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.

Background: Coxsackievirus A16 (CA16) is one of the neurotropic pathogen that has been associated with severe neurological forms of hand, foot, and mouth disease (HFMD), but its pathogenesis is not yet clear. The limited host range of CA16 make the establishment of a suitable animal model that can recapitulate the neurological pathology observed in human HFMD more difficult. Because the human scavenger receptor class B, member 2 (hSCARB2) is a cellular receptor for CA16, we used transgenic mice bearing human SCARB2 and nasally infected them with CA16 to study the pathogenicity of the virus. Methods: Coxsackievirus A16 was administered by intranasal instillation to groups of hSCARB2 transgenic mice and clinical signs were observed. Sampled at different time-points to document and characterize the mode of viral dissemination, pathological change and immune response of CA16 infection. Results: Weight loss and virus replication in lung and brain were observed in hSCARB2 mice infected with CA16, indicating that these animals could model the neural infection process. Viral antigens were observed in the alveolar epithelia and brainstem cells. The typical histopathology was interstitial pneumonia with infiltration of significant lymphocytes into the alveolar interstitial in lung and diffuse punctate hemorrhages in the capillaries of the brainstem. In addition, we detected the expression levels of inflammatory cytokines and detected high levels of interleukin IL-1β, IL-6, IL-18, and IFN-γ in nasal mucosa, lungs and brain tissues. Conclusions: The hSCARB2-transgenic mice can be productively infected with CA16 via respiratory route and exhibited a clear tropism to lung and brain tissues, which can serve as a model to investigate the pathogenesis of CA16 associated respiratory and neurological disease.

The mechanisms underlying pathological changes in the central nervous system (CNS) following Coxsackievirus A16 (CV-A16) infection have not yet been elucidated. IFN-γ-inducible protein-10 (IP-10) is often used as a predictive factor to monitor early virus infection. It has also been reported that IP-10 plays a pivotal role in neuroinflammation. In this study, we aimed to explore the role of IP-10 in the neuropathogenesis of CV-A16 infection. We observed that the level of IP-10, as well as the TLR3-TRIF-TRAF3-TBK1-NF-κB and RIG-I/MDA5-MAVS-TRAFS-TBK1-NF-κB pathways, which are the upstream of IP-10, were significantly elevated during the course of CV-A16 infection. This increase was accompanied by an increase in a series of inflammatory cytokines at different time-points during CV-A16 infection. To determine whether IP-10 influences BBB integrity, we examined junctional complexes. Our results revealed that the expression levels of Claudin5, Occludin, ZO-1 and VE-Cadherin were notably decreased in CV-A16-infected HUVECs, but these indicators were restored in CV-A16-infected HUVECs with Eldelumab treatment. Nevertheless, IP-10 is only a chemokine that primarily traffics CXCR3-positive immune cells to inflammatory sites or promotes the production of inflammatory cytokines. Therefore, the interactions between IP-10 and inflammatory cytokines were evaluated. Our data revealed that IP-10 mediated the production of TNF-α, which was also observed to change the junctional complexes. Moreover, in a suckling mouse model, IP-10 and TNF-α treatments exacerbated clinical symptoms, mortality and pathological changes in the brain of CV-A16-infected mice, but Anti-IP-10 and Anti-TNF-α treatments alleviated these changes. Our data also revealed that IP-10 may be detected early in CV-A16 infection, whereas TNF-α was detected late in CV-A16 infection, and the production of TNF-α was also found to be positively correlated with IP-10. In addition, IP-10 and TNF-α were observed to reduce junctional complexes and enhance virus entry into the CNS. Taken together, this study provides the first evidence that CV-A16 activates the IP-10/TNF-α regulatory axis to cause BBB damage and accelerate the formation of neuroinflammation in infected hosts, which not only provides a new understanding of the neuropathogenesis caused by CV-A16, but also offers a promising target for the development of CV-A16 antiviral drugs.

Background: Rabies remains a fatal zoonotic disease caused by rabies virus (RABV), posing substantial global health challenges. Current vaccine production faces challenges in manufacturing efficiency and cost-effectiveness. The RABV glycoprotein (RABV-G) serves as the key antigen for eliciting protective immunity. Methods: We developed a novel QS21+CpG-adjuvanted RABV-G subunit vaccine and systematically compared its performance against three control formulations: mRNA vaccine composed of H270P-targeted mutation packaged in lipid nanoparticles (LNP), named LNP-mRNA-G-H270P, commercial inactivated vaccine, and alum-adjuvanted RABV-G subunit vaccine. Results: The result show that the G+QS21+CpG subunit vaccine elicited superior humoral immunity, as evidenced by significantly higher RABV-G-specific IgG titers and virus-neutralizing antibody responses compared to all other groups. The LNP-mRNA-G-H270P vaccine maintained its expected cellular immunity advantage, with the G+QS21+CpG group exhibiting moderately reduced but still significant levels of IFN-γ-secreting splenocytes and levels of IL-2 in the supernatant of spleen cells, as well as IFN-γ-producing CD4+ T cells. Both LNP-mRNA-G-H270P and G+QS21+CpG vaccine groups provided 100% protection against lethal challenge (50LD₅₀ RABV). Conclusions: These findings provide novel vaccine/adjuvant strategies for rabies while elucidating platform-specific immunogenicity patterns, offering critical insights for pathogens requiring balanced humoral/cellular immunity.

We aimed to demonstrate whether coxsackievirus A10 (CV-A10) perturbed the fusion between autophagosomes and lysosomes to cause viral nonlytic spread and inflammatory cytokine release at the blood-brain barrier (BBB), thereby contributing to neuropathological damage. CV-A10-induced autophagic secretory pathway at the cellular level was examined using western blot, immunofluorescence, and flow cytometry methods. Then, the mechanism of autophagic secretory pathway in the neuropathogenesis of CV-A10 infection was demonstrated by constructing a suckling mouse model and combining behavioral, pathological, and molecular biological methods. The expression levels of autophagic secretory pathway-related proteins, extracellular inflammatory cytokines, and viral particles were significantly increased during CV-A10 infection. Moreover, 3-methyladenine significantly impeded the levels of autophagic secretory pathway-related proteins and the release of inflammatory cytokines or viruses; GW4869 and chloroquine partially suppressed these changes, whereas bafilomycin A1 had no obvious effects on these changes, implying that the autophagic secretory pathway without endosome or lysosome involvement might represent a new mode of inflammatory cytokine release and virus spread from intracellular to extracellular environments. Finally, an in vivo suckling mouse model further found that treatment with GW4869 significantly relieved the clinical symptoms and mortality of CV-A16-infected mice and inhibited the spread of the virus and the release of inflammatory cytokines. Our findings provide the first evidence that CV-A10 might trigger the autophagic secretory pathway by limiting autophagosome-lysosome fusion to complete the transmembrane nonlytic transmission of the virus at the BBB and the secretion of inflammatory cytokines, ultimately accelerating neuropathological damage. IMPORTANCE: This study provided the first evidence that coxsackievirus A10 (CV-A10) might use the autophagic secretory pathway for nonlytic intercellular release to complete transmembrane transmission at the blood-brain barrier and inflammatory cytokine secretion to accelerate the formation of neuroinflammation in infected hosts, which not only gave us a new understanding of the neuropathogenesis caused by CV-A10 but also offered a promising target to develop CV-A10 antiviral drugs.