Antigenicity

  • The virus cannot be grown in culture, although it can be seen by EM on tumor cells of infected sheep

Pathogenesis

  • Causes a proliferation of alveolar lining cells, producing massive amounts of fluid
  • Proliferative foci project into alveoli and bronchi and from slow-growing tumors
  • Death occurs between 3-4 years of age

Clinical signs:

  • Low exercise tolerance
  • Gradual weight loss
  • Dyspnoea
  • Coughing
  • Nasal fluid discharges during wheelbarrow test
  • Secondary bacterial infection by Pasteurella hemolytica often precipitates death
  • PM reveals fawn-gray tumor (for more see here)

Epidemiology

  • Found in 25% of pneumonia cases in Scotland
  • Absent in USA, common in UK

Diagnosis

  • Electron microscopy on lung biopsy

Control

  • Cull clinically affected animals