Association between route of inoculation with infectious bovine rhinotracheitis virus and site of recrudescence after dexamethasone treatment.

Four calves latently infected with infectious bovine rhinotracheitis virus (IBRV) were used to compare the ease of isolation of virus from neuronal ganglia and from mucosal surfaces. Two calves were slaughtered, and neuronal ganglia (cranial cervical, trigeminal, and 3rd and 4th sacral) were cocultivated on bovine fetal kidney cells. Virus was not isolated. Two calves given dexamethasone for 4 days were slaughtered on the 5th day. Virus was not isolated from cocultivated or macerated neuronal ganglia, but virus was isolated from nasal secretions taken from both calves on the day of slaughter. Eleven calves were inoculated with IBRV via different routes and were treated with dexamethasone 3 to 4 months after inoculation. virus was isolated from the nasal cavities, but not the vaginas of 6 heifers inoculated intranasally, and was isolated from the vaginas, but not the nasal cavities of 2 heifers inoculated intravaginally. Of 3 calves inoculated IV, virus was isolated from the nasal cavities of 3, from the oropharynxes of 2, and from the prepuce of 1.