Neural changes in calves after intraconjunctival inoculation with infectious bovine rhinotracheitis virus

Abstract

Six calves were given the Los Angeles strain of infectious bovine rhinotracheitis (IBR) virus by instillation into the conjunctival sacs, and were killed at 5, 9, 12, 16, 21 and 26 days after inoculation. IBR virus caused severe conjunctivitis with lachrymation and slight rhinitis. Recovery of the virus from ocular and nasal secretions was generally coincidental with the extent of clinical signs. In the conjunctiva, the most marked changes were ulceration and lymphocytic infiltration in the lamina propria, and they were observed up to 12 days after inoculation. In the peripheral and central nervous system (CNS), focal gliosis and perivascular cuffings were extensively and consistently observed in the trigeminal ganglia and medulla oblongata. The CNS changes were mostly located in 2 specific sites; the tractus solitarius and the main sensory and spinal tract nuclei of the trigeminal nerve. Trigeminal ganglionitis and non-suppurative encephalitis in these regions in the medulla oblongata were the most important feature in the calves.