Encephalomyocarditis virus Impairs the Blood-Brain Barrier by Degrading Tight Junction Proteins via AKT3-Dependent Autophagic and Apoptotic Pathways

The blood-brain barrier (BBB) is a critical anatomical barrier that maintains the homeostasis of the central nervous system (CNS), and tight junctions (TJs) are the key structural basis for its barrier function. Encephalomyocarditis virus (EMCV), a typical neurotropic virus, can induce severe encephalitis in some host. However, the molecular mechanisms by which EMCV compromises and crosses the BBB remain poorly understood, which hinders the development of effective therapeutic strategies. In this study, we systematically investigated the mechanisms of EMCV-induced BBB injury using mouse infection and in vitro cell models. Key findings: EMCV infection causes severe encephalitis and marked brain pathological damage in mice. In vivo and in vitro experiments confirm that EMCV impairs BBB integrity and increases permeability by downregulating tight junction (TJ) proteins (occludin, ZO-1) and inducing inflammation. AKT kinase is dynamically regulated during EMCV infection (early activation, reduced phosphorylation after 4 h), coinciding with TJ protein reduction. AKT inhibition decreases TJ proteins, while AKT3 silencing exacerbates EMCV-induced BBB disruption and enhances virus-triggered apoptosis/autophagy. Treatment with autophagy inhibitor CQ or apoptosis inhibitor Z-VAD-FMK attenuates TJ protein degradation, reduces BBB permeability, and inhibits viral translocation in hCMEC/D3 cells and in vitro BBB models. Collectively, EMCV downregulates AKT signaling, relieving its inhibition on autophagy and apoptosis, thereby promoting TJ protein degradation and facilitating viral BBB penetration. This study comprehensively elucidates the multidimensional molecular mechanisms of EMCV-induced BBB injury, which not only fills the gap in the current understanding of EMCV neurotropism and pathogenicity but also provides a important theoretical basis for the development of targeted therapeutic strategies against EMCV-induced encephalitis.