Eb. Belknap et al., EXPERIMENTAL-INFECTION OF NEONATAL CALVES WITH NEUROVIRULENT BOVINE HERPESVIRUS TYPE-1.3, Veterinary pathology, 31(3), 1994, pp. 358-365
A type of bovine herpesvirus, BHV-1.3, causes encephalitis in calves,
whereas BHV-1.1 causes respiratory disease. Three colostrum-deprived c
alves and two colostrum-fed calves were inoculated with BHV-1.3 by int
ranasal aerosolization. Two colostrum-deprived calves were inoculated
with BHV-1.1 by intranasal aerosolization. BHV-1.3-inoculated calves d
emonstrated 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 con
tained virus neutralizing antibodies were protected against neurologic
disease. Colostrum-fed BHV-1.3-inoculated calves did not develop dise
ase although they did become infected; virus was shed in respiratory s
ecretions for 10-13 days postinoculation, similar to infected colostru
m-deprived calves. BHV-1.3 was reactivated from a latent state from on
e colostrum-fed calf after administration of dexamethasone 60 days pos
tinoculation. Histopathologic examination of the three colostrum-depri
ved BHV-1.3-inoculated calves revealed severe lesions of encephalitis.
One of the two BHV-1.1-inoculated calves had one focal lesion of ence
phalitis. Virus was isolated from brain tissue of colostrum-deprived B
HV-1.3-inoculated calves and from one BHV-1.1-inoculated calf. Immunoh
istochemical staining for BHV-1 antigen was observed in neurons from t
he colostrum-deprived BHV-1.3-inoculated calves.