Human bornavirus encephalitis: Neuropathological insights from a rare but lethal disease

AIMS: This work aims at supporting structured neuropathological assessment and early case identification for human bornavirus encephalitis. It summarizes current neuropathological and immunopathogenic findings of infection with Borna disease virus 1 (BoDV-1) in humans, complemented by comparative data from animal dead-end hosts. MATERIALS AND METHODS: This narrative review is based on a targeted literature search in PubMed and Google Scholar. Of 114 identified records (PubMed: 62; Google Scholar: 52), 40 remained after duplicate removal. Following abstract and full-text screening, 16 studies, published between 1999 and 2025, were included. RESULTS: BoDV-1 encephalitis displays a largely uniform histopathological pattern, typically presenting as lymphocytic, sclerosing panencephalomyelitis with astroglial and microglial activation, and detection of intranuclear inclusions. In animals olfactory and limbic structures are predominantly affected, whereas in humans, the disease frequently extends to additional regions, particularly the basal ganglia. CONCLUSION: In both human and animal dead-end hosts, BoDV-1 encephalitis shows a consistent histomorphological profile that allows reliable recognition based on characteristic neuropathological features and distribution. Definitive diagnosis requires specific detection of BoDV-1, most commonly facilitated by immunohistochemistry.