Borna disease virus 1
- Virus
- Enveloped
- For completeness
A virus carried by a shrew in parts of central Europe. Spill-over to horses, sheep and rarely people causes brain inflammation that is almost always fatal.
Also called: BoDV-1, bornavirus
Quick facts
- Type
- Virus · Other viruses and prions
- Gram / shape
- Spherical
- Spread
- The exact route to humans is unclear
- Causes
- Severe · Borna disease in horses and sheep
- Treatment
- There is no proven antiviral or specific therapy
At a glance
- Shape
- Spherical
- Genome
- Single-stranded, negative-sense RNA, non-segmented
- Envelope
- Enveloped
- Family
- Bornaviridae (order Mononegavirales), species Mammalian 1 orthobornavirus
- Size
- About 70 to 130 nm
Morphology
- Unusual among RNA viruses that infect animals: it replicates and persists in the cell nucleus
- Non-cytolytic and highly neurotropic
- Related to variegated squirrel bornavirus 1 (VSBV-1), which infected people who bred exotic squirrels
Transmission
- Zoonotic spill-over from the bicoloured white-toothed shrew (Crocidura leucodon), which sheds virus in urine, faeces and saliva
- The exact route to humans is unclear; living in rural endemic areas is the common factor
- Organ transplantation from an infected donor has transmitted it
- No person-to-person spread in daily life; horses and sheep are dead-end hosts
Reservoir: Bicoloured white-toothed shrew (Crocidura leucodon) in endemic parts of Germany, Austria, Switzerland and Liechtenstein
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- Spreads along nerves to the brain and persists in neurons and glia
- Disease is largely immune-mediated: T cells attack infected brain cells, causing severe encephalitis
- In animals it causes Borna disease, a meningoencephalomyelitis with behaviour changes
Diseases it causes
- Severe, usually fatal BoDV-1 encephalitis Viral encephalitis (herpes simplex encephalitis) →
- Borna disease in horses and sheep (veterinary)
Clinical picture
- Fever, headache and behaviour change, then confusion, gait disturbance, seizures and coma
- Rapid course: death within weeks in almost all confirmed human cases
- Germany diagnoses only a few human cases a year, mostly in Bavaria
Diagnosis
- Suspect it in encephalitis of unknown cause in someone from an endemic rural area
- Serology (immunofluorescence screen, then confirmatory blot) plus RT-PCR
- CSF RT-PCR is often negative or weak; brain tissue is the most reliable sample
- MRI often shows basal ganglia and limbic involvement
Treatment
There is no proven antiviral or specific therapy: care is intensive and supportive.
Drug class only; doses and regimens are set by the clinician from the current guideline.
Prevention
- Avoid touching shrews and their droppings; wear gloves when disposing of dead shrews in endemic areas
- Screen organ donors with unexplained encephalitis
- No vaccine exists
Test yourself
Think of the answer, then tap the question to see it.
What animal is the natural reservoir of Borna disease virus 1?
The bicoloured white-toothed shrew (Crocidura leucodon).
What is unusual about where bornaviruses replicate?
They replicate in the cell nucleus, unlike most RNA viruses of animals.
Which sample most reliably confirms BoDV-1 encephalitis?
Brain tissue; CSF PCR is often negative or only weakly positive.
Connections
← Back to the group: Other viruses and prions
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Active Case Finding of Current Bornavirus Infections in Human Encephalitis Cases of Unknown Etiology, Germany, 2018–2020 (CDC, Emerging Infectious Diseases, 2021); Borna Virus (Austrian Agency for Health and Food Safety (AGES), 2026).
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Representative model, for educational purposes only.