Pathogenesis of meningoencephalitis in rabbits by bovine herpesvirus type-5 (BHV-5)

This article describes the main aspects of bovine herpesvirus type-5 (BHV-5 ) neurologic infection and disease in rabbits, a candidate animal model for studying BHV-5 neuropathogenesis. Intranasal inoculation of weanling rabbi ts with a Brazilian BHV-5 isolate produced neurological disease and death i n 78.8% (26/33) of the animals. Neurological signs started as early as 5 da ys post-inoculation and lasted from 10-12 hours up to several days. Most an imals evolved to a moribund state or death within 24 (69.2%) to 48 hours (8 8.5%). Neurological disease was characterized by excitability or depression , tremors, bruxism, walking or running in circles, backward arching of the head and body, incoordination, backward and sideways falling, paddling, pro found depression and death. Moderate levels of infectivity were detected in several areas of the brain, most consistently in the ventro-lateral hemisp here (in 16 out of 20 animals), anterior cerebrum (15/20), midbrain (11/20) , dorso-lateral hemisphere (10/20) and pens (12/26). Infectious virus was a lso recovered from the olfactory bulb (9/20), medulla oblongata (10/26), ce rebellum (7/20), posterior cerebrum (5/20) and trigeminal ganglia (4/20). N o gross lesions were observed. Microscopic lesions were mild and consisted of nonsuppurative meningitis, mononuclear perivascular cuffing and focal gl iosis. These changes were observed most consistently in the ventro-lateral hemisphere and anterior cerebrum. Passive immunity partially protected rabb its from BHV-5-induced encephalitis. Rabbits born to immunized dams showed a significative delay in the onset of clinical disease and reduced morbidit y and mortality rates compared to rabbits born to unvaccinated dams. These results demonstrate that BHV-5-induced neurological disease can consistentl y be reproduced in rabbits and point towards the use of this species as an animal model to study BHV-5 neuropathogenesis.