ABSTRACT
A selected panel of six monoclonal antibodies (mAbs) against Maedi-Visna virus (MVV), recognising the core proteins (p27 and p15) and the envelope protein (gp105) of MVV, was tested using different unmasking techniques on paraffin embedded lung samples of a seropositive sheep. Only three mAbs were chosen, according to their strong reactivity. mAbs 1A7, 1B6 and 4B3 were employed in an immunohistochemical trial focused on the diagnosis of the lungs of 26 sheep with progressive pulmonary distress. These mAbs demonstrated MVV in 21 out of 26 cases including lymphoid interstitial pneumonia (LIP) and pulmonary adenomatosis. In only nine cases did all three mAbs react positively with the same sample. The sensitivity of immunohistochemical diagnosis of Maedi pneumonia can be increased by using mAbs 1A7, 4B3 and 1B6 together; that is a panel of mAbs direct against the envelope (gp105) and capsid (p27) viral proteins. The positive signal was focal and confined to the cytoplasm of bronchoalveolar epithelial cells and alveolar-interstitial macrophages. The results suggest that this panel of mAbs is useful to confirm severe LIP lesions such as Maedi pneumonia, to demonstrate Maedi infections in mild LIP, to demonstrate MVV in mixed pulmonary changes, and to investigate the pathogenesis of Maedi-Visna.
Subject(s)
Antibodies, Monoclonal/immunology , Lung/virology , Pneumonia, Progressive Interstitial, of Sheep/virology , Viral Core Proteins/analysis , Viral Envelope Proteins/analysis , Visna-maedi virus/isolation & purification , Adenomatosis, Pulmonary/virology , Animals , Antibodies, Viral/immunology , Antibody Specificity , Chronic Disease , Immunohistochemistry , Lung/pathology , Paraffin Embedding , Pneumonia, Progressive Interstitial, of Sheep/diagnosis , Pneumonia, Progressive Interstitial, of Sheep/pathology , Pneumonia, Progressive Interstitial, of Sheep/physiopathology , Sheep , Viral Core Proteins/immunology , Viral Envelope Proteins/immunologyABSTRACT
Sheep respiratory infections appear as differing clinical syndromes. Mild, acute infections are usually due to parainfluenza 3 (PI3) virus. A mild but chronic respiratory problem in lambs under 1 year old is thought to be caused by Mycoplasma ovipneumoniae probably in association with Pasteurella and PI3. Acute bacterial pneumonia usually results from infection with Pasteurella of biotype A. Infection with PI3 can initiate invasion by Pasteurella. Bordetella parapertussis infection has also been implicated. Serotypes of biotype T P. haemolytica cause an acute septicaemia. Stressful management practices may be a predisposing factor. Chronic proliferative pneumonia results from infection by retroviruses of pulmonary adenomatosis or maedi-visna. Both infections have incubation periods extending into years. The former produces fatal tumorous masses in the lungs. Diagnostic tests are being actively sought. Maedi-visna can present as several clinical problems, frequently as an insidious but fatal proliferative pneumonia.
