The effect of parainfluenza virus type 3 and Pasteurella haemolytica on oxygen-dependent and oxygen-independent bactericidal mechanisms of ovine pulmonary phagocytic cells

Contribution of respiratory burst activity to innate immune function and the effects of disease status and agent on chemiluminescence responses by ruminant phagocytes in vitro

The mechanisms of interaction between phagocytes and different bacteria that help resolve lung infections or contribute to lung pathology are poorly defined. Alveolar phagocytes (resident macrophages and recruited neutrophils) make a major contribution to innate immunity by mounting a respiratory burst that helps kill internalised bacteria. However, this ability may be altered during or after exposure to infection. This review considers the application and limitations of a variety of analytical methods for oxygen-dependent mechanisms of respiratory burst in phagocytes initiated by soluble and particulate activators. Particular reference is given to the study in vitro of phagocytes from healthy and diseased ruminants during either natural infection with Mycobacterium avium paratuberculosis or experimental infection with Pasteurella multocida or Mannheimia haemolytica.

Pneumonia following experimental bronchial obstruction in sheep

Five of 7 sheep in which the bronchi supplying the right apical lobe of the lung were obstructed with a cottonwool plug developed pneumonia. Large numbers of bacteria were isolated from 4 of the 5 pneumonic lungs. Only minor pulmonary lesions, which are common in sheep on pasture, were observed in 5 sham operation and 5 control sheep. These results support a role for airway obstruction in compromising the antimicrobial defences of the lungs in naturally occurring bacterial pneumonias of sheep.