Borna disease virus

Borna Disease Virus

Structure of the Borna disease virus nucleoprotein.

Borna disease virus (BDV) is a member of the Bornaviridae family, which is part of the order Mononegavirales. It is a non-segmented, negative-strand RNA virus that primarily infects the central nervous system of warm-blooded animals. BDV is known for causing neurological disorders in a variety of animal hosts, including horses, sheep, and birds.

Virology

BDV is an enveloped virus with a spherical shape. Its genome is approximately 8.9 kb in length and encodes six proteins: the nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), polymerase (L), and an accessory protein (X). The virus replicates in the nucleus of infected cells, which is unusual for RNA viruses.

Genome Organization

The BDV genome is organized into six open reading frames (ORFs). The nucleoprotein (N) is responsible for encapsidating the viral RNA, forming the ribonucleoprotein complex. The phosphoprotein (P) acts as a cofactor for the viral polymerase (L), which is responsible for RNA synthesis. The matrix protein (M) is involved in virus assembly and budding, while the glycoprotein (G) mediates viral entry into host cells.

Pathogenesis

BDV is known for its ability to cause encephalitis in infected hosts. The virus primarily targets neurons, leading to neurological symptoms such as ataxia, behavioral changes, and paralysis. In horses, the disease is known as "Borna disease," characterized by severe neurological dysfunction and often leading to death.

Host Range

BDV has a broad host range, infecting various species of mammals and birds. In addition to horses and sheep, BDV has been detected in cats, dogs, and even humans, although its role in human disease remains controversial.

Epidemiology

Borna disease is endemic in certain regions, particularly in parts of Europe. The virus is transmitted through direct contact with infected animals or their secretions. The exact mechanism of transmission is not fully understood, but it is believed to involve the olfactory route.

Diagnosis and Treatment

Diagnosis of BDV infection is typically based on clinical signs and confirmed through laboratory tests such as RT-PCR and serological assays. There is currently no specific antiviral treatment for BDV infection, and management focuses on supportive care and symptomatic treatment.

Prevention

Preventive measures include minimizing contact with infected animals and implementing biosecurity protocols in endemic areas. Vaccination strategies are under investigation but are not yet available.

Related Pages

• Bornaviridae
• Encephalitis
• RNA virus
• Mononegavirales