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.

Epidemiological and Clinical Insights into the Enterovirus D68 Upsurge in Europe 2021-2022 and Emergence of Novel B3-Derived Lineages, ENPEN Multicentre Study.

Enterovirus D68 (EV-D68) infections are associated with severe respiratory disease and acute flaccid myelitis (AFM). The European Non-Polio Enterovirus Network (ENPEN) aimed to investigate the epidemiological and genetic characteristics of EV-D68 infections and its clinical impact during the fall-winter season of 2021-2022. From 19 European countries, 58 institutes reported 10 481 (6.8%) EV-positive samples of which 1004 (9.6%) were identified as EV-D68 (including 852 respiratory samples). Clinical data were reported for 969 cases; 78.9% of infections were reported in children (0-5 years); and 37.9% of cases were hospitalized. Acute respiratory distress was commonly noted (93.1%) followed by fever (49.4%). Neurological problems were observed in 6.4% of cases including 6 diagnosed with AFM. Phylodynamic/Nextstrain and phylogenetic analyses based on 694 sequences showed the emergence of 2 novel B3-derived lineages, with no regional clustering. In conclusion, we describe a large-scale European EV-D68 upsurge with severe clinical impact and the emergence of B3-derived lineages.

Enterovirus D68 molecular and cellular biology and pathogenesis.

In recent years, enterovirus D68 (EV-D68) has advanced from a rarely detected respiratory virus to a widespread pathogen responsible for increasing rates of severe respiratory illness and acute flaccid myelitis (AFM) in children worldwide. In this review, we discuss the accumulating data on the molecular features of EV-D68 and place these into the context of enterovirus biology in general. We highlight similarities and differences with other enteroviruses and genetic divergence from own historical prototype strains of EV-D68. These include changes in capsid antigens, host cell receptor usage, and viral RNA metabolism collectively leading to increased virulence. Furthermore, we discuss the impact of EV-D68 infection on the biology of its host cells, and how these changes are hypothesized to contribute to motor neuron toxicity in AFM. We highlight areas in need of further research, including the identification of its primary receptor and an understanding of the pathogenic cascade leading to motor neuron injury in AFM. Finally, we discuss the epidemiology of the EV-D68 and potential therapeutic approaches.

Acute flaccid myelitis: cause, diagnosis, and management.

Acute flaccid myelitis (AFM) is a disabling, polio-like illness mainly affecting children. Outbreaks of AFM have occurred across multiple global regions since 2012, and the disease appears to be caused by non-polio enterovirus infection, posing a major public health challenge. The clinical presentation of flaccid and often profound muscle weakness (which can invoke respiratory failure and other critical complications) can mimic several other acute neurological illnesses. There is no single sensitive and specific test for AFM, and the diagnosis relies on identification of several important clinical, neuroimaging, and cerebrospinal fluid characteristics. Following the acute phase of AFM, patients typically have substantial residual disability and unique long-term rehabilitation needs. In this Review we describe the epidemiology, clinical features, course, and outcomes of AFM to help to guide diagnosis, management, and rehabilitation. Future research directions include further studies evaluating host and pathogen factors, including investigations into genetic, viral, and immunological features of affected patients, host-virus interactions, and investigations of targeted therapeutic approaches to improve the long-term outcomes in this population.

Molecular characterization of non-polio enteroviruses isolated from acute flaccid paralysis patients in Uganda.

Enteroviruses (EVs) are RNA viruses that can cause many clinical syndromes including acute flaccid paralysis (AFP). Within the global polio laboratory network, EVs are categorized either as polioviruses or non-polio enteroviruses (NPEVs). Specific NPEVs have been described in polio-like residual paralytic events in AFP patients. Retrospective analysis of 112 NPEV isolates from AFP patients was performed and thirty one NPEV types were identified of which 91% were Enterovirus B and 9% were Enterovirus A species. The NPEVs were distributed across the country with most patients in the eastern region (41/89; 46.1%). The highest proportion of patients were children less than 5 years (77/89; 86.5%) and male patients were more common (54/89; 60.7%). Echovirus 11 (11/89; 12.4%) was frequently observed and phylogenetic analysis of these sequences revealed high diversity. Coxsackievirus B5 (CV-B5), CV-B6, E21, and EV-B69 were only seen in patients with residual paralysis. Analyses of the EV-A71 sequence indicated a unique genogroup.

Genotyping of non-polio enteroviruses associated with acute flaccid paralysis in Thailand in 2013 and 2014.

BACKGROUND: Acute flaccid paralysis (AFP) surveillance was conducted as part of the World Health Organization's strategy for completely eradicating poliomyelitis and leaving non-polio enteroviruses NPEVs as one of the main potential causes of AFP. We aimed to detect NPEV in association with AFP. METHODS: We used 459 isolates reported to be Negative Polio and some NPEVs by the World Health Organization Polio Regional Reference Laboratory (Thailand), which had been obtained during polio surveillance programmes conducted in Thailand in 2013-2014. Of 459 isolates, 35 belonged to the genus Enterovirus by RT-PCR and genotyping by DNA sequencing. RESULTS: This study found 17 NPEV genotypes, with 3, 13 and 1 belonging to enterovirus (EV) species A (EV-A), EV-B, and EV-C, respectively. The EV-A types identified included coxsackievirus A2 (CA2), CA4, and EV71, typically associated with hand, foot and mouth diseases. EV-B is the most prevalent cause of AFP in Thailand, while CA21 was the only type of EV-C detected. The EV-B species (13/35; 76.5%) constituted the largest proportion of isolates, followed by EV-A (3/35; 17.6%) and EV-C (1/35; 5.9%). For the EV-B species, Echovirus (E) 30 and CVB were the most frequent isolates. E30, CVB, E14, and E6 were considered endemic strains. CONCLUSION: NPEVs, e.g. CA4, are reported for the first time in Thailand. Despite some limitations to this study, this is the first report on the circulation patterns of NPEVs associated with AFP in Thailand. AFP surveillance has unearthed many unknown NPEVs and, the cases of death due to AFP occur annually. Therefore, it is important to study NPEVs in the wake of the eradication of poliovirus in the context of the continued incidence of paralysis.

Disease Surveillance Investments and Administration: Limits to Information Value in Pakistan Polio Eradication.

In Pakistan, annual poliovirus investment decisions drive quantities of supplemental immunization campaigns districts receive. In this article, we assess whether increased spending on poliovirus surveillance is associated with greater likelihood of correctly identifying districts at high risk of polio with assignment of an elevated "risk ranking." We reviewed programmatic documents from Pakistan for the period from 2012-2017, recording whether districts had been classified as "high risk" or "low risk" in each year. Through document review, we developed a decision tree to describe the ranking decisions. Then, integrating data from the World Health Organization and Global Polio Eradication Initiative, we constructed a Bayesian decision network reflecting investments in polio surveillance and immunization campaigns, surveillance metrics, disease incidence, immunization rates, and occurrence of polio cases. We test these factors for statistical association with the outcome of interest-a change in risk rank between the beginning and the end of the one-year time period. We simulate different spending scenarios and predict their impact on district risk ranking in future time periods. We find that per district spending increases are associated with increased identification of cases of acute flaccid paralysis (AFP). However, the low specificity of AFP investment and the largely invariant ranking of district risk means that even large increases in surveillance spending are unlikely to promote major changes in risk rankings at the current stage of the Pakistan polio eradication campaign.

Contemporary Circulating Enterovirus D68 Strains Infect and Undergo Retrograde Axonal Transport in Spinal Motor Neurons Independent of Sialic Acid.

Enterovirus D68 (EV-D68) is an emerging virus that has been identified as a cause of recent outbreaks of acute flaccid myelitis (AFM), a poliomyelitis-like spinal cord syndrome that can result in permanent paralysis and disability. In experimental mouse models, EV-D68 spreads to, infects, and kills spinal motor neurons following infection by various routes of inoculation. The topography of virus-induced motor neuron loss correlates with the pattern of paralysis. The mechanism(s) by which EV-D68 spreads to target motor neurons remains unclear. We sought to determine the capacity of EV-D68 to spread by the neuronal route and to determine the role of known EV-D68 receptors, sialic acid and intracellular adhesion molecule 5 (ICAM-5), in neuronal infection. To do this, we utilized a microfluidic chamber culture system in which human induced pluripotent stem cell (iPSC) motor neuron cell bodies and axons can be compartmentalized for independent experimental manipulation. We found that EV-D68 can infect motor neurons via their distal axons and spread by retrograde axonal transport to the neuronal cell bodies. Virus was not released from the axons via anterograde axonal transport after infection of the cell bodies. Prototypic strains of EV-D68 depended on sialic acid for axonal infection and transport, while contemporary circulating strains isolated during the 2014 EV-D68 outbreak did not. The pattern of infection did not correspond with the ICAM-5 distribution and expression in either human tissue, the mouse model, or the iPSC motor neurons.IMPORTANCE Enterovirus D68 (EV-D68) infections are on the rise worldwide. Since 2014, the United States has experienced biennial spikes in EV-D68-associated acute flaccid myelitis (AFM) that have left hundreds of children paralyzed. Much remains to be learned about the pathogenesis of EV-D68 in the central nervous system (CNS). Herein we investigated the mechanisms of EV-D68 CNS invasion through neuronal pathways. A better understanding of EV-D68 infection in experimental models may allow for better prevention and treatment strategies of EV-D68 CNS disease.

Acute flaccid paralysis due to Echovirus 30 in an immunosuppressed transplant recipient.

An Italian 13-year-old boy immunosuppressed due to kidney transplant presented in November 2018 with acute flaccid paralysis with anterior horn cell involvement resembling the clinical, radiological, and laboratory features of poliomyelitis. Enterovirus was molecularly identified in cerebral spinal fluid and stool samples and the sequence analysis of the VP1 gene of enterovirus genome revealed the presence of Echovirus 30 both in CSF and in stool samples. Echovirus 30 is an emerging neurotropic virus able to cause outbreaks of aseptic meningitis and meningoencephalitis all over the world, but acute flaccid paralysis is not a classical manifestation. A 6-month follow-up revealed a poor outcome with severe motor deficits and only slight improvement in disability. Clinicians must be aware of the possible role of Echovirus 30 in acute flaccid paralysis and active surveillance should consider the possible influence of immunosuppression on the symptoms caused by the widening spectrum of enterovirus infections.

Molecular characterization of non-polio enteroviruses isolated from children with acute flaccid paralysis in IRAN, 2015-2018.

In addition to polioviruses, non-polio enteroviruses (NPEVs) are frequently isolated from patients with acute flaccid paralysis (AFP) worldwide. In polio-free countries, there have been expectations that with disappearing wild poliovirus from the community, the rate of AFP would decrease, but the increasing number of AFP cases proved this notion to be wrong. There are speculations that NPEVs might be the cause of increasing AFP rate. The aim of this study was to investigate frequency, genetic diversity, circulation patterns of NPEVs isolated from AFP cases in Iran from 2015 to 2018. Fifty-three NPEVs were isolated from stool specimens of AFP cases during four years of AFP surveillance. Nested PCR and VP1 sequencing revealed 20 NPEV types in which Echovirus 3 (13.2%), Echovirus 6 (13.2%), Echovirus 7 (7.5%), Echovirus 13 (7.5%) and Echovirus 21 (7.5%) were the most frequent. Coxsackie B viruses were isolated for the first time in AFP cases in Iran. The phylogenetic analysis of Echovirus 3 and Echovirus 6 revealed that Iranian echovirus strains belonged to the same cluster, indicating these viruses have been circulating in Iran for a long time. Compared to global Echovirus 3 and Echovirus 6 references, Echovirus 3 and Echovirus 6 strains detected in this study were closely related to Indian and Malaysia strains, respectively. The results of this study demonstrated a wide variety of NPEV types in Iranian patients, some of which had not been reported in previous studies. Moreover, this study highlights the need for NPEV surveillance in AFP cases.

Enterovirus D68 in a 6-year-old acute flaccid myelitis case in China, 2018: a case report.

BACKGROUND: Acute flaccid myelitis (AFM) are reported to be associated with enterovirus D68 infection. Though an increasing number of AFM cases were reported with EV-D68 infection in the US, few such cases have been found in China. CASE PRESENTATION: A 6-year-old boy presented with acute flaccid myelitis (AFM) involving left arm after fever and respiratory symptoms for 6 days. Computed Tomography (CT) revealed inflammation in both lungs and magnetic resonance imaging (MRI) of the brain and spine showed swelling in the left frontal lobe and brain stem. The patient was diagnosed with meningomyelitis. EV-D68 was detected from pharyngeal samples 36 days after the onset of the disease. CONCLUSION: We report the first EV-D68 infection in case of AFM in mainland China. AFM surveillance systems is recommended to be established in China to guide diagnosis, case reporting, and specimen collection and testing for better understanding its etiologies.

Neuromuscular presentations in patients with COVID-19.

COVID-19 is caused by the coronavirus SARS-CoV-2 that has an affinity for neural tissue. There are reports of encephalitis, encephalopathy, cranial neuropathy, Guillain-Barrè syndrome, and myositis/rhabdomyolysis in patients with COVID-19. In this review, we focused on the neuromuscular manifestations of SARS-CoV-2 infection. We analyzed all published reports on SARS-CoV-2-related peripheral nerve, neuromuscular junction, muscle, and cranial nerve disorders. Olfactory and gustatory dysfunction is now accepted as an early manifestation of COVID-19 infection. Inflammation, edema, and axonal damage of olfactory bulb have been shown in autopsy of patients who died of COVID-19. Olfactory pathway is suggested as a portal of entry of SARS-CoV-2 in the brain. Similar to involvement of olfactory bulb, isolated oculomotor, trochlear and facial nerve has been described. Increasing reports Guillain-Barrè syndrome secondary to COVID-19 are being published. Unlike typical GBS, most of COVID-19-related GBS were elderly, had concomitant pneumonia or ARDS, more prevalent demyelinating neuropathy, and relatively poor outcome. Myalgia is described among the common symptoms of COVID-19 after fever, cough, and sore throat. Duration of myalgia may be related to the severity of COVID-19 disease. Few patients had muscle weakness and elevated creatine kinase along with elevated levels of acute-phase reactants. All these patients with myositis/rhabdomyolysis had severe respiratory complications related to COVID-19. A handful of patients with myasthenia gravis showed exacerbation of their disease after acquiring COVID-19 disease. Most of these patients recovered with either intravenous immunoglobulins or steroids.

Acute flaccid myelitis temporally associated with rhinovirus infection: just a coincidence?

We report the case of a 3.6-year-old male child who developed progressive hyposthenia of the left lower limb. Symptoms were preceded by rhinitis, malaise, and fever. Brain and spinal magnetic resonance imaging revealed diffuse signal abnormalities compatible with a subacute myeloencephalitis. A diagnostic lumbar puncture was performed and followed by an empirical therapy including Acyclovir, Ceftriaxone, and Clarithromycin. The cerebrospinal fluid analysis revealed clear fluid, glucose, proteins, albumin within the reference range, and 144 leukocytes/mm3. Oligoclonal bands were absent and a search for viruses was negative. Wide microbiological surveillance was performed on surface swabs, blood, urine, and stool. Both nasal and pharyngeal swabs were positive for PicoRNAvirus: sequencing identified Rhinovirus A44. This virus has been detected in association with acute flaccid paralysis in only a few patients worldwide, whereas in the great majority of patients with acute flaccid paralysis other Enterovirus species were identified. The most appropriate therapeutic approach towards acute flaccid paralysis is still a matter of debate in the scientific community, with no current definitivere commendations available. With a combined immunosuppressive and anti-inflammatory therapy including intravenous immunoglobulins, intravenous Methylprednisolone, oral Prednisone, and oral Ibuprofen, we experienced a positive outcome both from the clinical point of view and from three-month follow-up imaging studies. Given the rarity and the complexity of this condition, additional studies are needed to better define the potential role of Rhinovirus A44 in the pathogenesis of the disease and the efficacy of any therapeutic measure in the management of acute flaccid paralysis.

Association of Enterovirus D68 with Acute Flaccid Myelitis, Philadelphia, Pennsylvania, USA, 2009-2018.

Acute flaccid myelitis (AFM) is a polio-like disease that results in paralysis in previously healthy persons. Although the definitive cause of AFM remains unconfirmed, enterovirus D68 (EV-D68) is suspected based on 2014 data demonstrating an increase in AFM cases concomitant with an EV-D68 outbreak. We examined the prevalence in children and the molecular evolution of EV-D68 for 2009-2018 in Philadelphia, Pennsylvania, USA. We detected widespread EV-D68 circulation in 2009, rare detections in 2010 and 2011, and then biennial circulation, only in even years, during 2012-2018. Prevalence of EV-D68 significantly correlated with AFM cases during this period. Finally, whole-genome sequencing revealed early detection of the B1 clade in 2009 and continued evolution of the B3 clade from 2016 to 2018. These data reinforce the need to improve surveillance programs for nonpolio enterovirus to identify possible AFM triggers and predict disease prevalence to better prepare for future outbreaks.

Acute Flaccid Myelitis: Characteristics and Outcomes of 2014 and 2016 Cases at a Single Center.

Acute flaccid myelitis (AFM) is a rare condition associated with spinal cord gray matter abnormalities and frequent persistent motor deficits in the limbs. We present our experience with the diagnosis, management, and outcomes of affected children in 2014 and 2016, emphasizing features that should trigger early consideration of AFM. Early viral testing may increase the rate of detecting associated viruses.

Acute flaccid myelitis and enterovirus D68: lessons from the past and present.

Acute flaccid myelitis is characterized by the combination of acute flaccid paralysis and a spinal cord lesion largely restricted to the gray matter on magnetic resonance imaging. The term acute flaccid myelitis was introduced in 2014 after the upsurge of pediatric cases in the USA with enterovirus D68 infection. Since then, an increasing number of cases have been reported worldwide. Whereas the terminology is new, the clinical syndrome has been recognized in the past in association with several other neurotropic viruses such as poliovirus.Conclusion: This review presents the current knowledge on acute flaccid myelitis with respect to the clinical presentation and its differential diagnosis with Guillain-Barré syndrome and acute transverse myelitis. We also discuss the association with enterovirus D68 and the presumed pathophysiological mechanism of this infection causing anterior horn cell damage. Sharing clinical knowledge and insights from basic research is needed to make progress in diagnosis, treatment, and prevention of this new polio-like disease. What is Known: • Acute flaccid myelitis (AFM) is a polio-like condition characterized by rapid progressive asymmetric weakness, together with specific findings on MRI • AFM has been related to different viral agents, but recent outbreaks are predominantly associated with enterovirus D68. What is New: • Improving knowledge on AFM must increase early recognition and adequate diagnostic procedures by clinicians. • The increasing incidence of AFM urges cooperation between pediatricians, neurologists, and microbiologists for the development of treatment and preventive options.

Increased detection of enterovirus A71 infections, Germany, 2019.

We report on the increased circulation of enterovirus A71 in Germany in 2019. Strains were mainly identified in hospitalised patients with suspected aseptic meningitis/encephalitis. Molecular analysis showed co-circulation of EV-A71 sub-genogroups C1 and C4, a signal for physicians and public health authorities to include/intensify EV diagnostic in patients showing signs of aseptic meningitis, encephalitis or acute flaccid paralysis/myelitis.