84. Borna disease, avian diseases caused by bornaviruses.

Question 1

Bornaviruses info?

Answer 1

Bornaviruses

• Bornaviridae, Bornavirus genus
• Ss RNA, enveloped
• Low resistance
• Replication in nucleus of nerve cells
• Encephalomyelitis
• Nerve cell degeneration

• Hosts: mammals, birds, reptiles

Question 2

Borna disease Occurrence?

Answer 2

Borna disease

Etiology

• Uniform virus, 1 serotype, enveloped
• Occurrence
• Borna 1894-1896, Germany, Austria, Switzerland, Italy, France, Sweden, USA, Japan
• More widespread seropositivity
• Free virions produced in low number
• Virus remains cell bound
• Low resistance
• Horse, sheep, cattle, goat, rabbit, cat, human, rodent, lab mice, rats, shrew-mouse, voles

Question 3

Epidemiology of Borna disease?

Answer 3

Epidemiology

• Reservoir

• Shrew-mouse, rodents
• Frequently asymptomatic infection
• Shed in saliva, urine, faeces

• Infection

• Transmission with lymphoid cells
• Nasal discharge, saliva
• Pasture
• Contact with deceased animals
• Eating infected animals (carnivores)
• Endemic (only in certain parts of village)
• Spring-Summer
• Sporadic in horses, massive in sheep
• Low morbidity, High lethality
• Subclinical infection common

Question 4

Pathogenesis of Borna disease?

Answer 4

Pathogenesis

1. Infection: aerosol, PO
2. Nasal mucous membrane ➝ N. Olfactorius ➝ Brain (long persisted infection)
3. Replication in grey material of brain
4. Spread: cell-to-cell ➝ slow spread within host ➝ into spinal cord ➝ eye and organs along nerves (appears in discharge: saliva, nasal discharge, urine, faeces)
5. Antibody production (do not inhibit viral replication)
6. Long carriage of virus
7. Many asymptomatic infections
8. Pathological lesions ➝ meningoencephalitis, slow degeneration
9. Reasons for pathological lesions
   - Infected cells + T-cell cytotoxic reaction
   - Death of cells of limbic system
10. 90% animals with clinical signs die soon

Question 5

Clinical signs of Borna disease?

Answer 5

Clinical signs

• Horse

• Incubation: 1-3 months
• Appears slowly
• Depression, excitation, spasms, salivation, weakness, hyperaesthesia, apathy, somnolence, dullness, slowing down, ataxia, balance
• Lameness, death

• Sheep, cattle, cat ➝ ataxia, spasm, paralysis

Question 6

Pathology of Borna disease?

Answer 6

Pathology

• There are no gross pathological lesions
• Histopathology
• Meningeal plethora, brain oedema
• Polioencephalomyelitis (brain stem, limbic system)

Question 7

Diagnosis of Borna disease?

Answer 7

Diagnosis

• Epidemiology, clinical signs, pathology, histology (inclusion bodies)
• Virus detection ➝ PCR, IF, ELISA, isolation
• Serology (blood, liquor) ➝ IF, ELISA, blot
• DD: rabies, viral encephalitis of horses, tetanus, scrapie, BSE

Question 8

Prevention and Public health aspects of borna disease?

Answer 8

Prevention

• Diseased animals ➝ isolation, killing
• Infected herd
• Closed herd, removal of infected animals
• Vaccination

‣ Attenuated vaccine

‣ Vector vaccine

Public health aspects

• Psychiatric patients ➝ depression, schizophrenia ➝ seropositivity, presence of virus
• Way of infection unknown
• Rodent connection, Germany: squirrel breeders

Question 9

Proventricular dilation disease Ethiology and epidemiology?

Answer 9

Proventricular Dilatation Disease

Etiology

• Worldwide
• Avian bornaviruses
• Parrot, canary, wild living birds
• Several genotypes

Epidemiology

• Parrot breeding units
• Virus shed in faeces
• Disease in young and adult birds

Question 10

Pathogenesis of Proventricular dilation disease?

Answer 10

Pathogenesis

1. Infection PO
2. Viraemia

• • Brain, spinal cord, peripheral nerves, eye ➝ inflammation, perivascular infiltration, damage of nerve cells
• • Alimentary signs because of peripheral nerve inflammation

3. Shedding in urine and faeces

Question 11

Clinical signs of Proventricular dilation disease?

Answer 11

Clinical signs

• 2-4 weeks old, also adult birds ➝ alimentary and CNS signs
• Alimentary ➝ anorexia, difficulties swallowing, regurgitation, undigested feed in faeces
• Neurological ➝ ataxia, weakness, convulsion
• Diseased animals die

Question 12

Pathology and diagnosis of Proventricular dilation diagnosis?

Answer 12

Pathology

• Atrophy and dilatation of proventriculus
• Histology ➝ encephalomyelitis, inflammation and degeneration of peripheral nerves

Diagnosis

• Epidemiology, clinical signs, pathology
• Virus detection ➝ PCR, IF, immunohistochemistry, virus isolation
• Antibody detection ➝ iIF, immune blot
• Control ➝ general epidemiological measures