LESIONS IN LAMBS EXPERIMENTALLY INFECTED WITH BOVINE RESPIRATORY SYNCYTIAL VIRUS

An experimental model was designed to characterize lesions in the lung of lambs inoculated with bovine respiratory syncytial virus (BRSV). 2 5 Merino lambs of both sexes, with a live weight of 17+/-3 Kg, receive d an intratracheal inoculation of 20 ml saline solution containing 1.2 6x10(6) TCID50 BRSV (strain NMK-7) per ml. Lambs were laughtered 1, 3, 7, 11 and 15 postinoculation days (PID), and histopathological, immun ohistochemical and electron microscopic studies were performed. Result s reflected a series of lesions, the most noteworthy of which were bro nchiolitis obliterants with destruction of the mucociliary apparatus, the presence of syncytial cells in alveoli and a progressive interstit ial reaction. BRSV antigen was detected in lung samples. These changes might be expected to decrease the efficiency of respiratory tract def ence mechanisms, rendering the lung parenchyma susceptible to opportun ist bacterial infection.