Emergence of recent echovirus 30 lineages is marked by serial genetic recombination events

Genomic surveillance of enterovirus associated with aseptic meningitis cases in southern Spain, 2015-2018

New circulating Enterovirus (EV) strains often emerge through recombination. Upsurges of recombinant non-polio enteroviruses (NPEVs) associated with neurologic manifestations such as EVA71 or Echovirus 30 (E30) are a growing public health concern in Europe. Only a few complete genomes of EVs circulating in Spain are available in public databases, making it difficult to address the emergence of recombinant EVs, understand their evolutionary relatedness and the possible implication in human disease. We have used metagenomic (untargeted) NGS to generate full-length EV genomes from CSF samples of EV-positive aseptic meningitis cases in Southern Spain between 2015 and 2018. Our analyses reveal the co-circulation of multiple Enterovirus B (EV-B) types (E6, E11, E13 and E30), including a novel E13 recombinant form. We observed a genetic turnover where emergent lineages (C1 for E6 and I [tentatively proposed in this study] for E30) replaced previous lineages circulating in Spain, some concomitant with outbreaks in other parts of Europe. Metagenomic sequencing provides an effective approach for the analysis of EV genomes directly from PCR-positive CSF samples. The detection of a novel, disease-associated, recombinant form emphasizes the importance of genomic surveillance to monitor spread and evolution of EVs.

Molecular Epidemiology and Evolutionary Trajectory of Emerging Echovirus 30, Europe

In 2018, an upsurge in echovirus 30 (E30) infections was reported in Europe. We conducted a large-scale epidemiologic and evolutionary study of 1,329 E30 strains collected in 22 countries in Europe during 2016-2018. Most E30 cases affected persons 0-4 years of age (29%) and 25-34 years of age (27%). Sequences were divided into 6 genetic clades (G1-G6). Most (53%) sequences belonged to G1, followed by G6 (23%), G2 (17%), G4 (4%), G3 (0.3%), and G5 (0.2%). Each clade encompassed unique individual recombinant forms; G1 and G4 displayed >2 unique recombinant forms. Rapid turnover of new clades and recombinant forms occurred over time. Clades G1 and G6 dominated in 2018, suggesting the E30 upsurge was caused by emergence of 2 distinct clades circulating in Europe. Investigation into the mechanisms behind the rapid turnover of E30 is crucial for clarifying the epidemiology and evolution of these enterovirus infections.

Multiple genotypes of enterovirus G carrying a papain-like cysteine protease (PL-CP) sequence circulating on two pig farms in Japan: first identification of enterovirus G10 carrying a PL-CP sequence

Two and three genotypes of enterovirus G (EV-G) carrying a papain-like cysteine protease (PL-CP) sequence were detected on two pig farms and classified into genotypes G1 and G10, and G1, G8, and G17, respectively, based on VP1 sequences. A G10 EV-G virus bearing a PL-CP sequence was detected for the first time. Phylogenetic analysis of the P2 and P3 regions grouped the viruses by farm with high sequence similarity. Furthermore, clear recombination break points were detected in the 2A region, suggesting that PL-CP EV-G-containing strains gained sequence diversity through recombination events among the multiple circulating EV-G genotypes on the farms.

Global phylodynamics of Echovirus 30 revealed differential behavior among viral lineages

Echovirus 30 (E30) is an important causative agent of aseptic meningitis worldwide. Despite this, the global and regional dispersion patterns, especially in South America, are still largely unknown. We performed an in-depth analysis of global E30 population dynamics, by using the VP1 sequences of 79 strains isolated in Argentina, between 1998 and 2012, and 856 sequences from GenBank. Furthermore, the 3D^pol regions of 329 sequences were analyzed to study potential recombination events. E30 evolution was characterized by co-circulation and continuous replacement of lineages over time, where four lineages appear to circulate at present and another four lineages appear to have stopped circulating. Five lineages showed a global distribution, whereas three other lineages had a more restricted circulation pattern. Strains isolated in South America belong to lineages E and F. Analysis of the 3D^pol region of Argentinean strains indicated that recombination events occurred in both lineages.

Echovirus 30 detection in an outbreak of acute myalgia and rhabdomyolysis, Brazil 2016-2017

OBJECTIVES

To describe an outbreak of acute myalgia accompanied by elevated levels of muscle enzymes that occurred in the northeast region of Brazil from December 2016 through to May 2017.

METHODS

Clinical data were analysed and laboratory tests were performed in 86 specimens obtained from 52 individuals with suspected acute myalgia. A broader reactive enterovirus real-time RT-PCR followed by a semi-nested PCR amplification of partial VP1 gene were performed to identify the causative agent.

RESULTS

Eighty-six clinical samples were received in our laboratory during the myalgia outbreak. Median age of individuals was 39 years. Sudden acute myalgia and dark urine were the most common symptoms. Creatine phosphokinase levels were elevated with mean value ∼16 893 U/L. Human enterovirus was detected in 67% (58/86) of the patient's specimens (urine, serum, faeces and rectal swab). The enterovirus positivity per patient was 82.7% (43/52). Echovirus 30 (E-30) (82% of the typed specimens, 18/22; 76.4% (13/17) of the typed specimens per patient) was the main enterovirus identified. In addition to E-30, CV-A16 (1/22) and E-6 (3/22) were detected in 4% and 14% of the typed specimens, respectively. No deaths occurred.

CONCLUSION

The 2016-2017 outbreak of acute myalgia that occurred in the northeast region of Brazil can be associated with E-30. Despite the clinical manifestations, a favourable outcome was observed for all patients.

A complex mosaic of enteroviruses shapes community-acquired hand, foot and mouth disease transmission and evolution within a single hospital

Human enteroviruses (EV) pose a major risk to public health. This is especially so in the Asia-Pacific region where increasing numbers of hand, foot and mouth disease (HFMD) cases and large outbreaks of severe neurological disease associated with EV-A71 have occurred. Despite their importance, key aspects of the emergence, epidemiology and evolution of EVs remain unclear, and most studies of EV evolution have focused on a limited number of genes. Here, we describe the genomic-scale evolution of EV-A viruses sampled from pediatric patients with mild disease attending a single hospital in western Sydney, Australia, over an 18-month period. This analysis revealed the presence of eight viral serotypes-Coxsackievirus (CV) A2, A4, A5, A6, A8, A10, A16 and EV-A71-with up to four different serotypes circulating in any 1 month. Despite an absence of large-scale outbreaks, high levels of geographical and temporal mixing of serotypes were identified. Phylogenetic analysis revealed that multiple strains of the same serotype were present in the community, and that this diversity was shaped by multiple introductions into the Sydney population, with only a single lineage of CV-A6 exhibiting in situ transmission over the entire study period. Genomic-scale analyses also revealed the presence of novel and historical EV recombinants. Notably, our analysis revealed no association between viral phylogeny, including serotype, and patient age, sex, nor disease severity (for uncomplicated disease). This study emphasizes the contribution of EV-A viruses other than EV-A71 to mild EV disease including HFMD in Australia and highlights the need for greater surveillance of these viruses to improve strategies for outbreak preparedness and vaccine design.

Antiviral Activity of Itraconazole against Echovirus 30 Infection In Vitro

Objectives

Echovirus 30 is a major cause of meningitis in children and adults. The aim of this study was to investigate whether the antifungal drug itraconazole could exhibit antiviral activity against echovirus 30.

Methods

The cytopathic effect and viral RNA levels were assessed in RD cells as indicators of viral replication. The effects of itraconazole were compared to those of two known antiviral drugs, rupintrivir and pleconaril. The time course and time-of-addition assays were used to approximate the time at which itraconazole exerts its activity in the viral cycle.

Results

Itraconazole and rupintrivir demonstrated the greatest potency against echovirus 30, demonstrating concentration-dependent activity, whereas pleconaril showed no antiviral activity. Itraconazole did not directly inactivate echovirus 30 particles or impede viral uptake into RD cells, but did affect the initial stages of echovirus 30 infection through interference with viral replication.

Conclusion

Itraconazole can be considered a lead candidate for the development of antiviral drugs against echovirus 30 that may be used during the early stages of echovirus 30 replication.

Intertypic recombination of human parechovirus 4 isolated from infants with sepsis-like disease

BACKGROUND

Human parechoviruses (HPeVs) (family Picornaviridae), are common pathogens in young children. Despite their high prevalence, research on their genetic identity, diversity and evolution have remained scarce.

OBJECTIVES

Complete coding regions of three previously reported HPeV-4 isolates from Finnish children with sepsis-like disease were sequenced in order to elucidate the phylogenetic relationships and potential recombination events during the evolution of these isolates.

STUDY DESIGN

The isolated viruses were sequenced and aligned with all HPeV complete genome sequences available in GenBank. Phylogenetic trees were constructed and similarity plot and bootscanning methods were used for recombination analysis.

RESULTS

The three HPeV-4 isolates had 99.8% nucleotide sequence similarity. The phylogenetic analysis indicated that capsid-encoding sequences of these HPeV-4 isolates were closely related to other HPeV-4 strains (80.7-94.7% nucleotide similarity), whereas their non-structural region genes 2A to 3C clustered together with several HPeV-1 and HPeV-3 strains, in addition to the HPeV-4 strain K251176-02 (isolated 2002 in the Netherlands), but not with other HPeV-4 strains. However, in 3D-encoding sequence the Finnish HPeV-4 isolates did not cluster with the strain HPeV-4/K251176-02, but instead, formed a distinct group together with several HPeV-1 and HPeV-3 strains. Similarity plot and Bootscan analyses further confirmed intertypic recombination events in the evolution of the Finnish HPeV-4 isolates.

CONCLUSION

Intertypic recombination event(s) have occurred during the evolution of HPeV-4 isolates from children with sepsis-like disease. However, due to the low number of parechovirus complete genomes available, the precise recombination partners could not be detected. The results suggest frequent intratypic recombination among parechoviruses.

Direct Identification of Enteroviruses in Cerebrospinal Fluid of Patients with Suspected Meningitis by Nested PCR Amplification

Enteroviruses, the most common human viral pathogens worldwide, have been associated with serous meningitis, encephalitis, syndrome of acute flaccid paralysis, myocarditis and the onset of diabetes type 1. In the future, the rapid identification of the etiological agent would allow to adjust the therapy promptly and thereby improve the course of the disease and prognosis. We developed RT-nested PCR amplification of the genomic region coding viral structural protein VP1 for direct identification of enteroviruses in clinical specimens and compared it with the existing analogs. One-hundred-fifty-nine cerebrospinal fluids (CSF) from patients with suspected meningitis were studied. The amplification of VP1 genomic region using the new method was achieved for 86 (54.1%) patients compared with 75 (47.2%), 53 (33.3%) and 31 (19.5%) achieved with previously published methods. We identified 11 serotypes of the Enterovirus species B in 2012, including relatively rare echovirus 14 (E-14), E-15 and E-32, and eight serotypes of species B and 5 enteroviruses A71 (EV-A71) in 2013. The developed method can be useful for direct identification of enteroviruses in clinical material with the low virus loads such as CSF.

Fourteen types of co-circulating recombinant enterovirus were associated with hand, foot, and mouth disease in children from Wenzhou, China

BACKGROUND

Although hand, foot, and mouth disease (HFMD) is a major public concern in China, the prevalence and clinical symptoms associated with the different agents of HFMD in this country remain poorly understood.

OBJECTIVES

We investigated the clinical and molecular characteristics of enteroviruses in patients with HFMD from Wenzhou, China.

STUDY DESIGN

Patients with laboratory-confirmed HFMD admitted to the Yuying Children's Hospital in Wenzhou, China during 2013 were included in this study. Viral RNA sequences were amplified using RT-PCR, determined by sequencing, and compared by phylogenetic analysis.

RESULTS

A total of 955 clinically diagnosed HFMD cases were determined using PCR, with whole viral genomes obtained for each enterovirus type. 14 types of enterovirus belonging to two viral species were identified. Notably, Coxsackievirus A6 (CV-A6) was the most common species detected (77.8%), followed by EV-A71 (8.2%) and CV-A10 (8.1%). Phylogenetic analysis revealed multiple independent introductions of these viruses into Wenzhou. In addition, the enterovirus observed in Wenzhou had a recombinant history, with two or three recombination breakpoints. Although the illness associated with CV-A6 was milder than that of EV-A71, CV-A6 infection caused more widespread rash, larger blisters, and subsequent skin peeling and/or nail shedding.

CONCLUSION

Our study revealed the co-circulation of 14 types of enteroviruses in a single location - Wenzhou, China - with CV-A6 virus the predominant agent of HFMD. This work highlights the need to perform larger-scale surveillance to fully understand the epidemiology of enteroviruses in China and the wider Asia-Pacific region.

Transmission and Demographic Dynamics of Coxsackievirus B1

The infectious activity of coxsackievirus B1 (CV-B1) in Taiwan was high from 2008 to 2010, following an alarming increase in severe neonate disease in the United States (US). To examine the relationship between CV-B1 strains isolated in Taiwan and those from other parts of the world, we performed a phylodynamic study using VP1 and partial 3Dpol (414 nt) sequences from 22 strains of CV-B1 isolated in Taiwan (1989-2010) and compared them to sequences from strains isolated worldwide. Phylogenetic trees were constructed by neighbor-joining, maximum likelihood, and Bayesian Monte Carlo Markov Chain methods. Four genotypes (GI-IV) in the VP1 region of CV-B1 and three genotypes (GA-C) in the 3Dpol region of enterovirus B were identified and had high support values. The phylogenetic analysis indicates that the GI and GIII strains in VP1 were geographically distributed in Taiwan (1993-1994) and in India (2007-2009). On the other hand, the GII and GIV strains appear to have a wider spatiotemporal distribution and ladder-like topology A stair-like phylogeny was observed in the VP1 region indicating that the phylogeny of the virus may be affected by different selection pressures in the specified regions. Further, most of the GI and GII strains in the VP1 tree were clustered together in GA in the 3D tree, while the GIV strains diverged into GB and GC. Taken together, these data provide important insights into the population dynamics of CV-B1 and indicate that incongruencies in specific gene regions may contribute to spatiotemporal patterns of epidemicity for this virus.

Recombination among human non-polio enteroviruses: implications for epidemiology and evolution

Human enteroviruses (EV) belong to the Picornaviridae family and are among the most common viruses infecting humans. They consist of up to 100 immunologically and genetically distinct types: polioviruses, coxsackieviruses A and B, echoviruses, and the more recently characterized 43 EV types. Frequent recombinations and mutations in enteroviruses have been recognized as the main mechanisms for the observed high rate of evolution, thus enabling them to rapidly respond and adapt to new environmental challenges. The first signs of genetic exchanges between enteroviruses came from polioviruses many years ago, and since then recombination has been recognized, along with mutations, as the main cause for reversion of vaccine strains to neurovirulence. More recently, non-polio enteroviruses became the focus of many studies, where recombination was recognized as a frequent event and was correlated with the appearance of new enterovirus lineages and types. The accumulation of multiple inter- and intra-typic recombination events could also explain the series of successive emergences and disappearances of specific enterovirus types that could in turn explain the epidemic profile of circulation of several types. This review focuses on recombination among human non-polio enteroviruses from all four species (EV-A, EV-B, EV-C, and EV-D) and discusses the recombination effects on enterovirus epidemiology and evolution.

Recombination in the evolution of enterovirus C species sub-group that contains types CVA-21, CVA-24, EV-C95, EV-C96 and EV-C99

Genetic recombination is considered to be a very frequent phenomenon among enteroviruses (Family Picornaviridae, Genus Enterovirus). However, the recombination patterns may differ between enterovirus species and between types within species. Enterovirus C (EV-C) species contains 21 types. In the capsid coding P1 region, the types of EV-C species cluster further into three sub-groups (designated here as A–C). In this study, the recombination pattern of EV-C species sub-group B that contains types CVA-21, CVA-24, EV-C95, EV-C96 and EV-C99 was determined using partial 5′UTR and VP1 sequences of enterovirus strains isolated during poliovirus surveillance and previously published complete genome sequences. Several inter-typic recombination events were detected. Furthermore, the analyses suggested that inter-typic recombination events have occurred mainly within the distinct sub-groups of EV-C species. Only sporadic recombination events between EV-C species sub-group B and other EV-C sub-groups were detected. In addition, strict recombination barriers were inferred for CVA-21 genotype C and CVA-24 variant strains. These results suggest that the frequency of inter-typic recombinations, even within species, may depend on the phylogenetic position of the given viruses.

Molecular characterization of echovirus 30-associated outbreak of aseptic meningitis in Guangdong in 2012

Background

Evaluation of the primary etiologic agents that cause aseptic meningitis outbreaks may provide valuable information regarding the prevention and management of aseptic meningitis. An outbreak of aseptic meningitis occurred from May to June, 2012, in Guangdong Province, China. In order to determine the etiologic agent, CSF specimens from 121 children hospitalized for aseptic meningitis at Luoding People’s Hospital of Guangdong Province were tested for virus isolation and identification.

Results

Enterovirus RNA was positive in 62.0% of 121 CSF sspecimens by real-time polymerase chain reaction (RT-PCR). Amplification and sequencing of the VP1 region of enterovirus isolates revealed Echovirus 30 (E30) was the most common isolated serotype (80% of 40 enterovirus strains).For the molecular characterization of the E30 isolates, the VP1 gene sequence of 20 Luoding E30 isolates was compared pairwise using the MegAlign with reference strains from GenBank. The pairwise comparison of the nucleotide sequences of the VP1 genes demonstrated that the sequences of the strains differed from those of lineage groups C, D, E, F, and G. Reconstruction of the phylogenetic tree based on the VP1 nucleotide sequences resulted in a monophyletic tree, with seven clustered lineage groups. Most of the isolates were segregated from other lineage groups. Four E30 isolates causing this outbreak aggregated into the Lineage A cluster which was derived from E30 strains that circulated in other regions of China from 2003–2010.

Conclusions

This study demonstrated the Luoding strains were a distinct lineage of E30, and a probable cause of this outbreak. The study also demonstrated that different E30 variants existed in the local meningitis outbreak.

Complete genome sequence analysis of human echovirus type 30 isolated in China

We report here the complete genome sequence of a human echovirus type 30 strain ECV30/GX10/05 isolated in Guangxi, China, in 2010. Phylogenetic analysis showed that ECV30/GX10/05 was closely related to a Korean strain isolated in 2008. The sequence information will help in an understanding of the molecular epidemiology and evolution of echovirus.

Epidemics of viral meningitis caused by echovirus 6 and 30 in Korea in 2008

Background

Enteroviruses (EVs) are the leading cause of aseptic meningitis, which is the most frequent central nervous system infection worldwide. We aimed to characterize the EVs involved in an aseptic meningitis outbreak in Korea in 2008. In Korea, Echovirus type 30 (E30) and E6 have been associated with outbreaks and frequent meningitis.

Methods

During 2008, through nationwide surveillance, we collected specimens from 758 patients with aseptic meningitis-related clinical manifestations. The detection of EVs from specimens was subjected to a diagnostic real-time RT-PCR in the 5' NCR. A semi-nested polymerase chain reaction (PCR) to amplify sequences from the VP1 region and sequence comparison with reference strains registered in Genbank was performed for the genotype determination.

Results

Most patients (98%) in this outbreak were children < 15 years of age. The temporal distribution of the E6 and E30 epidemics showed an obvious seasonal pattern during the short period from June to July. A large majority of the EV-positive patients experienced fever, headache, vomiting, and neck stiffness. Some patients also showed cold symptoms, sore throat, altered mental status, and seizures. We did not observe a higher fatality rate in children with E6 or E30 infection. Most of the patients recovered uneventfully. In most cases, the cerebrospinal fluid (CSF) profile was studied, and generally showed a higher than normal white blood cell count (≥ 5/mm³). We detected EVs from 513 patients (67.68%) and identified the EV genotype in 287 patients. E30 (n = 155, 50.4%) and E6 (n = 95, 33.1%) were the predominant genotypes. E9, E1, E7, E16, coxsackievirus A3, 4, 6, coxsackievirus B1, 3, and 10 were also identified. According to phylogenetic analysis, E30 belonged to subgroup 4b, and E6, to the C4 subgroup.

Conclusions

Conclusively, aseptic meningitis was the most common manifestation in children with either echovirus 30 or 6 infection. Identification of E6 and E30 as the prominent EVs in the 2008 outbreak in South Korea shows the potential of EVs to cause a serious disease in an unpredictable (fashion. Our findings provide new) insights into the clinical and virological features of the aseptic meningitis outbreak caused by E30 and E6.

Molecular detection and identification of enteroviruses in children admitted to a university hospital in Greece

Although enteroviral infections occur frequently during childhood, the circulation of particular serotypes has never been studied in Greece. The objectives of the present report were molecular detection and identification of human enteroviruses in children admitted with nonspecific febrile illness or meningitis to a university hospital during a 22-month period. A one-step Real-Time RT-PCR protocol was used for rapid enterovirus detection in genetic material extracted directly from clinical samples, and a sensitive reverse transcription-semi-nested PCR targeting part of the VP1-coding region was used for genotypic identification of the different serotypes. Twenty-one enterovirus strains were detected and identified in 20 stool samples, one cerebrospinal fluid (CSF) sample, one whole blood sample and one throat swab from 21 out of 134 febrile patients (15.7%). Ten strains belonged to Human Enterovirus Species B (HEV-B) (six serotypes) and eleven to HEV-A (four serotypes). Most of the strains were closely associated with virulent strains circulating in Europe and elsewhere. Detection of the emerging pathogen enterovirus 71 for a first time in Greece was particularly important.

Molecular typing and epidemiology of enteroviruses in Cyprus, 2003-2007

Human enteroviruses (HEVs) are responsible for a wide spectrum of clinical diseases. Even though usually associated with non-specific febrile illness, they are the most common cause of viral meningitis and pose a serious public-health problem, especially during outbreaks. Rapid detection and identification of HEV serotypes in clinical specimens are important in appropriate patient management and epidemiological investigation. A 5 year study (2003-2007) of clinical specimens from patients with viral meningitis and/or symptoms of enteroviral infection was carried out in Cyprus to determine the underlying enteroviral aetiology. Reverse transcription, followed by a sequential PCR strategy targeting the 5' non-coding region and VP1 region, was used for typing the isolated enteroviruses. The serotype of each isolate was determined by blast search of the VP1 amplicon sequence against GenBank. Clinical specimens from a total of 146 patients were diagnosed as enterovirus-positive. Twenty-two different serotypes were identified. The main strains identified were echovirus 18 and echovirus 30, followed by coxsackievirus B5, echovirus 9, echovirus 6, coxsackievirus A10 and coxsackievirus B2. However, rapid changes in serotype frequency and diversity were observed over time. Serotype distribution corresponded essentially with observations reported from other European countries in the same period. The present report demonstrates the epidemiology of enteroviruses in Cyprus from 2003 to 2007.

Development of a recombinant CHO cell model for the investigation of CAR and DAF role during early steps of echovirus 6 infection

The early steps of echovirus 6 (E6) infection remain poorly understood and the only described receptor for haemagglutinating E6 strains is the decay accelerating factor (DAF). There is, however, accumulating evidence suggesting that E6 interaction with DAF is necessary but not sufficient for infection. In this report, we investigated the role of the coxsackie-adenovirus-receptor (CAR) as a potential DAF co-receptor during E6 infection. Using stably transfected Chinese Hamster Ovary (CHO) cells expressing CAR and DAF receptors, we found that DAF expression allowed attachment of both haemagglutinating and non-haemagglutinating E6 strains but was not sufficient for promoting E6 cell entry. Interestingly, the co-expression of DAF and CAR rendered 0.1-0.2% of cells permissive to some E6 strains' infection. Although our results did not show a major role of the CAR/DAF cooperation for E6 infection, it nevertheless indicated the use of CAR in the cell entry step of some minor E6 quasispecies. Moreover, the present report validates the use of recombinant CHO cells as valuable cellular model for the further characterisation of E6 receptors.

Molecular epidemiology of Echovirus 30 in Taiwan, 1988-2008

To investigate the molecular epidemiology of Taiwanese Echovirus 30 (E-30) strains, we analyzed the 876 bp sequence of the VP1 gene from 32 Taiwanese strains isolated in 1988-2008, 498 reference sequences, and one Echovirus 21 strain as the out-group. Phylogenetic analysis detected six E-30 genotypes (designated GI-GVI) that had circulated globally during the past five decades. The genotypes varied widely in geographic distribution and circulation half-life. The GI, GII, and GV were ancient genotypes in which the first strains emerged in the 1950s. The GIII was a reemerging genotype, in which strains had first appeared in Colombia in 1995 before reemerging in the New Independent States (NIS) in 2003. The GIV, an emerging genotype that recently appeared in Asia in 2003, was closely related to the ancient genotypes. The GVI was the circulating genotype, which included eight clusters (A-H) that had circulated since 1967. No GVI-A, C, D, or E strains have been identified during the past 10 years. The GVI-B first appeared in China in 1984 and later in Russia and Asia in the 2000s. The GVI-F, G, and H strains, which comprised the prevalent clusters, had been dominant in Asia Pacific area, globally, and Europe, respectively. Taiwanese strains were classified into GVI-D (1988-1989), GVI-F (1993-2004), and GVI-G (1993-2008). The quiescence period of E-30 is longer in Taiwan (5-8 years) than in other countries (3-5 years).

Epidemiology of human enterovirus 71 infections in France, 2000-2009

BACKGROUND

Human enterovirus 71 (EV-71) emerged as a significant pathogen able to cause large outbreaks involving severe neurological cases and children fatalities in Asia.

OBJECTIVES

To describe epidemiology of EV-71 infections in France.

STUDY DESIGN

Fifty-nine patients admitted in 12 different hospitals from 1994 to 2009 were included. The entire VP1 coding gene of 58 EV-71 strains was sequenced and phylogenetic analyses were performed to assign strains to genogroups/subgenogroups and to compare French isolates to European and worldwide isolates.

RESULTS

The median age of the patients was 1.04 years (9 days to 7 years). Among 46 documented EV-71 infections, 39 were self-limited. Seven children developed severe sepsis-like, respiratory or neurological complications. Among them, 2 children died from acute respiratory distress syndrome. All the EV-71 strains belonged to genogroup C: 31 isolates belonged to subgenogroup C1, 26 to subgenogroup C2 and 1 to subgenogroup C4. All the strains were genetically related to other European strains isolated at the same period of time. Although C1 isolates were predominant between 1994 and 2005, C2 strains have been predominant since 2007. No association was found between any genotype and the age or the clinical symptoms.

CONCLUSIONS

The C4 subgenogroup, which was associated with large outbreaks in China, did not spread in France. It is important to monitor more carefully the EV-71 strains circulating in France to detect the introduction of new genetic variants that could be associated with major outbreaks.

A large Finnish echovirus 30 outbreak was preceded by silent circulation of the same genotype

An outbreak of echovirus 30 (E-30) in 2009 was confirmed by both frequent isolation of the virus from sewage as well as from patient samples in Finland. Over the last 10 years E-30 had only been isolated sporadically in Finland. We here study the phylogenetic relationships of the strains from the outbreak in the context of E-30 circulation over the last 20 years. The analyzed region comprised 276 nucleotides in the 5' end of VP1 (nucleotides 132-407 in the VP1 of the E-30 Bastianni strain). The Finnish strains were clustered into at least four distinct genogroups, with seven clusters exceeding the genotype demarcation of 12% and the 2009 epidemic strains forming the largest genogroup VII. Moreover, we detected largely divergent genotypes in 2007 and 2009. Interestingly, close genetic relatives of the epidemic strains had already been isolated a few years before the outbreak. Phylodynamic analysis estimated 8.9 years (95% highest posterior density intervals 7.0-11.0) as the age of genogroup VII, indicating a probable origin and evolutionary history prior to its introduction and epidemic expansion in Finland. Finally, the most recent common ancestor for the current E-30 diversity dates back to 1939 (95% highest posterior density intervals 1913-1956).

Molecular identification of human enteroviruses in children with neurological infections from the central region of Argentina

In the central area of Argentina, epidemiological and molecular characteristics of human enterovirus infections are still unknown. RT-nested PCR of the highly conserved 5'NCR was used to detect enteroviruses in 168 samples of cerebrospinal fluid from hospitalized patients with suspected infection of the central nervous system (2007-2008), and 13 (7.7%) were positive. Molecular typing was performed by sequencing of the 3'-half VP1 region. Echovirus 30 was the predominant type detected, followed by coxsackie viruses A9 and B4. All echovirus 30 strains of 2007 clustered in lineage H, whereas the echovirus 30 isolate obtained in 2008 was more distantly related, possibly representing a new lineage.

Echoviruses are a major cause of aseptic meningitis in infants and young children in Kuwait

Background

The etiologic agents of aseptic meningitis (AM) often include human enteroviruses. The role of enteroviruses causing AM in young children was investigated during a 3-year period in Kuwait.

Results

Enteroviral RNA was detected in cerebrospinal fluid (CSF) by reverse transcription-PCR and specific genotypes of enteroviruses were identified by direct DNA sequencing of VP4-VP2 region. Enteroviral RNA was detected in 92 of 387 (24%) suspected AM cases and the results were confirmed by hybridization of amplicons with an internal, enterovirus-specific probe. The CSF samples from 75 of 281 (27%) children < 2 years old but only from 3 of 38 (8%) 4-12 year-old children were positive for enteroviral RNA (p = 0.011). Majority of infections in children < 2 years old (49 of 75, 65%) were due to three echoviruses; echovirus type 9 (E9), E11 and E30. Only three other enteroviruses, namely coxsackievirus type B4, coxsackievirus type B5 and enterovirus 71 were detected among AM cases in Kuwait.

Conclusions

Our data show that three types of echoviruses (E9, E11 and E30) are associated with the majority of AM cases in Kuwait. To the best of our knowledge, this is the first report to characterize different enterovirus genotypes associated with AM in the Arabian Gulf region.

Repeated genomic transfers from echovirus 30 to echovirus 6 lineages indicate co-divergence between co-circulating populations of the two human enterovirus serotypes

Human echovirus types 6 (E-6) and 30 (E-30) cause seasonal epidemics of aseptic meningitis. These two enteroviruses are frequently observed in co-circulation, an epidemiological pattern that is prerequisite for the occurrence of dual infections, which can lead to recombination between co-infecting virus strains. Viral sequences were determined at loci 1D (VP1 capsid protein) and 3CD (non structural proteins) in 49 E-6 strains recovered in a single geographical region in France from 1999 to 2007, during the epidemiological survey of enterovirus infections. They were compared with previously recorded sequences of E-30 strains to investigate their evolutionary histories and possible recombination patterns. Phylogenetic analyses identified two distinct E-6 populations and different subpopulations. Assuming a relaxed molecular clock model and a Bayesian skyline demographic model in coalescent analyses with the BEAST program, the substitution rate in E-6 was estimated at 8.597×10(-3) and 6.252×10(-3) substitution/site/year for loci 1D and 3CD respectively. Consistent estimates of divergence times (t(MRCA)) were obtained for loci 1D and 3CD indicating that two distinct E-6 populations originated in 1997 and 1999. Incongruent phylogenetic patterns inferred for the two loci were indicative of recombination events between the two populations. Phylogenies including the E-30 3CD sequences showed close genetic relationships between E-6 and discrete E-30 subpopulations. Recombination breakpoints were located with statistical significance in E-6 and E-30 genomes. Estimates of t(MRCA) of phylogenetic recombinant clades indicated directional genetic transfers from E-30 to E-6 populations and their co-divergence over the time period studied.

Phylogenetic evidence for a recent spread of two populations of human enterovirus 71 in European countries

Human enterovirus 71 (EV-71) is a cause of seasonal epidemics of hand, foot and mouth disease, and of less common but severe neurological manifestations. Uncertainty persists regarding the circulation of virus populations in several geographical areas and the timescale of their dissemination. We determined EV-71 sequences at loci 1D (VP1 capsid protein) and 3CD (non-structural proteins) in 86 strains recovered in Austria, France and Germany and performed an evolutionary genetic study of extant virus populations. Phylogenetic analyses positioned 78 of the 86 sequences within two clades among subgenogroups C1 and C2. A minor sequence cluster was assigned to subgenogroup C4. Analyses incorporating the available sequences estimated the substitution rate in genogroup C at 3.66 x 10(-3) and 4.46 x 10(-3) substitutions per site year(-1) for loci 1D and 3CD, respectively, assuming a relaxed molecular-clock model for sequence evolution. Most of the 'European' strains belonged to clades C1b and C2b, which originated in 1994 [95 % confidence interval (CI), 1992.7-1995.8] and 2002 (95 % CI, 2001.6-2003.8), respectively. Estimates of divergence times for locus 3CD were consistent with those measured for locus 1D. Intertwining between clades representing EV-71 subgenogroups and clades corresponding to other enterovirus types (notably early coxsackievirus A prototype strains) in the 3CD phylogeny is highly indicative of ancestral recombination events. Incongruent phylogenetic patterns estimated for loci 1D and 3CD show that a single tree cannot model the epidemic history of circulating EV-71 populations. The evolutionary timescale of genogroup C estimated for both loci was measured only in decades, indicating recent dissemination.

Phylogenetic analysis of Echovirus 30 isolated during the 2005 outbreak in France reveals existence of multiple lineages and suggests frequent recombination events

BACKGROUND

Echovirus 30 (E-30) was responsible in France for a major aseptic meningitis outbreak during 2005 summer season. However, the virological mechanisms responsible for the periodic emergence of the epidemic strains remain to be investigated.

OBJECTIVES

To assess the genetic diversity of two genome regions, VP1 and 3Dpol, of echovirus 30 strains isolated during the 2005 aseptic meningitis outbreak in Champagne Ardenne (CA) area (France).

STUDY DESIGN

Partial VP1 genomic region of 23 E-30 strains isolated in CA was sequenced and compared with 73 E-30 strains originating from different French areas to estimate the number and the diversity of E-30 lineages. Partial sequences for 3D polymerase (3Dpol) were analyzed to detect potential recombination events within the non-structural (NS) region of the genome of EV neurotropic strains.

RESULTS

Phylogenetic analysis of the VP1 evidenced the co-circulation of 6 distinct E-30 lineages responsible for the 2005 aseptic meningitis outbreak in France of which three had co-circulated in CA. Partial sequencing of the 3Dpol coding region showed that all of the E-30 strains exhibited different phylogenetic links between VP1 and 3Dpol genomic regions, suggesting multiple intra- or inter-serotypic recombination events within the NS part of the genome.

CONCLUSIONS

Our findings revealed existence of multiple lineages and suggested frequent recombination events among E-30 strains having co-circulated in a restricted area during a short time outbreak period. Moreover, our data demonstrated that study of single VP1 genome region analysis could not accurately describe the phylogenetic origin of E-30 isolates.

The complete genome sequences for a novel enterovirus type, enterovirus 96, reflect multiple recombinations

Enterovirus 96 (EV-96) is a recently described genotype in the species Human enterovirus C. So far, only partial genome sequences of this enterovirus type have been available. In this study, we report complete genome sequences for two EV-96 strains isolated from healthy children during enterovirus surveillance in Finland. Sequence analysis revealed substantial nucleotide divergence between EV-96 strains and suggested several recombination events between EV-96 and other HEV-C types.

Identification of potential recombination breakpoints in human parechoviruses

Based on a comparison of the phylogeny of two distant regions, evidence has been found for recombination within parechoviruses. However, recombination breakpoints could not be detected in this way. We searched for potential recombination breakpoints in parechovirus by analysis of complete parechovirus sequences, including a newly isolated strain. Bootscan analysis demonstrated that parechoviruses are mosaic viruses build of regions related to corresponding genomic regions of other parechoviruses. With a genetic algorithm for recombination detection, sites for recombination were found. Analysis of partial sequences, as defined by recombination breakpoints, showed phylogenetic segregation between regions.

Transmission networks and population turnover of echovirus 30

Globally, echovirus 30 (E30) is one of the most frequently identified enteroviruses and a major cause of meningitis. Despite its wide distribution, little is known about its transmission networks or the dynamics of its recombination and geographical spread. To address this, we have conducted an extensive molecular epidemiology and evolutionary study of E30 isolates collected over 8 years from a geographically wide sample base (11 European countries, Asia, and Australia). 3Dpol sequences fell into several distinct phylogenetic groups, interspersed with other species B serotypes, enabling E30 isolates to be classified into 38 recombinant forms (RFs). Substitutions in VP1 and 3Dpol regions occurred predominantly at synonymous sites (ratio of nonsynonymous to synonymous substitutions, 0.05) with VP1 showing a rapid substitution rate of 8.3 x 10(-3) substitutions per site per year. Recombination frequency was tightly correlated with VP1 divergence; viruses differing by evolutionary distances of >0.1 (or 6 years divergent evolution) almost invariably (>97%) had different 3Dpol groups. Frequencies of shared 3Dpol groups additionally correlated with geographical distances, with Europe and South Asia showing turnover of entirely distinct virus populations. Population turnover of E30 was characterized by repeated cycles of emergence, dominance, and disappearance of individual RFs over periods of 3 to 5 years, although the existence and nature of evolutionary selection underlying these population replacements remain unclear. The occurrence of frequent "sporadic" recombinants embedded within VP1 groupings of other RFs and the much greater number of 3Dpol groups than separately identifiable VP1 lineages suggest frequent recombination with an external diverse reservoir of non-E30 viruses.

Molecular epidemiological study of HEV-B enteroviruses involved in the increase in meningitis cases occurred in Spain during 2006

Human enteroviruses are one of the main etiological agents of aseptic meningitis and other central nervous system infections, particularly the serotypes included in the enterovirus B species. Molecular methods have proved useful to identify serotypes in clinical samples, facilitating the epidemiological study of these viruses. In the spring of 2006, there was a significant increase in meningitis cases caused by enteroviruses in Spain. In the present study, 138 enteroviruses directly detected in clinical samples of patients with aseptic meningitis (n = 116) and other neurological pathologies (n = 22) received by the National Center for Microbiology during the year, were genotyped by amplification and sequencing part of the VP1 region and phylogenetic analysis. Echovirus 30 was the most frequent serotype, followed in decreasing order by echovirus 6, 9, 13, 18, enterovirus 75, coxsackievirus A9, echovirus 11, 14, 29, 4, and coxsackievirus B4 and B5. Phylogenetic analysis with all Spanish echovirus 30 strains detected in 2006 and other reported echovirus 30 sequences, demonstrated that Spanish strains formed a new lineage, different from others previously described. In conclusion, echovirus 30 is the most commonly reported enterovirus serotype associated with aseptic meningitis in Spain. Direct molecular typing of clinical samples also allows rapid identification of the serotypes involved in an epidemic alert and phylogenetic analysis in the 3'-VP1 region is useful to study viral epidemiology.

Co-circulation and evolution of polioviruses and species C enteroviruses in a district of Madagascar

Between October 2001 and April 2002, five cases of acute flaccid paralysis (AFP) associated with type 2 vaccine-derived polioviruses (VDPVs) were reported in the southern province of the Republic of Madagascar. To determine viral factors that favor the emergence of these pathogenic VDPVs, we analyzed in detail their genomic and phenotypic characteristics and compared them with co-circulating enteroviruses. These VDPVs appeared to belong to two independent recombinant lineages with sequences from the type 2 strain of the oral poliovaccine (OPV) in the 5′-half of the genome and sequences derived from unidentified species C enteroviruses (HEV-C) in the 3′-half. VDPV strains showed characteristics similar to those of wild neurovirulent viruses including neurovirulence in poliovirus-receptor transgenic mice. We looked for other VDPVs and for circulating enteroviruses in 316 stools collected from healthy children living in the small area where most of the AFP cases occurred. We found vaccine PVs, two VDPVs similar to those found in AFP cases, some echoviruses, and above all, many serotypes of coxsackie A viruses belonging to HEV-C, with substantial genetic diversity. Several coxsackie viruses A17 and A13 carried nucleotide sequences closely related to the 2C and the 3D^pol coding regions of the VDPVs, respectively. There was also evidence of multiple genetic recombination events among the HEV-C resulting in numerous recombinant genotypes. This indicates that co-circulation of HEV-C and OPV strains is associated with evolution by recombination, resulting in unexpectedly extensive viral diversity in small human populations in some tropical regions. This probably contributed to the emergence of recombinant VDPVs. These findings give further insight into viral ecosystems and the evolutionary processes that shape viral biodiversity.

Following extensive vaccination campaigns using the attenuated oral polio vaccine, wild polioviruses remain endemic in only a few countries. Nevertheless, several poliomyelitis outbreaks associated with vaccine-derived polioviruses (VDPVs) were reported in different parts of the world in recent years, particularly in Madagascar in 2002. We analyzed the molecular characteristics of Madagascar VDPVs and compared them with those of co-circulating enteroviruses. These VDPVs appear to be recombinant viruses between vaccine polioviruses and human enteroviruses of species C (HEV-C) and to present phenotypic characteristics similar to those of wild polioviruses including pathogenicity. Similar VDPVs and other enteroviruses, including several HEV-C of different types, were found in the stools of healthy children living in neighboring villages to where most of the poliomyelitis cases occurred. Some HEV-Cs showed sequences closely related to those of VDPVs, indicating genetic recombination between these viruses and vaccine polioviruses. There was also evidence of multiple genetic recombination events among other HEV-C isolates resulting in numerous different genotypes. These findings indicate that co-circulation of HEV-C and vaccine polioviruses and their evolution by recombination results in unexpectedly extensive viral diversity, at least in some small human populations, probably contributing to the emergence of recombinant VDPVs. Results of this study give further insight into the world of viruses and their biodiversity.

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.

Analysis of echovirus 30 isolates from Russia and new independent states revealing frequent recombination and reemergence of ancient lineages

We studied two genome regions, VP1 and 3D, of 48 echovirus 30 (E30) isolates from Russia and the new independent states. In VP1, most isolates were similar to European strains reported earlier, and frequent change of circulating subgroups was noticed. We also observed, in 2003-2006, the reemergence of a group of E30 strains with a VP1 region very distant from most modern E30 strains and remotely similar to E30 isolates from the 1960s and the 1970s. A study of the 3D genome region detected multiple recombination events among the studied strains. Recombination presumably occurred every few years, and therefore, the study of a single VP1 genome region cannot accurately describe the phylogenetic history of the virus or predict pathogenetic properties of an isolate. In general, a comparison of the VP1 and 3D genome region phylogenies revealed, in some instances, virtually independent circulation of enterovirus genome fragments on a scale of years.

Epidemiological survey of enterovirus infections occurring in Taiwan between 2000 and 2005: analysis of sentinel physician surveillance data

Enterovirus (EV) infections are common. There are more than 60 known serotypes, and each has different epidemiologic or medical importance. Over 700 physicians from 75% of basic administrative units of Taiwan participated in the "Sentinel Physician Surveillance of Infectious Disease" and reported weekly to the Center for Disease Control-Taiwan with data on various infections. Data of laboratory-confirmed EV infections from this surveillance between 2000 and 2005 was analyzed. EV serotypes were determined by immunofluorescence staining and/or viral VP1 sequence analysis. A total of 12,236 EV cases, or approximately 1,300-2,500 per year, were identified, and 52% of the cases occurred between April and July. The median age was 3 years, and 57.6% of patients were male. Coxsackievirus A (CA) 16 and EV71, which primarily manifest as hand-foot-and-mouth disease, were the most prevalent serotypes every year except 2004. Other prevalent serotypes and associated symptoms varied from year to year. Echovirus (E) 30 and E6, which are associated with aseptic meningitis, were prevalent in 2001 and 2002, CA4 and CA10, which cause herpangina, were predominant in 2004, and coxsackievirus B (CB) 4 and CB3, which are associated with neonatal febrile disease, were most common in 2004 and 2005, respectively. Some of these epidemics overlapped with outbreaks of the same serotypes in other Asian Pacific countries. Of all serotypes, EV71 was associated with the highest number of severe complications in patients. Surveying the epidemic pattern, disease spectra, and severity associated with each EV serotype provided important information for public health and medical personnel.

Basic rationale, current methods and future directions for molecular typing of human enterovirus

Enterovirus is a genus of the Picornaviridae family including more than 80 serotypes belonging to four species designed Human enterovirus A to D. The antigens of the structural proteins support the subdivision of enteroviruses into multiple serotypes. Comparative phylogeny based on molecular typing methods has been of great help to classify former and new types of enterovirus, and to investigate the diversity of enteroviruses and the evolutionary mechanisms involved in their diversity. By now, molecular typing methods of enterovirus rely mainly on the sequencing of an amplicon targeting a variable part of the region coding for the capsid proteins (VP1 and, alternatively, VP2 or VP4), either from a strain recovered by cell culture or, more recently, by direct amplification of a clinical or environmental specimen. In the future, microarrays are thought to play a major role in enterovirus typing and in the analysis of the determinants of virulence that support the puzzling diversity of the pathological conditions associated with human infection by these viruses.

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.

Mosaic genome structure of echovirus type 30 that circulated in Taiwan in 2001

An echovirus type 30 (E30) outbreak occurred in Taiwan in 2001. In this study, one 1998 and nineteen 2001 enterovirus isolates from cerebrospinal fluid (CSF) of children with meningitis were genetically analyzed. Although negative results were obtained using the E30-specific monoclocal antibody in an immunofluorescent assay (IFA) test of all 20 isolates, molecular typing by partial VP1 sequences and subsequent neutralization test identified them as E30. Among those, seven of them were misidentified as echovirus type 4 (E4) when E4-specific monoclonal antibody was used. Complete genome sequences of one E30 isolate (TW-2513) that were IFA-positive to E4 and another (TW-3182) that was IFA-negative to both E30 and E4 were determined and analyzed. The overall percentage nucleotide identity in the structural coding region (P1) between these two isolates is 98.4, while those in the nonstructural regions P2 and P3 are only 83.2 and 84.4, respectively, indicating that the two 2001 Taiwanese E30 strains were probably recombinant. Recombination analysis of these two E30 genomes revealed that their genome structures are mosaic, which might have been formed gradually and frequently over time.

Natural recombination event within the capsid genomic region leading to a chimeric strain of human enterovirus B

Recombination between two strains is a known phenomenon for enteroviruses replicating within a single cell. We describe a recombinant strain recovered from human stools, typed as coxsackievirus B4 (CV-B4) and CV-B3 after partial sequencing of the VP1 and VP2 coding regions, respectively. The strain was neutralized by a polyclonal CV-B3-specific antiserum but not by a CV-B4-specific antiserum. The nucleotide sequence analysis of the whole structural genomic region showed the occurrence of a recombination event at position 1950 within the VP3 capsid gene, in a region coding for the 2b antigenic site previously described for CV-B3. This observation evidences for the first time the occurrence of an interserotypic recombination within the VP2-VP3-VP1 capsid region between two nonpoliovirus enterovirus strains. The neutralization pattern suggests that the major antigenic site is located within the VP2 protein.