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.


METHODS
Eleven 6- to 8-week-old Holstein bull calves.


METHODS
Aerosolized (99m)technetium ((99m)Tc)-labeled diethylene triamine pentacetate (DTPA; 3 calves), commonly used to measure integrity of the pulmonary epithelium, and (99m)Tc-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 (99m)Tc-DTPA was significantly increased during BRSV infection; clearance of (99m)Tc-OA was decreased on day 7 after inoculation. Clearance time was correlated with severity of clinical disease, and amounts of (99m)Tc-OA in plasma and lymph were inversely correlated with clearance time. Minimum amounts of (99m)Tc-OA were detected at time points when pulmonary clearance of (99m)Tc-OA was most delayed.


CONCLUSIONS
BRSV caused infection of the respiratory tract with peak signs of clinical disease at 7 or 8 days after inoculation. Concurrently, there was a diminished ability to move inhaled protein antigen out of the lungs. Prolonged exposure to inhaled antigens during BRSV infection may enhance antigen presentation with consequent allergic sensitization and development of chronic inflammatory lung disease.


CONCLUSIONS
Infection of humans with respiratory syncytial virus early after birth is associated with subsequent development of allergic asthma. Results for BRSV infection in these calves suggested a supportive mechanism for this scenario.
Gershwin
Laurel J
LJ
Department of Pathology, Microbiology, & Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Gunther
Robert A
RA
Hornof
William J
WJ
Larson
Richard F
RF
D000485:Allergens / Q000493:pharmacokinetics*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001784:Blood Gas Analysis / Q000662:veterinary; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000378:metabolism* / Q000821:virology*; D008297:Male; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology / Q000378:metabolism / Q000662:veterinary* / Q000821:virology; D018112:Respiratory Syncytial Virus, Bovine / Q000276:immunology*; D012140:Respiratory Tract Diseases / Q000276:immunology / Q000378:metabolism / Q000662:veterinary* / Q000821:virology; D012588:Scintillation Counting / Q000662:veterinary; D016284:Technetium Tc 99m Pentetate / Q000097:blood / Q000493:pharmacokinetics; D017201:Virus Shedding / Q000276:immunology
D000485:Allergens; D000914:Antibodies, Viral; D016284:Technetium Tc 99m Pentetate