Molecular characterization and complete genome analysis of human enterovirus 71 and coxsackievirus A16 from children with hand, foot and mouth disease in Thailand during 2008-2011

Hand, foot and mouth disease (HFMD) has mostly been caused by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). CA 16 was the most common cause of HFMD in 2010. EV71 had a high prevalence in 2008-2009 and has been identified with a higher frequency since 2011. Nearly complete genome sequences of three EV71 strains (2008-2009 strains) and two CA16 strains (2010 strains) obtained from outbreaks in Thailand in 2008 to 2010 were characterized. Based on a phylogenetic tree of the complete VP1 region, three EV71 strains grouped into the B5, C1 and C4 genotypes, and two CA16 strains grouped into the C genotype. Based on sequence analysis, nucleotide changes were found to cluster in the internal ribosome entry site (IRES) element of the 5′-untranslated region (5′-UTR). Amino acid differences identified in all strains were located in the non-structural protein. These data also provide the molecular epidemiology of EV71 and CA16 outbreaks in Thailand.     

柯萨奇病毒A组6型与肠道病毒71型感染所致手足口病临床特征比较

目的 了解柯萨奇病毒A组6型、肠道病毒71型手足口病临床特点,为指导临床诊断,调整手足口病防控策略提供科学依据.方法 采用前瞻性调查的方法,收集2013至2014年在北京市西城区手足口病临床确诊病例信息,将手足口病原核酸检测阳性的病例分为CA6、EV71组,分析比较2组的临床特点、流行特征、预后等.结果 CA6组130例,EV71组121例.2组的年龄、性别分布差异无统计学意义.CA6组发热比例高达82.3％,明显高于EV71组(34.7％,P＜0.05),其中大于等于38℃占85.0％.CA6组出现大疱疹(7.4％)、恢复期脱皮(16.9％)、脱甲(10.0％)的比例高于EV71组(P＜0.05).不同年份流行主要毒株不同.结论 与EV71感染相比,CA6感染引起的高热比例较高,部分病例可表现为大疱疹、脱皮、脱甲,整体预后较好.CA6和EV71感染所致的HFMD发病高峰季节不一致.     

Molecular epidemiology of enterovirus 71, coxsackievirus A16 and A6 associated with hand,foot and mouth disease in Spain

Hand, foot and mouth disease (HFMD) is a childhood illness frequently caused by genotypes belonging to the enterovirus A species, including coxsackievirus (CV)-A16 and enterovirus (EV)-71. Between 2010 and 2012, several outbreaks and sporadic cases of HFMD occurred in different regions of Spain. The objective of the present study was to describe the enterovirus epidemiology associated with HFMD in the country. A total of 80 patients with HFMD or atypical rash were included. Detection and typing of the enteroviruses were performed directly in clinical samples using molecular methods. Enteroviruses were detected in 53 of the patients (66%). CV-A6 was the most frequent genotype, followed by CV-A16 and EV-71, but other minority types were also identified. Interestingly, during almost all of 2010, CV-A16 was the only causative agent of HFMD but by the end of the year and during 2011, CV-A6 became predominant, while CV-A16 was not detected. In 2012, however, both CV-A6 and CV-A16 circulated. EV-71 was associated with HFMD symptoms only in three cases during 2012. All Spanish CV-A6 sequences segregated into one major genetic cluster together with other European and Asian strains isolated between 2008 and 2011, most forming a particular clade. Spanish EV-71 strains belonged to subgenogroup C2, as did most of the European sequences circulated. In conclusion, the recent increase of HFMD cases in Spain and other European countries has been due to a larger incidence of circulating species A enteroviruses, mainly CV-A6 and CV-A16, and the emergence of new genetic variants of these viruses.     

我国广东、福建地区2000～2001年手足口病肠道病毒71型分离株的种系进化分析

目的 采用逆转录聚合酶链反应(RT-PCR)检测我国广东、福建地区2000-2001年手足口病(HFMD)散发病例中的肠道病毒71型(EV71)，进而通过扩增VP1节段的核苷酸序列，进行毒株的种系进化分析。方法以肠道病毒特异引物对EV-1、EV-2进行RT-PCR，经琼脂糖凝胶电泳鉴定为阳性的标本，进一步用EV71特异引物对159S、162A进行RT-PCR，扩增的VP1节段经纯化后与测序载体pGEM-T连接，转化大肠埃希菌DH5a，筛选后测序。所得序列与我国深圳、上海、武汉地区的EV71流行株，中国台湾1998年4例HFMD暴发分离的EV71毒株，及来自美国、日本、匈牙利等国家地区的EV71毒株的核苷酸序列，用ClustalX1．8和PHYuP3．5进行比对分析，构建种系进化树。结果 25份标本检测EV71的阳性率为20％，所得序列经种系进化分析，与肠道病毒71型的其他毒株同源，与深圳1998年HFMD散发分离的EV71毒株同源性为94％，与上海2000年HFMD暴发分离株同源性为94％～96％，与武汉1987年HFMD病例中分离的毒株同源性为91％，而与国外EV71毒株同源性仅为82％～84％。结论 EV71是我国南方地区HFMD的主要病原之一；我国大陆地区的EV71毒株在种系进化上有较高的同源性；与我国台湾地区大部分分离株亦有90％～91％的核苷酸同源性，但大陆EV71引起的HFMD发病症状较轻，有别于1998年台湾地区EV71的大暴发。     

Neurovirulence in cynomolgus monkeys of enterovirus 71 isolated from a patient with hand,foot and mouth disease

Six cynomolgus monkeys were inoculated subcutaneously with enteroviurs 71 (E71), isolated from the stools of a patient with hand, foot and mouth disease (HFMD). Clinical symptoms were observed in three of the six monkeys. One monkey showed complete paralysis of the lower extremities and two animals showed weakness in the hind limbs 4 to 7 days after inoculation. Lesions were found in the central nervous system (CNS) of all monkeys. Mild to moderate vascular lesions, perivascular cuffings, degeneration and disappearance of the neurons and meningial lymphocytic infiltration were observed in the grey and/or white matter of the spinal cord, medulla oblongata, cerebral cortex and brain stem. No virus was recovered from the CNS or liver of any of the six monkeys. However, serum neutralizing antibody titers had risen in monkeys inoculated with E71.     

Use of molecular assay in diagnosis of hand, foot and mouth disease caused by enterovirus 71 or coxsackievirus A 16

Hand, foot and mouth disease is a common illness in children and is usually caused by coxsackievirus A 16 and enterovirus 71. It has been noted that enterovirus 71 infection is more severe with significantly greater frequency of serious complications and fatality than coxsackievirus A 16. Therefore, it is important to develop a rapid and specific assay for discriminating coxsackievirus A 16 and enterovirus 71 in hand, foot and mouth disease outbreaks. In this study we designed two sets of RT-PCR primers specific for coxsackievirus A 16 and enterovirus 71. One hundred and eighty-nine viruses were evaluated for this molecular diagnosis assay. Among 110 enterovirus 71 strains, the enterovirus 71 specific primers gave clear signal for 107 clinical enterovirus 71 isolates and three reference enterovirus 71 strains. None of coxsackievirus A 16, other enteroviruses or non-enteroviruses show signal for enterovirus 71-specific primers. On the other hand, among 28 coxsackievirus A 16 strains, the coxsackievirus A 16-specific primers detect 27 clinical isolates and one reference strain but show no cross-reaction with other viruses. The molecular assay developed in this study provides a sensitive and specific way to distinguish coxsackievirus A 16 and enterovirus 71 induced hand, foot and mouth disease, which will be a useful rapid diagnostic method in future outbreaks.     

Genetic characterization of emerging coxsackievirus A12 associated with hand,foot and mouth disease in Qingdao,China

To characterize the genetic properties of coxsackievirus A12 (CVA12) strains isolated from hand, foot and mouth disease (HFMD) patients in Qingdao during 2008-2011, the complete genome and VP1 coding region were sequenced and analyzed. Phylogenetic analysis showed that all strains from China clustered into three different branches, suggesting multiple lineages of CVA12 co-circulating in Asia. Sequence analysis indicated a monophyletic group only when the P1 region was examined, indicating possible recombination between CVA12 and other HEV-A serotypes. The emergence of CVA12 involved in an HFMD outbreak in China is a public-health issue.     

Complete genome sequence analysis of two human enterovirus C99 strains isolated in Xinjiang Uighur Autonomous Region,China, in 2011

Human enterovirus C99 (EV-C99) is a new member of the species Enterovirus C, and although only a few EV-C99 sequences have been obtained thus far, the strain has been identified on four continents. In 2011, two EV-C99 strains were isolated from two healthy children in Xinjiang, China, and to our knowledge, this is the first finding of EV-C99 in China. The two strains, designated HT-XEBGH09F and KSSC-ALXHH01F, showed 78.8–86.6 % similarity to other EV-C99 strains and exhibited intra-serotypic genetic recombination within the P2 coding regions. These findings reflect high genetic divergence among the EV-C99 strains.     

Complete genome analysis of human enterovirus B73 isolated from an acute flaccid paralysis patient in Shandong,China

Human enterovirus B73 (EV-B73) is a member of species Enterovirus B. To date, only one complete genome sequence of prototype strain CA55-1988 from California has been available. In this study, the complete genome analysis of an EV-B73 strain 088/SD/CHN/04 isolated from an acute flaccid paralysis case in Shandong Province, China in 2004 is conducted. It had 75.6 and 79.3 % nucleotide similarity with prototype strain CA55-1988 in the VP1 coding region and the complete genome, respectively. It had great VP1 nucleotide divergence (16.7–24.4 %) with EV-B73 strains from other parts of the world. Similarity plot and bootscanning analyses provided evidence of recombination with other EV-B viruses.     

Genetic analysis of enterovirus 71 isolated from fatal and non-fatal cases of hand, foot and mouth disease during an epidemic in Taiwan, 1998

A large scale outbreak of hand-foot-and-mouth disease (HFMD) occurred in Taiwan in 1998, in which more than 80 children died of shock syndrome with pulmonary edema/hemorrhage. Enterovirus 71 was implicated as the cause of this outbreak. In order to understand the virological basis responsible for mortality on this scale, nucleotide sequences of VP1 that is important for serotypic specificity, and the 5'-non-coding region (5'-NCR) that is important for replication efficiency, were analyzed comparatively. Phylogenetic analysis of both VP1 and 5'-NCR of nine EV71 isolates derived from specimens of fatal patients and seven isolates derived from uncomplicated HFMD patients showed that all but one isolate fell into genotype B. The one distinct isolate from a case of uncomplicated HFMD belonged to genotype C that was clustered along with one isolate from Taiwan in 1986. Complete sequence analysis of two selected isolates, one from the spinal cord of a fatal case and one from the vesicle fluid of a patient with mild HFMD, confirmed a high degree (97-100%) of identity in nucleotide sequence throughout the entire genome, except focal regions of 3C and 3'-NCR where the nucleotide homology was 90-91%. The identity of the deduced amino acid sequence in the 3C region that encodes viral proteinase dropped further to 86%, a result of missense mutations at the first nucleotide position of many codons.     

肠道病毒71型手足口病的疫苗筛选和观察

目的 筛选安全有效新型EV71候选疫苗,为将来EV71疫苗开发应用奠定基础.方法 以重组蛋白VP1为疫苗设计靶点,不同候选疫苗包括灭活疫苗、DNA疫苗、VP1蛋白疫苗在0、2周、4周分别按照不同剂量和肌内注射途径免疫BALB/c雌性小鼠,在0、2周、4周、6周、8周、10周、16周分别采集小鼠尾静脉血,16周处死小鼠,收集小鼠脾脏细胞,检测小鼠体液免疫和细胞免疫功能,筛选评价候选疫苗的疗效和安全性.结果 灭活病毒疫苗、VP1 DNA质粒疫苗、VP1蛋白疫苗免疫小鼠2周后IgG抗体滴度即开始升高,4周后明显升高,8周后达高峰,至少维持16周以上;IgG亚类以IgG2a和IgG1为主.三种疫苗能诱导以γ-IFN和IL-4为主的细胞免疫反应.灭活疫苗疗效优于其他候选疫苗,未发现疫苗相关不良反应.结论 灭活病毒疫苗、VP1 DNA质粒疫苗、VP1蛋白疫苗均能诱导持久的特异性细胞免疫和中和抗体反应,以灭活病毒疫苗疗效较好,需要将来攻毒实验可进一步验证其免疫力.     

Genetic and phenotypic characteristics of enterovirus 71 isolates from patients with encephalitis and with hand,foot and mouth disease

Summary Biological and biochemical characters of seven enterovirus 71 (E71) isolates were compared. Four isolates (two from patients with hand, foot and mouth disease [HFMD] and two from patients with encephalitis) grew in cynomolgus monkey kidney cells both at 39.5 and 35° C. However, the remaining three strains (from patients with HFMD) grew at 35° C, but not at 39.5° C. Three temperature-resistant and two temperature-sensitive strains were tested for neurovirulence in monkeys. Temperature-resistant strains were shown to be neurovirulent, whereas temperature-sensitive strains were less neurovirulent. The results suggest correlation between temperature-sensitive growth and neurovirulence in monkeys of E71. Variation in the electrophoretic mobility of the viral polypeptides was detected in three out of seven strains. The fingerprinting of oligonucleotides generated from the viral genome showed similar patterns in two isolates from patients with HFMD and one from patient with encephalitis and variable patterns in each genomic map of remaining four strains. These variations of polypeptide patterns and of oligonucleotide maps could not be correlated with pathogenicity (encephalitis or HFMD), temperature-sensitive growth and neurovirulence in monkeys.With 4 Figures     

Genetic diversity of enterovirus 71 isolated from cases of hand,foot and mouth disease in Yokohama City between 1982 and 2000

Summary.  Enterovirus 71 (EV71) is known as one of the major causative agents of hand, foot and mouse disease (HFMD) and is also associated with neurological manifestations such as aseptic meningitis, polio-like paralysis and encephalitis. Recently, large HFMD outbreaks, involving severe neurological complications, have been experienced in Malaysia, Taiwan and some other countries in the Western-Pacific region. To investigate the genetic diversity of EV71 isolates in a single community in Japan, nucleotide sequences of the VP4 region of 52 EV71 isolates in Yokohama City from 1982 to 2000 were determined and the phylogenetic relationship was compared with other referential EV71 strains in Japan and in the world. There were two major genotypes of EV71 in Yokohama City through the 1980’s and 1990’s. Six EV71 isolates in the early 1980’s in Yokohama City were closely related to those from HFMD outbreaks in Japan and from outbreaks of polio-like paralysis in Europe in the 1970’s. During recent HFMD outbreaks in 1997 and 2000, two distinct genotypes of EV71 were co-circulating in Yokohama City as in HFMD outbreaks in Malaysia and Taiwan. However, the genetic diversity of EV71 in Yokohama City was not directly correlated with the severity of HFMD. The results confirmed the circulation of two distinct genotypes of EV71 over the past 20 years in Japan. Received June 25, 2002; accepted September 16, 2002     

Molecular epidemiology of coxsackievirus A6 derived from hand,foot, and mouth disease in Fukuoka between 2013 and 2017

Coxsackievirus (CV)‐A6 has been the primary causative agent of hand, foot, and mouth disease (HFMD) in Japan since 2011. In Fukuoka, CV‐A6‐associated HFMD caused epidemics in 2013, 2015, and 2017. This paper reports the genetic characteristics of the CV‐A6 entire viral protein 1 (VP1) derived from patients with HFMD in Fukuoka between 2013 and 2017. CV‐A6 was detected in 105 of 280 clinical specimens, and the entire VP1 sequences could be analyzed for 90 of the 105 specimens. Phylogenetic analysis revealed that the CV‐A6 strains were classified into clade A and subgrouped into subclade A3 or subclade A4. Each subclade strain carried amino acid substitutions in the presumed DE and GH loops of the VP1, and no amino acid substitutions were identified as deleterious to the protein function. No significant difference was found in the clinical symptoms between the genetic subclades using statistical analyses. In conclusion, this study clarified the genetic diversity of CV‐A6 in Fukuoka from 2013 to 2017. The emergence of the CV‐A6 strains was classified into derived new subclades based on phylogenetic analysis of the VP1 gene that may cause CV‐A6‐associated HFMD epidemics approximately every 2 years.     

Genetic diversity of coxsackievirus A16 associated with hand, foot, and mouth disease epidemics in Japan from 1983 to 2003

To clarify the chronologic genetic diversity of coxsackievirus A16 (CV-A16) strains associated with hand, foot, and mouth disease (HFMD) epidemics in a restricted area and their genetic relation with those isolated in other areas, we investigated the genetic diversity of the 129 CV-A16 strains associated with HFMD epidemics in Fukushima, Japan, from 1983 to 2003, and compared their genetic relation to 49 CV-A16 strains isolated in other areas of Japan and in China by using phylogenetic analysis based on the VP4 sequences. Phylogenetic reconstruction of the CV-A16 strains isolated in Fukushima from 1983 to 2003 demonstrated three distinct genetically divergent clusters related to HFMD epidemics that occurred from 1984 to 1994 (including the 1985 and 1991 outbreaks), HFMD epidemics from 1987 to 1998 (including the 1988 and 1998 outbreaks), and HFMD epidemics from 1995 to 2003 (including the 1995 and 2002 outbreaks). CV-A16 strains isolated during each period in Fukushima formed a single cluster with those isolated during essentially the same time period in other areas of Japan and in China. Our results demonstrated that prevalent CV-A16 strains causing HFMD in Fukushima, Japan, genetically changed twice during 21 epidemics, and changes were also observed in the CV-A16 strains causing HFMD epidemics in other areas. We concluded that repeated outbreaks of CV-A16-related HFMD in Japan were caused, in part, by the introduction of genetically changed CV-A16 strains, which might be transmitted overseas.