High frequency of enterovirus D68 in children hospitalised with respiratory illness in Norway, autumn 2014

VP1 is the primary determinant of neuropathogenesis in a mouse model of enterovirus D68 acute flaccid myelitis

Enterovirus D68 (EV-D68) is an emerging pathogen that can cause severe respiratory and neurologic disease [acute flaccid myelitis (AFM)]. Intramuscular (IM) injection of neonatal Swiss Webster (SW) mice with US/IL/14-18952 (IL52), a clinical isolate from the 2014 EV-D68 epidemic, results in many of the pathogenic features of human AFM, including viral infection of the spinal cord, death of motor neurons, and resultant progressive paralysis. In distinction, CA/14-4231 (CA4231), another clinical isolate from the 2014 EV-D68 outbreak, does not cause paralysis in mice, does not grow in the spinal cord, and does not cause motor neuron loss following IM injection. A panel of chimeric viruses containing sequences from IL52 and CA4231 was used to demonstrate that VP1 is the main determinant of EV-D68 neurovirulence following IM injection of neonatal SW mice. VP1 contains four amino acid differences between IL52 and CA4231. Mutations resulting in substituting these four amino acids (CA4231 residues into the IL52 polyprotein) completely abolished neurovirulence. Conversely, mutations resulting in substituting VP1 IL52 amino acid residues into the CA4231 polyprotein created a virus that induced paralysis to the same degree as IL52. Neurovirulence following infection of neonatal SW mice with parental and chimeric viruses was associated with viral growth in the spinal cord.

IMPORTANCE

Emerging viruses allow us to investigate mutations leading to increased disease severity. Enterovirus D68 (EV-D68), once the cause of rare cases of respiratory illness, recently acquired the ability to cause severe respiratory and neurologic disease. Chimeric viruses were used to demonstrate that viral structural protein VP1 determines growth in the spinal cord, motor neuron loss, and paralysis following intramuscular (IM) injection of neonatal Swiss Webster (SW) mice with EV-D68. These results have relevance for predicting the clinical outcome of future EV-D68 epidemics as well as targeting retrograde transport as a potential strategy for treating virus-induced neurologic disease.

Clinical and molecular epidemiology of enterovirus D68 from 2013 to 2020 in Shanghai

Enterovirus D68 (EV-D68) is an emerging pathogen that has caused outbreaks of severe respiratory disease worldwide, especially in children. We aim to investigate the prevalence and genetic characteristics of EV-D68 in children from Shanghai. Nasopharyngeal swab or bronchoalveolar lavage fluid samples collected from children hospitalized with community-acquired pneumonia were screened for EV-D68. Nine of 3997 samples were EV-D68-positive. Seven of nine positive samples were sequenced and submitted to GenBank. Based on partial polyprotein gene (3D) or complete sequence analysis, we found the seven strains belong to different clades and subclades, including three D1 (detected in 2013 and 2014), one D2 (2013), one D3 (2019), and two B3 (2014 and 2018). Overall, we show different clades and subclades of EV-D68 spread with low positive rates (0.2%) among children in Shanghai between 2013 and 2020. Amino acid mutations were found in the epitopes of the VP1 BC and DE loops and C-terminus; similarity analysis provided evidence for recombination as an important mechanism of genomic diversification. Both single nucleotide mutations and recombination play a role in evolution of EV-D68. Genetic instability within these clinical strains may indicate large outbreaks could occur following cumulative mutations.

Optimization of RT-PCR methods for enterovirus detection in groundwater

Enteroviruses (EVs), which belong to the Picornaviridae family, infect individuals asymptomatically or cause mild symptoms (fever, runny nose, cough, skin rash, sneezing, mouth blister). Severe cases can cause various diseases, such as acute hemorrhagic conjunctivitis, aseptic meningitis, or myocarditis, especially in infants. These viruses can be transmitted via the fecal-oral route via contaminated water. In this study, we established a polymerase chain reaction (PCR) method for detecting EVs in water sample using Coxsackievirus B5 (CV-B5) and Echovirus 30 (E-30), which belong to species B of the four species of EVs (EV-A to D). Several methods have been investigated and compared for the detection of EVs, including real-time reverse transcription (RT) polymerase chain reaction and conventional RT-PCR. The most sensitive primer sets were selected, and the PCR conditions were modified to increase sensitivity. We also quantified the detection limits of real-time and conventional RT-PCR. The detection limits of conventional RT-PCR were detected in 105-106 copy/mL for CV-B5 and 106-107 copy/mL for E-30, respectively. This optimized method for detecting EVs is expected to contribute substantially to the investigation of EV outbreaks in water samples.

Prevalence and clinical presentation of EV-D68 infections in Kansas City children during the 2022 season

Seasonal EV-D68 infections can strain medical care resources due to increased pediatric hospitalizations for respiratory illness. In this study, we examine Kansas City's 2022 EV-D68 season. Rhinovirus/enterovirus (RV/EV) positive respiratory specimens from standard of care testing were salvaged and tested by EV-D68 specific PCR. Of the 1412 respiratory specimens tested from July 1 to September 15, 2022, 346 (23%) were positive for RV/EV and EV-D68 was detected in 134/319 (42%) salvaged RV/EV positive specimens. The median age of children with EV-D68 infections was 35.2 months (IQR 16.1, 67.3), which was older than children with non-EV-D68 RV/EV infections (16 months, IQR 5, 47.8), but younger than children infected during the 2014 EV-D68 outbreak. EV-D68 infection was more likely to cause severe disease in children with asthma compared to those without asthma. Real-time EV-D68 monitoring for outbreaks could potentially improve resource utilization by hospitals and help prepare for surges of respiratory disease.

Epidemiology and clinical manifestations of different enterovirus and rhinovirus types show EV‐D68 may still impact on severity of respiratory infections

Respiratory infections are often caused by enteroviruses (EVs). The aim of this study was to identify whether certain types of EV were more likely to cause severe illness in 2016, when an increasing spread of upper respiratory infections was observed in Gothenburg, Sweden. The EV strain in 137 of 1341 nasopharyngeal samples reactive for EV by polymerase chain reaction could be typed by sequencing the viral 5′‐untranslated region and VP1 regions. Phylogenetic trees were constructed. Patient records were reviewed. Hospital care was needed for 46 of 74 patients with available medical records. The majority of the patients (83) were infected with the rhinovirus (RV). The remaining 54 were infected with EV A, B, C, and D strains of 13 different types, with EV‐D68 and CV‐A10 being the most common (17 vs. 14). Significantly more patients with EV‐D68 presented with dyspnea, both when compared with other EV types (p = 0.003) and compared to all other EV and RV infections (p = 0.04). Phylogenetic analysis of the sequences revealed the spread of both Asian and European CV‐A10 strains and 12 different RV C types. This study showed an abundance of different EV types spreading during a year with increased upper respiratory increased infections. EV‐D68 infections were associated with more severe disease manifestation. Other EV and RV types were more evenly distributed between hospitalized and nonhospitalized patients. The EV type CV‐A10 was also found in infected patients, which warrants further studies and surveillance, as this pathogen could cause more severe disease and outbreaks of hand, foot, and mouth disease.

An Overview of Acute Flaccid Myelitis

Acute Flaccid Myelitis is defined by the presence of Acute Flaccid Paralysis (AFP) and a spinal cord lesion on magnetic resonance imaging that is primarily limited to the grey matter. AFM is a difficult situation to deal with when you have a neurologic illness. According to the Centers for Disease Control and Prevention (CDC), a large number of cases were discovered in the United States in 2014, with 90% of cases occurring in children. Although the exact cause of AFM is unknown, mounting evidence suggests a link between AFM and enterovirus D68 (EV-D68). In 2014, an outbreak of AFM was discovered in the United States. The condition was initially linked to polioviruses; however, it was later found that the viruses were caused by non-polioviruses Enteroviruses D-68 (EV-D68). The number of cases has increased since 2014, and the disease has been declared pandemic in the United States. The sudden onset of muscle weakness, usually in an arm or leg, as well as pain throughout the body, the change in patient's facial expression (facial weakness), and shortness of breath, ingesting, and speaking are all common symptoms in patients suffering from neurologic disease. This article includes graphic and histogram representations of reported AFM incidents and criteria for causality, epidemiology, various diagnostic approaches, signs and symptoms, and various investigational guidelines. It also includes key statements about recent clinical findings related to AFM disease.

Advanced Point-of-Care Testing Technologies for Human Acute Respiratory Virus Detection

The ever-growing global threats to human life caused by the human acute respiratory virus (RV) infections have cost billions of lives, created a significant economic burden, and shaped society for centuries. The timely response to emerging RVs could save human lives and reduce the medical care burden. The development of RV detection technologies is essential for potentially preventing RV pandemic and epidemics. However, commonly used detection technologies lack sensitivity, specificity, and speed, thus often failing to provide the rapid turnaround times. To address this problem, new technologies are devised to address the performance inadequacies of the traditional methods. These emerging technologies offer improvements in convenience, speed, flexibility, and portability of point-of-care test (POCT). Herein, recent developments in POCT are comprehensively reviewed for eight typical acute respiratory viruses. This review discusses the challenges and opportunities of various recognition and detection strategies and discusses these according to their detection principles, including nucleic acid amplification, optical POCT, electrochemistry, lateral flow assays, microfluidics, enzyme-linked immunosorbent assays, and microarrays. The importance of limits of detection, throughput, portability, and specificity when testing clinical samples in resource-limited settings is emphasized. Finally, the evaluation of commercial POCT kits for both essential RV diagnosis and clinical-oriented practices is included.

Enterovirus Surveillance (EVSurv) in Germany

The major aim of the enterovirus surveillance (EVSurv) in Germany is to prove the absence of poliovirus circulation in the framework of the Global Polio Eradication Program (GPEI). Therefore, a free-of-charge enterovirus diagnostic is offered to all hospitals for patients with symptoms compatible with a polio infection. Within the quality proven laboratory network for enterovirus diagnostic (LaNED), stool and cerebrospinal fluid (CSF) samples from patients with suspected aseptic meningitis/encephalitis or acute flaccid paralysis (AFP) are screened for enterovirus (EV), typing is performed in all EV positive sample to exclude poliovirus infections. Since 2006, ≈200 hospitals from all 16 German federal states have participated annually. On average, 2500 samples (70% stool, 28% CSF) were tested every year. Overall, the majority of the patients studied are children <15 years. During the 15-year period, 53 different EV serotypes were detected. While EV-A71 was most frequently detected in infants, E30 dominated in older children and adults. Polioviruses were not detected. The German enterovirus surveillance allows monitoring of the circulation of clinically relevant serotypes resulting in continuous data about non-polio enterovirus epidemiology.

Enteroviruses in Respiratory Samples from Paediatric Patients of a Tertiary Care Hospital in Germany

Enteroviruses are associated with various diseases accompanied by rare but severe complications. In recent years, outbreaks of enterovirus D68 and enterovirus A71 associated with severe respiratory infections and neurological complications have been reported worldwide. Since information on molecular epidemiology in respiratory samples is still limited, the genetic diversity of enteroviruses was retrospectively analysed over a 4-year period (2013-2016) in respiratory samples from paediatric patients. Partial viral major capsid protein gene (VP1) sequences were determined for genotyping. Enteroviruses were detected in 255 (6.1%) of 4187 specimens. Phylogenetic analyses of 233 (91.4%) strains revealed 25 different genotypes distributed to Enterovirus A (39.1%), Enterovirus B (34.3%), and Enterovirus D (26.6%). The most frequently detected genotypes were enterovirus D68 (26.6%), coxsackievirus A6 (15.9%), and enterovirus A71 (7.3%). Enterovirus D68 detections were associated with lower respiratory tract infections and increased oxygen demand. Meningitis/encephalitis and other neurological symptoms were related to enterovirus A71, while coxsackievirus A6 was associated with upper respiratory diseases. Prematurity turned out as a potential risk factor for increased oxygen demand during enterovirus infections. The detailed analysis of epidemiological and clinical data contributes to the non-polio enterovirus surveillance in Europe and showed high and rapidly changing genetic diversity of circulating enteroviruses, including different enterovirus D68 variants.

Epidemiology and Sequence-Based Evolutionary Analysis of Circulating Non-Polio Enteroviruses

Enteroviruses (EVs) are positive-sense RNA viruses, with over 50,000 nucleotide sequences publicly available. While most human infections are typically associated with mild respiratory symptoms, several different EV types have also been associated with severe human disease, especially acute flaccid paralysis (AFP), particularly with endemic members of the EV-B species and two pandemic types—EV-A71 and EV-D68—that appear to be responsible for recent widespread outbreaks. Here we review the recent literature on the prevalence, characteristics, and circulation dynamics of different enterovirus types and combine this with an analysis of the sequence coverage of different EV types in public databases (e.g., the Virus Pathogen Resource). This evaluation reveals temporal and geographic differences in EV circulation and sequence distribution, highlighting recent EV outbreaks and revealing gaps in sequence coverage. Phylogenetic analysis of the EV genus shows the relatedness of different EV types. Recombination analysis of the EV-A species provides evidence for recombination as a mechanism of genomic diversification. The absence of broadly protective vaccines and effective antivirals makes human enteroviruses important pathogens of public health concern.

Frequent detection of enterovirus D68 and rhinovirus type C in children with acute respiratory infections

This study aimed to evaluate the prevalence of human rhinoviruses (HRVs) and the emergence of enterovirus D68 (EV-D68) in children. A total of 322 nasopharyngeal swab samples were provided from children with an initial diagnosis of upper and lower respiratory tract infections. A total of 34 and 70 cases were positive for EV-D68 and HRV, respectively. The phylogenetic analysis revealed that the clades A and B are the prevalent genotypes for EV-D68 and the HRV-positive samples belong to three types including HRV-A, HRV-B, and HRV-C. The results showed that EV-D68 and HRV-C are circulating in Iran especially in the winter.

Mapping Attenuation Determinants in Enterovirus-D68

Enterovirus (EV)-D68 has been associated with epidemics in the United Sates in 2014, 2016 and 2018. This study aims to identify potential viral virulence determinants. We found that neonatal type I interferon receptor knockout mice are susceptible to EV-D68 infection via intraperitoneal inoculation and were able to recapitulate the paralysis process observed in human disease. Among the EV-D68 strains tested, strain US/MO-14-18949 caused no observable disease in this mouse model, whereas the other strains caused paralysis and death. Sequence analysis revealed several conserved genetic changes among these virus strains: nucleotide positions 107 and 648 in the 5′-untranslated region (UTR); amino acid position 88 in VP3; 1, 148, 282 and 283 in VP1; 22 in 2A; 47 in 3A. A series of chimeric and point-mutated infectious clones were constructed to identify viral elements responsible for the distinct virulence. A single amino acid change from isoleucine to valine at position 88 in VP3 attenuated neurovirulence by reducing virus replication in the brain and spinal cord of infected mice.

Molecular Characterization and Clinical Description of Non-Polio Enteroviruses Detected in Stool Samples from HIV-Positive and HIV-Negative Adults in Ghana

In the post-polio eradication era, increasing attention is given to non-polio enteroviruses. Most of the data about enteroviruses in sub-Saharan Africa are related to acute flaccid paralysis surveillance and target the pediatric population. This study aimed to investigate the presence of enterovirus in PLHIV (people living with HIV) and HIV-negative individuals in Ghana. Stool samples from HIV-positive individuals (n = 250) and healthy blood donors (n = 102) attending the Komfo Anokye Teaching Hospital in Kumasi, Ghana, were screened by real-time PCR for enterovirus. Molecular typing of the VP1 region was performed. Enterovirus-positive samples were tested for norovirus, adenovirus, rotavirus, sapovirus, and cosaviruses. Twenty-six out of 250 HIV-positive subjects (10.4%) and 14 out of 102 HIV-negative individuals (13.7%) were detected enterovirus-positive, not showing a significant different infection rate between the two groups. HIV-negative individuals were infected with Enterovirus C strains only. HIV-positive participants were detected positive for species Enterovirus A, Enterovirus B, and Enterovirus C. Co-infections with other viral enteric pathogens were almost exclusively detected among HIV-positive participants. Overall, the present study provides the first data about enteroviruses within HIV-positive and HIV-negative adults living in Ghana.

Current status of enterovirus D68 worldwide and in Taiwan

Enterovirus D68 was first identified in 1962 and caused a worldwide outbreak starting from the North America in 2014. Enterovirus D68 has been in continuous circulation among many countries recently, including Taiwan. Reports also reveal high seroprevalence, which indicates that the disease burden of enterovirus D68 may be underestimated via viral culture or polymerase chain reaction results. Although most infected cases have mild respiratory illness, severe complications including acute flaccid myelitis and acute respiratory distress syndrome have also been reported. In the position of an emerging pathogen, enterovirus D68 poses a threat to public health and may cause devastating diseases. Diverse severity of neurological sequelae remains inevitable among acute flaccid myelitis patients, but no curable treatment is available currently. According to the management suggestions of the American Centers of Disease Control, uses of corticosteroids and plasmapheresis are either preferred or avoided and intravenous immunoglobulin also has no clear indication in the treatment for acute flaccid myelitis. In this review article, we provide information about the epidemiology, clinical recognition and treatment strategy of enterovirus D68. Better understanding of this disease is the foothold for advanced investigation and monitoring in the future.

Enterovirus D68 outbreak detection through a syndromic disease epidemiology network

BACKGROUND

In 2014, enterovirus D68 (EV-D68) was responsible for an outbreak of severe respiratory illness in children, with 1,153 EV-D68 cases reported across 49 states. Despite this, there is no commercial assay for its detection in routine clinical care. BioFire® Syndromic Trends (Trend) is an epidemiological network that collects, in near real-time, deidentified. BioFire test results worldwide, including data from the BioFire® Respiratory Panel (RP).

OBJECTIVES

Using the RP version 1.7 (which was not explicitly designed to differentiate EV-D68 from other picornaviruses), we formulate a model, Pathogen Extended Resolution (PER), to distinguish EV-D68 from other human rhinoviruses/enteroviruses (RV/EV) tested for in the panel. Using PER in conjunction with Trend, we survey for historical evidence of EVD68 positivity and demonstrate a method for prospective real-time outbreak monitoring within the network.

STUDY DESIGN

PER incorporates real-time polymerase chain reaction metrics from the RPRV/EV assays. Six institutions in the United States and Europe contributed to the model creation, providing data from 1,619 samples spanning two years, confirmed by EV-D68 gold-standard molecular methods. We estimate outbreak periods by applying PER to over 600,000 historical Trend RP tests since 2014. Additionally, we used PER as a prospective monitoring tool during the 2018 outbreak.

RESULTS

The final PER algorithm demonstrated an overall sensitivity and specificity of 87.1% and 86.1%, respectively, among the gold-standard dataset. During the 2018 outbreak monitoring period, PER alerted the research network of EV-D68 emergence in July. One of the first sites to experience a significant increase, Nationwide Children's Hospital, confirmed the outbreak and implemented EV-D68 testing at the institution in response. Applying PER to the historical Trend dataset to determine rates among RP tests, we find three potential outbreaks with predicted regional EV-D68 rates as high as 37% in 2014, 16% in 2016, and 29% in 2018.

CONCLUSIONS

Using PER within the Trend network was shown to both accurately predict outbreaks of EV-D68 and to provide timely notifications of its circulation to participating clinical laboratories.

Molecular diversity and biennial circulation of enterovirus D68: a systematic screening study in Lyon, France, 2010 to 2016

Understanding enterovirus D68 (EV-D68) circulation patterns as well as risk factors for severe respiratory and neurological illness is important for developing preventive strategies. Methods: Between 2010 and 2016, 11,132 respiratory specimens from hospitalised patients in Lyon, France, were screened for EV-D68 by PCR. Phylogenetic relationships of the viral-protein-1 sequences were reconstructed using maximum-likelihood and Bayesian-Markov-Chain-Monte-Carlo approaches. Results: Overall, 171 infections with a biennial pattern were detected, including seven, one, 55, none, 42, one and 65 cases annually during 2010–16. Children (< 16 years-old; n = 150) were mostly affected and 71% (n = 121) of the total patients were under 5 years-old. In 146 patients with medical reviews, 73% (n = 107) presented with acute respiratory distress. Among paediatric patients with medical reviews (n = 133), 55% (n=73) had an asthma/wheezing history, while among adults (n = 13), 11 had underlying diseases. In total, 45 patients had severe infections and 28 patients needed intensive care unit stays. No acute flaccid myelitis (AFM) was detected. We found genotypes A, B1, B2 B3 and D circulating, and no associations between these and clinical presentations. During the study, new genotypes continuously emerged, being replaced over time. We estimated that ancestors of currently circulating genotypes emerged in the late-1990s to 2010. Rises of the EV-D68 effective population size in Lyon coincided with infection upsurges. Phylogenetic analyses showed ongoing diversification of EV-D68 worldwide, coinciding with more infections in recent years and increases of reported AFM paediatric cases. Conclusions: Reinforcement of diagnostic capacities and clinical-based surveillance of EV-D68 infections is needed in Europe to assess the EV-D68 burden.

Enterovirus pathogenesis requires the host methyltransferase SETD3

Enteroviruses (EVs) comprise a large genus of positive-sense, single-stranded RNA viruses whose members cause a number of important and widespread human diseases including poliomyelitis, myocarditis, acute flaccid myelitis (AFM) and the common cold. How EVs co-opt cellular functions to promote replication and spread is incompletely understood. Here, using genome-scale CRISPR screens, we identify the actin histidine methyltransferase SETD3 as critically important for viral infection by a broad panel of enteroviruses including rhinoviruses and non-polio EVs increasingly linked to severe neurological disease such as AFM (EV-D68) and viral encephalitis (EV-A71). We show that cytosolic SETD3, independent of its methylation activity, is required for the RNA replication step in the viral life cycle. Using quantitative affinity purification-mass spectrometry, we show that SETD3 specifically interacts with the viral 2A protease of multiple enteroviral species and we map the residues in 2A that mediate this interaction. 2A mutants that retain protease activity, but unable to interact with SETD3, are severely compromised in RNA replication. These data suggest a role of the viral 2A protein in RNA replication beyond facilitating proteolytic cleavage. Finally, we demonstrate that SETD3 is essential for in vivo replication and pathogenesis in multiple mouse models for enterovirus infection including CV-A10, EV-A71 and EV-D68. Our results reveal a crucial role of a host protein in viral pathogenesis and suggest targeting SETD3 as a potential mechanism for controlling viral infections.

Enterovirus D68 respiratory infection in a children's hospital in Japan in 2015

BACKGROUND

Outbreaks of enterovirus D68 (EV-D68) respiratory infections in children were reported globally in 2014. In Japan, there was an EV-D68 outbreak in the autumn of 2015 (September-October). The aim of this study was to compare EV-D68-specific polymerase chain reaction (PCR)-positive and EV-D68-specific PCR-negative patients.

METHODS

Pediatric patients admitted for any respiratory symptoms between September and October 2015 were enrolled. Nasopharyngeal swabs were tested for multiplex respiratory virus PCR and EV-D68-specific reverse transcription-PCR. EV-D68-specific PCR-positive and -negative patients were compared regarding demographic data and clinical information.

RESULTS

A nasopharyngeal swab was obtained from 76 of 165 patients admitted with respiratory symptoms during the study period. EV-D68 was detected in 40 samples (52.6%). Median age in the EV-D68-specific PCR-positive and -negative groups was 3.0 years (IQR, 5.5 years) and 3.0 years (IQR, 4.0 years), respectively. The rates of coinfection in the two groups were 32.5% and 47.2%, respectively. There was no significant difference in the history of asthma or recurrent wheezing, length of hospitalization, or pediatric intensive care unit admission rate between the groups. The median days between symptom onset and admission was significantly lower for the EV-D68-positive group (3.0 days vs 5.0 days, P = 0.001). EV-D68 was identified as clade B on phylogenetic analysis. No cases of acute flaccid myelitis were encountered.

CONCLUSIONS

More than half of the samples from the children admitted with respiratory symptoms were positive for EV-D68-specific PCR during the outbreak. Asthma history was not associated with the risk of developing severe respiratory infection.

Upsurge of Enterovirus D68 and Circulation of the New Subclade D3 and Subclade B3 in Beijing, China, 2016

We conducted a surveillance among acute respiratory tract infection (ARTI) cases to define the epidemiology, clinical characteristics and genetic variations of enterovirus D68 (EV-D68) in Beijing, China from 2015 to 2017. Nasopharyngeal swabs and sputum were collected from 30 sentinel hospitals in Beijing and subjected to EV and EV-D68 detection by real-time PCR. The VP1 gene region and complete genome sequences of EV-D68 positive cases were analyzed. Of 21816 ARTI cases, 619 (2.84%) were EV positive and 42 cases were EV-D68 positive. The detection rates of EV-D68 were 0 (0/6644) in 2015, 0.53% (40/7522) in 2016 and 0.03% (2/7650) in 2017, respectively. Two peaks of EV-D68 infections occurred in late summer and early-winter. Ten cases (23.81%) with upper respiratory tract infection and 32 cases (76.19%) presented with pneumonia, including 3 cases with severe pneumonia. The phylogenetic analysis suggested 15 subclade D3 strains and 27 subclade B3 strains of EV-D68 were circulated in China from 2016 to 2017. A total of 52 amino acid polymorphisms were identified between subclades D1 and D3. These data suggest an upsurge of EV-D68 occurred in Beijing in 2016, the new subclade D3 emerged in 2016 and co-circulated with subclade B3 between 2016 and 2017.

Contemporary Circulating Enterovirus D68 Strains Have Acquired the Capacity for Viral Entry and Replication in Human Neuronal Cells

Since the EV-D68 outbreak during the summer of 2014, evidence of a causal link to a type of limb paralysis (AFM) has been mounting. In this article, we describe a neuronal cell culture model (SH-SY5Y cells) in which a subset of contemporary 2014 outbreak strains of EV-D68 show infectivity in neuronal cells, or neurotropism. We confirmed the difference in neurotropism in vitro using primary human neuron cell cultures and in vivo with a mouse paralysis model. Using the SH-SY5Y cell model, we determined that a barrier to viral entry is at least partly responsible for neurotropism. SH-SY5Y cells may be useful in determining if specific EV-D68 genetic determinants are associated with neuropathogenesis, and replication in this cell line could be used as rapid screening tool for identification of neurotropic EV-D68 strains. This may assist with better understanding of pathogenesis and epidemiology and with the development of potential therapies.

Enterovirus D68 (EV-D68) has historically been associated with respiratory illnesses. However, in the summers of 2014 and 2016, EV-D68 outbreaks coincided with a spike in polio-like acute flaccid myelitis/paralysis (AFM/AFP) cases. This raised concerns that EV-D68 could be the causative agent of AFM during these recent outbreaks. To assess the potential neurotropism of EV-D68, we utilized the neuroblastoma-derived neuronal cell line SH-SY5Y as a cell culture model to determine if differential infection is observed for different EV-D68 strains. In contrast to HeLa and A549 cells, which support viral infection of all EV-D68 strains tested, SH-SY5Y cells only supported infection by a subset of contemporary EV-D68 strains, including isolates from the 2014 outbreak. Viral replication and infectivity in SH-SY5Y were assessed using multiple assays: virus production, cytopathic effects, cellular ATP release, and VP1 capsid protein production. Similar differential neurotropism was also observed in differentiated SH-SY5Y cells, primary human neuron cultures, and a mouse paralysis model. Using the SH-SY5Y cell culture model, we determined that barriers to viral binding and entry were at least partly responsible for the differential infectivity phenotype. Transfection of genomic RNA into SH-SY5Y generated virions for all EV-D68 isolates, but only a single round of replication was observed from strains that could not directly infect SH-SY5Y. In addition to supporting virus replication and other functional studies, this cell culture model may help identify the signatures of virulence to confirm epidemiological associations between EV-D68 strains and AFM and allow for the rapid identification and characterization of emerging neurotropic strains.

Comparison of the Severity of Respiratory Disease in Children Testing Positive for Enterovirus D68 and Human Rhinovirus

OBJECTIVE

To compare the characteristics and severity of respiratory disease in children testing positive for enterovirus D68 (EV-D68) and for human rhinovirus (RhV).

STUDY DESIGN

A retrospective single center study of children presenting with acute respiratory symptoms and positive polymerase chain reaction for RhV/EV from September 1, 2014 through October 31, 2014 was performed. Specimens were subsequently tested specifically for EV-D68 and specimens identified as RhV were subtyped when possible into RhV-A, RhV-B, and RhV-C species. Clinical manifestations in patients with EV-D68 were compared with those with non-EV-D68, RhV, and RhV-C.

RESULTS

Of the 173 patients included in the analysis, 72 tested positive for EV-D68, 61 for RhV, and 30 for RhV-C. There were significantly fewer infants in the EV-D68 group. Patients with EV-D68 were more likely than those without EV-D68, and specifically with RhV-C, to have fever and wheezing. Patients with EV-D68 received more magnesium sulfate for respiratory distress not responding adequately to repeated doses of inhaled albuterol. Hospitalized patients with EV-D68 received more bronchodilator therapy than patients with RhV. Patients with EV-D68 were more likely to be admitted to the intensive care unit and were older than patients without EV-D68. There was no difference in length of overall hospitalization or time in the pediatric intensive care unit.

CONCLUSIONS

Children with EV-D68 appeared to have more severe respiratory disease on admission than children with RhV as evidenced by higher rates of fever, wheezing, bronchodilator use and pediatric intensive care unit admission. Despite the initial difference in severity, no significant difference in length of stay was found suggesting that patients with EV-D68 recovered as quickly as other groups.

The association between acute flaccid myelitis (AFM) and Enterovirus D68 (EV-D68) - what is the evidence for causation?

BackgroundEnterovirus D68 (EV-D68) has historically been a sporadic disease, causing occasional small outbreaks of generally mild infection. In recent years, there has been evidence of an increase in EV-D68 infections globally. Large outbreaks of EV-D68, with thousands of cases, occurred in the United States, Canada and Europe in 2014. The outbreaks were associated temporally and geographically with an increase in clusters of acute flaccid myelitis (AFM).
Aims: We aimed to evaluate a causal association between EV-D68 and AFM. 
Methods: Using data from the published and grey literature, we applied the Bradford Hill criteria, a set of nine principles applied to examine causality, to evaluate the relationship between EV-D68 and AFM. Based on available evidence, we defined the Bradford Hill Criteria as being not met, or met minimally, partially or fully. 
Results: Available evidence applied to EV-D68 and AFM showed that six of the Bradford Hill criteria were fully met and two were partially met. The criterion of biological gradient was minimally met. The incidence of EV-D68 infections is increasing world-wide. Phylogenetic epidemiology showed diversification from the original Fermon and Rhyne strains since the year 2000, with evolution of a genetically distinct outbreak strain, clade B1. Clade B1, but not older strains, is associated with AFM and is neuropathic in animal models. 
Conclusion: While more research is needed on dose-response relationship, application of the Bradford Hill criteria supported a causal relationship between EV-D68 and AFM.

Enterovirus D68 Infection in Children with Acute Flaccid Myelitis, Colorado, USA, 2014

Odds of this viral infection in the nasopharynx were 10 times greater for children with this condition than for controls.

During August 8, 2014–October 14, 2014, a total of 11 children with acute flaccid myelitis and distinctive neuroimaging changes were identified near Denver, Colorado, USA. A respiratory prodrome was experienced by 10, and nasopharyngeal specimens were positive for enterovirus D68 (EV-D68) for 4. To determine whether an association exists between EV-D68 infection and acute flaccid myelitis, we conducted a retrospective case–control study comparing these patients with 2 groups of outpatient control children (1 group tested for acute respiratory illness and 1 for Bordetella pertussis infection). Adjusted analyses indicated that, for children with acute flaccid myelitis, the odds of having EV-D68 infection were 10.3 times greater than for those tested for acute respiratory infection and 4.5 times greater than for those tested for B. pertussis infection. No statistical association was seen between acute flaccid myelitis and non–EV-D68 enterovirus or rhinovirus infection. These findings support an association between EV-D68 infection and acute flaccid myelitis.

Enterovirus genotypes among patients with severe acute respiratory illness, influenza-like illness, and asymptomatic individuals in South Africa, 2012-2014

Enteroviruses can cause outbreaks of severe acute respiratory illness (SARI) and EV-A, -B, -C, and -D species have different pathogenic profiles and circulation patterns. We aimed to characterize and determine the prevalence of enterovirus genotypes among South African patients with respiratory illness and controls during June 2012 to July 2014. Syndromic SARI and influenza-like illness (ILI) surveillance was performed at two sentinel sites. At each site nasopharyngeal/oropharyngeal specimens were collected from SARI and ILI patients as well as controls. Specimens were tested for enterovirus by real-time PCR. Positive specimens were further genotyped by sequencing a region of the VP1 gene. The prevalence of enterovirus was 5.8% (87/1494), 3.4% (103/3079), and 3.4% (46/1367) among SARI, ILI, and controls, respectively (SARI/controls, P = 0.002 and ILI/control, P = 0.973). Among the 101/236 (42.8%) enterovirus-positive specimens that could be genotyped, we observed a high diversity of circulating enterovirus genotypes (a total of 33 genotypes) from all four human enterovirus species with high prevalence of Enterovirus-B (60.4%; 61/101) and Enterovirus-A (21.8%; 22/101) compared to Enterovirus-C (10.9%; 11/101) and Enterovirus-D (6.9%; 7/101) (P = 0.477). Of the enterovirus genotypes identified, Echovirus 30 (9.9%, 10/101), Coxsackie virus B5 (7.9%, 8/101) and Enterovirus-D68 (6.9%, 7/101) were most prevalent. There was no difference in disease severity (SARI or ILI compared to controls) between the different enterovirus species (P = 0.167). We observed a high number of enterovirus genotypes in patients with respiratory illness and in controls from South Africa with no disease association of EV species with disease severity.

Seroepidemiological and phylogenetic characterization of neurotropic enteroviruses in Ireland, 2005-2014

Enteroviruses (EVs) are associated with a broad spectrum of clinical presentation, including aseptic meningitis (AM), encephalitis, hand, foot and mouth disease, acute flaccid paralysis, and acute flaccid myelitis. Epidemics occur sporadically and are associated with increased cases of AM in children. The present study describes the seroepidemiological analysis of circulating EVs in Ireland from 2005 to 2014 and phylogenetic characterization of echovirus 30 (E-30), enterovirus A71 (EV-A71), and enterovirus D68 (EV-D68). EV VP1 genotyping was applied to viral isolates and clinical samples, including cerebrospinal fluid (CSF), and those isolates that remained untypeable by neutralising anti-sera. An increase in AM cases from 2010 to 2014 was associated with an E-30 genogroup variant VII and sequences clustered phylogenetically with those detected in AM outbreaks in France and Italy. EV-D68 viral RNA was not detected in CSF samples and no neurological involvement was reported. Three EV-A71 positive CSF samples were identified in patients presenting with AM. A phylogenetic analysis of respiratory-associated EV-D68 and EV-A71 cases in circulation was performed to determine baseline epidemiological data. EV-D68 segregated with clades B and B(1) and EV-A71 clustered as subgenogroup C2. The EV VP1 genotyping method was more sensitive than neutralising anti-sera methods by virus culture and importantly demonstrated concordance between EV genotypes in faecal and CSF samples which should facilitate EV screening by less invasive sampling approaches in AM presentations.

Seroepidemiology of enterovirus D68 infection in China

Human enterovirus 68 (EV-D68) is a rarely reported virus that has been linked to respiratory disease. In recent years, reports about EV-D68 infection have markedly increased worldwide. However, the epidemiological features of this emerging infection are not well understood. To evaluate the emerging EV-D68 epidemic, we isolated the circulating viral strain and investigated the seroprevalence of neutralizing antibodies (NAbs) in Beijing between 2004 and 2011. We found that the titers of EV-D68 NAbs were generally low in all age groups in sampled populations in 2004 but significantly higher in 2009. From 2007 to 2011, the NAbs against EV-D68 significantly increased over time. These findings indicate that EV-D68 has spread widely in the Chinese population in recent years, although only a limited number of cases were reported.

The emergence of enterovirus D68 in England in autumn 2014 and the necessity for reinforcing enterovirus respiratory screening

In autumn 2014, enterovirus D68 (EV-D68) cases presenting with severe respiratory or neurological disease were described in countries worldwide. To describe the epidemiology and virological characteristics of EV-D68 in England, we collected clinical information on laboratory-confirmed EV-D68 cases detected in secondary care (hospitals), between September 2014 and January 2015. In primary care (general practitioners), respiratory swabs collected (September 2013-January 2015) from patients presenting with influenza-like illness were tested for EV-D68. In secondary care 55 EV-D68 cases were detected. Among those, 45 cases had clinical information available and 89% (40/45) presented with severe respiratory symptoms. Detection of EV-D68 among patients in primary care increased from 0.4% (4/1074; 95% CI 0.1-1.0) (September 2013-January 2014) to 0.8% (11/1359; 95% CI 0.4-1.5) (September 2014-January 2015). Characterization of EV-D68 strains circulating in England since 2012 and up to winter 2014/2015 indicated that those strains were genetically similar to those detected in 2014 in USA. We recommend reinforcing enterovirus surveillance through screening respiratory samples of suspected cases.

Epidemiological and clinical characteristics of patients infected with enterovirus D68, France, July to December 2014

In 2014, the United States (US) experienced a nationwide outbreak of enterovirus D68 (EV-D68) infection with 1,152 cases reported mainly in hospitalised children with severe asthma or bronchiolitis. Following the US alert, 11 laboratories of the French enterovirus (EV) surveillance network participated in an EV-D68 survey. A total of 6,229 respiratory samples, collected from 1 July to 31 December 2014, were screened for EV-D68 resulting in 212 EV-D68-positive samples. These 212 samples corresponded to 200 EV-D68 cases. The overall EV-D68 positivity rates among respiratory samples were of 5% (184/3,645) and 1.1% (28/2,584) in hospitalised children and adults respectively. The maximum weekly EV-D68 positivity rates were of 16.1% for children (n = 24/149; week 43) and 2.6% for adults (n = 3/115; week 42). Of 173 children with EV-D68 infection alone, the main symptoms were asthma (n = 83; 48.0%) and bronchiolitis (n = 37; 21.4%). One child developed acute flaccid paralysis (AFP) following EV-D68-associated pneumonia. Although there was no significant increase in severe respiratory tract infections reported to the French public health authorities, 10.7% (19/177) of the EV-D68 infected children and 14.3% (3/21) of the EV-D68 infected adults were hospitalised in intensive care units. Phylogenetic analysis of the viral protein 1 (VP1) sequences of 179 EV-D68 cases, revealed that 117 sequences (65.4%), including that of the case of AFP, belonged to the B2 variant of clade B viruses. Continuous surveillance of EV-D68 infections is warranted and could benefit from existing influenza-like illness and EV surveillance networks.

Enterovirus D68-Associated Community-Acquired Pneumonia in the Pediatric Age Group

PURPOSE OF REVIEW

This review summarizes the current knowledge regarding the role of Enterovirus D68 (EV-D68) in community-acquired pneumonia (CAP) in children.

RECENT FINDINGS

EV-D68 is an emergent viral pathogen. Since its first isolation in 1962 in California in four children suffering from CAP and bronchiolitis, EV-D68 has been rarely detected from respiratory specimens. However, recently, EV-D68 infection has raised concerns in the international community because of outbreaks in 2014 in the USA and the increased number of children with EV-D68-associated severe respiratory illnesses, including pneumonia, that have been reported in many other countries around the world. EV-D68 causes severe and life-threatening respiratory diseases in the pediatric population, particularly in children with underlying conditions such as prematurity or chronic diseases. Since no specific treatment or vaccinations are available for EV-D68 infections, greater surveillance as well as the use of sensitive and rapid diagnostic methods are essential to prevent and manage new outbreaks.

Respiratory infections associated with enterovirus D68 from 2011 to 2015 in Beijing, China

Enterovirus D68 (EV-D68) is an emergent viral pathogen associated with mild to severe respiratory infections. In this study, we describe respiratory infections associated with EV-D68 in Beijing over a 4 year period. Total nucleic acid was extracted from 7,945 clinical specimens collected between January 5, 2011 and July 30, 2015 in Beijing and used for detecting EV-D68 and other enteroviruses by real-time PCR. Overall, 555/7,945 (6.99%) specimens were enterovirus positive: 12/7,945 (0.2%) specimens were EV-D68 positive. Of these patients, 11 were pediatric patients and 1 was a 76-year-old man. The main symptoms for the 12 EV-D68 positive patients were fever (10/12, 83.3%) and cough (6/12, 50%). Ten EV-D68 infection cases were identified in autumn or winter season. The phylogenetic relationships of the 12 EV-D68 viral strains with other strains were analyzed based on the sequences of viral protein 1(VP1). The EV-D68 strains from 2011 to 2013 belonged to groups 1 or 3, while all strains in 2014 were clustered into group 1 together with the strains circulating in the USA. In conclusion, EV-D68 played a role in respiratory infections in Beijing during this period. In addition, the most common EV-D68 strain detected was similar to that circulating in the USA in 2014. J. Med. Virol. 88:1529-1534, 2016. © 2016 Wiley Periodicals, Inc.

Enterovirus D68 and Human Respiratory Infections

Enterovirus D68 (EV-D68) is a member of the species Enterovirus D in the genus Enterovirus of the Picornaviridae family. EV-D68 was first isolated in the United States in 1962 and is primarily an agent of respiratory disease. Infections with EV-D68 have been rarely reported until recently, when reports of EV-D68 associated with respiratory disease increased notably worldwide. An outbreak in 2014 in the United States, for example, involved more than 1,000 cases of severe respiratory disease that occurred across almost all states. Phylogenetic analysis of all EV-D68 sequences indicates that the circulating strains of EV-D68 can be classified into two lineages, lineage 1 and lineage 2. In contrast to the prototype Fermon strain, all circulating strains have deletions in their genomes. Respiratory illness associated with EV-D68 infection ranges from mild illness that just needs outpatient service to severe illness requiring intensive care and mechanical ventilation. To date, there are no specific medicines and vaccines to treat or prevent EV-D68 infection. This review provides a detailed overview about our current understanding of EV-D68-related virology, epidemiology and clinical syndromes, pathogenesis, and laboratory diagnostics.

A prospective study of enterovirus D68 in a regional UK center

Aim: A prospective study was undertaken to establish the prevalence of enterovirus D68 (EV-D68) in the northwest of England. Patients & samples: In the period 24 October through 31 December 2014, respiratory samples were screened by a specific real-time PCR and EV-D68 was identified by nucleotide sequence-based typing. Results: Enterovirus was detected in 7.4% of samples and EV-D68 was confirmed in 32 cases. Phylogenetic analysis showed that EV-D68 strains corresponded to clades A and B. Clinical presentation of cases ranged from mild to severe respiratory infection. The majority of cases had comorbidities that might predispose to severe infection. Conclusion: EV-D68 was circulating in our region during late 2014 and has the potential to cause severe disease.

Genetic changes found in a distinct clade of Enterovirus D68 associated with paralysis during the 2014 outbreak

Enterovirus D68 (EV-D68) caused a severe respiratory illness outbreak in the United States in 2014. Reports of acute flaccid myelitis (AFM)/paralysis (AFP) in several independent epidemiological clusters of children with detectable EV-D68 have raised concerns that genetic changes in EV-D68 could be causing increased disease severity and neurological symptoms. To explore the potential link between EV-D68 genetic variations and symptom changes, we performed a series of comparative genomic analyses of EV-D68 2014 outbreak isolate sequences using data and analytical tools in the Virus Pathogen Resource (ViPR; www.viprbrc.org). Our results suggest that (1) three distinct lineages of EV-D68 were co-circulating in 2013 and 2014; (2) isolates associated with AFM/AFP belong to a single phylogenetic subclade - B1; (3) the majority of isolates from the B1 subclade have 21 unique substitutions that distinguish them from other isolates, including amino acid substitutions in the VP1, VP2, and VP3 capsid proteins and the 3D RNA-dependent RNA polymerase, and nucleotide substitutions in the internal ribosome entry sequence (IRES); (4) at 12 of these positions, B1 isolates carry the same residues observed at equivalent positions in paralysis-causing enteroviruses, including poliovirus, EV-D70 and EV-A71. Based on these results, we hypothesize that unique B1 substitutions may be responsible for the apparent increased incidence of neuropathology associated with the 2014 outbreak.

Clinical Characterization of Children Presenting to the Hospital with Enterovirus D68 Infection During the 2014 Outbreak in St. Louis

BACKGROUND

The largest known outbreak of enterovirus D68 (EV-D68) infections occurred during 2014. The goal of our study is to characterize the illness severity and clinical presentation of children infected with EV-D68 in comparison to non-EV-D68-human rhinoviruses/enteroviruses (HRV/EV).

METHOD

Our study is a retrospective analysis of severity level, charges and length of stay of children who presented to St. Louis Children's Hospital from August 8, 2014 to October 31, 2014 and tested positive for EV-D68 in comparison to non-EV-D68-HRV/EV-infected patients. Chart review was performed for all EV-D68-infected patients and age and severity matched non-EV-D68-HRV/EV-infected patients.

RESULT

There was a striking increase in hospital census in August of 2014 in our hospital with simultaneous increase in the number of patients with EV-D68 infection. There was no significant difference in severity of illness, length of stay or total charges between EV-D68-infected and non-EV-D68-HRV/EV-infected children. EV-D68 infection was characterized by presenting complaints of difficulty breathing (80%) and wheezing (67%) and by findings of tachypnea (65%), wheezing (71%) and retractions (65%) on examination. The most common interventions were albuterol (79%) and corticosteroid (68%) treatments, and the most common discharge diagnosis was asthma exacerbation (55%).

CONCLUSION

EV-D68 caused a significant outbreak in 2014 with increased hospital admissions and associated increased charges. There was no significant difference in severity of illness caused by EV-D68 compared with non-EV-D68-HRV/EV infections suggesting that the impact from EV-D68 was because of increased number of infected children presenting to the hospital and not necessarily due to increased severity of illness.

Enterovirus D68 Infections Associated with Severe Respiratory Illness in Elderly Patients and Emergence of a Novel Clade in Hong Kong

Despite the recent emergence of enterovirus D68 (EV-D68), its clinical impact on adult population is less well defined. To better define the epidemiology of EV-D68, 6,800 nasopharyngeal aspirates (NPAs) from 2010–2014 were subject to EV-D68 detection by RT-PCR and sequencing of 5′UTR and partial VP1. EV-D68 was detected in 30 (0.44%) NPAs from 22 children and 8 adults/elderlies. Sixteen patients (including five elderly) (53%) had pneumonia and 13 (43%) patients were complicated by small airway disease exacerbation. Phylogenetic analysis of VP1, 2C and 3D regions showed four distinct lineages of EV-D68, clade A1, A2, B1 and B3, with adults/elderlies exclusively infected by clade A2. The potentially new clade, B3, has emerged in 2014, while strains closely related to recently emerged B1 strains in the United States were also detected as early as 2011 in Hong Kong. The four lineages possessed distinct aa sequence patterns in BC and DE loops. Amino acid residues 97 and 140, within BC and DE-surface loops of VP1 respectively, were under potential positive selection. EV-D68 infections in Hong Kong usually peak in spring/summer, though with a delayed autumn/winter peak in 2011. This report suggests that EV-D68 may cause severe respiratory illness in adults/elderlies with underlying co-morbidities.

Systematic community- and hospital-based surveillance for enterovirus-D68 in three Canadian provinces, August to December 2014

Respiratory specimens collected from outpatients with influenza-like illness in three Canadian provinces (British Columbia (BC), Alberta and Quebec) participating in a community-based sentinel surveillance network were prospectively screened for enterovirus-D68 (EV-D68) from 1 August to 31 December 2014 and compared to specimens collected from 1 October 2013 to 31 July 2014. Eighteen (1%) of 1,894 specimens were EV-D68-positive: 1/348 (0.3%) collected from October to December 2013 and 11/460 (2.4%) from October to December 2014, an eight-fold increase in detection rates (p=0.01), consistent with epidemic circulation in autumn 2014. The remaining EV-D68 detections were in September 2014 (6/37). Enhanced passive surveillance was also conducted on all inpatient and outpatient EV-D68 cases (n=211) detected at the BC provincial reference laboratory from 28 August to 31 December 2014. Incidence of hospitalisations was 3/100,000 overall and 21, 17, 4 and 1/100,000 among those<5, 5-9, 10-19 and ≥20-years-old with male-to-female ratios>1 among paediatric but not adult cases. Three cases in BC with comorbidity or co-infection died and five exhibited neurological features persisting >9 months. Active surveillance in outpatient and inpatient settings is needed from more areas and additional seasons to better understand EV-D68 epidemiology and potential at-risk groups for severe or unusual manifestations.

Recent Developments in Pediatric Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) is the most common acute infectious cause of death in children worldwide. Consequently, research into the epidemiology, diagnosis, treatment, and prevention of pediatric CAP spans the translational research spectrum. Herein, we aim to review the most significant findings reported by investigators focused on pediatric CAP research that has been reported in 2014 and 2015. Our review focuses on several key areas relevant to the clinical management of CAP. First, we will review recent advances in the understanding of CAP epidemiology worldwide, including the role of vaccination in the prevention of pediatric CAP. We also report on the expanding role of existing and emerging diagnostic technologies in CAP classification and management, as well as advances in optimizing antimicrobial use. Finally, we will review CAP management from the policy and future endeavors standpoint, including the influence of clinical practice guidelines on clinician management and patient outcomes, and future potential research directions that are in the early stages of investigation.

Global emergence of enterovirus D68: a systematic review

Since its discovery in California in 1962, reports of enterovirus D68 have been infrequent. Before 2014, infections were confirmed in only 699 people worldwide. In August, 2014, two paediatric hospitals in the USA reported increases in the number of patients with severe respiratory illness, with an over-representation in children with asthma. Shortly after, the authorities recognised a nationwide outbreak, which then spread to Canada, Europe, and Asia. In 2014, more than 2000 cases of enterovirus D68 were reported in 20 countries. Concurrently, clusters of children with acute flaccid paralysis of unknown cause were reported in several US states and in Europe. Enterovirus D68 infection was confirmed in some of the paralysed children, but not all. Complications in patients who were severely neurologically affected resemble those caused by poliomyelitis. In this paper we systematically review reports on enterovirus D68 to estimate its global epidemiology and its ability to cause respiratory infections and neurological damage in children. We extracted data from 70 papers to report on prevalence, symptoms, hospitalisation and mortality, and complications of enterovirus D68, both before and during the large outbreak of 2014. The magnitude and severity of the enterovirus D68 outbreak underscores a need for improved diagnostic work-up of paediatric respiratory illness, not only to prevent unnecessary use of antibiotics, but also to ensure better surveillance of diseases. Existing surveillance systems should be assessed in terms of capacity and ability to detect and report any upsurge of respiratory viruses such as enterovirus D68 in a timely manner, and focus should be paid to development of preventive measures against these emerging enteroviruses that have potential for severe disease.

3C Protease of Enterovirus D68 Inhibits Cellular Defense Mediated by Interferon Regulatory Factor 7

Human enterovirus 68 (EV-D68) is a member of the EV-D species, which belongs to the EV genus of the Picornaviridae family. Over the past several years, clusters of EV-D68 infections have occurred worldwide. A recent outbreak in the United States is the largest one associated with severe respiratory illness and neurological complication. Although clinical symptoms are recognized, the virus remains poorly understood. Here we report that EV-D68 inhibits innate antiviral immunity by downregulation of interferon regulatory factor 7 (IRF7), an immune factor with a pivotal role in viral pathogenesis. This process depends on 3C(pro), an EV-D68-encoded protease, to mediate IRF7 cleavage. When expressed in host cells, 3C(pro) targets Q167 and Q189 within the constitutive activation domain, resulting in cleavage of IRF7. Accordingly, wild-type IRF7 is fully active. However, IRF7 cleavage abrogated its capacity to activate type I interferon expression and limit replication of EV-D68. Notably, IRF7 cleavage strictly requires the protease activity of 3C(pro). Together, these results suggest that a dynamic interplay between 3C(pro) and IRF7 may determine the outcome of EV-D68 infection.

IMPORTANCE

EV-D68 is a globally emerging pathogen, but the molecular basis of EV-D68 pathogenesis is unclear. Here we report that EV-D68 inhibits innate immune responses by targeting an immune factor, IRF7. This involves the 3C protease encoded by EV-D68, which mediates the cleavage of IRF7. These observations suggest that the 3C(pro)-IRF7 interaction may represent an interface that dictates EV-D68 infection.

Respiratory Infections by Enterovirus D68 in Outpatients and Inpatients Spanish Children

BACKGROUND

The incidence of enterovirus D68 (EV-D68) and the spectrum of clinical disease in children are not well known in European countries. We have designed a study with the objective of describing the clinical impact of EV-D68 detected in children with respiratory tract infections.

METHODS

As a part of a prospective study to identify the etiology and clinical characteristics of viral respiratory infections in children in Spain, we performed the analysis of the cases of EV infections in all children hospitalized in a secondary hospital in Madrid, during the epidemic respiratory season 2012-2013. A second group of samples was corresponded to infants of the same area, with ambulatory respiratory infection or asymptomatic. Phylogenetic EV-D68 analysis was made using the viral protein 1 gene (VP1). Clinical data of EV-D68 patients were compared with those infected by rhinovirus in the same period and population.

RESULTS

The study population consisted of 720 patients corresponding to 399 episodes of hospitalization for respiratory causes, 44 episodes of ambulatory respiratory infections and 277 children determined as a healthy control group. A total of 22 patients were positive for EVs (3.05%), and 12 of them were specifically typed as EV-D68 (11/443 respiratory infections, 2.5%). The most frequent diagnosis in the 10 hospitalized children with EV-D68 detection was recurrent wheezing. Hypoxia was present in 70% of cases, but admission in the intensive care unit was not required. No neurological signs or symptoms were observed. One patient had an ambulatory mild bronchiolitis and another was asymptomatic. No differences were found with rhinovirus infections except less duration of hypoxia and fever in EV-D68 group.

CONCLUSIONS

EV-D68 infections were detected in 3.05% of respiratory studied samples (2.5% of admissions). The infection was associated with wheezing episodes with hypoxia. No admissions to intensive care unit or neurological symptoms were found.

Rhinovirus, Coronavirus, Enterovirus, and Bocavirus After Hematopoietic Cell Transplantation or Solid Organ Transplantation

Respiratory viral infections represent a significant cause of morbidity and mortality in immunocompromised hosts. Newer molecular detection assays have allowed for the characterization of several respiratory viruses not previously recognized as having significant clinical impact in the immunocompromised population. Human rhinoviruses are the most common respiratory viruses detected in the upper respiratory tract of hematopoietic cell transplant and lung transplant recipients, and evidence on the impact on clinical outcomes is mounting. Other respiratory viruses including enteroviruses (EVs), coronaviruses (CoVs), and bocavirus may also contribute to pulmonary disease; however, data is limited in the immunocompromised population. Further studies are needed to define the epidemiology, risk factors, and clinical outcomes of these infections; this data will help inform decisions regarding development of antiviral therapy and infection prevention strategies.

Molecular Evolution and Intraclade Recombination of Enterovirus D68 during the 2014 Outbreak in the United States

In August 2014, an outbreak of enterovirus D68 (EV-D68) occurred in North America, causing severe respiratory disease in children. Due to a lack of complete genome sequence data, there is only a limited understanding of the molecular evolution and epidemiology of EV-D68 during this outbreak, and it is uncertain whether the differing clinical manifestations of EV-D68 infection are associated with specific viral lineages. We developed a high-throughput complete genome sequencing pipeline for EV-D68 that produced a total of 59 complete genomes from respiratory samples with a 95% success rate, including 57 genomes from Kansas City, MO, collected during the 2014 outbreak. With these data in hand, we performed phylogenetic analyses of complete genome and VP1 capsid protein sequences. Notably, we observed considerable genetic diversity among EV-D68 isolates in Kansas City, manifest as phylogenetically distinct lineages, indicative of multiple introductions of this virus into the city. In addition, we identified an intersubclade recombination event within EV-D68, the first recombinant in this virus reported to date. Finally, we found no significant association between EV-D68 genetic variation, either lineages or individual mutations, and a variety of demographic and clinical variables, suggesting that host factors likely play a major role in determining disease severity. Overall, our study revealed the complex pattern of viral evolution within a single geographic locality during a single outbreak, which has implications for the design of effective intervention and prevention strategies.

IMPORTANCE

Until recently, EV-D68 was considered to be an uncommon human pathogen, associated with mild respiratory illness. However, in 2014 EV-D68 was responsible for more than 1,000 disease cases in North America, including severe respiratory illness in children and acute flaccid myelitis, raising concerns about its potential impact on public health. Despite the emergence of EV-D68, a lack of full-length genome sequences means that little is known about the molecular evolution of this virus within a single geographic locality during a single outbreak. Here, we doubled the number of publicly available complete genome sequences of EV-D68 by performing high-throughput next-generation sequencing, characterized the evolutionary history of this outbreak in detail, identified a recombination event, and investigated whether there was any correlation between the demographic and clinical characteristics of the patients and the viral variant that infected them. Overall, these results will help inform the design of intervention strategies for EV-D68.

Enterovirus D68 Infection

First described in 1962 in children hospitalized for pneumonia and bronchiolitis, the Enterovirus D68 (EV-D68) is an emergent viral pathogen. Since its discovery, during the long period of surveillance up to 2005, EV-D68 was reported only as a cause of sporadic outbreaks. In recent years, many reports from different countries have described an increasing number of patients with respiratory diseases due to EV-D68 associated with relevant clinical severity. In particular, an unexpectedly high number of children have been hospitalized for severe respiratory disease due to EV-D68, requiring intensive care such as intubation and mechanical ventilation. Moreover, EV-D68 has been associated with acute flaccid paralysis and cranial nerve dysfunction in children, which has caused concerns in the community. As no specific antiviral therapy is available, treatment is mainly supportive. Moreover, because no vaccines are available, conventional infection control measures (i.e., standard, for contacts and droplets) in both community and healthcare settings are recommended. However, further studies are required to fully understand the real importance of this virus. Prompt diagnosis and continued surveillance of EV-D68 infections are essential to managing and preventing new outbreaks. Moreover, if the association between EV-D68 and severe diseases will be confirmed, the development of adequate preventive and therapeutic approaches are a priority.

Prevalence and Phylogenetic Characterization of Enterovirus D68 in Pediatric Patients with Acute Respiratory Tract Infection in Thailand

Enterovirus D68 (EV-D68) is associated with severe lower respiratory tract infection and neurological abnormalities including acute myelitis and cranial nerve dysfunction. To determine whether an increased incidence of EV-D68 occurs in Southeast Asia, we retrospectively tested specimens collected from Thai pediatric patients who were less than 5 years of age and presented with acute respiratory tract infections between 2012 and 2014. Reverse transcription-polymerase chain reaction and nucleotide sequencing of the 5'-UTR/VP2 region were used to identify EV-D68. We also examined the epidemiological pattern of EV-D68 since 2009, when it was first identified in Thailand, and compiled records of clinical manifestations in children with confirmed EV-D68 infection. From 837 samples, 5 samples (0.6%) tested positive for EV-D68. All patients presented with viral pneumonia and required hospitalization. Phylogenetic analysis of the VP4/VP2 regions revealed that EV-D68 strains circulating in Thailand between 2012 and 2014 were closely related to strains reported in Japan, United Kingdom, China, and France. Continued surveillance of probable EV-D68-associated severe respiratory tract infection and the development of a rapid diagnostic test for EV-D68 are essential in supporting awareness and facilitating disease prevention and control.

Whole-Genome Sequence Analysis Reveals the Enterovirus D68 Isolates during the United States 2014 Outbreak Mainly Belong to a Novel Clade

In the late summer and the fall of 2014, the United States experienced an unprecedented outbreak of enterovirus D68 (EV-D68) infections. During the outbreak, we collected nasopharyngeal swab specimens from patients in the Lower Hudson Valley of New York. Here, we conduct a retrospective study on the genomic diversity of EV-D68 strains. We first employ a metagenomic shotgun sequencing protocol on a total of 93 clinical samples, including 21 negative controls, the results of which allow assembly of 20 EV-D68 genomes, six complete and 14 near-complete. We then investigate their genetic relationships, along with additional 20 EV-D68 strains having whole-genome sequences publicly available. Our comparative genomic analysis uncovers that the majority (26/29) of EV-D68 strains circulating in the 2014 outbreak differ significantly from prior ones, have a main feature of three variables, C1817T, C3277A, and A4020G, and belong to a new clade. C3277A causes amino acid substitution T860N in the protease 2A^pro cleavage site between VP1 and 2A, whereas A4020G causes S1108G in a 3C^pro cleavage site between 2B and 2C. The two functional mutations may alter the proteases’ cleavage efficiency, leading to increased rate of viral replication and transmission. These provide insights into the evolution of epidemic EV-D68 strains.

Clinical severity of pediatric respiratory illness with enterovirus D68 compared with rhinovirus or other enterovirus genotypes

BACKGROUND

Enterovirus D68 (EV-D68) resulted in a reported increase in the number of children needing hospital or critical care admission because of respiratory insufficiency during 2014. It remains unclear, however, whether EV-D68 infections were more severe than rhinovirus or non-EV-D68 enterovirus infections.

METHODS

We evaluated consecutive children presenting to a pediatric hospital between Aug. 1 and Oct. 31, 2014, with positive nasopharyngeal swabs for rhinovirus or enterovirus that were sent automatically for EV-D68 testing. We compared characteristics and outcomes of patients with EV-D68 with those with rhinovirus or non-EV-D68 enterovirus in a matched cohort study.

RESULTS

A total of 93/297 (31.3%) of rhinovirus or enterovirus samples tested positive for EV-D68, and it was possible to compare 87 matched pairs. Children with EV-D68 infection were more likely to have difficulty breathing (odds ratio [OR] 3.00, 95% confidence interval [CI] 1.47-6.14). There was no significant difference in admission to the critical care unit or death among children with EV-D68 infection compared with those with other rhinovirus or enterovirus infections (adjusted OR 1.47, 95% CI 0.61-3.52). Children with EV-D68 infection were more often admitted to hospital, but not significantly so (adjusted OR 2.29, 95% CI 0.96-5.46).

INTERPRETATION

Enterovirus D68 seems to be a more virulent pulmonary pathogen than rhinovirus or non-EV-D68 enterovirus, but we did not find a significant difference in death or need for critical care.

Replication and Inhibitors of Enteroviruses and Parechoviruses

The Enterovirus (EV) and Parechovirus genera of the picornavirus family include many important human pathogens, including poliovirus, rhinovirus, EV-A71, EV-D68, and human parechoviruses (HPeV). They cause a wide variety of diseases, ranging from a simple common cold to life-threatening diseases such as encephalitis and myocarditis. At the moment, no antiviral therapy is available against these viruses and it is not feasible to develop vaccines against all EVs and HPeVs due to the great number of serotypes. Therefore, a lot of effort is being invested in the development of antiviral drugs. Both viral proteins and host proteins essential for virus replication can be used as targets for virus inhibitors. As such, a good understanding of the complex process of virus replication is pivotal in the design of antiviral strategies goes hand in hand with a good understanding of the complex process of virus replication. In this review, we will give an overview of the current state of knowledge of EV and HPeV replication and how this can be inhibited by small-molecule inhibitors.