Effect of viral dose on experimental pneumonia caused by aerosol exposure of calves to bovine herpesvirus 1 and Pasteurella haemolytica.
The effect of various aerosol doses of bovine herpesvirus 1, followed four days later by aerosol exposure to a constant level of Pasteurella haemolytica, was studied in 16 crossbred Hereford range calves. A Collision nebulizer was used to generate aerosols from virus suspensions with concentrations of 10(8.2) (high), 10(5.2) (moderate) or 10(2.2) (low) TCID50/mL. The bacterial suspension contained 10(7) colony forming units/mL. Control calves exposed only to P. haemolytica developed no pulmonary lesions. Calves in the low, moderate and high virus exposure groups developed lobular areas of atelectasis; in addition, one calf in the moderate and all four in the high virus exposure group developed fibrinous pneumonia. One of the latter calves died. The 50% effective dose for fibrinous pneumonia under these experimental conditions was 10(6.0) TCID50 bovine herpesvirus 1/mL of suspension in the nebulizer reservoir, and approximately 10(4.0) infectious units inhaled per calf.
D000336:Aerosols; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology* / Q000473:pathology; D006564:Herpesviridae / Q000472:pathogenicity*; D006566:Herpesviridae Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D007928:Lethal Dose 50; D008168:Lung / Q000473:pathology; D010325:Pasteurella / Q000472:pathogenicity*; D010326:Pasteurella Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D011024:Pneumonia, Viral / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*
D000336:Aerosols