissue culture infective dose of virus particles.     

Manifestations of enterovirus D68 and high seroconversion among children attending a kindergarten

Background/purpose(s)Enterovirus D68(EV-D68) is an emerging disease that affects mostly children. There have been few relevant investigations to clarify transmission and seroprevalence within daycares and kindergartens.MethodsThis prospective cohort study investigated respiratory viral transmission among preschool children in a public kindergarten in Taipei City of Taiwan between September 2006 and June 2008. After children were enrolled, daily monitoring of illness and regular biweekly physical examinations were performed. We performed viral isolation to detect acute EV-D68 infection and neutralization tests to detect specific EV-D68 antibodies and to measure the seroprevalence and seroconversion rates.ResultsAmong 190 kindergarten attendees aged between two to five years old, nine children had acute EV-D68 infection in September 2007. The clinical manifestations included pharyngitis, cough and other unspecified upper respiratory tract infection. None of the infected children had acute flaccid paralysis or severe respiratory illness. The phylogenetic tree of partial viral protein 3 and viral protein 1 was clustered in clade A1. The EV-D68 seropositive rate increased from 19% (25/130) at the beginning to 67% (83/124) at the end of the study. The seroconversion rate of 49 children with initial seronegative and paired sera was 73% (36/49).ConclusionsA high seroconversion rate (73%) for EV-D68 was found among kindergarten attendees, which indicates preschool-aged children are highly susceptible to EV-D68 infection and that the disease burden may be extremely underestimated. Once EV-D 68 circulates, preventive measures may be advocated, especially within kindergartens or daycares, to reduce transmission and subsequent development of severe cases.     

抗肠道病毒71型特异性卵黄抗体的制备及鉴定

目的:制备特异性抗肠道病毒71型(Enterovirus 71,EV71)的卵黄抗体并检测其生物学性能,这对EV71感染手足口病的预防和治疗具有重大的意义。方法:用纯化并灭活后EV71作为抗原免疫健康产蛋鸡。采用本实验室水提综合聚乙二醇法提取纯化鸡卵黄抗体;用Bradford法测定卵黄抗体提取液的蛋白含量;还原性SDS-PAGE凝胶电泳分析测定提取蛋白的纯度及相对分子质量;分别用ELISA、双向免疫琼脂扩散检测纯化特异性卵黄抗体抗EV71效价;Western blot分析特异性卵黄抗体的免疫反应性。结果:卵黄中卵黄抗体含量达7.76 mg/ml,卵黄抗体的纯度为94.86%。初免10天后蛋黄中可检测到特异性抗EV71卵黄抗体,初免40天后ELISA检测抗体效价高达1∶20 480,双向琼脂扩散检测效价达1∶16。提取的卵黄抗体具有良好的免疫反应性,能与EV71特异性结合。结论:水提综合聚乙二醇法提取纯化得到的抗EV71卵黄抗体产量和纯度高、效价好且具有良好的免疫反应性。     

In vitro and in vivo protection against enterovirus 71 by an antisense phosphorothioate oligonucleotide

Enterovirus 71 (EV71) is a highly infectious virus that is a major cause of hand, foot, and mouth disease (HFMD), which can lead to severe neurological complications. Currently, there is no effective therapy against EV71. Five antisense oligodeoxynucleotides targeting the 5′-terminal conserved domain of the viral genome were designed using a method based on multiple predicted target mRNA structures. They were then screened for anti-EV71 activity in vitro based on their ability to inhibit an EV71-induced cytopathic effect (CPE). A novel antisense oligonucleotide (EV5) was tested both in rhabdomyosarcoma (RD) cells and in vivo using a mouse model, with a random oligonucleotide (EV5R) of EV5 as a control. EV5 was identified as having significant anti-EV71 activity in vitro and in vivo without significant cytotoxicity. Treatment of RD and Vero cells with antisense oligodeoxynucleotide EV5 significantly and specifically alleviated the cytopathic effect of EV71 in vitro. The inhibitory effect was dose dependent and specific, with a corresponding decrease in viral RNA and viral protein levels. In vivo, EV5 was specifically effective against EV71 virus in preventing death, decreasing weight reduction and reducing the viral RNA copy number and the level of viral proteins in the lungs, intestines and muscles. These results demonstrate the potential and feasibility of using antisense oligodeoxynucleotides specific for the 5′-terminal conserved domain of the viral genome as an antiviral therapy for EV71 disease.     

Molecular characterization of human enteroviruses in the Central African Republic: uncovering wide diversity and identification of a new human enterovirus A71 genogroup

Human enteroviruses (HEV) are among the most common viruses infecting humans. Their circulation has been widely studied in most parts of the world but not in sub-Saharan Africa, where poliomyelitis remains prevalent. We report here the molecular characterization of 98 nonpoliovirus (non-PV) HEV strains isolated from 93 randomly selected cell culture-positive supernatants from stool samples collected from 1997 through 2006 from children with acute flaccid paralysis living in the Central African Republic (CAR). The isolates were typed by sequencing the VP1 coding region and sequenced further in the VP2 coding region, and phylogenetic studies were carried out. Among the 98 VP1 sequences, 3, 74, 18, and 3 were found to belong to the HEV-A, -B, -C, and -D species, respectively. Overall, 42 types were detected. In most cases, the VP2 type was correlated with that of the VP1 region. Some of the isolates belonged to lineages that also contain viruses isolated in distant countries, while others belonged to lineages containing viruses isolated only in Africa. In particular, one isolate (type EV-A71) did not fall into any of the genogroups already described, indicating the existence of a previously unknown genogroup for this type. These results illustrate the considerable diversity of HEV isolates from the stools of paralyzed children in the CAR. The presence of diverse HEV-C types makes recombination between poliovirus and other HEV-C species possible and could promote the emergence of recombinant vaccine-derived polioviruses similar to those that have been implicated in repeated poliomyelitis outbreaks in several developing countries.     

In vitro and in vivo evaluation of ribavirin and pleconaril antiviral activity against enterovirus 71 infection

Enterovirus 71(EV71) causes recurring outbreaks of hand, foot and mouth disease and encephalitis leading to complications or death in young children. More effective antiviral drugs are needed to prevent or reduce EV71-related disease and complications. However, there are no standard models currently in use to evaluate activity against EV71 infection both in vitro and in vivo. In this study, the activity of ribavirin and pleconaril against EV71 infection was evaluated in two models. An in vitro EV71 infection model was developed in RD cells, and an in vivo EV71 infection model was applied. Ribavirin and pleconaril effectively increased the viability of infected cells. Pleconaril reduced the morbidity and mortality of one-day-old infected mice, but ribavirin did not protect the infected mice. In all, the results demonstrated that infected cells and infected mice can be used to evaluate antiviral activity of ribavirin and pleconaril against EV71 infection in vitro and in vivo.     

EV71、CA16及通用型肠道病毒实时荧光定量PCR诊断试剂盒的研发

目的 研制一种新的含竞争性内标引物,能同时检测EV71、CA16及通用型肠道病毒的四重实时荧光定量PCR诊断试剂盒,用于手足口病的临床诊断及流行病学监测.方法 设计特异性的EV71型、CA16型及其他型肠道病毒和内参基因的引物,改进病毒核酸提取方法,优化实时荧光定量PCR检测体系,并研究产品的准确度、稳定性、精密度和扩增效率和检测线性范围.结果 本试剂盒的引物和探针特异性好,试剂盒采用的的病毒RNA抽提效果与QIAGEN公司QIAamp Viral RNAmini Kit抽提效果相当,但具有更低的试剂成本.优化引物探针浓度分别为0.2μmol/L的上下游引物浓度、0.06 μmol/L的通用探针浓度、0.08 μmol/L的EV71分型探针浓度和0.08μmol/L的CA16分型探针浓度.产品具有较好的稳定性和良好的准确度、精密度,CA16、EV71和肠道病毒通用型对引物的扩增效率分别是106％、101％和105％,线性检测范围是109拷贝/μl ～ 102拷贝/μl.结论 采用四重荧光定量PCR技术开发的能同时检测EV71、CA16、其他肠道病毒和内标的手足口病诊断试剂盒具有良好的准确性、稳定性、精密度和扩增效率等,具有很好的临床应用价值.     

Relationship between serologic response and clinical symptoms in children with enterovirus 71-infected hand-foot-mouth disease

This study aimed to explore the correlation between clinical symptoms, including rash and fever, and serum antibody reaction to enterovirus 71 (EV71) infection in children hospitalized due to hand-foot-mouth disease (HFMD). From May 2014 to July 2014, a total of 547 children hospitalized due to HFMD in Children’s Hospital of Fudan University were enrolled retrospectively. RNA levels of EV71 and CA16 in fecal, serum, and cerebrospinal fluid specimens were measured using quantitative real-time RT-PCR, and EV71-IgM antibody in the serum was detected using immune colloidal gold assays. Of the 547 fecal specimens, 296 were EV71 RNA positive, 109 were CA16 RNA positive, and 8 were positive for both EV71 RNA and CA16 RNA. The total positive rate for either EV71 or CA16 in feces was 72.58% (397/547). Additionally, 544 serum specimens were collected, and 409 were EV71-IgM positive (75.18%). The duration of rash and fever was found to be correlated to the positive rate of serum EV71-IgM, and the positive rate of serum EV71-IgM plus EV71 RNA in feces. The positive rates of serum EV71-IgM and serum EV71-IgM plus EV71 RNA in fecal collected at day 3 of fever were 79.7% and 52.8%, respectively. In conclusion, EV71 and CA16 were found to be the major pathogens responsible for the epidemics of HFMD in children during May to July 2014 in Shanghai, China. There is a close relationship between the positive rate of serum EV71-IgM and the duration of fever and rash.     

郑州市某寄宿制幼儿园学龄前儿童营养状况调查

目的了解郑州市某寄宿制幼儿园儿童的膳食结构和营养状况,提出改进意见。方法采用5日连续称重记账法进行膳食调查,同时进行体格检查和营养生化指标的测定。结果郑州市某寄宿制幼儿园学龄前儿童热能和三大营养素的摄入量达到了相应供给量标准,钙、锌、视黄醇当量、硫胺素的摄入量分别是(RDA)52.7%、82.4%、51.4%、81.3%,铁的摄入量为供给量的135.8%,但来源于动物性食物的铁仅达到17%。营养过剩表现较突出,其发生率为17.4%;贫血的患病率为6.27%。结论调整膳食结构,增加副食摄入,增加钙、锌、视黄醇当量、硫胺素、铁的供给,减少动物性脂肪及胆固醇的摄入量,适当增加碳水化合物的摄入,增加来源于动物性食物的血色素铁的供给,增加幼儿的运动量,达到平衡膳食,合理营养。     

Higher incidence of Dermatophagoides pteronyssinus allergy in children of Taipei city than in children of rural areas.

BACKGROUND AND PURPOSE: House dust mites are the most common cause of sensitization in wheezing children in most parts of the world. The aim of this study was to investigate prevalence of sensitization and the levels of specific immunoglobulin E (IgE) to Dermatophagoides pteronyssinus (Der p) in wheezing children in Taipei city and central rural Taiwan. METHODS: A total of 3546 children were enrolled in this study. Children were grouped into those living in Taipei city (n = 1340) and those residing in the rural part of central Taiwan (2206). The prevalence of sensitization and level of specific IgE antibody to Der p and cockroach were analyzed by age and geographic area. RESULTS: The results showed significantly higher sensitization rates and mean specific IgE levels to Der p with increasing age of patients in both Taipei city and rural central Taiwan. In addition, children from Taipei city had a significantly higher average sensitization rate of Der p than rural children (p<0.05). The proportion of children sensitized to cockroach increased with age both in Taipei city and central rural Taiwan, but the specific IgE levels to cockroach were not statistically different between the 2 groups (p=0.061). CONCLUSIONS: Sensitivity to aeroallergens varies with age and with geographical location (city vs rural) in asthmatic children. Circulating IgE antibodies against Der p were common at all ages. Cockroach allergen is also associated with recurrent wheezing in Taiwan. Avoidance of indoor aeroallergens such as Der p and cockroach allergen should be an important component in plans for the management of recurrent wheezing.     

Identification and characterization of a monoclonal antibody recognizing the linear epitope RVADVI on VP1 protein of enterovirus 71

Several large outbreaks of hand–foot–mouth disease (HFMD) have occurred in the Asian‐Pacific region since 1997, with Enterovirus 71 (EV71) and/or Coxsackievirus A16 (CAV16) as the main causative agents. Despite the close genetic relationship between the two viruses, only EV71 is associated with severe clinical manifestations and deaths. Effective antiviral treatment and vaccines are not available. High‐quality monoclonal antibodies (mAbs) are necessary to improve the accuracy of the diagnosis of EV71. In this study, a mAb (designated 1D9) was generated using EV71 C5 strain virus particles as immunogens. Examined by indirect immunofluorescence assay (IFA) and Western blotting, 1D9 detected successfully all 11 subgenotypes of EV71 and showed no cross‐reactivity to the four selected subgenogroups of Coxsackieviruses CAV4, CAV6, CAV10, and CAV16. A linear motif, R₃VADVI₈, which is located at the N‐terminus of the EV71 VP1 protein, was identified as the minimal binding region of 1D9. Alignment and comparison of the 1D9‐defined epitope sequence against the listed sequences in the NCBI EV71 database indicated that this epitope R₃VADVI₈ was highly conserved among EV71 strains, while no significant similarity was observed when blasted against the Coxsackieviruses. This suggests that the mAb 1D9 may be useful for the development of a cost‐effective and accurate method for surveillance and early differentiation of EV71 from CAV16 infection. J. Med. Virol. 84:1620–1627, 2012. © 2012 Wiley Periodicals, Inc.     

Analysis of recombination and natural selection in human enterovirus 71

The development of effective vaccines and antiviral prophylaxis against human enterovirus 71 (EV71) has been hampered by the extensive antigenic diversity of the virus. To gain new insights into the evolutionary processes that create this genetic diversity, the TreeOrder Scan Method and RDP program were employed to detect recombination events in the genome, and then parsimony-based and maximum-likelihood-based methods were used to detect natural selection effects on viral proteins. Recombination analysis provided strong evidence for recombination events in the majority of the sequences analyzed. Recombination events were found to be distributed nonrandomly with the highest frequency at the 3D region. Furthermore, positive selection was only detected at site 145 of VP1 by the maximum likelihood-based method. These results reveal that EV71 proteins are extensively influenced by stabilizing selection. We conclude that recombination may play a more important role than positive selection in the formation of genetic diversity.     

Partial protection against enterovirus 71 (EV71) infection in a mouse model immunized with recombinant Newcastle disease virus capsids displaying the EV71 VP1 fragment

Enterovirus 71 (EV71) infection may cause severe neurological complications, particularly in young children. Despite the risks, there are still no commercially available EV71 vaccines. Hence, a candidate vaccine construct, containing recombinant Newcastle disease virus capsids that display an EV71 VP1 fragment (NPt-VP1(1-100) ) protein, was evaluated in a mouse model of EV71 infection. Previously, it was shown that this protein construct provoked a strong immune response in vaccinated adult rabbits. That study, however, did not address the issue of its effectiveness against EV71 infection in young animals. In the present study, EV71 viral challenge in vaccinated newborn mice resulted in more than 40% increase in survival rate. Significantly, half of the surviving mice fully recovered from their paralysis. Histological analysis of all of the surviving mice revealed a complete clearance of EV71 viral antigens from their brains and spinal cords. In hind limb muscles, the amounts of the antigens detected correlated with the degrees of tissue damage and paralysis. Findings from this study provide evidence that immunization with the NPt-VP1(1-100) immunogen in a newborn mouse model confers partial protection against EV71 infection, and also highlights the importance of NPt-VP1(1-100) as a possible candidate vaccine for protection against EV71 infections.     

A novel method to diagnose the infection of enterovirus A71 in children by detecting IgA from saliva

Enterovirus A71 (EV-A71) is one of the main pathogens causing hand, foot, and mouth disease, and often causes diseases of the central nervous system. Early diagnosis is important to prevent EV-A71 outbreaks. The detection of serum immunoglobulin M (IgM) is widely used for the early diagnosis of EV-A71 in clinics, especially in rural areas. However, this technique requires the extraction of blood from children who have thin blood vessels and who might fear the use of needles. Therefore, difficulties in the detection process are often encountered. This study developed a noninvasive method to detect EV-A71-specific immunoglobulin A (IgA) in saliva for the diagnosis of EV-A71 infection. The sensitivity and specificity of IgA detection did not differ significantly compared with IgM detection. IgA antibodies were present in saliva for a relatively shorter period than IgM antibodies were present in serum. The sensitivity of IgA detection was higher than that of IgM detection for secondary EV-A71 infections. These results suggest that the detection of EV-A71-specific IgA in the saliva allows the effective early diagnosis of EV-A71 and may be suitable for detecting EV-A71 infections in children.