Borna disease virus (BoDV, Orthobornavirus; Bornaviridae), is the causative agent of Borna disease, mostly lethal polioencephalomyelitis that affects primarily horse and sheep but also and other mammals. It is ssRNA virus, that replicates within the nucleus of target cells, at first at the entry site, than it migrates intraaxonally towards the brain, cerebellum and medulla oblongata. The infection of the central nervous system results in severe neurological disorder that is caused primarily by the hosts cell-mediated immunopathological reactions. The clinical manifestations of the bornaviral diseases are highly variable. Thus, in addition to acute, lethal encephalitis, they can cause persistent neurologic disease associated with diverse behavioral changes. They also cause a severe retinitis resulting in blindness. The zoonotic potential of the virus has been a matter of an unresolved scientific dispute for decades. The impact of BDV on mental health still remains controversial. BoDV‑1 can induce encephalitis cases, establishing the infection as a potentially lethal zoonosis which can impact both immunocompromised and healthy individuals. Diagnosis can be made serologically (ELISA, IF, Western blot), but detection of antigen markers in peripheral white blood cells (ELISA, FACS) and/or in the brain combined with nucleic acid amplification (nested RT-PCR), is more profitable.