Experimental infection of neonatal calves with neurovirulent bovine herpesvirus type 1.3.
A type of bovine herpesvirus, BHV-1.3, causes encephalitis in calves, whereas BHV-1.1 causes respiratory disease. Three colostrum-deprived calves and two colostrum-fed calves were inoculated with BHV-1.3 by intranasal aerosolization. Two colostrum-deprived calves were inoculated with BHV-1.1 by intranasal aerosolization. BHV-1.3-inoculated calves demonstrated severe encephalitis with minimal respiratory lesions, and BHV-1.1-inoculated calves demonstrated severe respiratory lesions and no clinical signs of neurologic disease. Calves fed colostrum that contained virus neutralizing antibodies were protected against neurologic disease. Colostrum-fed BHV-1.3-inoculated calves did not develop disease although they did become infected; virus was shed in respiratory secretions for 10-13 days postinoculation, similar to infected colostrum-deprived calves. BHV-1.3 was reactivated from a latent state from one colostrum-fed calf after administration of dexamethasone 60 days postinoculation. Histopathologic examination of the three colostrum-deprived BHV-1.3-inoculated calves revealed severe lesions of encephalitis. One of the two BHV-1.1-inoculated calves had one focal lesion of encephalitis. Virus was isolated from brain tissue of colostrum-deprived BHV-1.3-inoculated calves and from one BHV-1.1-inoculated calf. Immunohistochemical staining for BHV-1 antigen was observed in neurons from the colostrum-deprived BHV-1.3-inoculated calves.
Belknap
E B
EB
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins.
Collins
J K
JK
Ayers
V K
VK
Schultheiss
P C
PC
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000473:pathology; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D002478:Cells, Cultured; D003126:Colostrum / Q000276:immunology*; D004660:Encephalitis / Q000382:microbiology / Q000473:pathology / Q000662:veterinary*; D006566:Herpesviridae Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D007242:Herpesvirus 1, Bovine / Q000472:pathogenicity*