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Objective: To study the virulence variation of enterovirus 71 (EV71) during thermal adaptive evolution, providing references for the prevention and control of the EV71-related hand, foot and mouth disease., Methods: Parental strains and thermal-adapted strains originating from EV71 sibling strains (lineage #100 and #101) were used for plaque assay validation, CCK-8 cytotoxicity experiment, and host proteomics studies after Vero cell infection. Plaque morphology and cell inhibition rate of the viral strains were obtained. Mass spectrometry was used to examine and analyze the functions of proteins that were differential expressed in the host cells., Results: Plaque morphology variation was found only in the heat-adapted strain of lineage #101. Increase in cell inhibition rate was observed in all the thermal-adapted strains, but the amount of increase varied in different strains. According to the results of clustering analysis and principal component analysis, after infection of Vero cells, the host cell protein profile of the heat-adapted strains was similar to that of the parental strains and the host cell protein profile of cold-adapted strains was similar to that of cell-adapted strains. It showed that 500 kinds of proteins presented inter-group difference in their expression, with 239 kinds being up-regulated proteins and 261 being down-regulated. The function of the up-regulated proteins were related to post-translational protein modification, while the functions of the down-regulated proteins were related to SRP-dependent cotranslational protein translocation/targeting to membrane and retrograde protein transport., Conclusion: Virulence variations of enterovirus 71 may accompany thermal adaptive evolution, but its mechanism of action still awaits further investigation., (Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).)

Objective: To study the genomic sequence of Coxsackievirus A8 (CV-A8) associated with hand, foot and mouth disease (HFMD) from 2013 to 2018 in China and to analyze the genetic evolution of each coding region of the full-length genome. Methods: The genome sequences of 11 CV-A8 strains isolated from patients with HFMD in different regions of China from 2013 to 2018 were determined. Sequence alignment and genetic evolution analysis were performed by Sequencher 5.0 and MEGA 7.0 software, etc. Results: Sequence alignment showed that the genome length of 11 CV-A8 strains ranged from 7 393 bp to 7 400 bp. There was no base insertion or deletion in the coding region compared with the prototype strain, but there were individual base insertion or deletion in the non-coding region. The nucleotide and amino acid similarities in the VP1 region of 11 CV-A8 strains were 78.3%-98.6% and 92.6%-99.7%, respectively, and the nucleotide and amino acid sequences identities with the CV-A8 prototype strain were 78.3%-98.2% and 92.6%-99.7%, respectively. Based on the phylogenetic analysis of VP1 region sequences, the CV-A8 can be divided into five genotypes: A, B, C, D and E. The 11 CV-A8 strains in this study belonged to genotypes C (1 strain), D (2 strains) and E (8 strains). The nucleotide and amino acid similarities of 11 CV-A8 full-length genomes were 81.3%-98.8% and 95.9%-99.5%, respectively. The phylogenetic tree of the P2 region showed that the eight E genotypes CV-A8 had the closest evolutionary distance with CV-A4, CV-A14, and CV-A16. The phylogenetic tree of the P3 region showed that the eight E genotypes CV-A8 had a close evolutionary distance with CV-A5, CV-A16, CV-A14 and CV-A4. Conclusions: The 11 CV-A8 stains in this study showed significant intra-genotype diversity in capsid region and recombinant diversity in non-capsid region which indicated that CV-A8 quasispecies were still undergoing dynamics variation. CV-A8 may become an important pathogen of HFMD and the monitoring of CV-A8 needs to be further strengthened.

To understand the prevalence and etiological characteristics of hand, foot and mouth disease(HFMD) in Yangzhou, so as to provide scientific basis for prevention and control of HFMD. HFMD cases from six sentinel hospitals in Yangzhou from January 2015 to December 2019 were taken as the subject of study. The epidemiological data of HFMD were analyzed by descriptive epidemiology method, the enterovirus were detected using RT-PCR method and the etiological characteristics were analyzed. The data were collected by Excel 2007 and statistically analyzed by SPSS22.0 software. A total of 1 151 positive cases were detected from all 2 129 HFMD clinical specimens collected in Yangzhou from 2015 to 2019, with a total positive rate of 54.06%, including 148 cases of EV71(6.95%), 382 cases of CA16(17.94%) and 621 cases of other enterovirus(29.17%). The difference of positive rate in different years( χ 2 =99.28, P <0.05), different months( χ 2 =92.09, P <0.05) and different districts( χ 2 =71.39, P <0.05)was statistically significant. Each subtype of enterovirus showed alternating prevalence in different years. The peak period of detection rate was from April to September (720 cases, 62.55%). The reported incidence for males was higher than females, with the male-female ratio of 1.58∶1 and children under six (971 cases, 84.36%) as the major attacked population. There were obvious seasonal, regional and population characteristics of HFMD in Yangzhou City from 2015 to 2019. It reminds us that surveillance of HFMD should be continually implemented, more attention should be paid to the prevention and control of key population in high-risk seasons, and the booming HFMD cases caused by other enterovirus should be emphasized especially.

Objective: To estimate the serotype and age-specific hospitalization burden associated with hand, foot and mouth disease (HFMD) in Anhua county of Hunan province, between October 2013 and September 2016. Methods: We collected hospitalization records of HFMD patients from 6 virological surveillance hospitals, and reimbursement records through new rural cooperative medical system from 23 township health centers to estimate the age-specific hospitalization burden of HFMD in Anhua. Combined with the results of virological surveillance, the serotype-specific hospitalization burden of HFMD in Anhua, was estimated. Results: During the three years, it was estimated that 3 541 clinical diagnosed HFMD cases, including 3 146 laboratory-confirmed HFMD cases, were hospitalized in Anhua, but only one was diaguosed as being severe. The estimated average hospitalization rate was 723/100 000(95 %CI : 699/100 000-747/100 000) for clinical diagnosed HFMD and 642/100 000 (95 %CI : 620/100 000-665/100 000) for laboratory-confirmed HFMD between October 2013 and September 2016. The cases caused by Cox A16 (208/100 000) and Cox A6 (202/100 000) had higher hospitalization rates compared with the cases caused by EV71 (130/100 000), Cox A10 (38/100 000) and other enterovirus (64/100 000), and the difference was statistically significant ( P <0.001). HFMD-associated hospitalization rates peaked in children aged 1 year (3 845/100 000), and then decreased with age. Compared with the hospitalized HFMD caused by EV71 and Cox A16, Cox A6-associated hospitalizations mainly occurred in younger age groups ( P <0.001). Conclusion: Our study revealed a substantial hospitalization burden associated with mild HFMD caused by EV71, Cox A16, Cox A6 and Cox A10, especially in young children, in Anhua.

Objective To study the mechanism ofhuman enterovirus 71 (EV71) entering human neuroblastoma SK-N-SH cells. Methods After the SK-N-SH cells were pretreated with chlorpromazine (CPZ) or nystatin (NT), real-time quantitative PCR (qRT-PCR) was employed to measure EV71 mRNA level, and indirect immunofluorescence microscopy was used to detect the expression level of viral protein 1 (VP1) in the target cells. In order to reveal the colocalization of EV71 with clathrin, laser confocal microscopy was performed on the infected cells. Results CPZ could significantly inhibit EV71 mRNA level and the expression of VP1 in the target cells, while NT had no effect on EV71 infection. Confocal microscopy showed that EV71 was colocalize with clathrin. Conclusion EV71 infects human neuroblastoma SK-N-SH cells by the clathrin-mediated endocytosis.

Hand, foot, and mouth disease(HFMD)is caused by mainly enterovirus 71(EV-A71)and coxsackievirus A16(CV-A16),and is a serious healthcare problem worldwide.EV-A71 infection is thought to progress readily to serious complications whereas CV-A16 infection, in general, results in mild symptoms and presents repeatedly. However, the underlying mechanisms leading to these differences are not known. We compared changes in expression of type-I interferon(IFN-I)-related genes in normal human bronchial epithelial(16HBE) cells. Gene-expression levels of TLR3,MAVS,MDA5,MyD88,IRF7,IFNαand IFNβwere elevated significantly after EVA71 infection.MDA5expression was increased markedly, and that of TLR3 and IRF3was decreased obviously after CV-A16 infection, but that of MAVS,MyD88,IFNαand IFNβdid not show significant differences. Viral copy number and viral titers suggested that CV-A16 replicates more efficiently than EV-A71 in 16HBE.These results suggest that IFN-I production pathway-related genes in response to infection by EV-A71 and CV-A16 have notable discrepancies. Such information could shine a light on the different manifestations caused by EV-A71 and CV-A16,and the mechanism of repeat infection by CV-A16.

The aim of this study was to analyze the genetic characteristics of the VP1 gene of coxsackievirus A16(CA16)strains isolated from Jiangsu Province, China, in 2015.The VP1 regions of 20CA16 virus strains from Jiangsu Province in 2015 were amplified, and the amplification products were sequenced. Mega 6.0and DNA Star software were applied to build the phylogenetic tree and analyze the homogeneity of nucleotides and amino acids. The sequence homologies of the nucleotides and amino acids of the VP1 gene were 88.2%~100.0%and 98.0%~100.0%among 20CA16 isolates, respectively. Comparison with the sequence of the prototype strain A-G10 showed 75.3%~77.4% homologies in nucleotide sequence and90.6%~92.3%in amino-acid sequences, respectively. Comparison with the sequence of the representative strain B1 showed 88.3%~98.4% homologies in nucleotide sequence and 96.3%~100.0%in amino-acid sequence, respectively. Comparison with the sequence of the representative strain B2 showed 88.4%~90.8% homologies in nucleotide sequence and 96.6%~100.0%in amino-acid sequence, respectively. Twenty CA16 isolates were subgenotype B1.One isolate was subgenotype B1a, whereas the remainder of isolates was subgenotype B1b among 20 CA16 isolates. A subgenotype B1b transmission chain was also noted. The CA16 strains isolated from Jiangsu Province in 2015 belonged to subgenotype B1.There were two evolutionary branches, whereby B1 a and B1bwere co-circulating and evolving together. The epidemic strain was subgenotype B1b.

We aimed to study infections in neonatal ICR mice of different ages infected with Enterovirus 71(EV-A71)through three routes of infection, and to explore the dynamic distribution and infection mechanism of EV-A71 in vivo.Three-,5-and 9-day-old neonatal ICR mice were infected with an EV-A71 strain isolated from a child with severe hand, foot and mouth disease through intramuscular(IM), intraperitoneal (IP)and intracerebral (IC)injection, respectively. Consequently, blood, brain, hind-limb muscle, heart, and intestines of mice were collected at regular intervals. Changes in viral load in organs were measured using real-time polymerase chain reaction. Hematoxylin and eosin staining and immunohistochemical (IHC)analyses were undertaken to detect pathogenic and pathologic changes in infected mice.Five-day-old neonatal mice infected with EV-A71 through IM,IP or IC routes had obvious neurologic symptoms and a high mortality rate. Symptoms were alleviated slightly with increasing age of mice upon injection. However, the pathogenicity associated with IM and IP injections was more severe than that of IC injection. Also, the mortality rates of IM and IP injections were significantly higher than that of IC injection. Compared with the control group, the mean body weight(in g)of 3-day-old neonatal mice at 6days post-infection(dpi)injected by IM,IP and IC routes decreased by 1.54(31.43%),1.31(15.06%)and 2.52(44.28%),respectively. Similarly, the mean body weight(in g)of 5-day-old neonatal mice at 6dpi injected by IM and IP decreased by 0.605(8.95%),0.886(15.51%),whereas that of mice injected by IC increased by 0.904(14.70%).The body weight of all infection groups was significantly lower than that of the control group(P<0.05).All 3-day-old neonatal mice infected with EV-A71 through IM,IP and IC routes died at 9dpi.Survival rates of 5-day-old neonatal mice infected through IM,IP and IC routes at 9dpi and14 dpi were 42.8%,25%,and 87.5%,and 0%,0%,and 25%,respectively.Those of 9-day-old neonatal mice at 14 dpi were 70%,69.23% and 100%,respectively.Pathologic and IHC examination showed that EV-A71 had a strong preference for infecting nervous systems and skeletal muscle, and could also lead to: viremia; necrosis of brain neurons and skeletal muscle; myocardial interstitial edema; inflammatory response of multiple organs. These data suggest that 5-day-old ICR neonatal mice injected through IM or IP routes can establish an ideal model of infection by EV-A71 in mice.

To study the genetic characteristics of coxsackievirus (CV)-A6 strains isolated from hand, food and mouth(HFMD)cases in Ningxia Province, China, in 2013~2015.A total of 998 specimens identified as non-EV71,non-CVA16 enteroviruses by real-time polymerase chain reaction were collected in 2013~2015and cultured using RD cells. The viral protein(VP)1gene of isolated strains was amplified by reverse transcription-polymerase chain reaction with degenerate primers and sequenced.Sequences were compared using the GenBank database by the BLAST algorithm to identify virus genotypes. All CV-A6 stains identified underwent homologous comparison and phylogenetic analyses. A total of 227 virus strains were isolated from 998 clinical specimens, and 61 stains were identified as CV-A6.Homologies of nucleotides and amino acids among Ningxia CV-A6 strains were 96.1%~99.8% and 98%~100%,respectively.The nucleotide homogeneity of Ningxia CV-A6 strains with Gudla strains, and the similarity of nucleotides and amino-acid sequences with VP1 of CV-A6 were 82.0%~83.5% and 93.8%~95.7%,respectively.CVA6 was the main pathogen of HFMD apart from EV71 and CV-A16 in Ningxia Province in 2013~2015.

In this study, the epidemiology of Hand-foot-mouth disease(HFMD)composition of enterovirus (EV) pathogen and VP1 coding gene of Enterovirus A71(EV-A71)were analyzed in Chongqing from 2014 to 2015,to provide a scientific basis for strategies of prevention and control of HFMD in Chongqing. It is reported that there were a total of 100,176 cases of HFMD, of which 284 cases of severe,37 cases of death in Chongqing.39counties(autonomous counties)of Chongqing have reported cases, and the urbans reported incidence rate(298.83/100,000)was significantly higher than the suburbs(103.37/100,000),children 3and under 3years old accounted for 83.21%%,and 5and under 5years old accounted for 95.64%of reported cases, the big peak of epidemics of HFMD was from April to July and the small peak took shape from October to November. Severe cases(96.83%)and deaths(100%)were concentrated in the age group of 5years old and below. The severe cases were mainly in the three districts, WanZhou District, Liangping County and FuLing District, accounting for 74.65% of reported cases, and death cases were widely distributed, scattered in 17 counties.7503nucleic acid of clinical specimens of HFMD were detected, suggested that EV-A71,CV-A16,non-EV-A71/CV-A16 of other EV accounted for 23.54%,33.21%,43.25% respectively,Non-EV-A71/ CV-A16 of other EV became the dominant pathogen of HFMD in Chongqing, but EV-A71 was still the dominant pathogen in severe and death cases. The results showed that 54 strains belonged to C4a and one strain belonged to B5 in the analyses of the VP1 sequences of 55 strains during2014-2015 in Chongqing. This study provides important epidemiological and etiological data for HFMD prevention and control strategies and reduction of severe and death caused by EV-A71 in Chongqing.

To understand the epidemiological etiology characteristics of hand, foot and mouth disease(HFMD)in Guangdong province, and to explore the risk change trend of the whole province. By using the descriptive epidemiological methods, the whole province’s incidence trend, population distribution and pathogenic form of HFMD were analyzed with the HFMD surveillance data,population data and geographic information of Guangdong province from 2008 to 2015.The analysis results show: A total of 2,133,722 cases of HFMD, including 5,066 severe cases and 259 death cases were reported in Guangdong province from 2008 to 2015.All the cities of Guangdong had HFMD cases, especially the Pearl River Delta Regions, which were on high-risk areas. There were two peaks every year, with the main peak of incidence occurred in spring and summer, and the sub peak occurred in autumn.Most cases were children aged<5years old, the proportion of this group in overall infections, the severe and death cases were 90.58%,95.93%and 97.30%,respectively,while the proportion for the children less than 3years old were 77.32% and 81.85%,respectively. The incidence of this disease among men was higher than that of women. Dynamic changes were presented between different years and seasons:CV-A16 was more popular in 2009,and enterovirus that none EV-A71 and none CV-A16 were predominant strains in 2013 and 2015.Especially in 2015,the proportion of other EV ranged as high as 71.97%.Besides,EV-A71 was the absolute predominance pathogen within death cases and was important pathogen in severe cases. This study suggests that HFMD epidemiology and laboratory monitoring in Guangdong Province should be strengthened, and provides scientific data support for further improvement of HFMD prevention and control strategies in Guangdong Province.

In this study, we examined the complete genome of coxsackievirus A6 (CVA6) from hand, foot, and mouth disease in Guangdong Province from 2013,and explored the genetic similarities and differences in epidemic and non-epidemic stains of CVA6.Eighteen strains of CVA6 were included in complete genome sequencing, and the sequences were subject to phylogenetic analysis,sequence alignment analysis and genetic recombination analysis using the software DNASTAR6.0,MEGA5.2and SimPlot3.5.1.The results showed that the complete genome of 18 Guangdong CVA6strains ranged from 7390bp to 7392bp.No insertions or deletions were detected in the coding region. There were several insertions and deletions in 5′UTR and 3′UTR.Phylogenetic analysis indicated that the nucleotide and amino acid sequence identity between the 18 complete genomes were 90.5%-99.6% and 97.5%-99.9%,respectively.The strains isolated in2013 could be further divided into two clusters, III and IV, while the strains isolated in 2011 were only present in the IV cluster. Genetic recombination analysis revealed that the Guangdong representative strain of CVA6,GD870/2013,had gene recombination in the P2 and P3regions,while the GD839/2013 strain did not show obvious genetic recombination. Genome-wide analysis of CVA6 revealed that there are two possible transmitted chains, III and IV, in epidemic strains from Guangdong Province in 2013.The transmitted chain Ⅲ originated from the strain with genetic recombination in the P2 and P3regions,whichwas completely different from the chain IV. Transmission of chain IV of CVA6 was only observed in the nonepidemic 2011 strain.

Enterovirus 71（EV71）is one of the major pathogens of hand, foot and mouth disease (HFMD). The EV71 genome encodes an RNA-dependent RNA polymerase（RdRp）,3D(pol),which is critical for genome transcription and translation. However, how the 3D(pol) interacts with the host remains unclear. Yeast two-hybrid systems provide an effective approach for detecting protein-protein interactions. In this report, we inserted the DNA sequence of 3D(pol) into the pGBKT7 vector as the bait plasmid for the yeast two-hybrid experiment and transformed the plasmid into the yeast AH109 strain. We detected the expression,cytotoxicity and self-activity of 3D(pol).The 3D(pol) expressed well without affecting cell growth but exhibited strong transcriptional activation in yeast cells. We further constructed a series of pGBKT7-3D(pol) deletion mutants and identified the shortest transcriptional activation domain（1-94aa）using a self-activation assay. The results provide a molecular basis for screening the host proteins that interact with 3D(pol) using the yeast two hybrid system.

Objective To develop the monoclonal antibodies (mAbs) against enterovirus type 71 (EV71). Methods Two neutralization epitopes, SP70 and SP55, from EV71 were cloned into the hexon gene of adenovirus type 3 to generate a recombinant adenovirus type 3 (R1R2A3) presenting SP70 and SP55 antigens. BALB/c mice were immunized with the R1R2A3. The mAbs were developed with hybridoma technology and were analyzed with microneutralizing assay, indirect ELISA, Western blotting and direct immunofluorescence assay (DFA). Results The study obtained four hybridoma cell clones, 2C4, D2C9, I2G2 and I12C3. ELISA showed that the titer of D2C9 against EV71 was 1:8 000 000 and the titers of 2C4, I2G2, and I12C3 all were 1:500 000. ELISA and Western blotting demonstrated that all mAbs could specifically recognize the VP1 of EV71. In addition, D2C9 recognized the SP70 epitope, and 2C4, I12C3 and I2G2 all recognized the SP55 epitope. DFA revealed that all mAbs could react with EV71, but not with Coxsackie virus A16 (CoxA16). Conclusion Four mAbs against EV71 have been developed successfully, and all of them could react with EV71 rather than CoxA16.

Enterovirus 71 (EV71) is a major agent of hand, foot, and mouth disease in children under five years of age. In some cases,infection with EV71 can result in herpangina, pulmonary edema and/or brainstem encephalitis. In recent years, many advances have been made towards an understanding of EV71 pathogenesis. In this review, we summarize the cell types targeted by EV71,the activation of signaling pathways, the innate antiviral immune response and immune evasion by EV71 to better understand the immunopathogenesis of EV71 and to aid in the development of antiviral drugs.

This study aims to investigate the etiologic spectrum features of hand, foot and mouth disease(HFMD)and the VP1 region of coxsackievirus A6(CV-A6)in the Anyang area of China during 2013.A total of 479 HFMD fecal specimens were identified using real-time RT-PCR. The positive specimens of the different serotypes and the proportion of each serotype were calculated. A total of 10 positive of CV-A6 specimens were amplified and sequenced to obtain the profile of the VP1 region. Based on the data of the VP1 sequences from the Anyang strains and other referenced strains deposited in the NCBI database, the similarities of the nucleotide and amino-acid sequences for the VP1 region, as well as phylogenetic analyses were performed by the BIOEIDT 7.2and MEGA 5.1software packages. The results revealed that 429 positive specimens of enterovirus, including 90 positive specimens of CV-A6 were identified. The CV-A6 specimens accounted for 20.98%of the total positive specimens.CV-A6 had become the second preponderant pathogen of the HFMD in the Anyang area during 2013.It was the first record of an enterovirus serotype of which was neither CV-A16 nor EV-A71,had become one of the primary pathogens associated with HFMD in the region. A great diversity of the nucleotide and amino-acid sequences between 10 Anyang strains and a prototype strain (Gdula) was found. Compared with the Henan strain(HN421),four Anyang sequences with nucleotide and amino-acid sequences exhibited greater diversity than the other six Anyang sequences. The phylogenetic analysis showed that all of 49CV-A6 strains could be clustered into four branches. Branch D could be further clustered into two sub-branches;6 Anyang sequences belonged to sub-branch D1,and the other four belonged to sub-branch D2.

To study the replication and antiviral innate immunity of EV-A71 in mouse macrophages, we selected the mouse macrophage RAW264.7cell line as a model. An absolute quantitative PCR detection method was constructed to detect the viral load of EV-A71 in RAW264.7cells.RT-qPCR detected the fold changes of the proinflammatory cytokine, chemokine, and pattern recognition receptors at different time points post-infection in RAW264.7cells infected with EV-A71 and UV-inactivated EV-A71.The results revealed that the viral load of EV-A71 in RAW264.7cells decreased as the time post-infection increased. Proinflammatory cytokines, including IL-1β,IL-6,TNF-α,and chemokines, including IP-10,MCP-1,and MIP-1αwere induced, and the mRNA expression levels of TLR2,TLR1,TLR6,MDA5,and RIG-I were up-regulated. These results indicate that EV-A71 could replicate in mouse macrophages at a lower level, and proinflammatory cytokine and chemokine responses were induced.

Objective: To investigate the etiology of severe hand-foot-mouth disease (HFMD) in children in Henan province., Methods: A total of 244 HFMD cases admitted to a hospital in Zhengzhou from April to June of 2014 were recruited for research sampling, Real-time RT-PCR, virus isolation, VP1 sequencing and alignment methods were used to test the enterovirus-related etiology. SPSS 17.0 was used in performing statistical analysis., Results: There were 109 severe and 135 mild cases among all the 244 HFMD cases. The number of enterovirus positive stool samples was 229, with positive rate as 93.85%. EV71, Cox A16 and Cox A10 made up 83.84%, 5.68% and 8.30% of the enterovirus etiologicy, strains, respectively. EV71 infection caused 8 HFMD cases with heart-lung failure and 2 death, Cox A10 infection led to 1 HFMD case with heart-lung failure and death. There were statistically differences seen regarding the enterovirus infection rates between severe and the mild HFMD cases (χ(2)=5.312,P=0.021). Statistically significant difference was seen in the constituent ratio of EV71, Cox A16 and the others by Fisher' s exact test (P=0.048). There was statistically significant difference seen between the cardiorespiratory failure rate and the fatality rate by EV71 and Cox A10 infection (χ(2)=0.051,P=0.821; χ(2)=2.198,P=0.138). Cox A10 strains idenfied in Henan in 2014 belonged to genotype 6. The rates on homology of nucleotide and amino acid among the Cox A10 strains in Henan in 2014 were 94.3%-99.7% and 96.3%-100.0% respectively., Conclusions: EV71 still remained the most common pathogen that causing severe HFMD in children, with the increasing Cox A10 percentage in the pathogens spectrum of HFMD infection. Cox A10 strains in Henan in 2014 belonged to genotype 6. Genotype 6 Cox A10 had appeared and widely distributed in Henan for long time, but not yet variated or reconstructed. Cox A10 infection could lead to cardio-respiratory failure thus called for the monitoring program on non-EV71 and non-Cox A16 enterovirus, especially Cox A10 to be strenthened.

Objective: To study the molecular epidemiology of hand-foot-mounth disease (HFMD) associated Coxsackievirus A10 (Cox A10) identified in Fujian province., Methods: A total of 1 525 specimens from non-EV71 non-Cox A16 HFMD patients were collected during 2011-2014. Isolated virus strains were identified and sub-typed. Full-length coding regions for the VP1 gene of the predominant serotype Cox A10 isolates were amplified and sequenced., Results: Among the 407 non-EV71 non-Cox A16 HFMD cases confirmed by virus isolation and molecular subtyping, 103 (25.3%) were caused by Cox A10, accounting for 11.0%, 6.0%, 18.4% and 9.2% among the HFMD-associated entero-viruses identified in 2011, 2012, 2013 and 2014, respectively, in Fujian province. Compared to the general features observed in the HFMD epidemics, no differences on the Cox A10-specificity rates were observed among factors as geographical origins, gender or age groups, but all with high rates of severity. Data from the nucleotide sequence analyses on VP1 genes showed low homology levels of 76.0%-77.1% among Cox A10 strains from Fujian province, in contrast to the prototype Cox A10 strain, but with high levels of homology in the amino acid sequences (91.9%-93.6%). RESULTS from the Phylogenetic analysis also indicated that Cox A10 isolates from Fujian province were distinct from the prototype strain or other isolates from other countries but was homologous to domestic strains, but the Fujian isolates clustered into multiple branches., Conclusions: Cox A10 remained one of the predominant serotypes of HFMD in Fujian province. Cox A10 isolates identified in Fujian province were co-circulating and co-evolving with other domestic strains.

We analyzed the genetic characteristics of coxsackievirus A4 (CV-A4) based on the entire VP1 coding region. Samples were isolated from patients with acute flaccid paralysis (AFP) in Shaanxi, China from 2006 to 2010. We wished to ascertain the predominant genotype and the relationship between CV-A4 infection and AFP. Sixty-eight non-polio enteroviruses were inoculated onto RD cells (to increase the virus titer) and molecular typing was undertaken. The entire VP1 coding region was amplified. Percentage of CV-A4 was 10.3% (7/68). Analyses of genetic identify and creation of phylogenetic trees revealed that CV-A4 could be classified into A, B and C genotypes. Seven CV-A4 strains from Shaanxi and other CV-A4 strains from China formed an independent evolution lineage located in group 4 and belonged to the C2 sub-genotype. These data suggested that CV-A4 strains of sub-genotype C2 were the predominant genotypes in China. These strains co-evolved and co-circulated with those from other provinces in China, so continued monitoring of CV-A4 (by clinical and genetic surveillance) should be enhanced.

To study on the phylogenetic characterization of the VP1 genes of coxsackievirus A16 (CVA16) causing hand-food-mouth disease (HFMD) isolated from Anhui province in 2014. A total of 413 throat swab specimens from HFMD patients were collected during January to November, 2014 for the isolation and identification of enteroviruses using real-time RT-PCR assays. The VP1 regions of CVA16 isolates were amplified using RT-PCR and sequenced. And the phylogenetic tree was constructed among the VP1 regions of those isolates, the different genotypes and sub-genotypes of CVA16 strains. A total of 97 enteroviruses were isolated from 413 samples, the positive rate was 23.49% (97/413), including seventeen CVA16, seventy six HEV71 and four other enteroviruses. The results of the phylogenetic tree showed that 17.CVA16 strains isolated from Anhui in 2014 clustered within B1b evolution branch of B1 genotype. The nucleotide and amino acid sequence identities were 95.30%-100% and 98.70%-100% among the isolates, respectively, but within B1b branch of 17 strains formed several small transmission chains. The nucleotide acid of 17 CVA16 isolates in Anhui province were closed to the strains isolated from Yunnan, Hunan, Guangdong, Tibet and Jiangsu, especially from Hunan in 2013 and from Shenzhen of Guangdong in 2014, the identity were 96.40%-99.70%. The CVA16 strains isolated from Anhui in 2014 were all belong to genetic subtype B1b of B1 genotype was dominant, and among those isolates, several small virus transmission chains had formed with co-circulating and evolution.

Enterovirus 71 (EV71) is a major agent of hand, foot and mouth disease that can cause a severe burden of disease to children. To identify an effective method for the control and prevention of EV71, we studied the effect of exposure to heat and ultraviolet (UV) light upon EV71 inactivation. We found that exposure to 50 degrees C could not inactivate the infectivity of EV71. However, exposure to 60 degrees C and 70 degrees C could inactivate EV71 effectively. EV71 could be inactivated after exposure to UV light at a distance between the sample and a lamp of 30 cm for 30 min or 60 min because viral genomic RNA was destroyed. However, fetal bovine serum (FBS) could attenuate the inactivation proffered by heat and UV light. Attenuation effects of FBS were correlated positively with FBS concentration. Hence, EV71 can be inactivated by exposure to heat and UV light, and our results could provide guidance on prevention of the spread of EV71.

Objective: To study the genetic characteristics of VP1 region of coxsackievirus A10 (Cox A10) strains isolated from hand foot and mouth disease (HFMD) cases in Ningxia Hui Autonomous Region (Ningxia) in 2013., Methods: A total of 280 specimens, which were identified as non-enterovirus 71 and non-Cox A16 by real-time PCR, were collected and cultured by using RD cell, and the VP1 genes of isolated strains were amplified by using reverse transcriptase PCR (RT-PCR) with degenerated primers and sequenced. The sequencing results were aligned with the sequences in GenBank with BLAST algorithm to identify the virus genotypes. Homologous comparison and phylogenetic analysis were conducted for all the Cox A10 strains identified., Results: Among 36 virus strains isolated from 280 clinical specimens, 6 were identified as Cox A10. The homologies of nucleotide and amino acid of the Cox A10 strains isolated in Ningxia were 97.0%-99.8% and 99.0%-99.7% respectively, and the Cox A10 strains isolated in Ningxia shared 76.3%-77.2%, 81.6%-83.1%, 94.4%-98.9% and 80.0%-82.3% nucleotide homologies respectively and shared 92.3%-93.0%, 94.0%-95.3%, 98.0%-99.7% and 90.6%-94.0% amino acid homologies respectively with the representative strains of A, B, C and D genotypes. Phylogenetic tree analysis revealed that Cox A10 strains isolated in Ningxia belonged to genotype C., Conclusion: Cox A10 is one of the most common pathogen causing HFMD in Ningxia in 2013. All the Cox A10 stains isolated from HFMD patients in Ningxia belonged to genotype C.

Objective: To understand the correlation of enterovirus 71 (EV71), P-selectin glycoprotein ligand-1 (PSGL-1), and scavenger receptor B2 (SCARB2) and to explore the possible pathway and mechanism of EV71 infection by observing the expression of EV71, PSGL-1 and SCARB2 in tissues of infants with brain stem encephalitis., Methods: The organs and tissues of infants with EV71-VP1 positivity in their brain stems were chosen. Expression and distribution of EV71-VP1, PSGL-1, and SCARB2 were detected and compared by immunohistochemistry., Results: Strong staining of EV71 -VP1 was observed in the neuron, glial cells, the inflammatory cells of perivascular cuffing, parietal cells of the gastric fundus gland while alveolar macrophages, intestinal gland epithelium cells, mucosa lymphoid nodule and lymphocyte of palatine tonsil showed moderate staining and weak staining were displayed in mesenteric lymph nodes and lymphocyte of spleen. PSGL-1 expression was detected in parietal cells of the gastric fundus gland, tonsillar crypt squamous epithelium, alveolar macrophages and leukocytes in each tissue. SCARB2 expression was observed in all the above tissues except the intestines and spleen., Conclusion: The distribution of EV71 correlates with SCARB2 expression. SCARB2 plays an important role in virus infection and replication. Stomach may be an important site for EV71 replication.

Enterovirus 71 (EV71) is a neurotropic pathogen that can induce hand, foot and mouth disease in children. There is an appreciable mortality rate after EV71 infections. The mechanism of action of EV71 replication is not known. Recent work has identified some of cell factors of the host that participate in the synthesis of the RNA and proteins of EV71 (e.g., hnRNP K, reticulon 3 (RTN 3)). In that work, researchers used a competitive assay to show that hnRNP K can interact with EV71 5' UTR, which is required for efficient synthesis of viral RNA. Using a yeast two-hybrid system, other researchers demonstrated that RTN 3 interacts with the N-terminal domain of EV71 2C, which is crucial for replication of viral RNA. Here, we discuss recent work focusing on the molecular mechanisms of hnRNP K and RTN 3 in the synthesis of the RNA and proteins of EV71.

Enterovirus 71 (EV71) is a major causative agent of hand, foot and mouth disease (HFMD). belongs to family Picornaviridae, genus Enterovirus, species A. EV71 infection usually affects subjects aged <5 years. HFMD caused by EV71 infection is usually mild in children. However, in some cases EV71 infection can lead to severe neurogenic disease and even death. EV71 infection has caused epidemic worldwide (especially in the Asia Pacific). HFMD caused by EV71 has become a major public-health prol lem across the Asia Pacific. In EV71 infection, the pathogenesis is determined by viral and host factor, Here, we review research on host susceptibility and how EV71 suppresses immune and intracellular ri

The aim of this study was to understand the enterovirus types and biological features of pediatric cases of HFMD in Sanmenxia City during 2011, and compare the latter to a cohort of healthy children. Stool samples of 55 cases of HFMD and 60 healthy children were collected for the isolation and identification of enteroviruses using RNA extraction and real-time RT-PCR assays. EV71 and CA16 were identified by nucleotide sequencing using virus-specific VP1 primers; for the other enteroviruses, 012/011 and 008/013 primers were used for amplification and sequencing. The results were analysed by sequence alignment with known sequences, and the characteristics of the EV71 VP1 gene were also analyzed. The detection rates for enteroviruses in cases of HFMD and healthy children were 52.73% (29/55) and 18.33% (11/60), respectively. Among these, there were 22 cases of EV71, four cases of CA16 and three cases of other enteroviruses in the cases with HFMD. Eleven healthy children had intestinal viruses, of which nine were Coxsackie B virus strains (81.82%, 9/11). Gene sequencing of the 19 EV71 strains illustrated that they were all subgenotype C4a, but the evolutionary tree showed an obvious clustering between cases from Lingbao City and Lushi County. This study demonstrates that the EV71 subgenotype C4a and CA16 strains were the most common cause of HFMD in Sanmenxia City in 2011, and that Coxsackie B strains were prevalent in healthy children. This finding may indicate that there is a widespread source of recessive infection in the community.

In order to characterize the molecular epidemiology of HFMD-associated Coxsackievirus A6 (CVA6) in Fujian Province, a total of 1340 specimens from non-EV71 non-CVA16 HFMD patients were collected during 2011-2013. Isolated virus strains were identified and subtyped. Full-length coding regions for the VP1 gene of the predominant serotype CVA6 isolates were amplified and sequenced. Among the 375 non-EV71 non-CVA16 HFMD cases confirmed by virus isolation and molecular subtyping, 182 (48.5%) were found to be caused by CVA6, accounting for 7.9%, 16.2% and 39.6% HFMD-associated enteroviruses in FujianProvince during 2011, 2012, and 2013, respectively. Compared with general features observed in the HFMD epidemic, no difference in CVA6-specificity or severity rates was observed between geographical origins, gender, or age groups. Nucleotide sequence analyses of VP1 genes revealed high diversity levels of 16.2%-18.6% among CVA6 strains from Fujian Province, in contrast to the prototype CVA6 strain, and showed low levels of diversity in the amino acid sequences (4.3%-6.2%). Phylogenetic analysis also indicated that CVA6 isolates from Fujian Province were distinct from the prototype strain and other isolates from abroad; however, it was homologous to domestic strains, although the Fujian isolates clustered into multiple branches. These results suggested that significant changes in the pathogenic spectrum of HFMD in Fujian Province occurred during 2011-2013, as CVA6 was one of the predominant serotypes of HFMD. CVA6 isolates from Fujian Province were co-circulating and co-evolving with other domestic strains as multiple closely related CVA6 transmission chains were observed in Fujian Province overall and within each prefecture.

The highly-pathogenic EV71 strain is the primary cause of mortality in hand-foot-and-mouth disease (HFMD) associated with neurological symptoms, for which no clinically effective drugs or vaccines exist. This study aimed to construct infectious cDNA clones of the EV71 highly-pathogenic strain and the cell-culture adapted strain using a reverse genetics approach. The genomic RNAs of EV71 parent strains were used as the templates for RT-PCR amplification, and then the PCR products that overlapped the full-length genome were connected into the pBR322 vector to produce infectious clones of pEV71 (HP) and pEV71 (CCA), respectively. The results showed that the HP strain propagated much more quickly than the CCA strain. The rescued viruses derived from the infectious clones not only maintained their consistency with their parent strains in terms of genomic sequences, but also retained their respective biological phenotypes. This research will contribute to our understanding of EV71 pathogenesis and the development of novel vaccines against HFMD.

This study aimed to investigate antibody levels of the newer human enteroviruses (EV) A71, A90, and B87 in the population of Shandong Province, and provide a scientific basis for the development of prevention and control measures. In this study, serum specimens were collected from 400 individuals living in Yantai city, Shandong Province in 2010. EV-A71, A90, and B87 antibodies were detected using neutralization tests, and the results were analyzed by statistical methods. It was found that the positive neutralizing antibody rates of EV-A71, A90 and B87 in the population were 46.0%, 8.8%, and 47.0%, respectively. Their geometric mean titers (GMT) were 1 : 5.20, 1 : 1.49, and 1 : 4.02, respectively. Positive antibody rates for EV-A71 and EV-B87 were lowest in the 1-yr and 7-mo age groups, respectively. Positive rates increased gradually with age, and become consistent in the population aged >5 years. Positive antibody rates of EV-A90 were consistent across all age groups. Maternal antibody levels of EV-A71 declined rapidly after birth, and the increase in seroprevalence among 3-7 years old children implied that most EV-A71 infections occurred in preschool and early elementary school children. High positive antibody rates of EV-B87 in healthy individuals, especially children, implied that there may be an immune barrier within the general population. The population monitoring of EV-A90 should be strengthened, as its positive antibody rate is low.

Methods for analyses of protein-protein interactions include: yeast two hybrid (Y2H), phage dis- play (PD), co-immunoprecipitation (Co-IP), glutathione S-transferase pull-down (GST pull-down), cellular co-localization, far-western blotting, virus overlay protein binding assay (VOPBA), surface plasmon resonance (SPR), and fluorescence resonance energy transfer (FRET). Technologies for the detection of protein-nucleic acid interactions include: yeast one hybrid (Y1H), chromatin immunoprecipitation (ChIP), electrophoretic mobility shift assay (EMSA), Southwestern blotting, reporter gene, Co-IP, GST pull-down, and PD. These methods are often used in the study of the human enterovirus A71 (EV-A71) by our research team. Reviews in the Chinese literature in this field are lacking, so we reviewed applications of these methods in the study of EV-A71. This review may impart important knowledge in the research of other viruses with regard to protein-protein and protein-nucleic acid interactions.

We wished to understand the genetic recombination and phylogenetic characteristics of human en- terovirus A71 (EV-A71) and to explore its potential virulence-related sites. Full-length genomes of three EV-A71 strains isolated from patients in Chenzhou City (China) were sequenced and analyzed. Possible re- combination events and crossover sites were analyzed with Recombination Detection Program v4. 1. 6 by comparison with the complete genome sequences of 231 strains of EV-A71. Similarly, plot and bootscanning analyses were undertaken with SimPlot v3. 5. 1. Phylogenetic trees based on the sequences of VP1 regions were constructed with MEGA v5. 2 using the Kimura two-parameter model and neighbor-joining method. Results suggested that recombination events were detected among the three EV-A71 isolates from Chenzhou City. The common main parent sequence was from JF799986 isolated from samples in Guang- zhou City (China) in 2009, and the minor parent sequence was TW/70516/08. Intertypic recombination e- vents were found in the C4b strain (strain SHZH98 isolated in 1998) and C4a strain (Fuyang strain isola- ted in 2008) with the prototype strains of CVA4 and CVA14 in the 3D region. The chi-square test was used to screen-out potential virulence-related sites with nucleotide substitutions of different types of hand, foot, and mouth disease (HFMD) cases using SPSS v19.0. Results suggested that there were no significant nucleotide substitutions between death cases and severe-HFMD cases. Eighteen significant nucleotide substitutions were found between death/severe-HFMD cases and mild-HFMD cases, and all these 18 substitutions were distributed only in P2 and P3 regions. Intertypic recombination among the predominant circulating EV-A71 strains in the Chinese mainland and other EV-A strains probably dates before 1998, and intratypic recombination might have occurred frequently in the HFMD outbreak from 2008 to 2012. Substitutions in the non-capsid region may be correlated with the changes in virulence of EV-A71. These data suggest that researchers should pay more attention to the relationships between substitutions in the noncapsid region and the virulence of the virus.

Epidemics of hand, foot and mouth disease (HFMD) have mainly been caused by Coxsackievirus A16 (CVA16) and Enterovirus A 71 (EV-A71), which circulated alternatively or together in the affected area. CVA16 has caused numerous outbreaks and epidemics in multiple countries and geographical regions, and has become an important public health problem. Based on an analysis of the complete VP1 coding region, all CVA16 strains can be divided into genotypes A, B1, and B2. Furthermore, genotype B1 can be divided into subgenotypes B1a, B1b, and B1c. After 2000, no reports of genotype B2 virus strains have been reported. All of the CVA16 strains reported in mainland China have belonged to subgenotypes B1a and B1b. Most CVA16-associated infections cause only mild symptoms; however, some CVA16 infections can lead to severe complications and even death. Vaccination is considered to be the most effective method to control the transmission and infection rate of this virus. A number of research groups are studying various vaccine types, including inactivated vaccines, genetic engineering vaccines, and DNA vaccines, amongst others. In this review, an overview is provided of the research advances in molecular epidemiology and vaccines of CVA16.

Objective: MicroRNAs (miRNAs) play an important role in infection and replication of virus in host cells. In this study, we examined miRNAs' effects on the replication of Coxsackievirus A16 (CA16) in rhabdomyosarcoma cells., Methods: We constructed target gene of miRNAs screening system. We used 3'untranslated region (UTR) dual luciferase reporter analysis to identify putative miRNA targets in the CA16 virus genome. First, 12 segments of CA16 virus genome were inserted to the pMIR vector and the luciferase expression were assayed to identify the target gene of putative miRNA. The reporter gene expression of the cells transfected with the vector containing 5'-UTR was significantly downregulated. Then, using online analysis programs we screened the miRNAs that may target to 5'-UTR. Furthermore, Western blot and real-time PCR test were used to study the effect of miRNAs on viral replication., Results: The study showed that miR432 * could stimulate the replication of CA16 virus. On the contrary, miR432 * inhibitor could suppress CA16 virus replication., Conclusion: Cellular miRNAs could regulate the replication of CA16 virus in host cells. Our findings support the notion that the cellular miRNAs play an important role in the host and virus infection.

To evaluate the adjuvant effect of recombinant enterovirus 71 (EV71) subunit vaccine formulated with chitosan, rabbits were orally immunized with recombinant VP1 (rVP1) or rVP1 mixed with chitosan adjuvant. Levels of virus-specific IgG and IgA antibodies in sera, mucosal wash buffer (intestine, nasal cavity, and lung), and feces were determined by indirect enzyme-linked immunosorbent assay (ELISA). The titers of neutralizing antibodies against EV71 were determined using cytopathic effect-based neutralizing assay, and levels of cytokines (IFN-gamma and IL-4) secreted from in vitro-cultured rabbit splenic lymphocytes under antigen stimulation were also determined by ELISA. Results showed that immunization with rVP1 alone could only induce low levels of serum IgG and mucosal IgA, while rVP1 combined with chitosan adjuvant were able to induce significantly higher levels of antibodies, rVP1 can only induce neutralizing antibodies when used in combination with chitosan. Levels of IFN-gamma and IL-4 in the group immunized with rVP1 plus chitosan were significantly higher than those in the group immunized with rVP1 only or those in the control groups. Our study lays the foundation for development of oral VP1 vaccine against EV71 infection.

Objective: To clone and express the recombinant capsid protein VP2 of enterovirus type 71 (EV71) and to identify the immune activity of expressed protein in order to build a basis for the investigation work of vaccine and diagnostic antigen., Methods: VP2 gene of EV71 was amplified by PCR, and then was cut by restriction enzyme and inserted into expression vector pMAL-c2X. The positive recombinants were transferred into E.coli TB1, the genetically engineered bacteria including pMAL-c2X-VP2 plasmids were induced by isopropyl thiogalactoside ( IPTG) , and the expression products were analyzed by SDS-PAGE and western blotting method. EV71 IgM antibody detection method by ELISA was set up, and the sensitivity and specificity of this method was assessed; 60 neutralizing antibody positive serum samples from hand foot and mouth disease (HFMD) patients were determined, of which 52 samples were positive and 8 samples were negative; a total of 88 acute phase serum samples of HFMD patients diagnosed in clinical were also detected., Results: VP2 gene of 762 bp was obtained by PCR, the gene segment inserted into the recombinant vector was identified using restriction enzyme digestion. The recombinant vector could express a specific about 71 500 fusion protein in E.coli by SDS-PAGE. The purified recombinant protein of EV71-VP2 can react with the serum of HFMD patients to produce a specific band by western blotting. The sensitivity and specificity of ELISA was 87% and 83%, respectively. Of the 88 acute phase serum samples from children with HFMD, 48 samples (55%) were positive by the ELISA assay., Conclusions: VP2 gene of EV71 has been cloned and a prokaryotic high expression system for VP2 gene was successfully constructed in the present study. The recombination EV71-VP2 has well antigenicity, which could be useful for developing diagnose reagent or vaccine of EV71.

Objective: To observe the duration of enterovirus-71 (EV71) and coxsackievirus A 16 (CoxA16) viral shedding in stool samples of children with hand, foot and mouth disease (HFMD) infected with EV71 and CoxA16 and to explore the relationship between the duration of intestinal virus shedding and the severity of illness of children with HFMD., Method: Totally 113 laboratory-confirmed cases of children with HFMD infected with EV71 and CoxA16 were followed up. The stool samples were collected with the interval of 4 to7 days and the viral nucleic acids were detected by fluorescent PCR until the stool viral nucleic acids of infected children turned to be negative. The cases in EV71 group were further divided into "ordinary EV71 group" and "severe EV71 group" according to the severity of the illness. The positive rates of viral nucleic acid and the differences of distribution among different groups were analyzed by Kaplan-Meier survival analysis during the follow-up period., Result: The 113 cases of infected children were grouped as follows: 65 cases of EV71 positive children, 44 cases of CoxA16 positive children, 4 cases of EV71/CoxA16 mixed infection. The median duration of the stool viral nucleic acids turning to negative was 26 (18.25-32.50) days in EV71 group and 27 (14.50-33.75) days in CoxA16 group (Z = 1.51, P > 0.05). At 1, 4, 6 and 10 weeks, the positive rates of stool viral nucleic acid of children with HFMD in EV71 group were 100%, 48.1%, 17.2% and 0 respectively. At 1, 4 and 6 weeks, the positive rates of stool viral nucleic acid of children with HFMD in CoxA16 group were 95.5%, 53.8% and 0 respectively (χ(2) = 0.18, P > 0.05). At 1, 4 and 6 weeks, the positive rates of stool viral nucleic acid of children with HFMD in ordinary EV71 group were 100%, 23.5% and 0 respectively, while at 1, 4, 6 and 10 weeks, the positive rates of stool viral nucleic acid of children with HFMD in severe EV71 group were 100%, 62.4%, 26.0% and 0 respectively (χ(2) = 5.689, P < 0.05)., Conclusion: The duration of enterovirus shedding in stool samples of children with HFMD lasted for a long period. The maximum duration of EV71 and CoxA16 in stool of children with HFMD was 10 weeks and 6 weeks, respectively. The duration of intestinal virus shedding of children with HFMD infected with EV71 was related with the severity of the illness.

Objective: Identification and characterization of eight enterovirus 71 samples isolated from Yunnan province., Methods: Collecting specimens from cases of Hand, Foot and Mouth Disease (HFMD), samples were identificated by RT-PCR, isolated the virus with cells. The isolating virus passaged in vero cells, and the vpl genes sequencing. Immunization the mice with the virus, neutralization test and cross-protection test were conducted with those antisera., Result: All samples were identified as EV71, and eight strains had cytopathic effect (CPE) in vero cells, some antisera titers were more than 1:10,000., Conclusion: Eight strains of the virus grow well in vero cell, antiserum showed protection against EV71 A and C4 genotype.

To study the impact of the enterovirus 71(EV71) on the nuclear transport mechanism,The pGFP-NLS vector with nuclear location signal(NLS) was constructed, RD cells transfected by the pGFP-NLS vector were inoculated with the EV71 or cotransfected by EV71-2A vector. The results showed that GFP protein with NLS was expressed in the cytoplasm due to the inhibition of nuclear transport. In order to further study the mechanism of the EV71 to prevent nuclear transport,Nup62 was detected by Western blotting after RD cells were infected with EV71 or transfected by EV71-2A vector. The results showed that decreased expression of Nup62 could be detected after infection with EV71 and transfection by EV71-2A vector. This study demonstrates that the cleavage of Nup62 by EV71 2A protease may be the mechanism of nuclear transport inhibition.

To describe the recombination features of human enterovirus 71 strain Guangzhou09 isolated in Guangzhou in 2009, the complete nucleotide sequences of Guangzhou09 were analyzed by various of bioinformatics software. Phylogenetic analysis based on P1, P2 and P3 regions indicated that recombination occurred between EV71 and CVA4. Phylogenetic, similarity plot and bootscan analysis further revealed the recombination between EV71 genotype C strain Shanghai-FJ713317 and CVA4 strain HQ728260 at region 2B was close to the nucleotide position 4 027. This represents the first evidence for intertypic recombination between EV71 subtype C4 and CVA4 in Guangzhou.

To study the pathogenic spectrum of hand, foot and mouth disease (HFMD) and the molecular characterizations of human enteroviruses 71 (HEV71) isolated from the clinical specimens of HFMD patients in Inner Mongolia in 2010. A total of 921 clinical specimens including stools and throat swabs were collected from HFMD patients in outpatient service in Inner Mongolia and then viral isolation was performed, the positive viral isolates were identified by using the real-time PCR method (detecting EV, HEV71 and CVA16 in a single tube), and VP4 and VP1 coding region amplification and sequencing was performed with the viral isolates that were identified as non-HEV71, non-CVA16 HEVs. A total of 153 viruses were isolated form 921 clinical specimens, the positive rate was 16.61%, of which 61 (39.87%) were HEV71, 82 (53.59%) were CVA16, 7 (6.53%) were other HEVs(6 were CVB4 and 1 was polio vaccine virus type II) and 3 (1.96%) were adenoviruses. Nine viruses were isolated from severe cases, of which 6 were HEV71 and 3 were CVA16. Thirty two HEV71 isolates were selected from the patients presenting mild symptoms and the patients presenting severe symptoms randomly, and the VP1 coding regions of represented HEV71 isolates were amplified and sequenced. Finally the phylogenetic tree was constructed among the VP1 coding regions of the different genotypes and subgenotypes of HEV71 strains. The nucleotide acid and amino acid of 32 represented HEV71 strains in Inner Mongolia were closed to HEV71 strains isolated from mainland China since 2007, especially from Beijing in 2008, and it showed that all HEV71 strains clustered within the C4a evolution branch of C4 subgenotype. There was slight difference in the nucleotide and the amino acid sequence in VP1 region among the 32 Inner Mongolia HEV71 strains, the identity were 96.4%-100% and 98.14%-100%, respectively, and there was a little difference in the nucleotide acid sequence between the HEV71 strains from Inner Mongolia in 2010 and in 2007, the identity was from 96.95% to 97.87%. Thirty two HEV71 strains were in different lineages in the phylogenetic tree, and it indicated that these strains belonged to many different viral transmission chains. HEV71 and CVA16 were the main pathogens of HFMD in Inner Mongolia in 2010 and most severe cases were caused by HEV71. All the HEV71 strains circulated in Inner Mongolia belonged to C4a evolution branch within C4 subgenotype. Phylogenetic analysis revealed that 2010 Inner Mongolia HEV71 strains were located in different lineages, and had more nucleotide identity with 2008 Beijing HEV71 strains than with 2007 Inner Mongolia HEV71 strains. This indicated that Inner Mongolia HEV71 strains had not evolved independently, but co-evolved with the HEV71 strains in other provinces in mainland China.

To study the genotype and molecular epidemiological features of enterovirus type 71 (EV71) in Guizhou Province. The hand-foot-mouth disease(HFMD) patients since 2008 in Guizhou Province were surveyed. EV71 RNA positive samples, including mild cases, death cases and cases of serious conditions, were used for subsequent cell culture and sequencing of VP1 complete gene. Genotypes were compared between domestic and foreign epidemic strains. The results showed that the main pathogenwas EV71 subtype C4a in 2008, 2009 and 2011. The nucleotide homology was 95. 3 - 99. 7% among 109 sequenced strains isolated in Guizhou Province. Guizhou strains were more similar to the representative strains from neighbor Province or City, including Shandong, Shanghai, Nanjing, Jilin and Ningbo. There was no distinct sequence difference among the isolates from either of death, mild case or case of serious condition at the nucleotide and amino acid levels. The diversity of nucleotide sequence of isolates was less within same region and year than those trans-regional strains or strains in different year.

To reveal the epidemiological and pathogenic characteristics of Hand-foot-and-mouth disease (HFMD) in Hainan province in 2010, epidemiology data of HFMD reporting cases were analyzed, clinical specimens from 1346 HFMD cases were collected for enterovirus (EV) detection. Viral isolation was performed for EV nucleic acid positive samples. Complete VP1 encoding region of EV71 were sequenced and analyzed with Sequencher (version 5.0) and MEGA software (version 5.0). The epidemiology data showed that all 18 prefectures in Hainan had reporting cases during 2010, with higher incidence in the northeast; and the children less than 4 years old accounted for the majority of the suffered; the epidemic reached peak during September to October, which was different from other Provinces in China. The laboratory results indicated that EV71 and CA16 were identified as the major causative pathogens in Hainan in 2010, however, EV71 infection was absolutely dominant among severe and fatal cases. In addition, some HFMD cases were identified associated with other serotypes of EV infections. Molecular epidemiological analysis showed that all the EV71 strains belonged to C4a evolutionary branch, which is the dominant evolutionary branch in China in recent years, and at least three transmission chains existed. This study has an important information in clarifying the characteristics of epidemics and transmission of HFMD in Hainan, and to provide the guidance for HFMD prevention and control in the future.

Objective: To analyze the genetic evolution for the common causative agent of hand, foot and mouth disease(HFMD) that VP4 of human enterovirus 71 in Shenzhen district., Method: 491 sttol specimen were collected from, children with hand, foot and mouth diease in Shenzhen Children's Hospital 2009. After cell culture, VP4 gene of eight EV71 strains were amplified by reverse-transcriptase PCR( RT-PCR), phylogenetic analysis of the VP4 gene was constructed by using MEGA 4. 0., Result: The VP4 gene of eight EV71 strains encoding 69 amino acids with full length 207 bp. The nucleotide homology of VP4 gene among eight EV71 strains was 94. 2% -98. 1%, compared with VP4 gene of EV71 strains retrieved from Shenzhen 2001 to 2004 and GenBank was 89. 1%-98. 1% and 79.2%-100% respectively. Asian epidemic strain Fuyang had the highest nucleotide homology, representative strain C4 and Shenzhen strain (AY895144) with 94. 2% -98. 1% secondly. Except for the 54th amino acid of VP4 gene of India reported strain and one of the eight EV71 strains, the homology of the rest amino acids between the eight EV71 strains and those in GenBank was 100%. Compared with representative strain C4,there were seventeen differences in nucleotide sequences of VP4 of the eight EV71 strains. All of the different nucleotides were located at the degenerate password sites except one. There was no significant difference in VP4 gene between the severe and the mild cases of strainS. The eight Shenzhen EV71 strains were classified as sub-genotype C4 in the phylogenetic tree., Conclusions: The epidemic of EV71 in Shenzhen 2009 was sub-genotype C4. VP4 gene of EV71 was very conservative which dose not belong to the variation section. The variation of most of nucleotide was invalid variation. The amino acids encoded by VP4 gene which variation was almost zero.

Objective: To clone and express VP1-VP4 genes encoding the structural proteins of Coxsackie virus A16 and analyze the antigenicity of the expressed recombinant proteins., Methods: The VP1-VP4 cDNAs were amplified with RT-PCR from the extracted viral RNA and cloned into pMD19-T vectors. The VP1-VP4 genes were inserted to the multi-cloning sites of the plasmid pQE30a, and the protein expressions in E. coli M15 were induced by IPTG. After purification by washing with 8 mol/L urea under denaturing condition, the recombinant proteins were identified by Western blotting and ELISA for their immunogenicity against rabbit antisera of Coxsackie virus A16 and enterovirus 71, respectively., Results: The recombinant VP1-VP4 proteins were highly expressed in E. coli M15. The purified proteins could be recognized by rabbit antiserum of Coxsackie virus A16 and showed cross reactivity with the rabbit antiserum of Enterovirus 71., Conclusion: The recombinant Coxsackie virus A16 VP1-VP4 proteins obtained possess good antigenicity.

Objective: Explore the relationship between the HLA-G 14bp insertion/deletion polymorphism and the infection of Enterovirus 71 (EV71) for children., Methods: We genotyped HLA-G 14bp insertion/deletion polymorphism of 125 severe HFMD children infected with EV71 and 133 normal controls by PCR-PAGE;detected the plasma sHLA-G level of 66 heavy type and 15 critical type and 133 normal controls by ELISA., Results: Frequencies of the genotype 14 bp - / - ,14 bp + / - and 14 bp + / + were 49.6% , 42.4% and 8.0% for the severe HFMD children infected with EV71, and 34.6%, 48.9% and 16.5% for the normal controls, respectively. A significant difference was observed for the frequencies of the HLA-G 14bp genotype between the two groups(chi2 = 7.850, P = 0.020). And for the allele frequencies. The plasma sHLA-G levels in heavy type were dramatically higher than that in normal controls (Z = -9.692, P = 0.000). The plasma sHLA-G levels in children with critical HFMD were dramatically higher than that with heavy type (Z = -2.420, P = 0.016)., Conclusion: There was a relationship between the HLA-G 14 bp insertion/deletion polymorphism and the susceptibility to the severe HFMD children infected with EV71 and the plasma sHLA-G might be considered as a index for auxiliary diagnosis the severe HFMD infected with EV71.

Objective: To understand the evolutionary relationship between the C4a evolutionary lineage of human enterovirus 71 (HEV71) strains circulating in mainland of China during 2008-2010 and 2008 Fuyang strains and study the prevalence and transmission patterns of 2008 Fuyang strains., Methods: Download all the complete VP1 ( > or = 891 bp) or approximate complete VP1 (> or = 876 bp) gene nucleotide sequences from GenBank of HEV71 strains circulating in Mainland of China during 2008-2010. And analyze the phylogenetic relationship between Fuyang strains and other provinces' strains using the MEGA software, version 5.0., Results: All of the HEV71 isolates circulating in Mainland of China during 2008-2010 were clustered into evolutionary lineage C4a except for eight strains grouped in the genotype A and one isolate belongs to evolutionary lineage C4b; the homology analysis showed there were 96.5%-100% identity between C4a viruses circulating in mainland China during 2008-2010 and 2008 Fuyang strains, and they were evolved from C4b viruses of 1998. The transmission chains of Fuyang strains were mainly transmitted in Guangdong, Jiangsu, Shanghai, Hunan, Shandong provinces., Conclusion: The predominant viruses circulating in Mainland of China during 2008-2010 were evolutionary lineage C4a of human Enterovirus 71; Fuyang transmission chains mainly distributed in southern of China and the Central China around Anhui provinces.

Molecular detection of enterovirus (EV)71 RNA based on PCR methods is a quick and sensitive approach. At present, different PCR-based methods for EV71 RNA detection are available, but comparisons of results obtained using different approaches are limited. This study is to compare the analytical sensitivity and specificity of different real-time reverse transcription-polymerase chain reaction (rRT-PCR) and conventional reverse transcription-polymerase chain reaction (cRT-PCR) assays for enterovirus and EV71 detection, Altogether, three rRT-PCR assays and one cRT-PCR assay targeting the 5'UTR gene for universal detection of enterovirus; two rRT-PCR assays andone cRT-PCR assay targeting the VP1 gene for specific detection of EV 71 were examined. All assays showed good specificity. The detection sensitivity ranged from 8.19 x 10 to 8.19 x 10(5) copy equivalents. In general, rRT-PCR assays were more sensitive than cRT-PCR assays. All rRT-PCR assays showed 100% sensitivity for clinical specimens.