Nasal Infection of Enterovirus D68 Leading to Lower Respiratory Tract Pathogenesis in Ferrets (Mustela putorius furo)

Abstract

Data from EV-D68-infected patients demonstrate that pathological changes in the lower respiratory tract are principally characterized by severe respiratory illness in children and acute flaccid myelitis. However, lack of a suitable animal model for EV-D68 infection has limited the study on the pathogenesis of this critical pathogen, and the development of a vaccine. Ferrets have been widely used to evaluate respiratory virus infections. In the current study, we used EV-D68-infected ferrets as a potential animal to identify impersonal indices, involving clinical features and histopathological changes in the upper and lower respiratory tract (URT and LRT). The research results demonstrate that the EV-D68 virus leads to minimal clinical symptoms in ferrets. According to the viral load detection in the feces, nasal, and respiratory tracts, the infection and shedding of EV-D68 in the ferret model was confirmed, and these results were supported by the EV-D68 VP1 immunofluorescence confocal imaging with α2,6-linked sialic acid (SA) in lung tissues. Furthermore, we detected the inflammatory cytokine/chemokine expression level, which implied high expression levels of interleukin (IL)-1a, IL-8, IL-5, IL-12, IL-13, and IL-17a in the lungs. These data indicate that systemic observation of responses following infection with EV-D68 in ferrets could be used as a model for EV-D68 infection and pathogenesis.

Neurotropism of Enterovirus D68 Isolates Is Independent of Sialic Acid and Is Not a Recently Acquired Phenotype

“…A transient viremia developed in ferrets after intranasal inoculation, and virus-specific RNA was detected in feces from infected animals, neither of which is observed during most human infections. No neurological disease developed, nor did virus replicate in this animal model of EV-D68 infection (60).…”

“…Four mouse models of EV-D68 infection have been established (13, 35, 59–61). One model examined the immune response within the respiratory tract elicited after intranasal inoculation with EV-D68 using 8- to 10-week-old wild-type BALB/c mice; however, no virus replication was observed in these animals (61).…”

Current status of enterovirus D68 worldwide and in Taiwan

“…These findings support that EV-D68 mostly causes respiratory illness. 35,37,38 EV-D68 also has tropism of motor nerve cells and may lead to neurological involvement (Table 3). 39…”

“…Animal study found that EV-D68 infection induces inflammation and diffuse alveolar hemorrhage in the lungs and leads to lung injury at the middle and late stages of infection. 38 Clinically, patients may have severe respiratory illness which needs hospitalization and even intensive care or ventilator support. 19,24 Common features of hospitalized patients include tachypnea, hypoxia, asthma attack, pneumonia or acute respiratory distress syndrome.…”

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

“…Previously Patel et al found that four to six week-old cotton rats were permissive to transient EVD68 replication following intranasal infection; however, the infectious virus was cleared from the nose and lung tissues 48 h post infection, and no clinical symptoms or death were observed in the rats [ 20 ]. Similarly, intranasal infection of EVD68 resulted in minimal clinical symptoms in ferrets [ 21 ]. Therefore, the two animal models are not suitable for evaluation of EVD68 vaccines and antiviral agents.…”