Experimental reactivation of bovine herpesvirus 1 (BHV-1) by means of corticosteroids in an intranasal rabbit model.

Intranasal inoculation of the rabbit was shown to be a viable alternative to eye inoculation as a model to study latency and reactivation of bovine herpesvirus 1 (BHV-1). In four different experiments, separate groups of rabbits were intranasally inoculated with BHV-1. In two experiments some rabbits were inoculated instead with a TK-defective (TK-) mutant strain of BHV-1. The development of a specific antibody response was monitored by both virus neutralization and ELISA assays. Cell-mediated immunity was measured by means of a skin test. Many weeks after virus inoculation the rabbits were treated with corticosteroid. Antibody formation after treatment was markedly different in wild type and in TK- virus inoculated groups. In the former, virus reactivation was suggested by a sudden rise in serum antibody levels with kinetics closely resembling those reported in infected calves following corticosteroid administration, whereas in the case of the TK- group no significant increase in antibody activity was measured. Histopathological changes in trigeminal ganglia also indicated reactivation of virus in the wild-type virus infected animals. Further evidence for reactivation was obtained by virus isolation from nasal swabs after corticosteroid treatment.