A mouse model of paralytic myelitis caused by enterovirus D68

Abstract

In 2014, the United States experienced an epidemic of acute flaccid myelitis (AFM) cases in children coincident with a nationwide outbreak of enterovirus D68 (EV-D68) respiratory disease. Up to half of the 2014 AFM patients had EV-D68 RNA detected by RT-PCR in their respiratory secretions, although EV-D68 was only detected in cerebrospinal fluid (CSF) from one 2014 AFM patient. Given previously described molecular and epidemiologic associations between EV-D68 and AFM, we sought to develop an animal model by screening seven EV-D68 strains for the ability to induce neurological disease in neonatal mice. We found that four EV-D68 strains from the 2014 outbreak (out of five tested) produced a paralytic disease in mice resembling human AFM. The remaining 2014 strain, as well as 1962 prototype EV-D68 strains Fermon and Rhyne, did not produce, or rarely produced, paralysis in mice. In-depth examination of the paralysis caused by a representative 2014 strain, MO/14-18947, revealed infectious virus, virion particles, and viral genome in the spinal cords of paralyzed mice. Paralysis was elicited in mice following intramuscular, intracerebral, intraperitoneal, and intranasal infection, in descending frequency, and was associated with infection and loss of motor neurons in the anterior horns of spinal cord segments corresponding to paralyzed limbs. Virus isolated from spinal cords of infected mice transmitted disease when injected into naïve mice, fulfilling Koch’s postulates in this model. Finally, we found that EV-D68 immune sera, but not normal mouse sera, protected mice from development of paralysis and death when administered prior to viral challenge. These studies establish an experimental model to study EV-D68-induced myelitis and to better understand disease pathogenesis and develop potential therapies.

Enteroviruses Remodel Autophagic Trafficking through Regulation of Host SNARE Proteins to Promote Virus Replication and Cell Exit

“…Neuroped., abstract). Though the link between EV-D68 and AFM is still under investigation, a mouse model fulfills Koch's postulates for virus as a cause of paralysis, suggesting that EV-D68 may be a cause of AFM cases (Hixon et al, 2017). EV-D68 remains relatively understudied, and much about the interactions between the cell and the virus has yet to be elucidated.…”

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

“…11,12 There is increasing evidence of an association between AFM and EV infection, but whether this association is related to direct viral invasion of the spinal cord, para-infectious autoimmune response to infection, or a combination of the two, remains unclear. 3,13,14 We did not find EV by PCR testing in cerebrospinal fluid from the 13 children that underwent lumbar puncture. We did, however, find evidence of EV infection in multiple other sites.…”

“…These concerns are based on historical data from human EV A71 outbreaks, in which steroids were felt to worsen clinical course, a murine model of EV D68-associated AFM that found mice treated with high-dose steroids had increased mortality compared with untreated mice, and older poliovirus data demonstrating accelerated poliovirus replication in chick embryos when treated with cortisone. 13,16,17 However, definitive evidence of an adverse effect has never been clearly shown in humans. These concerns, as well as a perceived lack of efficacy of methylprednisolone in 2016, led to changes in our internal treatment protocol in 2016 with more judicious use of steroids, primarily restricted to concern for spinal cord edema with risk of secondary injury.…”

Enterovirus D68–Associated Acute Flaccid Myelitis in Immunocompromised Woman, Italy

“…The case reported here is 1 of only a handful of cases in which the EV-D68 genome was evidenced in CSF and not only in respiratory specimens, suggesting a possible causal association between EV-D68 and neurologic disease in adults. Recent findings in a mouse model provide evidence of a specific tropism of EV-D68 for spinal cord motor neurons, suggesting that direct viral injury, rather than a postinfection immune-mediated process, is the most likely mechanism of neuronal cell loss and paralysis ( 13 ). The phylogenetic analysis indicates that the strain detected in the patient described here, like one recently detected in a child with neurologic illness ( 14 ), is genetically linked to those involved in the recent outbreak in the Netherlands ( 4 ).…”