Difference between revisions of "Bovine Respiratory Syncytial Virus"

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== Introduction ==
 
  
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Bovine Respiratory Syncitial Virus ('''BRSV''') is a respiratory condition in cattle that is more serious than [[Bovine Parainfluenza - 3|PI-3]]. It replicates in nasal epithelium and then disperses throughout the upper respiratory tract to the bronchial tree. Here, syncytia form and further spread into the bronchioles occurs.
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Outbreaks of RSV associated disease usually occur associated with winter housing and also during periods of stress such as mixing of calves and transport. The virus can contribute to [[Enzootic Pneumonia - Calves|calf enzootic pneumonia]].
 
  
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Subclinical reinfections are important in spreading disease and more than 70% of cattle in the UK have antibodies to BRSV.
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====Pathogenesis====
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*More serious than [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
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== Classification ==  
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*Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]
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*Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
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BRSV's Baltimore Classification is V, ssRNA negative sense virus, and is a part of the Orthopneumovirus genus. It is an enveloped virus, utilizing fusion proteins to facilitate cellular fusion and syncytium formation.
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*Syncytia form -> shed into bronchioles
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*Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle
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== Signalment ==
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====Epidemiology====
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**Subclinical reinfections are important in spreading disease
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This virus can occur as part of the [[Enzootic Pneumonia - Calves|calf pneumonia syndrome]] along with [[Bovine Parainfluenza - 3|Parainflunza]] and [[Infectious Bovine Rhinotracheitis|Herpesvirus (IBR)]] as well as the bacteria [[Mannheimia haemolytica|''Mannheimia'']], [[:Category:Mycoplasmas|''Mycoplasmas'']] and [[Pasteurella multocida|''Pasturella'']].
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**More than 70% of cattle in the UK have antibodies to BRSV
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====Diagnosis====
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It can cause disease in adult cattle too however, it is more severe in young stock.
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*Diseased lung tissue from dead animals or centrifuged cells from lung lavage
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*Virus is too fragile for cell culture isolation (often inactivated in transport)
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== Clinical Signs ==
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*Antigen detection by ''' immunocytochemistry''' for intracytoplasmic viral inclusions containing labelled viral protein
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*Serology: 4-fold rise in ELISA antibody in paired serum samples from several animals
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Clinical signs include [[Pulmonary Emphysema|emphysema]] and [[Pulmonary Oedema|oedema]]. In adult cattle, you may see a drop in milk yield.
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====Control====
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*Improve husbansry as in [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
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== Diagnosis ==
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*Vaccines are available but not effective as need to stimulate [[Lymphocytes - WikiBlood#Cytotoxic CD8+|cytotoxic T-cells]]
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====Secondary Concerns====
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Often when in combination with other viral agents and bacteria then diagnosis is presumptive due to number of animal affected and the age and circumstances of these (housed etc). A dose of [[antibiotics]] is usually given and an effect is often seen quickly.
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*<small>'''Reference''': Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95</small>
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If the animal has succumbed to the disease a post mortem can be performed to aid diagnosis. Diseased lung tissue from dead animals or centrifuged cells from lung lavage can be used for this. The virus is too fragile for cell culture isolation (often inactivated in transport).
 
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Grossly on post mortem, one will see cranioventral [[atelectasis]] and consolidation, interstitial emphysema, which is more prominent in the caudal lung lobes. The results from bronchoconstriction which results in airway obstruction - this constriction is thought to arise from mast cell degranulation and histamine release.
 
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Histologically, one may see acute [[bronchiolitis]], characteristic of the bronchiolar response is the formation of syncytial giant cells (formed by proliferating bronchiolar epithelial cells which may contain intracytoplasmic inclusion bodies). The alveolar epithelium is sometimes affected. The bronchioles are often obstructed by exudate and these may later become obliterated by the fibrous tissue of organisation.
 
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Antigen detection by '''immunocytochemistry''' for intracytoplasmic viral inclusions containing labelled viral protein can also be performed as well as serology. A 4-fold rise in ELISA antibody in paired serum samples from several animals is indicative of the disease.
 
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== Treatment and Control ==
 
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Treatment with antibiotics is often used to treat secondary infections and lessen clinical signs and help the body focus on eliminating the virus.
 
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It is important to try to improve husbandry as in [[Bovine Parainfluenza - 3#Treatment and Control|PI-3]] in order to prevent the disease from occurring. Avoiding mixing of different aged calves is very important in the control of the disease, as is good hygiene.
 
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[[Vaccines]] are available but not effective as need to stimulate [[T cells#Cytotoxic_CD8.2B|cytotoxic T-cells]].
 
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== References ==
 
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<small>Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95</small>
 
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Andrews, A.H, Blowey, R.W, Boyd, H and Eddy, R.G. (2004) Bovine Medicine (Second edition), Blackwell Publishing
 
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Blood, D.C. and Studdert, V. P. (1999) Saunders Comprehensive Veterinary Dictionary (2nd Edition), Elsevier Science
 
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Divers, T.J. and Peek, S.F. (2008) Rebhun's diseases of dairy cattle, Elsevier Health Scieneces
 
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Radostits, O.M, Arundel, J.H, and Gay, C.C. (2000) Veterinary Medicine: a textbook of the diseases of cattle, sheep, pigs, goats, Elsevier Health Sciences
 
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{{review}}
 
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{{OpenPages}}
 
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[[Category:Pneumovirinae]] [[Category:Cattle_Viruses]] [[Category:Expert_Review - Farm Animal]] [[Category:Respiratory_Viral_Infections]]
 
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[[Category:Respiratory Diseases - Cattle]]
 

Revision as of 18:54, 13 October 2008


 This article is still under construction.


Infectious agents and parasitesWikiBugs Banner.png
VIRUSES
PARAMYXOVIRIDAE




Pathogenesis

  • More serious than PI-3
  • Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]
  • Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
  • Syncytia form -> shed into bronchioles
  • Complications include emphysema and oedema, drop in milk yield in adult cattle

Epidemiology

    • Subclinical reinfections are important in spreading disease
    • More than 70% of cattle in the UK have antibodies to BRSV

Diagnosis

  • Diseased lung tissue from dead animals or centrifuged cells from lung lavage
  • Virus is too fragile for cell culture isolation (often inactivated in transport)
  • Antigen detection by immunocytochemistry for intracytoplasmic viral inclusions containing labelled viral protein
  • Serology: 4-fold rise in ELISA antibody in paired serum samples from several animals

Control

  • Improve husbansry as in PI-3
  • Vaccines are available but not effective as need to stimulate cytotoxic T-cells

Secondary Concerns

  • Reference: Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95
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