GENERAL INTRODUCTION: BORNAVIRIDAE

BORNAVIRIDAE

A General Introduction has been added to each disease chapter in an attempt to give a brief updated overview of the taxonomic, biological and other characteristics of the virus family or group of bacteria /protozoa that cause disease in livestock and, where relevant, involve wildlife. As the text of the three-volume book Infectious Diseases of Livestock is currently under revision the Editors are aware that there are inconsistencies between the updated introductions to chapters and the content of the chapters themselves. Once the chapters have been updated – a process that is currently underway – these inconsistencies will be removed.

Bornaviridae viruses are classified as members of the Order Mononegavirales; however, the family contains only one genus, Bornavirus, that at present, includes seven species. These viruses infect humans, horses, sheep, cattle, rodents, birds and reptiles. Only two species of this genus are infections of mammals – Mammalian 1 bornavirus (the causative agent of Borna disease of horses (possibly also infecting sheep and cattle) that has two subspecies, BoDV-1 and BoDV-2 and Mammalian 2 bornavirus (formerly squirrel bornavirus 1). The remaining viruses are infections of birds or reptiles.

Characteristically infection with Bornaviruses is noncytolytic and persistent; transcription and replication occur in the host-cell nucleus.

There is evidence for two human deaths resulting from infection with squirrel bornavirus 1, i.e. it is potentially a fatal zoonotic infection. There have also been suspicions of human disease caused by Mammalain 1 bornavirus although definitive proof of pathogenicity for people is lacking.

Bornaviruses are spherical, enveloped and approximately 90 nm in diameter with an inner nucleocapsid 50-60 nm in diameter. The genome comprises a molecule of single-stranded, negative sense RNA that contains at least six overlapping open reading frames.

The virus is sensitive to heat, acidic environments, lipids solvents and common disinfectants.

References

  1. International Committee for Taxonomy of Viruses https://talk.ictvonline.org/taxonomy/
  2. (accession date: 26/05/2017)
  3. MACLACHLAN N.J. & DUBOVI, E.J. (eds.), 2016. Veterinary Virology, 5th edition, Academic Press.