[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Other viruses and prions](https://durgical.com/en/microbiology/groups/other-viruses-and-prions/) › Borna disease virus 1

# 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.

Updated Nov 13, 2026

Also called: BoDV-1, bornavirus

## Quick facts

**Type**
Virus · [Other viruses and prions](https://durgical.com/en/microbiology/groups/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

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Enveloped negative-sense RNA virus that replicates in the nucleus
- Reservoir: bicoloured white-toothed shrew in central Europe
- Rare human encephalitis, almost always fatal
- Diagnosis by serology and PCR; brain tissue most reliable
- Link to psychiatric illness was claimed in the past but is not established

## 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) →](https://durgical.com/en/conditions/viral-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

## Memory aid

"Born in the nucleus, carried by the shrew": Borna is the RNA virus that copies itself inside the nucleus, and its keeper is a small shrew.

## 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.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/borna-disease-virus-1/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 3

- [Rabies virus](https://durgical.com/en/microbiology/rabies-virus/)
- [West Nile virus](https://durgical.com/en/microbiology/west-nile-virus/)
- [Hendra and Nipah viruses](https://durgical.com/en/microbiology/hendra-and-nipah-viruses/)

## Related conditions 1

- [Viral encephalitis (herpes simplex encephalitis)](https://durgical.com/en/conditions/viral-encephalitis/)

[← Back to the group: Other viruses and prions](https://durgical.com/en/microbiology/groups/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](https://wwwnc.cdc.gov/eid/article/27/5/20-4490_article) (CDC, Emerging Infectious Diseases, 2021); [Borna Virus](https://ages.at/en/human/disease/pathogens-from-a-to-z/borna-virus) (Austrian Agency for Health and Food Safety (AGES), 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/borna-disease-virus-1/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/borna-disease-virus-1/