Respiratory syncytial virus-induced chronic bronchiolitis in experimentally infected calves

Human (RSV) and bovine (BRSV) respiratory syncytial virus cause similar inf ections of the lower respiratory tract. Therefore, experimentally infected calves are suited to the study of RSV-induced chronic bronchiolitis. Colost rum-fed calves aged 17-24 days were successfully infected with BRSV. BRSV s train 375 was applied as an aerosol on 4 consecutive days. Clinical symptom s were already evident on the Ist day after infection. The calves were necr opsied 12 weeks after the first infection. Focal severe chronic bronchiolit is with atelectasis and focal bronchiolitis obliterans were demonstrated. T he bronchiolar lumina were filled with secretion. Transmission electron mic roscopy revealed an alteration of the ciliogenesis and partial loss of cili a. Immunhistochemically virus P protein could still be detected, mainly in the epithelial cells of the inflamed bronchioli.