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

Chemoproteomics enables identification of coatomer subunit zeta-1 targeted by a small molecule for enterovirus A71 inhibition

Human enterovirus A71 (EV-A71) is a significant etiological agent responsible for epidemics of hand, foot, and mouth disease (HFMD) in Asia-Pacific regions. There are presently no licensed antivirals against EV-A71, and the druggable target for EV-A71 remains very limited. The phenotypic hit 10,10'-bis(trifluoromethyl) marinopyrrole A derivative, herein termed MPA-CF3, is a novel potent small-molecule inhibitor against EV-A71, but its pharmacological target(s) and antiviral mechanisms are not defined. Here, quantitative chemoproteomics deciphered the antiviral target of MAP-CF3 as host factor coatomer subunit zeta-1 (COPZ1). Mechanistically, MPA-CF3 disrupts the interaction of COPZ1 with the EV-A71 nonstructural protein 2C by destabilizing COPZ1 upon binding. The destruction of this interaction blocks the coatomer-mediated transport of 2C to endoplasmic reticulum, and ultimately inhibits EV-A71 replication. Taken together, our study disclosed that MPA-CF3 can be a structurally novel host-targeting anti-EV-A71 agent, providing a structural basis for developing the COPZ1-targeting broad-spectrum antivirals against enteroviruses. The mechanistic elucidation of MPA-CF3 against EV-A71 may offer an alternative COPZ1-involved therapeutic pathway for enterovirus infection.

Structural insight into EV-A71 3A protein and its interaction with a peptide inhibitor

•Our results disclosed a dihelical structure of Enterovirus A71 3A1–57 protein in apo form. •We depicted rigid helices and a unique flexible C-terminus for apo-form 3A1–57. •This study revealed a competitive binding-based molecular mechanism underlying inhibition of dimeric 3A by ER-DRI.

Screening of a new candidate coxsackievirus B1 vaccine strain based on its biological characteristics

Coxsackievirus B1 (CVB1) is one of the significant pathogens causing viral myocarditis, hand, foot, and mouth disease (HFMD), and aseptic meningitis, and it has been associated with type 1 diabetes (T1DM). No effective antiviral drugs against CVB1 infection or preventive vaccines are available. Due to the success of two inactivated vaccines against enterovirus 71 and poliovirus, an inactivated Vero cell-based CVB1 vaccine could be developed. In this study, we isolated a high-growth CVB1 virus strain KM7 in Vero cells and developed a Vero-adapted vaccine candidate strain KM7-X29 via three rounds of plaque purification and serial passages. The KM7-X29 strain was grouped into the GII sub-genotype, which belonged to the Chinese epidemic strain and grew to a titer of more than 10⁷ CCID50/ml in Vero cells. The inactivated CVB1 vaccine produced by the KM7-X29 strain induced an effective neutralizing antibody response in BALB/c mice, and maternal antibodies were able to provide a 100% protective effect against lethal challenges with a CVB1 strain in suckling BALB/c mice. Thus, the KM7-X29 strain might be used as a new candidate coxsackievirus B1 vaccine strain. The neonatal murine model of CVB1 infection will contribute to the development of the CVB1 vaccine.

Enterovirus B types cause severe infection in infants aged 0-3 months

BACKGROUND

Enterovirus (EV) infections are being increasingly seen in younger infants, often being more severe than in older children. The risk factors of EV infection in infants have been inadequately investigated till date.

METHODS

We conducted a retrospective study on hospitalized children with laboratory-confirmed EV infection (50 infants aged 0-3 months and 65 older than 3 months) at a tertiary care center in China. Prevalence, clinical characteristics, and genetic features of the virus were analyzed, and independent predictors for severe infection were assessed.

RESULTS

Clinical findings showed that severe infection was more common in infants aged 0-3 months than in older children (78.0% vs. 35.4%, p < 0.001), with higher morbidity of pneumonia, meningitis, and sepsis (p < 0.01). EV-B types were detected more frequently in infants aged 0-3 months than in older children (88.0% vs. 7.7%, p < 0.001). Echovirus 11 was the most identified EV-B, and it recombined with E6 in P2 and P3 regions. Risk factors for severe EV infection included EV-B types infection, age less than 3 months, elevated alanine aminotransferase level, abnormal platelet count, and abnormal cerebrospinal fluid characteristics.

CONCLUSIONS

Our data indicated that EV-B types mainly cause severe infection in infants aged 0-3 months. Therefore, knowledge about EV-B types could have implications in designing effective intervention and prevention strategies for young infants with severe EV infection.

Immunogenicity and safety of an inactivated enterovirus 71 vaccine coadministered with trivalent split-virion inactivated influenza vaccine: A phase 4, multicenter, randomized, controlled trial in China

Background

Few data exist on the immunogenicity and safety of an inactivated enterovirus 71 vaccine (EV71 vaccine) coadministered with trivalent split-virion inactivated influenza vaccine (IIV3) in infants.

Methods

This trial was a phase 4, randomized, controlled trial. Infants aged 6-11 months were eligible, with no history of hand, foot and mouth disease (HFMD) and no history of EV71 vaccine or any influenza vaccine. Eligible infants were randomly assigned to EV71+IIV3 group, EV71 group or IIV3 group. Blood samples were collected on day 0 and 56.

Results

Between September 2019 and June 2020, 1151 infants met eligibility criteria and 1134 infants were enrolled. 1045 infants were included in the per-protocol population, including 347 in the EV71+IIV3 group, 343 in the EV71 group, and 355 in the IIV3 group. The seroconversion rate (98.56% vs 98.54%; seroconversion rates difference of 0.02% [95% CI: 0.70-0.98]) and GMT (419.05 vs 503.72; GMT ratio of 0.83 [95% CI 0.70 - 0.98]) of EV71 neutralizing antibodies in the EV71+IIV3 group was not inferior to those in the EV71 group. The non-inferiority results for influenza virus antibodies (A/H1N1, A/H3N2 and B) showed that the seroconversion rates and GMTs of the EV71+IIV3 group were non-inferiority to those of the IIV3 group. Systemic and local adverse event rates were similar between groups. None of serious adverse events (SAEs) were related to vaccination.

Conclusions

Coadministration of the EV71 vaccine with IIV3 was safe and did not interfere with immunogenicity. These findings support a viable immunization strategy for infants with the EV71 vaccine coadministered with IIV3 in China. This trial is registered with ClinicalTrials.gov, number NCT04091880.

Bacterial and Viral Co-Infection in the Intestine: Competition Scenario and Their Effect on Host Immunity

Bacteria and viruses are both important pathogens causing intestinal infections, and studies on their pathogenic mechanisms tend to focus on one pathogen alone. However, bacterial and viral co-infections occur frequently in clinical settings, and infection by one pathogen can affect the severity of infection by another pathogen, either directly or indirectly. The presence of synergistic or antagonistic effects of two pathogens in co-infection can affect disease progression to varying degrees. The triad of bacterial–viral–gut interactions involves multiple aspects of inflammatory and immune signaling, neuroimmunity, nutritional immunity, and the gut microbiome. In this review, we discussed the different scenarios triggered by different orders of bacterial and viral infections in the gut and summarized the possible mechanisms of synergy or antagonism involved in their co-infection. We also explored the regulatory mechanisms of bacterial–viral co-infection at the host intestinal immune interface from multiple perspectives.

Isolation and characterization of a novel clade of coxsackievirus B2 associated with hand, foot, and mouth disease in Southwest China

Coxsackievirus B2 (CVB2) is an enterovirus B (EV-B) species and can cause aseptic meningitis, myocarditis and hand, foot, and mouth disease (HFMD). We characterized a novel CVB2 (YN31V3) associated with HFMD in Yunnan, Southwest China in 2019. Although YN31V3 and other Mainland China epidemic strains mainly belonged to genotype C, YN31V3 formed an independent branch. The genome sequence of the strain YN31V3 from this study showed 12.91% nucleotide difference to its closest strain RW41-2/YN/CHN/2012. Recombination analyses showed that the newly isolated YN31V3 was probably a recombinant, which was closely related to CVB2 strains in the genomic P1 region and other EV-B strains in the P2 and P3 regions, respectively. YN31V3 strain had a temperature-sensitive phenotype. Challenge of suckling BALB/c mice with YN31V3 could cause symptoms of disease and severe pathological lesions. This article is protected by copyright. All rights reserved.

Molecular characterization of echovirus 9 strains isolated from hand-foot-and-mouth disease in Kunming, Yunnan Province, China

Echovirus 9 (E9) belongs to the species Enterovirus B. So far, 12 whole genome sequences of E9 are available in GenBank. In this study, we determined the whole genomic sequences of five E9 strains isolated from the stools of patients with hand-foot-and-mouth disease in Kunming, Yunnan Province, China, in 2019. Their nucleotide and amino acid sequences shared 80.8–80.9% and 96.4–96.8% identity with the prototype Hill strain, respectively, and shared 99.3–99.9% and 99.1–99.8% mutual identity, respectively. Recombination analyses revealed that intertype recombination had occurred in the 2C and 3D regions of the five Yunnan E9 strains with coxsackieviruses B5 and B4, respectively. This study augmented the whole genome sequences of E9 in the GenBank database and extended the molecular characterization of this virus in China.

Description of non-polio enteroviruses identified in two national surveillance programmes in South Africa

Background

Human enteroviruses (EV) consist of 106 serotypes and four species: EV-A, EV-B, EV-C and EV-D. Enteroviruses cause clinical symptoms varying from severe to mild. Knowledge of EV burden in South Africa is limited, and as non-polio EV are important causes of acute flaccid paralysis (AFP) and meningitis, information on the circulating serotypes is vital.

Methods

Between 2010 and 2012, a total of 832 stool and viral isolate specimens were obtained from two national surveillance programmes at the National Institute for Communicable Diseases: the Rotavirus Sentinel Surveillance Programme (RSSP) and the AFP surveillance programme. Real-time polymerase chain reaction and Sanger sequencing were performed to detect and serotype EV.

Results

Non-polio EV were detected in 446 specimens, of which 308 were sequenced. Stool specimens yielded a greater variety of serotypes than viral cultures. EV-B viruses were predominant (58.44%), whilst EV-C viruses were detected in 31% of the specimens tested. South African prevalence for these viruses was higher than other countries, such as France with less than 2%, and Spain and the United States with less than 10%. The most common serotype detected was Enterovirus 99 (EV-C, 8.63%), which has not been reported in other regions.

Conclusion

Direct sequencing from stool specimens yields a broader, more comprehensive description of EV infections compared to sequencing from viral cultures. Disease-associated serotypes were detected, but only in small numbers. This study provides a baseline for EV strain circulation; however, surveillance needs to be expanded to improve EV knowledge in South Africa.

DNAzyme Walker for Homogeneous Detection of Enterovirus EV71 and CVB3

When dealing with infectious pathogens, the risk of contamination or infection in the process of detecting them is nonnegligible. Separation-free detection will be beneficial in operation and safety. In this work, we proposed a DNAzyme walker for homogeneous and isothermal detection of enterovirus. The DNAzyme is divided into two inactivate subunits. When the subunit-conjugated antibody binds to the target virus, the activity of the DNAzyme recovers as a result of spatial proximity. The walker propels, and the fluorescence recovers. The final fluorescence intensity of the reaction mixture is related to the concentration of the target virus. The detection limit of this proposed method is 6.6 × 10⁴ copies/mL for EV71 and 4.3 × 10⁴ copies/mL for CVB3, respectively. Besides, this method was applied in detection of EV71 in clinical samples with a satisfactory result. The entire experiment is easy to operate, and the proposed method has great potential for practical use.

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa

Enteric viruses are a diverse group of human pathogens which are primarily transmitted by the faecal-oral route and are a major cause of non-bacterial diarrhoeal disease in both developed and developing countries. Because they are shed in high numbers by infected individuals and can persist for a long time in the environment, they pose a serious threat to human health globally. Enteric viruses end up in the environment mainly through discharge or leakage of raw or inadequately treated sewage into water sources such as springs, rivers, dams, or marine estuaries. Human exposure then follows when contaminated water is used for drinking, cooking, or recreation and, importantly, when filter-feeding bivalve shellfish are consumed. The human health hazard posed by enteric viruses is particularly serious in Africa where rapid urbanisation in a relatively short period of time has led to the expansion of informal settlements with poor sanitation and failing or non-existent wastewater treatment infrastructure, and where rural communities with limited or no access to municipal water are dependent on nearby open water sources for their subsistence. The role of sewage-contaminated water and bivalve shellfish as vehicles for transmission of enteric viruses is well documented but, to our knowledge, has not been comprehensively reviewed in the African context. Here we provide an overview of enteric viruses and then review the growing body of research where these viruses have been detected in association with sewage-contaminated water or food in several African countries. These studies highlight the need for more research into the prevalence, molecular epidemiology and circulation of these viruses in Africa, as well as for development and application of innovative wastewater treatment approaches to reduce environmental pollution and its impact on human health on the continent.

Abnormalities of ILC1 in children with hand, foot and mouth disease during enterovirus 71 infection

Children with HFMD due to EV71 infection are more likely to suffer from neurogenic complications, leading to higher morbidity and mortality. ILCs play crucial roles in the initiation of host immunity. However, the contribution of ILCs to the occurrence and development of HFMD due to EV71 infection remains to be explored. The results of our study showed that the levels of peripheral ILC1s and Th1 cells were increased in children with severe HFMD compared to healthy children, as were ILC1- and Th1-related cytokines and transcription factors. Furthermore, HFMD children with a higher frequency of circulating ILC1s exhibited a 2.9-fold greater risk of severity when HFMD was accompanied by VEM. Our study is the first to show that ILC1 abnormalities contribute to the pathogenesis of the severity of HFMD, in which ILC1s are aberrant increased and affect the cellular and humoral immunity. ILC1s could be used in the diagnosis of HFMD.

Co-circulation of coxsackieviruses A-6, A-10, and A-16 causes hand, foot, and mouth disease in Guangzhou city, China

Background

Hand, foot, and mouth disease (HFMD) is a common infectious disease occurring in children under 5 years of age worldwide, and Enterovirus A71 (EV-A71) and Coxsackievirus A16 (CVA-16) are identified as the predominant pathogens. In recent years, Coxsackievirus A6 (CVA-6) and Coxsackievirus A10 (CVA-10) have played more and more important role in a series of HFMD outbreaks. This study aimed to understand the epidemic characteristics associated with HFMD outbreak in Guangzhou, 2018.

Methods

The clinical and laboratory data of 1220 enterovirus-associated HFMD patients in 2018 were analysed in this study. Molecular diagnostic methods were performed to identify its serotypes. Phylogenetic analyses were depicted based on the complete VP1 gene.

Results

There were 21 enterovirus serotypes detected in Guangzhou in 2018. Three serotypes of enterovirus, CVA-6 (364/1220, 29.8%), CVA-10 (305/1220, 25.0%), and CVA-16 (397/1220, 32.5%), were identified as the causative pathogens and accounted for 87.3% among all 1220 HFMD patients. In different seasons, CVA-6 was the predominant pathogen of HFMD during autumn, and CVA-10 as well as CVA-16 were more prevalent in summer. Patients infected by CVA-6, CVA-10 or CVA-16 showed similar clinical features and laboratory characteristics, and the ratios of severe HFMD were 5.8, 5.9, and 1.5% in the three serotypes. Phylogenetic analyses of VP1 sequences showed that the CVA-6, CVA-10, and CVA-16 sequences belonged to the sub-genogroup E2, genogroup E, and genogroup B1, respectively.

Conclusions

CVA-6, CVA-10, and CVA-16 were the predominant and co-circulated serotypes in Guangzhou China, 2018, which should be the new target for prevention and control of HFMD. Our findings provide useful information for diagnosis, treatment, and prevention of HFMD.

Characterization of a novel echovirus 21 strain isolated from a healthy child in China in 2013

Echovirus 21 (E21) belongs to the species Enterovirus B, whose members are frequently associated with acute flaccid paralysis. E21 strain 553/YN/CHN/2013 was isolated from a healthy child in Yunnan, China, in 2013. This is the first report of the complete genome sequence of E21 in China. This strain shared 81.7% nucleotide sequence identity and 96.8% amino acid sequence identity with the E21 prototype strain Farina. Although strain 553/YN/CHN/2013 belongs to the E21 serotype, the only similarity to the E21 strain was in the VP1 region, as other genomic regions, including VP2-VP4, were more similar to other EV-B members. Recombination analysis showed evidence of recombination events between E21 and other EV-B viruses. E21 strain 553/YN/CHN/2013 failed to infect suckling mice via intracerebral injection. Surveillance of E21 is very important to help forecast the potential of emerging E21 outbreaks and related diseases.

Target-Induced Cascade Amplification for Homogeneous Virus Detection

Detection of viruses with high sensitivity is critical for the prevention and treatment of the related disease. Two homogeneous target-induced cascade amplification methods were proposed for the detection of enterovirus 71 and coxsackievirus B3. These methods both employ DNAzyme but differ in the way in which the DNAzyme is amplified. In the hybridization chain reaction (HCR)-based strategy, the DNAzyme is assembled by hairpin DNA strands, while in the rolling circle amplification (RCA)-based strategy, the DNAzyme is synthesized by the polymerase. On the basis of the virion structure, we investigated the effects of using only VP1-antibody or VP1-antibody and VP2-antibody on the detection. And the combination of two kinds of antibodies was found to further improve the performance of the detection. Subsequently, the simultaneous detection of EV71 and CVB3 was achieved by the RCA-based strategy. And the proposed methods were also applied in clinical samples analysis with a satisfactory result, showing great potential for applications in virus detection.

High Amplification of the Antiviral Activity of Curcumin through Transformation into Carbon Quantum Dots

It is demonstrated that carbon quantum dots derived from curcumin (Cur-CQDs) through one-step dry heating are effective antiviral agents against enterovirus 71 (EV71). The surface properties of Cur-CQDs, as well as their antiviral activity, are highly dependent on the heating temperature during synthesis. The one-step heating of curcumin at 180 °C preserves many of the moieties of polymeric curcumin on the surfaces of the as-synthesized Cur-CQDs, resulting in superior antiviral characteristics. It is proposed that curcumin undergoes a series of structural changes through dehydration, polymerization, and carbonization to form core-shell CQDs whose surfaces remain a pyrolytic curcumin-like polymer, boosting the antiviral activity. The results reveal that curcumin possesses insignificant inhibitory activity against EV71 infection in RD cells [half-maximal effective concentration (EC₅₀ ) >200 µg mL^-1 ] but exhibits high cytotoxicity toward RD cells (half-maximal cytotoxic concentration (CC₅₀ ) <13 µg mL^-1 ). The EC₅₀ (0.2 µg mL^-1 ) and CC₅₀ (452.2 µg mL^-1 ) of Cur-CQDs are >1000-fold lower and >34-fold higher, respectively, than those of curcumin, demonstrating their far superior antiviral capabilities and high biocompatibility. In vivo, intraperitoneal administration of Cur-CQDs significantly decreases mortality and provides protection against virus-induced hind-limb paralysis in new-born mice challenged with a lethal dose of EV71.

Molecular epidemiology analysis of enterovirus 71 strains isolated in Dak Lak, Vietnam, 2011-2016

Human enterovirus 71 (EV71) is the major etiologic agent of hand, foot, and mouth disease (HFMD). EV71 outbreaks have been reported in Dak Lak in recent years, however, the genotypes/subgenotypes information and phylogeny of circulating EV71 strains are limited. The objectives of this study were to determine the genotypes/subgenotypes and investigate the phylogeny of EV71 isolates in Dak Lak over a 6-year period. Viruses were isolated from clinical samples from patients with HFMD. In total, 43 EV71 isolates circulated in Dak Lak during 2011-2016 were used for the phylogenetic analysis using complete VP1 gene. The phylogenetic analysis of the VP1 gene revealed that two major genotypes, B and C, were found. Among the 43 EV71 strains, 29 belonged to subgenotype C4, 2 belonged to subgenotype C5, and 12 belonged to subgenotype B5. Of these, the subgenotype C4 was predominant in 2011-2013 and this was later replaced by the subgenotype B5 in 2014. The subgenotype B5 was dominant between 2014 and 2015, and then C4 recirculated in 2016. Our study also indicated that the subgenotypes C4 and B5 emerged into Dak Lak were closely related to variants causing epidemics of HFMD in the southern and central region of Vietnam and Thailand. Sequence analysis showed that nine amino acid mutations were detected in the VP1 region. Our results identified two significant amino acid substitutions (D31N and E145G/Q) associated with enhancing EV71 virulence.

Molecular diversity of Coxsackievirus A10 circulating in the southern and northern region of India [2009-17]

Non-Polio EnteroViruses (NPEV) are one of the known causative agents of Acute Flaccid Paralysis (AFP). In the present study, we identified, sequenced and characterized the complete genome of sixty-five Coxsackievirus-A10, an NPEV. These were isolated from stool specimens of AFP cases from Bihar, Karnataka, Kerala, and Uttar Pradesh (UP) states of India. Evolutionary analysis of complete genome (7420 nucleotides) and VP1 gene (894 nucleotides) demonstrates that there are four different intra-typic strains circulating in India which were dissimilar to Chinese strains. First intratypic strain circulating in UP, Bihar, and Karnataka; second in UP and Karnataka; third in UP and Bihar and; fourth was restricted only to Kerala state. The divergence of Kerala strain with respect to all other circulating strain of UP, Bihar and Karnataka states in India is 24%, 24.9%, and 24.4% respectively. Recombinations were observed between few of these strains which might be one of the factors of the observed intra-typic diversity. ARTICLE SUMMARY LINE: We report the identification, characterization and phylogenetic analysis of sixty-five Non-Polio Enterovirus (NPEV) isolates, performed during the year 2009-17, causing acute flaccid paralysis in pediatric cases with their divergences and recombinations from four states of India.

Molecular characterization of echovirus 12 strains isolated from healthy children in China

Human echovirus 12 (E-12) belongs to the enterovirus B species. To date, only one full-length genome sequence of E-12 (prototype strain Travis) is available in the GenBank database. This study determined the complete sequence of three E-12 strains, which were isolated from the stools of three healthy children in Yunnan, China, in 2013. We revealed that the three Yunnan E-12 strains had only 80.8-80.9% nucleotide identity and 96.4-96.8% amino acid identity with the Travis strain based on pairwise comparisons of the complete genome nucleotide and amino acid sequences. The three Yunnan strains shared 99.7% nucleotide identity and 99.1-99.5% amino acid similarity. Phylogenetic and similarity plot analyses showed that intertypic recombination occurred in the non-structural regions of the three Yunnan E-12 strains. This is the first report of the complete genome sequence of E-12 in China and it enriches the complete genome sequences of E-12 in the GenBank database.

Molecular characteristics of hand, foot, and mouth disease for hospitalized pediatric patients in Yunnan, China

Hand, foot, and mouth disease (HFMD) is a common infectious disease caused by multiple enteroviruses (EVs) in China. To better define the etiologic agents and clinical characteristics of HFMD, we conducted this study in Yunnan, China.In this study, 1280 stool specimens were collected from pediatric patients hospitalized for treatment of HFMD in 2010. EV was detected with nested reverse transcription polymerase chain reaction and directly genotyped by gene sequencing of the viral protein 1 (VP1) region. Phylogenetic analysis was performed based on the VP1 partial gene and the clinical characteristics were analyzed using SPSS Software.Of 1280 specimens, 1115 (87.1%) tested positive for EV. Seventeen different EV serotypes were detected. Coxsackievirus A16 (CA16) was the most frequently detected serotype (615/1115 cases, 55.1%), followed by enterovirus 71 (EV71; 392/1115, 35.2%), CA10 (45/1115, 4.0%), and CA4 (23/1115, 2.1%). Among the 709 severe cases, CA16, EV71, CA10, and CA4 accounted for 48.0%, 42.0%, 3.5%, and 2.3%, respectively. Of the 26 critical cases, 13 were caused by EV71, 9 by CA16, 2 by CA4, and 1 each were the result of CA10 and E9, respectively. All EV71, CA16, CA10, and CA4 isolates were highly homologous to the strains isolated from mainland China, and belonged to the C4a, B1a, G, and C genotypes, respectively.Our study showed that EV71 and CA16 were the main causative agents for severe and critical HFMD, but other serotypes can also cause severe and critical cases.

Acute Flaccid Paralysis and Enteroviral Infections

PURPOSE OF REVIEW

The focus of this review is on enterovirus (EV)-associated acute flaccid paralysis (AFP) due to spinal cord anterior horn cell disease. Emphasis is placed on the epidemiology, pathogenesis, diagnosis, treatment, and outcome of AFP caused by polioviruses, vaccine-derived polioviruses, EV-D68, and EV-A71.

RECENT FINDINGS

Since the launch of The Global Polio Eradication Initiative in 1988, the worldwide incidence of polio has been reduced by 99.9%, with small numbers of poliomyelitis cases being reported only in Afghanistan, Pakistan, and Nigeria. With the planned phaseout of oral polio vaccine, vaccine-associated poliomyelitis is also expected to be eliminated. In their place, other EVs, chiefly EV-D68 and EV-A71, have emerged as the principal causes of AFP. There is evidence that the emergence of EV-D68 as a cause of severe respiratory disease and AFP was due to recent genetic virus evolution. Antiviral medications targeting EV-D68, EV-A71, and other EVs will likely be available in the near future. An effective EV-A71 vaccine has been developed, and preliminary investigations suggest an EV-D68 vaccine could be on the horizon. The eradication of poliomyelitis and vaccine-associated poliomyelitis is near, after which other EVs, presently EV-D68 and EV-A71, will be the principle viral causes of AFP. Moving forward, it is essential that EV outbreaks, in particular those associated with neurologic complications, be investigated carefully and the causal strains identified, so that treatment and prevention efforts can be rapidly developed and implemented.

Five-year immunity persistence following immunization with inactivated enterovirus 71 type (EV71) vaccine in healthy children: A further observation

The longevity of antibodies induced by inactivated enterovirus 71 type (EV71) vaccine is not well studied. To estimate the immunity persistence following two-dose vaccination of EV71 vaccine, a five-year follow-up study was conducted as an extension of a Phase III clinical trial. In this study, a sub-cohort of volunteers who was eligible for enrollment and randomly administrated either 2 dose EV71 vaccine or placebo in the phase III clinical trial was selected, and then further observed 64 months post the 1st vaccination. 211 Subjects (106 vaccine subjects and 105 placebo subjects) who provided a full series of blood samples (at all the sampling points) were included in the final analyzed population. Seropositive rate (SR) and geometric mean titer (GMT) of the neutralizing antibodies (NAb) was calculated to detect the dynamic profiles of EV71 vaccine-induced immunogenicity. SR at the 5th year remained 94.34% in the vaccine subjects, with a GMT of 141.42. The SR was 71.43% in the placebo subjects, with a GMT of 71.83. Despite natural infection consistently promoted the NAb increase in the placebo subjects, the SR and GMT in vaccine subjects remained significantly higher than that in the placebo subjects at all the sampling points. The inactivated EV71 vaccine-induced immunity had a good persistence, within 5 years following the primary vaccination.

Development of a reverse transcription recombinase-aided amplification assay for the detection of coxsackievirus A10 and coxsackievirus A6 RNA

Hand, foot and mouth disease (HFMD) is a serious public health problem, and coxsackievirus A6 (CVA6) and coxsackievirus A10 (CVA10) are two of the major causative pathogens, in addition to enterovirus 71 (EV71) and coxsackievirus A16 (CVA16). A simple and rapid reverse transcription recombinase-aided amplification assay (RT-RAA) was developed for the detection of CVA10 and CVA6 in this study. The analytical sensitivity for detection of CVA10 and CVA6 at 95% probability by probit regression analysis was 35 copies per reaction and 38 copies per reaction, respectively, with 100% specificity. Compared with commercial RT-qPCR assays, when testing 455 fecal specimens, the kappa value of the RT-RAA assay for CVA10 and CVA6 was 0.920 (p < 0.001) and 0.952 (p < 0.001), respectively. Moreover, four samples that were positive for CVA10 and five that were positive for CVA6 by RT-RAA but negative by RT-qPCR were further determined to be true positives. These results demonstrate that the proposed RT-RAA assays are very valuable tools for the detection of CVA10 and CVA6 and have potential for use in resource-limited settings.

Changes of circulating Th22 cells in children with hand, foot, and mouth disease caused by enterovirus 71 infection

Interleukin (IL)-22+CD4+T (Th22) cells play crucial roles in the pathogenesis of autoimmune diseases and infectious diseases, although the role of Th22 cells remains largely unclear in children with hand, foot, and mouth disease (HFMD) caused by enterovirus 71 (EV71). This study aims to explore the role of circulating IL-22+IL-17A-CD4+T (cTh22) cells in children with EV71-associated HFMD. We found that during the acute stage of illness, the frequencies of cTh22 and circulating IL-22+IL-17A+CD4+T (IL-22+cTh17) cells in CD4+T cells infrom affected patients, and especially in severely affected patients, were significantly higher than in healthy controls (HC). The major source of IL-22 production was cTh22 cells, partially from cTh17 cells. Moreover, the protein and mRNA levels of IL-22, IL-17A, IL-23, IL-6, and TNF-α were significantly different among the mild patients, severe patients and HC, as well as AHR and RORγt mRNA levels. A positive correlation was found between plasma IL-22 levels and cTh22 cell frequencies, and cTh17 cell and IL-22+ cTh17 cell frequencies. Furthermore, the frequencies of cTh22 were significantly decreased in the convalescent patients. Our findings indicated that cTh22 cells could play critical roles in the pathogenesis of EV71 infection, and are potential therapeutic targets for patients with EV71-associated HFMD.

Regulation of enterovirus 2A protease-associated viral IRES activities by the cell's ERK signaling cascade: Implicating ERK as an efficiently antiviral target

In a previous study the ERK1/2 pathway was found to be crucially involved in positive regulation of the enterovirus A 71(EV-A71) IRES (vIRES), thereby contributing to the efficient replication of an important human enterovirus causing death in young children (<5yrs) worldwide. This study focuses on unraveling more about the detailed mechanism of ERK's involvement in this regulation of vIRES. Through the use of siRNAs and specifically pharmacological inhibitor U0126, the ERK cascade was shown to positively regulate EV-A71-mediated cleavage of eIF4GI that established the cellular conditions which favour vIRES-dependent translation. Site-directed mutagenesis of the viral 2A protease (2A^pro) was undertaken to show that the positive regulation of virus replication by the ERK cascade was mediated through effects on both the cis-cleavage of the viral polyprotein by 2A^pro and its trans-cleavage of cellular eIF4GI. This ERK-2A^pro linked network coordinating vIRES efficiency was also found in other important human enteroviruses. This identification of the ERK cascade as having a key role in maintaining the 2A^pro proteolytic activity required to maximize enterovirus IRES activity, expands current understanding of the diverse functions of the ERK signaling cascade in the regulation of viral translation, therefore providing a potentially comprehensive drug target for anti-enterovirus infection.

Human Gut-On-A-Chip Supports Polarized Infection of Coxsackie B1 Virus In Vitro

Analysis of enterovirus infection is difficult in animals because they express different virus receptors than humans, and static cell culture systems do not reproduce the physical complexity of the human intestinal epithelium. Here, using coxsackievirus B1 (CVB1) as a prototype enterovirus strain, we demonstrate that human enterovirus infection, replication and infectious virus production can be analyzed in vitro in a human Gut-on-a-Chip microfluidic device that supports culture of highly differentiated human villus intestinal epithelium under conditions of fluid flow and peristalsis-like motions. When CVB1 was introduced into the epithelium-lined intestinal lumen of the device, virions entered the epithelium, replicated inside the cells producing detectable cytopathic effects (CPEs), and both infectious virions and inflammatory cytokines were released in a polarized manner from the cell apex, as they could be detected in the effluent from the epithelial microchannel. When the virus was introduced via a basal route of infection (by inoculating virus into fluid flowing through a parallel lower 'vascular' channel separated from the epithelial channel by a porous membrane), significantly lower viral titers, decreased CPEs, and delayed caspase-3 activation were observed; however, cytokines continued to be secreted apically. The presence of continuous fluid flow through the epithelial lumen also resulted in production of a gradient of CPEs consistent with the flow direction. Thus, the human Gut-on-a-Chip may provide a suitable in vitro model for enteric virus infection and for investigating mechanisms of enterovirus pathogenesis.

Epidemiological and etiological characteristics of herpangina and hand foot mouth diseases in Jiangsu, China, 2013-2014

Herpangina (HA) and hand, foot, and mouth disease (HFMD) are common infectious diseases caused by human enteroviruses and frequently occurr in young children. Previous published studies have mainly focused on HFMD, while the HA epidemiological and etiological characteristics in mainland China have not been described. From June, 2013 to March, 2014, HA and HFMD patients were monitored in participants from clinical trial of EV-A71 vaccine conducted during 2012-2013. A total of 95 HA patients and 161 HFMD patients were defined. Enteroviruses of HA samples were differentiated into 17 serotypes (EV-A71, CV-A16, CV-A24, E6, CV-B5, CV-A22, CV-A6, CV-A10, CV-B3, E9, CV-A9, CV-B4, CV-B2, E1, E7, E21 and CV-A20), the most common serotypes were EV-A71(10/95,10.5%), CV-A16(4/95,4.2%) and CV-A24(4/95,4.2%); while enteroviruses detected from HFMD samples were classfied into 21 serotypes ( EV-A71, CV-A16, CV-A10, CV-A6, E6, CV-B3, CV-B5, CV-A9, E9, CV-B2, CV-B4, E3, E11, E15, E16, CV-A1, EV-A69, E5, CA22, CA24 and EV99), the most common serotypes were EV-A71(28/161,17.4%), CV-A16(7/161,4.4%) and CV-A10(5/161,3.1%). The first HA epidemic peak occurred in summer and a second smaller peak occurred in January. In HA patients, the body temperature (P < 0.0001) and the incidence of fever (P < 0.05) were significant higher than those in HFMD patients. Between HA and HFMD patients infected with EV-A71, no significant differences were found in age, sex, circulating season, and the viral genome diversity. In summary, we firstly reported the epidemiological and etiological characteristics of HA in mainland China. Developing a multivalent vaccine will be helpful for the control of the HA/HFMD epidemic.

Role and evolution trend of multiple enteroviruses in epidemic of hand, foot and mouth disease

There are a variety of enteroviruses (EV) that can cause hand, foot and mouth disease (HFMD), and the major pathogens include enterovirus 71 (EV71) and coxasckievirus A16 (CVA16). EV71 and CVA16 have attracted much attention for their high prevalence and pathogenicity, and disease surveillance and vaccine development are mainly concentrated on them. EV71 can cause serious harm to children with HFMD, especially the damage to the nervous system such as aseptic meningitis, brain stem encephalitis and paralytic disease, or even lead to death. However, in recent years, due to the epidemic of EV71 and CVA16, people have established an immune barrier through natural infection in a certain degree. Although there is no cross protection between types, the immune protection against the relevant type can persist for a long time. Thus, the number of HFMD cases caused by EV71 and CVA16 shows a decreasing trend, while the epidemic of HFMD caused by other EV exhibits an upward trend. Further studies found that non-EV71 and non-CVA16 EV are very complex, and there are also differences in EV prevalence each year, which makes the development, evolution and control of HFMD become complicated. At present, there is no enough attention paid to the sporadic virus in the HFMD epidemic, and a complete research system for non-EV71 and non-CVA16 EV has not formed. Therefore, it is necessary to strengthen the monitoring of multiple non-EV71 and non-CVA16 EV, further investigate their pathogenicity and genetic characteristics, and evaluate the relative frequency and biological hazard of infection. In this review, we summarize a variety of EV changes, molecular evolution, as well as typical epidemics, which may provide clues to the development of antiviral drugs and vaccines, and prevention and control of HFMD.

Molecular epidemiology of human enterovirus 71 at the origin of an epidemic of fatal hand, foot and mouth disease cases in Cambodia

Human enterovirus 71 (EV-A71) causes hand, foot and mouth disease (HFMD). EV-A71 circulates in many countries and has caused large epidemics, especially in the Asia-Pacific region, since 1997. In April 2012, an undiagnosed fatal disease with neurological involvement and respiratory distress occurred in young children admitted to the Kantha Bopha Children's Hospital in Phnom Penh, Cambodia. Most died within a day of hospital admission, causing public panic and international concern. In this study, we describe the enterovirus (EV) genotypes that were isolated during the outbreak in 2012 and the following year. From June 2012 to November 2013, 312 specimens were collected from hospitalized and ambulatory patients and tested by generic EV and specific EV-A71 reverse transcription PCR. EV-A71 was detected in 208 clinical specimens while other EVs were found in 32 patients. The VP1 gene and/or the complete genome were generated. Our phylogenetic sequencing analysis demonstrated that 80 EV-A71 strains belonged to the C4a subgenotype and 3 EV-A71 strains belonged to the B5 genotype. Furthermore, some lineages of EV-A71 were found to have appeared in Cambodia following separate introductions from neighboring countries. Nineteen EV A (CV-A6 and CV-A16), 9 EV B (EV-B83, CV-B3, CV-B2, CV-A9, E-31, E-2 and EV-B80) and 4 EV C (EV-C116, EV-C96, CV-A20 and Vaccine-related PV-3) strains were also detected. We found no molecular markers of disease severity. We report here that EV-A71 genotype C4 was the main etiological agent of a large outbreak of HFMD and particularly of severe forms associated with central nervous system infections. The role played by other EVs in the epidemic could not be clearly established.

Genotyping of enteroviruses isolated in Kenya from pediatric patients using partial VP1 region

Enteroviruses (EV) are responsible for a wide range of clinical diseases in humans. Though studied broadly in several regions of the world, the genetic diversity of human enteroviruses (HEV) circulating in the sub-Saharan Africa remains under-documented. In the current study, we molecularly typed 61 HEV strains isolated in Kenya between 2008 and 2011 targeting the 3′-end of the VP1 gene. Viral RNA was extracted from the archived isolates and part of the VP1 gene amplified by RT-PCR, followed by sequence analysis. Twenty-two different EV types were detected. Majority (72.0 %) of these belonged to Enterovirus B species followed by Enterovirus D (21.3 %) and Enterovirus A (6.5 %). The most frequently detected types were Enterovirus-D68 (EV-D68), followed by Coxsackievirus B2 (CV-B2), CV-B1, CV-B4 and CV-B3. Phylogenetic analyses of these viruses revealed that Kenyan CV-B1 isolates were segregated among sequences of global CV-B1 strains. Conversely, the Kenyan CV-B2, CV-B3, CV-B4 and EV-D68 strains generally grouped together with those detected from other countries. Notably, the Kenyan EV-D68 strains largely clustered with sequences of global strains obtained between 2008 and 2010 than those circulating in recent years. Overall, our results indicate that HEV strains belonging to Enterovirus D and Enterovirus B species pre-dominantly circulated and played a significant role in pediatric respiratory infection in Kenya, during the study period. The Kenyan CV-B1 strains were genetically divergent from those circulating in other countries. Phylogenetic clustering of Kenyan EV-D68 strains with sequences of global strains circulating between 2008 and 2010 than those obtained in recent years suggests a high genomic variability associated with the surface protein encoding VP1 gene in these enteroviruses.

Enterovirus Migration Patterns between France and Tunisia

The enterovirus (EV) types echovirus (E-) 5, E-9, and E-18, and coxsackievirus (CV-) A9 are infrequently reported in human diseases and their epidemiologic features are poorly defined. Virus transmission patterns between countries have been estimated with phylogenetic data derived from the 1D/VP1 and 3CD gene sequences of a sample of 74 strains obtained in France (2000–2012) and Tunisia (2011–2013) and from the publicly available sequences. The EV types (E-5, E-9, and E-18) exhibited a lower worldwide genetic diversity (respective number of genogroups: 4, 5, and 3) in comparison to CV-A9 (n = 10). The phylogenetic trees estimated with both 1D/VP1 and 3CD sequence data showed variations in the number of co-circulating lineages over the last 20 years among the four EV types. Despite the low number of genogroups in E-18, the virus exhibited the highest number of recombinant 3CD lineages (n = 10) versus 4 (E-5) to 8 (E-9). The phylogenies provided evidence of multiple transportation events between France and Tunisia involving E-5, E-9, E-18, and CV-A9 strains. Virus spread events between France and 17 other countries in five continents had high probabilities of occurrence as those between Tunisia and two European countries other than France. All transportation events were supported by BF values > 10. Inferring the source of virus transmission from phylogenetic data may provide insights into the patterns of sporadic and epidemic diseases caused by EVs.

Identification, synthesis and pharmacological evaluation of novel anti-EV71 agents via cyclophilin A inhibition

In this work, the relationship between cyclophilin A (CypA) and EV71 prompted us to screen a series of small molecular CypA inhibitors which were previously reported by our group. Among them, compounds 1 and 2 were discovered as non-immunosuppressive anti-EV71 agents with an EC50 values of 1.07±0.17μM and 3.36±0.45μM in virus assay, respectively, which were desirably for the further study. The subsequent chemical modifications derived a novel class of molecules, among which compound 11 demonstrated the most potent anti-EV71 activity in virus assay (EC50=0.37±0.17μM), and low cytotoxicity (CC50>25μM). The following CypA enzyme inhibition studies indicated that there was not only the enzyme inhibition activity, undoubtedly important, functioning in the antiviral process, but also some unknown mechanisms worked in combination, and the further study is underway in our laboratory. Nevertheless, to the best of our knowledge, compound 11 was probably the most potent small molecular anti-EV71 agent via CypA inhibitory mechanism to date. Consequently, our study provided a new potential small molecule for curing EV71 infection.

Complete genome sequence of a new recombinant echovirus 25 strain isolated from a neonatal patient with hand, foot, and mouth disease complicated by encephalitis in Beijing, China

Although human echovirus 25 (E-25), a type of the enterovirus B species, is implicated in aseptic meningitis, information on its gene structure, evolution, and virulence are limited. We report here the complete genome sequence of a novel recombinant E-25 strain (E25/2010/CHN/BJ) isolated from a neonate with hand, foot, and mouth disease complicated by encephalitis in Beijing, China in 2010. The complete viral genome consists of 7429 nucleotides (nts), including a 6585-nt open reading frame. Phylogenetic dendrogram based on VP1 gene regions revealed that this strain belonged to subgroup D4, which contains the other E-25 strains isolated from China in recent years. The difference in the amino acid sites (P130S, K/T135I) of the VP1 region may affect its immunogenicity. SimPlot and Bootscan analyses suggested that E25/2010/CHN/BJ is a recombination result of E-25 and Coxsackievirus B3 (CVB-3) strains. Our results would facilitate the study of the origin, evolution, and molecular epidemiology of E-25.

Increased frequency of circulating follicular helper T cells in children with hand, foot, and mouth disease caused by enterovirus 71 infection

Enterovirus 71 (EV71) is a major causative agent of hand, foot, and mouth disease (HFMD) in children. The role of T follicular helper (TFH) cells in EV71-infected children remains unclear in regulating humoral immunity. The frequency of circulating ICOS^high/PD-1^highCXCR5⁺CD4⁺ TFH cells in the children with mild and severe EV71 infection and healthy controls (HC) was detected by flow cytometry, respectively. IL-21 and IL-6 mRNA expression and their serum levels, Bcl-6 mRNA expression, and specific neutralizing antibodies against EV71 (NAb-EV71) were measured. In the acute stage of patients with EV71 infection, increased frequencies of circulating TFH cells with ICOS^high and PD-1^high expression in the mild and severe patients were observed, and the positive correlations among the frequencies of circulating TFH cells and the serum levels of IL-21, IL-6, and NAb-EV71 titres were detected, respectively. Moreover, the expressions of IL-6 and IL-21 mRNA in PBMCs from patients were also significantly higher than those of HC. However, further analysis did not reveal any significant differences between mild and severe patients. These data indicate a role of TFH cells and associated cytokines in modulating the humoral response during the pathogenesis of EV71 infection.

The multi-targeted kinase inhibitor sorafenib inhibits enterovirus 71 replication by regulating IRES-dependent translation of viral proteins

The activation of ERK and p38 signal cascade in host cells has been demonstrated to be essential for picornavirus enterovirus 71 (EV71) replication and up-regulation of virus-induced cyclooxygenase-2 (COX-2)/prostaglandins E2 (PGE2) expression. The aim of this study was to examine the effects of sorafenib, a clinically approved anti-cancer multi-targeted kinase inhibitor, on the propagation and pathogenesis of EV71, with a view to its possible mechanism and potential use in the design of therapy regimes for Hand foot and mouth disease (HFMD) patients with life threatening neurological complications. In this study, non-toxic concentrations of sorafenib were shown to inhibit the yield of infectious progeny EV71 (clinical BC08 strain) by about 90% in three different cell types. A similar inhibitory effect of sorafenib was observed on the synthesis of both viral genomic RNA and the VP1 protein. Interestingly, sorafenib exerted obvious inhibition of the EV71 internal ribosomal entry site (IRES)-mediated translation, the first step in picornavirus replication, by linking it to a firefly luciferase reporter gene. Sorafenib was also able to prevent both EV71-induced CPE and the activation of ERK and p38, which contributes to up-regulation COX-2/PGE2 expression induced by the virus. Overall, this study shows that sorafenib strongly inhibits EV71 replication at least in part by regulating viral IRES-dependent translation of viral proteins, indicating a novel potential strategy for the treatment of HFMD patients with severe neurological complications. To our knowledge, this is the first report that investigates the mechanism by which sorafenib inhibits EV71 replication.

Partial sequencing of the VP2 capsid gene for direct enterovirus genotyping in clinical specimens

Typing of human enterovirus (EV) remains a major goal for diagnostic and epidemiological purposes. Whereas sequencing of the VP1 coding region is the reference standard for EV typing, a method relying on sequencing of the VP2 coding region has been proposed as an alternative; however, this has been validated only on cell culture supernatants. To avoid the selection of cultivable strains and to quicken the identification step, a new semi-nested PCR method targeting the VP2 region was developed by use of the CODEHOP strategy. After validation of the method on reference and clinical strains, a total of 352 clinical specimens found to be positive for EV RNA (138 with the GeneXpert EV kit and 214 with the Enterovirus R-gene kit) during a 3-year period (2010-2012) were analysed prospectively for VP2 genotyping. Overall, 204 (58%) specimens were typeable. A higher proportion of throat swab/stool specimens than of cerebrospinal fluid (CSF) specimens was found to be typeable (94 of 142 (66.2%) vs. 83 of 169 (49.1%), respectively, p <0.01 by the chi-square test). Moreover, the median Ct value obtained was lower for typeable specimens than for untypeable specimens (32.20 vs. 33.01, p <0.05, and 25.96 vs. 31.74, p <0.001, for the GeneXpert and R-gene tests, respectively, by the Mann-Whitney-Wilcoxon test). These results suggest that, in cases of EV meningitis, a peripheral specimen (i.e. throat swab or stool) that is susceptible to exhibiting a higher viral load should be used in preference to CSF for identifying the causative EV genotype by use of the VP2 typing method without cell culture isolation.

Enterovirus genotypes causing hand foot and mouth disease in Shanghai, China: a molecular epidemiological analysis

Background

A rapid expansion of hand, foot, and mouth disease (HFMD) outbreaks has occurred and caused deaths in China in recent years, but little is known about the other etiologic agents except enterovirus 71 (EV71) and coxsackievirus A 16 (CA16). The objective of this study is to determine the genotype compositions of enterovirus causing HFMD in Shanghai and identify any associations between enterovirus types and clinical manifestations.

Methods

Stool specimens were collected from patients hospitalized for treatment of HFMD, from May 2010 to April 2011. Enterovirus was detected by reverse transcription PCR and directly genotyped by sequencing the PCR products. Phylogenetic analysis was based on the VP1 partial gene.

Results

Of 290 specimens, 277 (95.5%) tested positive for enterovirus. The major genotypes were EV71 (63.8%), CA10 (9.0%), CA6 (8.3%), CA16 (6.9%), CA12 (2.4%), and CA4 (1.4%). The EV71 strains belonged to the C4a subtype and CA16 belonged to the B subtype. CA6 was closely related to strains detected in Japan, Taiwan and China, and CA10, CA12 and CA4 were phylogenetically similar to other strains circulating in China. Mean hospital stays and the prevalence of complications in patients with EV71 infection were higher than those in patients in CA6, CA10 or CA16 infection (P < 0.05 for all comparisons). Children with CA12 infection were the youngest, and most likely have the highest risk of complications when compared to the other non-EV71 infection groups.

Conclusions

This study demonstrated a diversified pathogen compositions attributing to HFMD and clinical symptoms differing in enterovirus genotypes. It deserves our attention as early identification of enterovirus genotypes is important for diagnosis and treatment of HFMD patients.

Human astrocytic cells support persistent coxsackievirus B3 infection

Enteroviruses can frequently target the human central nervous system to induce a variety of neurological diseases. Although enteroviruses are highly cytolytic, emerging evidence has shown that these viruses can establish persistent infections both in vivo and in vitro. Here, we investigated the susceptibility of three human brain cell lines, CCF-STTG1, T98G, and SK-N-SH, to infection with three enterovirus serotypes: coxsackievirus B3 (CVB3), enterovirus 71, and coxsackievirus A9. Persistent infection was observed in CVB3-infected CCF-STTG1 cells, as evidenced by prolonged detection of infectious virions, viral RNA, and viral antigens. Of note, infected CCF-STTG1 cells expressed the nonfunctional canonical viral receptors coxsackievirus-adenovirus receptor and decay-accelerating factor, while removal of cell surface chondroitin sulfate from CCF-STTG1 cells inhibited the replication of CVB3, suggesting that receptor usage was one of the major limiting factors in CVB3 persistence. In addition, CVB3 curtailed the induction of beta interferon in infected CCF-STTG1 cells, which likely contributed to the initiation of persistence. Furthermore, proinflammatory chemokines and cytokines, such as vascular cell adhesion molecule 1, interleukin-8 (IL-8), and IL-6, were upregulated in CVB3-infected CCF-STTG1 cells and human progenitor-derived astrocytes. Our data together demonstrate the potential of CCF-STTG1 cells to be a novel cell model for studying CVB3-central nervous system interactions, providing the basis toward a better understanding of CVB3-induced chronic neuropathogenesis.

Detection and distribution of culturable Human Enteroviruses through environmental surveillance in Milan, Italy

AIMS

Human Enteroviruses (HEVs) infections have a significant impact on public health, being implicated in outbreaks of meningitis, encephalitis, hand-foot-mouth disease and other acute and chronic manifestation. In the strategic plan for poliomyelitis eradication, the environmental surveillance of poliovirus (PV) has been identified by the World Health Organization (WHO) as an activity that can complement the surveillance of polio. Having wastewater samples available for PV surveillance allows us to study nonpolio enteroviruses (NPEVs) circulating in the study population, which are widely spread.

METHODS AND RESULTS

This study was carried out according to the WHO guidelines for environmental surveillance of PV and analysed the circulation of PV and NPEVs through the isolation of viruses in cell cultures in Milan area; from 2006 to 2010, 321 wastewater samples were collected, regularly over time, at the inlet of three diverse waste water treatment plants (WWTPs). Culturable HEVs were isolated in 80% of sewage samples: all isolates belonged to the HEV-B group and those circulating more intensely were CVB5 and Echo 6, while CVB4 was the predominant serotype found in 2010. In this study, two type 2 PVs were isolated, both characterized as Sabin like.

CONCLUSION

Environmental monitoring of HEVs in Milan has proved to be an interesting tool to investigate the circulation and distribution of viruses.

SIGNIFICANCE AND IMPACT OF THE STUDY

The detection of PV and other NPEV could be predictive of possible re-emergence of these viruses with an impact on public health. NPEV monitoring could also be a powerful public health tool to investigate the possible role of NPEV in different clinical manifestations.

Patterns of polymorphism and divergence in the VP1 gene of enterovirus 71 circulating in the Asia-Pacific region between 1994 and 2013

Enterovirus 71 has been implicated in several outbreaks of hand, foot and mouth disease in the Asia-Pacific region. The present study aimed to achieve comprehensive evolutionary dynamic aspects of EV71 during 1994-2013, based on phylogenetic analyses of the VP1 sequences. The results indicated that 4 genotypes, namely C4, C1, C2 and B4 are the predominant strains, especially in Southeast Asian countries. No common ancestor was shared in different countries. Fourteen sites of substitutions were detected in the VP1 gene sequences; including the most common sites related to neutralization at position V249I [47.1% (189/401)] and A289T [42.6% (171/401)]. However, the sites Q22H and Q22R associated with increased virulence were recognized only in 13.7% (55/401) and 18% (72/401), respectively. None of the above mutations seemed to become fixed because the ratio of Ka/Ks was greater than 1.0. Mutations K43E, A58T, S184T, and T240S could possibly change the spatial structure. Two mutations, G145E and T240S, could obviously affect the hydrophobicity of VP1 and thus alter the EV71 immunoreactivity. In conclusion, the VP1 gene of EV71 strains circulating in the Asia-Pacific region during 1994-2013, showed polymorphisms and divergence with very slow evolution rate, which may be one of the reasons for periodic outbreaks in this area.

Molecular identification and analysis of human enteroviruses isolated from healthy children in Shenzhen, China from 2010 to 2011

Objective

To determine the prevalence and distribution of human enteroviruses (HEVs) among healthy children in Shenzhen, China.

Method

Clinical specimens were obtained from 320 healthy children under 5 years old in Shenzhen, China from 2010 to 2011. The specimens were evaluated using real-time PCR and cell cultures. The positive specimens were further tested using reverse transcription-seminested PCR (RT-snPCR). Molecular typing and phylogenetic analysis were based on the sequence determined.

Results

Among the 320 samples, 34 were tested positive for HEVs (10.6%) and 22 different serotypes were identified using RT-snPCR. PV1 and PV2 were also detected. The predominant serotype observed was EV71 (17.6%), followed by CV-B4 (14.7%). HEV-B was detected most frequently, with an overall prevalence of 47.1%. HEV-A and HEV-C were found in 32.3% and 20.6% of the samples, respectively. No HEV-D was identified. Molecular phylogeny indicated that all EV71 strains were of C4 genotype.

Conclusion

Although a variety of HEVs was detected in healthy children, HEV-B was relatively more prevalent than other HEV species. Considering HEV-A is more prevalent than HEV-B among patients with hand-foot-mouth disease, additional long-term surveillance of HEV is warranted in both asymptomatic and symptomatic populations.

Characterization of the non-polio enterovirus infections associated with acute flaccid paralysis in South-Western India

Non-polio enteroviruses (NPEVs) have been reported frequently in association with acute flaccid paralysis (AFP) cases during Polio Surveillance Programs (PSPs) worldwide. However, there is limited understanding on the attributes of their infections. This study reports characteristics of NPEVs isolated from AFP cases, investigated during PSPs held in 2009-2010, in Karnataka and Kerala states of south-western India having varied climatic conditions. NPEV cell culture isolates derived from stool specimens that were collected from 422 of 2186 AFP cases (<1-14 years age) and 17 of 41 asymptomatic contacts; and details of all AFP cases/contacts were obtained from National Polio Laboratory, Bangalore. The distribution of NPEV infections among AFP cases and circulation pattern of NPEV strains were determined by statistical analysis of the data. Genotyping of all NPEV isolates was carried out by partial VP1 gene sequencing and phylogenetic analysis. NPEV positive AFP cases were significantly higher in children aged <2 years; with residual paralysis; in summer months; and in regions with relatively hot climate. Genotyping of NPEVs identified predominance of human enteroviruses (HEV)-B species [81.9%-Echoviruses (E): 57.3%; coxsackieviruses (CV) B: 15%; numbered EVs: 8.9%; CVA9: 0.7%] and low levels of HEV-A [14.5%-CVA: 6%; numbered EVs: 8.5%] and HEV-C [3.6%-CVA: 2.6%; numbered EVs: 1%] species, encompassing 63 genotypes. EV76 (6.3%) and each of E3, CVB3 and E9 (4.97%) were found frequently during 2009 while E11 (6.7%), CVB1 (6.1%), E7 (5.1%) and E20 (5.1%) were detected commonly in 2010. A marked proportion of AFP cases from children aged <2 years; presenting with fever; and from north and south interior parts of Karnataka state was detected with E/numbered EVs than that found with CVA/CVB. This study highlights the extensive genetic diversity and diverse circulation patterns of NPEV strains in AFP cases from different populations and climatic conditions.

Genetic characterization of a Coxsackie A9 virus associated with aseptic meningitis in Alberta, Canada in 2010

Background

An unusually high incidence of aseptic meningitis caused by enteroviruses was noted in Alberta, Canada between March and October 2010. Sequence based typing was performed on the enterovirus positive samples to gain a better understanding of the molecular characteristics of the Coxsackie A9 (CVA-9) strain responsible for most cases in this outbreak.

Methods

Molecular typing was performed by amplification and sequencing of the VP2 region. The genomic sequence of one of the 2010 outbreak isolates was compared to a CVA-9 isolate from 2003 and the prototype sequence to study genetic drift and recombination.

Results

Of the 4323 samples tested, 213 were positive for enteroviruses (4.93%). The majority of the positives were detected in CSF samples (n = 157, 73.71%) and 81.94% of the sequenced isolates were typed as CVA-9. The sequenced CVA-9 positives were predominantly (94.16%) detected in patients ranging in age from 15 to 29 years and the peak months for detection were between March and October. Full genome sequence comparisons revealed that the CVA-9 viruses isolated in Alberta in 2003 and 2010 were highly homologous to the prototype CVA-9 in the structural VP1, VP2 and VP3 regions but divergent in the VP4, non-structural and non-coding regions.

Conclusion

The increase in cases of aseptic meningitis was associated with enterovirus CVA-9. Sequence divergence between the prototype strain of CVA-9 and the Alberta isolates suggests genetic drifting and/or recombination events, however the sequence was conserved in the antigenic regions determined by the VP1, VP2 and VP3 genes. These results suggest that the increase in CVA-9 cases likely did not result from the emergence of a radically different immune escape mutant.

Persistent digestive disorders in the tropics: causative infectious pathogens and reference diagnostic tests

BACKGROUND

Persistent digestive disorders account for considerable disease burden in the tropics. Despite advances in understanding acute gastrointestinal infections, important issues concerning epidemiology, diagnosis, treatment and control of most persistent digestive symptomatologies remain to be elucidated. Helminths and intestinal protozoa are considered to play major roles, but the full extent of the aetiologic spectrum is still unclear. We provide an overview of pathogens causing digestive disorders in the tropics and evaluate available reference tests.

METHODS

We searched the literature to identify pathogens that might give rise to persistent diarrhoea, chronic abdominal pain and/or blood in the stool. We reviewed existing laboratory diagnostic methods for each pathogen and stratified them by (i) microscopy; (ii) culture techniques; (iii) immunological tests; and (iv) molecular methods. Pathogen-specific reference tests providing highest diagnostic accuracy are described in greater detail.

RESULTS

Over 30 pathogens may cause persistent digestive disorders. Bacteria, viruses and parasites are important aetiologic agents of acute and long-lasting symptomatologies. An integrated approach, consisting of stool culture, microscopy and/or specific immunological techniques for toxin, antigen and antibody detection, is required for accurate diagnosis of bacteria and parasites. Molecular techniques are essential for sensitive diagnosis of many viruses, bacteria and intestinal protozoa, and are increasingly utilised as adjuncts for helminth identification.

CONCLUSIONS

Diagnosis of the broad spectrum of intestinal pathogens is often cumbersome. There is a need for rapid diagnostic tests that are simple and affordable for resource-constrained settings, so that the management of patients suffering from persistent digestive disorders can be improved.