[Genetic characterization of enterovirus 71 complete genome isolated in Beijing, 2008]

OBJECTIVE

To investigate the characterization of the complete genome of EV71 in Beijing, 2008 and to provide basis for selecting appropriate virus strain to develop vaccine.

METHODS

12 throat swab samples were collected from children with hand-foot-mouth disease (HFMD). One sample named 08YM-3 was cultured and isolated in vero cells. Viral RNA was extracted and carried out by RT-PCR and 5', 3' rapid amplification of cDNA ends (RACE) to obtain the sequence from 08YM-3. PCR products were cloned and analyzed. Nucleotide identity between sequences was calculated and sequence alignments were made to generate phylogenetic trees using MegAlign in DNAStar.

RESULTS

3 clones were constructed that covered EV71 complete genome. Data from sequences analysis showed that this viral strain named BJ08 shared 95.6%-96.7%, 88.3%-96.1%, 78.1%-94.0%, 90.8%-94.6%, 85.9%-94.1% and 90.9%-93.9% in 5' UTR, P1, P2, P3, 3' UTR region and complete genome with C4 subtype, respectively. BJ08 showed low nucleotides identity (<90%) with other subtypes. Phylogenetic trees established from alignment of the complete genome and VP1 region indicated that BJ08 belonged to C4 subtype. BJ08 and C4 subtype strains shared the same amino acids in 6 sites in VP1 region, which were associated with EV71 subtype. There was no mutation in VP1 antigen epitope (92-107aa).

CONCLUSION

This BJ08 strain belonged to C4 subtype. Further study on EV71 complete genome would have great significance for vaccine research.

Genetic changes of coxsackievirus A16 and enterovirus 71 isolated from hand, foot, and mouth disease patients in Toyama, Japan between 1981 and 2007

We characterized the genetic diversity of the complete VP1 region of coxsackievirus A16 (CA16) and enterovirus 71 (EV71) isolated from patients with hand, foot, and mouth disease in Toyama from 1981 to 2007 to evaluate the relationship between epidemics and genetic changes. The predominant genogroups of CA16 changed from B to C in 1995-1998, and genogroup C further changed from subgenogroup C1 to C2 around 2002, and to C3 in 2005-2007. The subgenogroups of the EV71 isolates were classified into B1, B4, C1, and C3 in 1983-1994, and into C4 in 1997-2006. However, changes of the amino acid sequences of the VP1 regions of CA16 were restored, and those of the EV71 isolates were not observed among the same subgenogroups during this survey period, indicating that the prevalence that occurred at intervals of several years seemed to depend on an accumulating number of immunologically naive children, not viral antigenic changes.

[The epidemiologic and virological analysis of an outbreak of hand, foot, and mouth disease in Inner Mongolia in 2007]

In 2007, an outbreak of hand, foot, and mouth disease (HFMD) occurred in Jungar Banner, Erdos city, Inner Mongolia Autonomous Region, China Fever, vesicular exanthema on the hands, feet, mouth, and buttocks were presented in most of the patients. Most of the patients were infants less than 5 years old, and an obvious peak period appeared in the disease outbreak. From 28 hospitalized patients, 23 stool specimens and 6 throat swab specimens were collected for enterovirus isolation, and 15 enteroviruses were isolated, 9 were identified as Human Enterovirus 71 (HEV71, the isolation rate is 31.03%) and 1 was identified as Coxsackievirus A16 (CVA16). According to the comprehensive analysis of clinical manifestation, epidemiology data and laboratory results, this outbreak was probably mainly caused by HEV71. The variability at nucleotide acid level and amino acid level among 9 HEV71 was relatively low, and the homology was more than 99.4% and 99.0% respectively, showing that this outbreak was caused by only one viral transmission chain. Phylogenetic analysis of 9 HEV71 strains isolated during this outbreak revealed that they all belonged to subgenotype C4, which has been continuously circulating in mainland China since its first reported occurrence in Shenzhen City in 1998. It was also suggested that subgenotype C4 HEV71 had a widely distribution and transmission in mainland China.

[Molecular confirmation of enterovirus type 71 infection: a post-mortem study of two cases]

OBJECTIVE

To investigate the diagnostic application of molecular detection of enterovirus type 71 (EV71) infection using post-mortem paraffin-embedded tissue.

METHODS

Two autopsy cases of EV71 infection were studied by histopathological and immunohistochemical methods. Reverse transcription polymerase chain reaction (RT-PCR) was performed to detect the viral RNA in paraffin-embedded tissue samples.

RESULTS

Characteristic features of acute encephalitis were seen in the brain, with most prominent lesions found in the brain stem in both cases. Inflammatory cells were largely CD68-positive microglia with a few CD15-positive neutrophils in the areas of neuronal necrosis. The 5'-untranslated region of EV71 was detected in the medulla by RT-PCR using paraffin-embedded tissues of both cases. Sequencing analysis of the RT-PCR products showed 100% homology to the EV71 strain, recently submitted to the GenBank database from Fuyang, Anhui province.

CONCLUSIONS

Molecular detection of EV71 can be performed on formalin-fixed, paraffin-embedded tissue samples from fatally infected patients. Timely and accurate diagnosis of the infection by such molecular approach is crucial for the proper clinical and public health intervention.

[Analysis on the epidemiological and genetic characteristics of enterovirus type 71 and Coxsackie A16 virus infection in Jiangsu, China]

OBJECTIVE

To determine the epidemiological features of hand-foot-and-mouth disease (HFMD) outbreaks and the genetic characteristics of enterovirus type 71(EV71) isolates from patients in Lianyungang, Jiangsu province in May, 2008.

METHODS

Epidemiological, microbiological, cellular and molecular methods were performed to investigate pathogens and to describe the homogeneity of isolated strains.

RESULTS

21 cases were reported in this HFMD outbreak with the attack rate as 20.0%. 3 EV71 virus strains were isolated from 10 stool samples. The nucleotide and amino acid homogeneity of these 3 Jiangsu strain with Anhui Fuyang strains were 97.9%-100.0% and 99.7%-100.0%, respectively. These 4 Jiangsu strains were within genotype C sub-geno group C4 in phylogenetic tree. Data from the follow-up study showed that shedding of EV71 and Coxsackie A16 virus (CA16) in the latent period appeared in the outbreak of HFMD. Human beings could be infected by both EV71 virus and CA16 at the same time and could also carry the two viruses. We also discovered that EV71 virus could be expelled out of the human body through stool in the first week and last for 10 weeks.

CONCLUSION

The recently identified EV71 isolates from this HFMD outbreak belonged to sub-geno group C4. Facts as: the release of viruses in the latent period, co-infection or coexisting of two viruses at the same time and super long period of expulsion of toxin exist in EV71 and CA16 did exist.

An outbreak of hand, foot, and mouth disease associated with subgenotype C4 of human enterovirus 71 in Shandong, China

BACKGROUND

An outbreak of hand, foot, and mouth disease (HFMD) included 1149 people in Linyi City, Shandong Province, China, in 2007: three children died.

OBJECTIVES

To characterize the pathogens responsible for this outbreak and to analyze their genetic features.

STUDY DESIGN

A total of 233 clinical specimens were collected from 105 hospitalized patients, including 11 patients with severe HFMD. Virological investigations (direct RT-PCR, viral isolation and molecular identification) and phylogenetic analysis were performed.

RESULTS

Human enterovirus 71 (HEV71) was the main pathogen that caused this outbreak, based on clinical manifestations, epidemiological data, and laboratory results. Phylogenetic analysis indicated that the Shandong HEV71 isolates belonged to 3 lineages in subgenotype C4. Subgenotype C4 could be further divided into two clusters (C4a and C4b), which corresponded to two time periods. Cluster C4a HEV71 has been the predominant virus circulating in mainland China in the past 5 years.

CONCLUSIONS

The 2007 HFMD outbreak was mainly caused by HEV71 subgenotype C4 with 3 transmission chains. This virus has been continuously circulating in China since 1998. The Shandong strains co-evolved with isolates from other provinces in mainland China and neighboring countries.

[Multiple viral transmission chains of human enterovirus 71 co-circulated in Gansu Province in 2008]

OBJECTIVE

To study the molecular evolution of Human enterovirus 71 (HEV71) isolated from clinical specimens of Hand, Foot and Mouth Disease (HFMD)patients in Gansu in 2008.

METHODS

Clinical samples including stools, throat swabs and vesicle fluids were collected from HFMD patients in outpatient service in Gansu province and then viral isolation was performed. Reverse Transcription-Polymerase Chain Reactions (RT-PCR) specific for HEV71 were performed with the viral isolates. Then 20 HEV71 isolates were selected randomly for entire VP1 coding gene amplification and sequencing, finally phylogenetic tree was constructed among these 20 Gansu HEV71 strains and 38 HEV71 representative strains of known genotypes and subgenotypes.

RESULTS

The nucleotide acid and amino acid of 20 Gansu HEV71 strains were closed to HEV71 strains isolated in Mainland China since 1998, especially has the highest homology to HEV71 stains circulated in mainland China in 2008 and it showed that all strains clustered within the C4b evolution branch of C4 Subgenotype. But there was some difference in the nucleotide and the amino acid in VP1 region among the 20 Gansu HEV71 strains, the homology were 92.5%-100.0% and 96.9%-100% respectively. 20 HEV71 strains lie in several lineages in the phylogenetic tree, and it revealed that these strains belonged to at least 7 viral transmission chains.

CONCLUSIONS

The HEV71 strains circulated in Gansu province in 2008 were all belong to C4b evolution branch of C4 subgenotype. Phylogenetic analysis revealed these HEV71 strains located in different lineages,and a close phylogenetic and chronological relationship with HEV71 isolated in other provinces in mainland China had been observed in 2008. This confirmed Gansu HEV71 strains had not evolved independently, but coevolved with the HEV71 strains in other provinces in mainland China.

[Human enterovirus 71 was isolated from specimens of hand foot mouth disease in Beijing in 2007]

OBJECTIVE

Analyzing and identifying the type of enterovirus of human Hand Foot Mouth Disease (HFMD) outbreak in Daxing district in Beijing at the end of May in 2007.

METHODS

The liquid of Herpes, throat swab and stool specimen were collected. Using reverse transcription-polymerase chain reaction (RT-PCR) method to amplify the enterovirus specific nucleotide acid fragment from specimens and virus positive cultures, the sensitivity of two methods was compared. Then identifying and typing of the enterovirus of HFMD through analyzing the results of nucleotide sequencing of the virus positive cultures.

RESULTS

In 10 specimens from 5 HFMD children patients, enterovirus specific nucleotide acid fragment was detected in 8 patients, the RT-PCR positive ratio (80%) was higher than enterovirus isolation positive ratio (30%). In 5 enteroviruses isolated from 5 patients and 9 close contacts, 4 isolated from 2 patients and 1 close contact were Enterovirus 71.1 isolated from close contact was Coxsackievirus A16.

CONCLUSION

Enterovirus 71 was the pathogen of HFMD outbreak in Daxing district at the end of May in 2007.

[Genotype analysis of enterovirus type 71 detected from patients with hand-foot-mouth disease in Shenzhen]

OBJECTIVE

To carry out genotype analysis of enterovirus type 71, detected from hand-foot-mouth disease patients in Shenzhen in 2004.

METHODS

All samples were tested by reverse transcription-polymerase chain reaction (RT-PCR) using EV71 specific primer. The VP1 and VP4 of EV71 were cloned and sequenced. A phylogenetic tree was constructed by comparing the sequences with genogroups A, B and C genotypes using TreeView and PHYLIP software (3.6b).

RESULTS

The VP1 nucleotide sequence of 4 strains isolated from Shenzhen shared 87.8% - 92.0% identity with genogroup C, while the homogeneity of the VP4 nucleotide sequence was between 85.9% - 87.4%. The homogeneity of the VP1 nucleotide sequence with genotypes A and B was between 81.9% - 84.2% and was 80.6% - 85.0% with VP4. Among the 4 strains, the homogeneity of the VP1 nucleotide sequence was between 94.1% - 99.8% and was 100% with VP4 which formed a small group and could denominate EV71 genetype C4.

CONCLUSION

Similar results were obtained from phylogenetic analysis of EV71 based on VP1 and VP4 nucleotide sequence. The four EV71 strains causing epidemic in Shenzhen could be named as C4 subgroups.

Genetic evolution of enterovirus 71: epidemiological and pathological implications

Since its discovery in the 1970s, enterovirus 71 (EV71) has become one of the most pathogenic enterovirus serotypes causing recurrent outbreaks in different parts of the world. Three waves of outbreaks globally have been recorded over the last three decades and more recently active circulation of EV71 is evident amongst countries in South East Asia and beyond. There is evidence of a continuous evolution in its genetic make up which is likely to impact on its epidemiology and pathological potential. This review examines the molecular genetics and evolution of EV71 in relation to its epidemiological and pathological properties. A thorough understanding of the relationship between the genetic changes and the resulting host-virus interaction is essential for successful control.

Characteristics of bacterial and viral contamination of urban waters: a case study in Xi'an, China

In order to gain knowledge on the presence of bacteria and viruses in urban waters, the authors started a long-term study on the microbiological quality of urban lakes and rivers in Xi'an, China. In the current study, enteroviruses were chosen as typical viruses and RT-nested PCR was conducted for their detection. Universal primers were designed for simultaneous detection of poliovirus, coxsackievirus, and enterovirus 71 which are the most frequently encountered enteroviruses in China. The RT-nested PCR protocol established in this study showed high sensitivity and specificity. The detection limit was equivalent to 0.038 CCID50 per litre by applying a modified adsorption-elution concentration method. No cross-reactivity was observed using the genome of pathogenic bacteria as of PCR template. The occurrence of enteroviruses was compared with fecal coliform count in a 6-month period from July to December 2006 for the urban waters. As a result, it was noticed that the presence of enteroviruses might not relate to the fecal coliform count so much. Statistical analysis also indicated that there was no significant correlation between the presence of enteroviruses and that of total bacteria, total coliform, and fecal coliform.

Prospective identification of enteroviruses involved in meningitis in 2006 through direct genotyping in cerebrospinal fluid

Enterovirus infections were investigated with special emphasis on performing rapid molecular identification of enterovirus serotypes responsible for aseptic meningitis directly in cerebrospinal fluid (CSF). Enterovirus genotyping was carried out directly with specimens tested for the diagnostic procedure, using two seminested PCR assays designed to amplify the complete and partial gene sequences encoding the VP1 and VP4/VP2 capsid proteins, respectively. The method was used for identifying the enterovirus serotypes involved in meningitis in 45 patients admitted in 2005. Enterovirus genotyping was achieved in 98% of the patients studied, and we obtained evidence of 10 of the most frequent serotypes identified earlier by genotyping of virus isolates. The method was applied for the prospective investigation of 54 patients with meningitis admitted consecutively in 2006. The enterovirus serotypes involved were identified with the cerebrospinal fluid (CSF) of 52 patients (96%) and comprised 13 serotypes within the human enterovirus B species and 1 within the human enterovirus A species. The three most common serotypes were echovirus 13 (E13; 24%), E6 (23%), and coxsackievirus B5 (11.5%), a pattern different from that observed in 2005. Genotyping of virus isolates was also performed in 35 patients in 2006 (meningitis, n = 31; other diseases, n = 4). By comparison, direct genotyping in CSF yielded a more complete pattern of enterovirus serotypes, thereby allowing the detection of rare serotypes: three less common serotypes (CB2, E21, and E27) were not detected by indirect genotyping alone. The study shows the feasibility of prospective enterovirus genotyping within 1 week in a laboratory setting.

Genetic diversity of enterovirus 71 isolated from cases of hand, foot and mouth disease in the 1997, 2000 and 2005 outbreaks, Peninsular Malaysia

All known field isolates of enterovirus 71 (EV71) can be divided into three distinct genogroups (A, B, C) and 10 subgenogroups (A, B1-5, C1-4) based on VP1 gene sequences. We examined VP1 gene sequences of 10, 12 and 11 EV71 strains isolated in peninsular Malaysia during the outbreaks of hand, foot and mouth disease in 1997, 2000 and 2005 respectively. Four EV71 strains isolated in the hand, foot and mouth disease outbreak of 2006 in Sarawak (Malaysian Borneo) were included to describe their genetic relationship. Four subgenogroups (C1, C2, B3 and B4) of EV71 co-circulated and caused the outbreak of hand, foot and mouth disease in peninsular Malaysia in 1997. Two subgenogroups (C1 and B4) were noted to cause the outbreak in 2000. In the 2005 outbreak, besides EV71 strains of subgenogroup C1, EV71 strains belonged to subgenogroup B5 were isolated but formed a cluster which was distinct from EV71 strains of the subgenogroup B5 isolated in 2003. The four EV71 strains isolated from clinical specimens of patients with hand, foot and mouth disease in the Sarawak outbreak in early 2006 also belonged to subgenogroup B5. Phylogenetic analysis of the VP1 gene sequences showed that the four Sarawak EV71 isolates belonged to the same cluster as the EV71 strains that were isolated in peninsular Malaysia as early as May 2005. The data suggested that the EV71 strains causing the outbreak in Sarawak could have originated from peninsular Malaysia.

Outbreak of Neurologic Enterovirus Type 71 Disease: A Diagnostic Challenge

BACKGROUND

Similar to poliovirus, enterovirus type 71 (EV71) causes severe disease, including aseptic meningitis, encephalitis, acute flaccid paralysis, and acute cardiopulmonary dysfunction. Large epidemics of EV71 infection have been reported worldwide.

METHODS

After recognition of a cluster of cases of EV71 disease, we reviewed records of patients with EV71 disease who required hospitalization at The Children's Hospital in Denver, Colorado, from 2003 through 2005. The presence of enterovirus was detected by reverse-transcriptase polymerase chain reaction (PCR) and/or viral culture of specimens from multiple sources, and the virus was typed as EV71 using genetic sequencing.

RESULTS

Eight cases of EV71 disease were identified in both 2003 and 2005. Fifty-six percent of patients with EV71 disease were < or = 6 months of age (range, 4 weeks to 9 years). All 16 patients had EV71 central nervous system infection. Enterovirus PCR (EV-PCR) of cerebrospinal fluid specimens yielded positive results for only 5 (31.2%) of the 16 patients; all of these patients were < 4 months of age and had less severe disease. However, EV-PCR of upper respiratory tract specimens yielded positive results for 8 (100%) of 8 patients, and EV-PCR of lower gastrointestinal tract specimens yielded positive results for 7 (87.5%) of 8 patients.

CONCLUSIONS

An outbreak of neurologic EV71 disease occurred in Denver, Colorado, during 2003 and 2005. Likely, EV71 disease remains unrecognized in other parts of the United States, because EV-PCR of cerebrospinal fluid frequently yields negative results. EV-PCR of specimens from the respiratory and gastrointestinal tracts had higher diagnostic yields than did EV-PCR of cerebrospinal fluid. EV71 infection should be considered in young children presenting with aseptic meningitis, encephalitis, acute flaccid paralysis, or acute cardiopulmonary collapse. EV71 infection may be an underrecognized emerging disease in the United States.

[Study on the association of hand, foot and mouth disease and enterovirus 71/CA16 among children in Beijing, 2007]

OBJECTIVE

To reveal the etiological agent of hand, foot and mouth disease in children in Beijing.

METHODS

Throat swabs were collected from 6 infants and young children with hand, foot and mouth disease who visited the affiliated Children's Hospital from May to June 2007. Aspirated fluid from tracheal intubatton, serum and cerebral spinal fluid (CSF) were collected from a 9 years old girl (No.4243) having central neural system complication of severe hand, foot and mouth disease and admitted to the hospital from the Emergency Department. Throat swab and aspirated fluid were inoculated into the cell lines Hep-2, MDCK and Vero for virus isolation. RNAs were extracted by Trizol from 6 throat swab specimens and aspirated fluid, serum while CSF was from that severe case (No.4243). The gene fragment from 5' UTR of enterovirus was amplified from throat swabs and aspirated fluid by reverse transcription-polymerase chain reaction (RT-PCR) with the primer pairs located at the untranslated region of all enterovirus. EV71 was identified by RT-PCR with the 2 and half primer pairs located at different parts of VP1 gene of EV71. The PCR products for VP1 encoding gene of EV71 from the specimens were sequenced and sequence analysis was performed by comparing those published VP1 genes of EV71. EV71 and CA16 specific primers were used to identify the isolates by RT-PCR and the sequences were directly determined from PCR products.

RESULTS

Gene fragments with expected molecular weight were amplified from all 6 throat swabs and the aspirate by the primer pairs universal for the 5' UTR of enterovirus, suggesting that these patients with hand, foot and mouth disease were infected by entorovirus. Out of these 7 specimens, 2 throat swabs and the aspirate were also showing positive for the VP1 of the EV71 by different primer sets. Sequence analysis revealed that the sequences for the amplicons from 1 throat swab (No. F4211) and the aspirate shared highest homology with those published EV71, indicating that these specimens were truly positive for EV71. The sequences amplified from these specimens shared 100% and 98.9% homology to each other and were closer to the sequences of EV71 identified from Zhejiang province than those from Taiwan and strain BrCr. Gene fragments for 5' UTR of enterovirus were obtained by RT-PCR after CPE appeared in 6 out of 7 inoculations including that aspirate fluid in Vero cell, indicating that enteroviruses were isolated from these specimens. Virus isolates from one throat swab (No. F4211) and the aspirate (No. 4243) were positive by RT-PCR with the primer pairs for EV71, which was consistent with RT-PCR amplification directly from specimens. Virus isolates from other 4 specimens were CA16 by RT-PCR and sequence analysis.

CONCLUSION

These data suggested that hand, foot and mouth disease recently appeared in children in Beijing was related with EV71 and CA16. EV71 could cause severe clinical manifestations with central nerve system complications even in the child older than 5 years.

Enterovirus surveillance reveals proposed new serotypes and provides new insight into enterovirus 5'-untranslated region evolution

Human enteroviruses are currently grouped into five species Human enterovirus A (HEV-A), HEV-B, HEV-C, HEV-D and Poliovirus. During surveillance for enteroviruses serologically non-typable enterovirus strains were found from acute flaccid paralysis patients and healthy individuals. In this study, we report isolates of recently described enterovirus types EV76 and EV90 of HEV-A species and characterize two new enterovirus type candidates, EV96 and EV97, to species HEV-C and HEV-B, respectively. Analysis of partial 3D regions of EV96 strains revealed sequence divergence consistent with several recombination events between EV96, other HEV-C viruses and polioviruses. Phylogenetic analysis of all available 5'-untranslated region sequences of human entero- and rhinovirus prototype strains and 10 simian enterovirus strains suggested interspecies recombination involving this region.

Molecular phylogeny of modern coxsackievirus A16

A phylogenetic analysis of VP1 and VP4 nucleotide sequences of 52 recent CVA16 strains demonstrated two distinct CVA16 genogroups, A and B, with the prototype strain being the only member of genogroup A. CVA16 G-10, the prototype strain, showed a nucleotide difference of 27.7-30.2% and 19.9-25.2% in VP1 and VP4, respectively, in relation to other CVA16 strains, which formed two separate lineages in genogroup B with nucleotide variation of less than 13.4% and less than 16.3% in VP1 and VP4, respectively. Lineage 1 strains circulating before 2000 were later displaced by lineage 2 strains.

Phylogenetic evidence for inter-typic recombination in the emergence of human enterovirus 71 subgenotypes

Background

Human enterovirus 71 (EV-71) is a common causative agent of hand, foot and mouth disease (HFMD). In recent years, the virus has caused several outbreaks with high numbers of deaths and severe neurological complications. Several new EV-71 subgenotypes were identified from these outbreaks. The mechanisms that contributed to the emergence of these subgenotypes are unknown.

Results

Six EV-71 isolates from an outbreak in Malaysia, in 1997, were sequenced completely. These isolates were identified as EV-71 subgenotypes, B3, B4 and C2. A phylogenetic tree that correlated well with the present enterovirus classification scheme was established using these full genome sequences and all other available full genome sequences of EV-71 and human enterovirus A (HEV-A). Using the 5' UTR, P2 and P3 genomic regions, however, isolates of EV-71 subgenotypes B3 and C4 segregated away from other EV-71 subgenotypes into a cluster together with coxsackievirus A16 (CV-A16/G10) and EV-71 subgenotype C2 clustered with CV-A8. Results from the similarity plot analyses supported the clustering of these isolates with other HEV-A. In contrast, at the same genomic regions, a CV-A16 isolate, Tainan5079, clustered with EV-71. This suggests that amongst EV-71 and CV-A16, only the structural genes were conserved. The 3' end of the virus genome varied and consisted of sequences highly similar to various HEV-A viruses. Numerous recombination crossover breakpoints were identified within the non-structural genes of some of these newer EV-71 subgenotypes.

Conclusion

Phylogenetic evidence obtained from analyses of the full genome sequence supports the possible occurrence of inter-typic recombination involving EV-71 and various HEV-A, including CV-A16, the most common causal agent of HFMD. It is suggested that these recombination events played important roles in the emergence of the various EV-71 subgenotypes.

High prevalence of human enterovirus a infections in natural circulation of human enteroviruses

Human enterovirus (HEV) infections can be asymptomatic or cause only mild illness; recent evidence may implicate HEV infection in type 1 diabetes mellitus and myocarditis. Here, we report the molecular characterization of HEV obtained in serial monthly collections from healthy Norwegian infants. A total of 1,255 fecal samples were collected from 113 healthy infants beginning at age 3 months and continuing to 28 months. The samples were analyzed for HEV nucleic acid by real-time PCR. Fifty-eight children (51.3%) had HEV infections. One hundred forty-five positive samples were typed directly by nucleotide sequencing of the VP1 region. HEV-A was detected most frequently, with an overall prevalence of 6.8%. HEV-B was present in 4.8% of the samples and HEV-C in only 0.2% of the samples. No poliovirus or HEV-D group viruses were detected. Twenty-two different serotypes were detected in the study period: the most common were EV71 (14.5%), CAV6 (10.5%), CAV4 (8.9%), E18 (8.9%), and CBV3 (7.3%). These findings suggest that the prevalence of HEV infections in general, and HEV-A infections in particular, has been underestimated in epidemiological studies based on virus culture.

Molecular epidemiology of enterovirus 71 over two decades in an Australian urban community

Enterovirus 71 (EV71), first isolated in 1969, has been responsible for numerous outbreaks of hand, foot and mouth disease (HFMD) with a small proportion of cases associated with neurological disease. Since 1997 there has been a significant increase in both the prevalence and virulence of EV71 in the Asia-Pacific region. We have examined the genetic diversity of EV71 in a large Australian city (Sydney N.S.W.) over a nineteen-year period. We determined the VP1 gene sequence of forty-eight EV71 strains isolated between 1983 and 2001. Analysis by molecular phylogeny revealed the presence of four subgenogroups B2, B4, C1 and C2. The results indicate that the major lineage circulating in Sydney N.S.W. was subgenogroup C1 with a recent switch in dominance to B4 in 2000 and 2001.

Nucleotide analysis and phylogenetic study of the homology boundaries of coxsackie A and B viruses

Modern molecular methods use VP1 coding region as a target for RT-PCR assays followed by sequencing, in order to identify new untyped enteroviruses' strains. In the present study, two different genomic portions of VP1 and the full length of 2A coding region of 53 clinical isolates, mostly belonging to HEV-B species, were amplified and sequenced. Nucleotide analysis of the produced sequences revealed that the values that define an unknown strains serotype vary according to the serotype and the specific part of VP1, which is investigated. The correlation, however, with the serotype was affirmed in both VP1 portions that were studied, as well as in the first 20 bases of 2A region. In the rest of 2A, no correlation with the serotype and disruption of monophyly was observed. Phylogenetic analysis of the same sequences confirmed, in most cases, the results of the nucleotide analysis.

RNA interference against enterovirus 71 infection

Enterovirus 71 (EV71) is a highly infectious major causative agent of hand, foot, and mouth disease (HFMD) which could lead to severe neurological complications. There is currently no effective therapy against EV71. In this study, RNA interference (RNAi) is employed as a therapeutic approach for specific viral inhibition. Various regions of the EV71 genome were targeted for inhibition by chemically synthesized siRNAs. Transfection of rhabdomyosarcoma (RD) cells with siRNA targeting the 3'UTR, 2C, 3C, or 3D region significantly alleviated cytopathic effects of EV71. The inhibitory effect was dosage-dependent with a corresponding decrease in viral RNA, viral proteins, and plaque formations by EV71. Viral inhibition of siRNA transfected RD cells was still evident after 48 h. In addition, no significant adverse off-target silencing effects were observed. These results demonstrated the potential and feasibility for the use of siRNA as an antiviral therapy for EV71 infections.

[A study on enterovirus infection in Osaka prefecture --comparison with virus isolation and RT-PCR amplifying viral protein 1 region]

Detection of viral genomes with RT-PCR, which amplifies viral protein 1 region, as well as virus isolation was performed on 860 patients (996 specimens) who had been suspected for enterovirus (EV) infection in Osaka Prefecture from April 2003 to Jury 2004. The viral positive rates of the clinical materials, combining above two procedures, were as follows: 48.2% from the feces, 38.3% from the throat swabs, and 18.0% from the cerebrospinal fluids. The positive rate by the clinical diagnosis indicated that herpangina was the highest at 44.7%, while encephalitis was the lowest at 13.4%. Out of the all specimens, the viral positive rate of RT-PCR varied from 22.3 to 24.7%, while that of virus isolation was 15.6%. The total viral positive rate of both procedures combined was 29.8%. Since the detection of EV by RT-PCR amplifing viral protein 1 region was more rapid than virus isolation and superior in detection of coxsackie group A virus, RT-PCR is an effective procedure for diagnosis of herpangina.

Enteroviruses 76, 89, 90 and 91 represent a novel group within the species Human enterovirus A

Molecular methods have enabled the rapid identification of new enterovirus (EV) serotypes that would have been untypable using existing neutralizing antisera. Nineteen strains of four new EV types termed EV76 (11 isolates), EV89 (two isolates), EV90 (four isolates) and EV91 (two isolates), isolated from clinical specimens from patients in France (one isolate) and Bangladesh (18 isolates), are described. Nucleotide sequences encoding the VP1 capsid protein (882–888 nt) are less than 65 % identical to the homologous sequences of the recognized human EV serotypes, but within each group the sequences are more than 78 % identical. The deduced amino acid sequences of the complete capsid (P1) region are more than 94 % identical within type but less than 76 % identical to those of the recognized serotypes. For both VP1 and P1, the 19 isolates are monophyletic by type with respect to all other EV serotypes. Using the proposed molecular typing scheme, these data support their identification as four new types within the species Human enterovirus A (HEV-A). In almost all cases, the VP1 sequences were more similar to those of some simian EVs than to the human EVs. Partial 3D sequences of all 19 isolates also clustered within HEV-A; they were monophyletic as a group, but not by type, suggesting that recombination has occurred among viruses of these four types. Partial 3D sequences were more closely related to those of simian EVs than to human viruses in HEV-A. These results suggest that the four new types may represent a new subgroup within HEV-A, in addition to the existing human and simian subgroups.