A Mouse Model of Enterovirus D68 Infection for Assessment of the Efficacy of Inactivated Vaccine.

In recent years, enterovirus D68 (EVD68) has been reported increasingly to be associated with severe respiratory tract infections and acute flaccid myelitis (AFM) in children all over the world. Yet, no effective vaccines or antiviral drugs are currently available for EVD68. Although several experimental animal models have been developed, immunogenicity and protective efficacy of inactivated EVD68 vaccines has not been fully evaluated. To promote the development of vaccines, we established an Institute of Cancer Research (ICR) suckling mouse model of EVD68 infection in this study. The results showed that ICR neonatal mice up to about nine days of age were susceptible to infection with EVD68 clinical strain US/MO/14-18947 by intraperitoneal injection. The infected mice exhibited progressive limb paralysis prior to death and the mortality of mice was age- and virus dose-dependent. Tissue viral load analysis showed that limb muscle and spinal cord were the major sites of viral replication. Moreover, histopathologic examination revealed the severe necrosis of the limb and juxtaspinal muscles, suggesting that US/MO/14-18947 has a strong tropism toward muscle tissues. Additionally, ß-propiolactone-inactivated EVD68 vaccine showed high purity and quality and induced robust EVD68-specific neutralizing antibody responses in adult mice. Importantly, results from both antisera transfer and maternal immunization experiments clearly showed that inactivated EVD68 vaccine was able to protect against lethal viral infection in the mouse model. In short, these results demonstrate the successful establishment of the mouse model of EVD68 infection for evaluating candidate vaccines against EVD68 and also provide important information for the development of inactivated virus-based EVD68 vaccines.

Surveillance and laboratory detection for non-polio enteroviruses in the European Union/European Economic Area, 2016.

Enteroviruses (EVs) cause severe outbreaks of respiratory and neurological disease as illustrated by EV-D68 and EV-A71 outbreaks, respectively. We have mapped European laboratory capacity for identification and characterisation of non-polio EVs to improve preparedness to respond to (re)-emerging EVs linked to severe disease. An online questionnaire on non-polio EV surveillance and laboratory detection was submitted to all 30 European Union (EU)/European Economic Area (EEA) countries. Twenty-nine countries responded; 26 conducted laboratory-based non-polio EV surveillance, and 24 included neurological infections in their surveillance. Eleven countries have established specific surveillance for EV-D68 via sentinel influenza surveillance (n = 7), typing EV-positive respiratory samples (n = 10) and/or acute flaccid paralysis surveillance (n = 5). Of 26 countries performing non-polio EV characterisation/typing, 10 further characterised culture-positive EV isolates, whereas the remainder typed PCR-positive but culture-negative samples. Although 19 countries have introduced sequence-based EV typing, seven still rely entirely on virus isolation. Based on 2015 data, six countries typed over 300 specimens mostly by sequencing, whereas 11 countries characterised under 50 EV-positive samples. EV surveillance activity varied between EU/EEA countries, and did not always specifically target patients with neurological and/or respiratory infections. Introduction of sequence-based typing methods is needed throughout the EU/EEA to enhance laboratory capacity for the detection of EVs.

Enterovirus D68 in Critically Ill Children: A Comparison With Pandemic H1N1 Influenza.

OBJECTIVE: In 2014, the Unites States experienced an outbreak of enterovirus D68 associated with severe respiratory illness. The clinical characteristics associated with severe illness from enterovirus D68 during this outbreak compared with those associated with the 2009 H1N1 influenza virus outbreak are unknown. DESIGN AND SETTING: In this retrospective cohort study, we characterized the clinical features of children with enterovirus D68 admitted to the PICU between August 1, 2014, and November 1, 2014, and compared them with critically ill children infected with H1N1 influenza during the pandemic admitted between May 1, 2009, and January 31, 2010. PATIENTS: PICU patients. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Ninety-seven severely ill children with enterovirus D68 infections were compared with 68 children infected with H1N1 influenza during the 2009 pandemic. Children with enterovirus D68 were more likely to have asthma (62% vs 23%; p < 0.001) and present with reactive airway disease exacerbations, with greater receipt of albuterol (94% vs 49%) and steroids (89% vs 40%; p < 0.0001 for both). Although more children with enterovirus D68 were admitted to the ICU compared with those with H1N1 influenza, they had a shorter hospital length of stay (4 vs 7 d; p < 0.0001), with lower intubation rates (7% vs 44%), vasopressor use (3% vs 32%), acute respiratory distress syndrome (3% vs 24%), shock (0% vs 16%), and death (0% vs 12%; p < 0.05 for all). Compared with children with other enteroviruses and rhinoviruses, children with enterovirus D68 were more likely to have a history of asthma (64% vs 45%) or multiple prior wheezing episodes (54% vs 34%; p < 0.01 for both). CONCLUSIONS: Critically ill children with enterovirus D68 were more likely to present with reactive airway disease exacerbations, whereas children with H1N1 influenza were more likely to present with pneumonia. Compared with the pandemic H1N1 influenza outbreak, the enterovirus D68 outbreak resulted in more children requiring admission to the ICU, but was associated with less severe outcomes.

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.