Bovine Respiratory Syncytial Virus

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 husbandry 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