Examination of lung lesions in Parainfluenza-3 infections in ruminants with pathological and immunohistochemical methods

Parainfluenza 3 (PI3) infection is one of the most common viral respiratory diseases in domestic and wild ruminants. The most common finding is characteristic bronchointerstitial pneumonia. Concurrent viral and bacterial infections may exacerbate this condition and lead to fibrinopurulent-necrotic bronchopneumonia. The aim of this study was to investigate the histopathological findings of PI3 infection in ruminants, the release of mannose binding lectin (MBL) and surfactant protein B (SP-B) in lung tissue during inflammation, their role and importance in pathogenesis and their interrelationship. Paraffin-embedded lung tissue blocks were used from 30 ruminants with suspected viral pneumonia and 10 ruminants without lesions. Histopathologically, the acute destructive phase was observed in most cases (78%), whereas the chronic proliferative phase was observed in 4 cases (22%). Immunohistochemistry revealed anti-PI3 positivity in 15 animals (50%). In addition, MBL release was found to be high in acute cases but decreased in subacute or chronic cases. SP-B release was higher in subacute and chronic cases compared to acute cases. In conclusion, it was suggested that MBL release may be insufficient for recovery in cases of immunodeficiency or mixed infections, whereas early and accurate treatment could increase the chances of survival through the effects of SP-B.