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

Abstract

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, β-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.

A Novel Neutralizing Antibody Specific to the DE Loop of VP1 Can Inhibit EV-D68 Infection in Mice

“…EV-D68 causes infection and death in some reports of mouse infection models (38)(39)(40)(41). Thus, we evaluated the protective efficacy of A6-1 in 2-d-old suckling C57BL/6 mice.…”

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

“…Human AFM patients present with inflammation and the loss of motor neurons in the brain stem and spinal cord but do not show signs of generalized encephalitis (7,10). Consistent with this observation, studies with mouse models developed by several independent research groups have shown that infection by contemporary EV-D68 strains results in minimal replication within the brains of infected animals but robust replication in spinal cord and muscle tissue (17,41,42). In addition, motor pathways from the upper motor neurons of the brain to the lower motor neurons are anterograde connections.…”

Development and structural characterization of a two-MAb cocktail for delayed treatment of enterovirus D68 infections

“…The protective e cacy of anti-EV-D68 MAbs was evaluated in a previously established mouse model of EV-D68 infection 28 . For prophylactic e cacy evaluation, ve groups of newborn ICR mice (n = 12-14/group) were adminstered PBS, or a single dose (10 µg/g) of 2H12, 8F12, IgG2a isotype control (1C11), or IgG2b isotype control (1F4), respectively.…”

“…4). Inspection of the original micrographs of the EV-D68/8F12 Fab (abbreviated as EV-D68/8F12) complex indicated a high occupancy of the Fab on the capsid with a hedgehog-like appearance (distinct from the smooth spherical appearance of EV-D68 virion 18,28 ) ( Supplementary Fig. 4a).…”

“…MAb 2H12 differed signi cantly from 8F12 in their antigen-binding and neutralization pro les, yet they complemented each other in conferring broad-spectrum neutralization in vitro and cross-clade protection in vivo. Notably, the 2H12/8F12 antibody cocktail was able to effectively treat EV-D68-infected mice even when administered three days after viral challenge, a time point by which the virus has spread into the brain and spinal cord 28 . The atomic resolution (up to 2.9 Å) cryo-electron microscopy (cryo-EM) structures of EV-D68 virion in complex with 2H12 or 8F12 Fab show that both MAbs target the same previously unreported antigenic site located at the south rim of the canyon yet they exert distinct effects on EV-D68 virion stability, highlighting the uniqueness of this pair of MAbs.…”