Bovine Immunodeficiency Virus
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Description
Bovine Imunodeficiency Virus (BIV) is a Lentivirus (non-oncogenic), a genus of the Retroviridae family. BIV causes a persistent viral infection in cattle, and has been reported in the US, Canada,Europe, Pakistan, Korea, Japan, New Zealand, Australia and several other countries. The virus is morphologically, antigenetically and genetically related to HIV. It was first isolated in 1969 from a cow with a wasting syndrome.
Pathogenesis
The mechanism of transfer is not well known,but the following possibilites are being researched :
- Transplacental
- Transmammary
- Vertical transfer through infected Semen (e.g. Artificial insemination)
Clinical Signs
The virus was originally isolated in 1969 from an 8 year old Holstein cow in the US with lymphocytosis and lymphadenopathy. Bovine immunodeficiency Virus has been associated with the folowing signs:
- Decreased milk yield
- Clinical immunodeficiency
- Encephalitis
- Bovine paraplegic syndrome
- Skin infections
- Emaciation
Immunocompromised cattle, arising from BIV infection, can develop secondary diseases associated with stress (e.g. parturition or environmental conditions) or sytemic disease. It may also be responsible for a poor antibody response to viral vaccines in calves.
Diagnosis
There are difficulties in the isolation of BIV from clincial cases. Serological tests such as immunoflorescence and western blot have ben used to identify the virus although virus isolation from these cases has been unsuccessful. Diagnosis by PCR remains the most sensitive test at present.
Treatment and Control
The Incidence of Bovine immunodeficiency virus appears to be low (1%) although can reach >15 % in some herds. Due to the unkown prevelance of the virus in most herds, prevention and control methods are not widely practiced. Treatment is symptomatic.
References
- Merck & Co (2008) The Merck Veterinary Manual (Eighth Edition) Merial
- Quinn, P.J., Markey, B.K., Carter, M.E., Donnelly, W.J., Leonard, F.C. (2007) Veterinary Microbiology and Microbial Disease Blackwell Publishing
- Marie-Claude St-Louis, Mihaela Cojocariu and Denis Archambault (2004). The molecular biology of bovine immunodeficiency virus: a comparison with other lentiviruses. Animal Health Research Reviews 5, pp 125-143