Effect of infection with bovine respiratory syncytial virus on pulmonary clearance of an inhaled antigen in calves

Objective—To evaluate the effect of infection with bovine respiratory syncytial virus (BRSV) on clearance of inhaled antigens from the lungs of calves. Animals—Eleven 6- to 8-week-old Holstein bull calves. Procedures—Aerosolized 99mtechnetium (99mTc)-labeled diethylene triamine pentacetate (DTPA; 3 calves), commonly used to measure integrity of the pulmonary epithelium, and 99mTc-labeled ovalbumin (OA; 8 calves), commonly used as a prototype allergen, were used to evaluate pulmonary clearance before, during, and after experimentally induced infection with BRSV or sham inoculation with BRSV. Uptake in plasma (6 calves) and lung-efferent lymph (1 calf) was examined. Results—Clearance of 99mTc-DTPA was significantly increased during BRSV infection; clearance of 99mTc-OA was decreased on day 7 after inoculation. Clearance time was correlated with severity of clinical disease, and amounts of 99mTc-OA in plasma and lymph were inversely correlated with clearance time. Minimum amounts of 99mTc-OA were detected at...