Neuronal Apoptotic Bodies Facilitate Japanese Encephalitis Virus Infection and Pathogenicity.

Japanese encephalitis (JE) caused by Japanese encephalitis virus (JEV) infection remains one of the major types of viral encephalitis. The mechanisms underlying JEV infection and pathogenesis have not been fully elucidated, resulting in the absence of specific therapies for JE. Neuronal apoptosis is a well-established outcome of JEV infection; however, its secondary contributions to JE pathogenesis remain largely uncharacterized. Here, we demonstrate that apoptotic bodies (ApoBDs) derived from JEV-infected neurons package infectious JEV particles, facilitating viral transmission between neurons, as well as between neurons and microglia. Further investigations revealed that microglia predominantly internalize the ApoBDs via phagocytosis and dynamin 2-dependent endocytosis. Moreover, lipids, rather than nucleic acids or proteins, are the key pro-inflammatory constituents of ApoBDs. Subsequent studies demonstrated that ApoBDs activate microglia through the TLR2/TLR4-NF‑κB signalling. In vivo experiments showed that JEV-loaded ApoBDs elicit significantly more severe neuroinflammation and pathological lesions compared to ApoBD-free virions. These findings underscore the non-negligible contribution of neuron-derived ApoBDs to JEV pathogenesis, providing valuable insights for the development of novel therapeutic strategies against JE.