Borna disease virus-induced hippocampal dentate gyrus damage is associatedwith spatial learning and memory deficits

In neonatally inoculated rats, Borna disease virus (BDV) leads to a persist ent infection of the brain in the absence of an inflammatory response and i s associated with neuroanatomic, developmental, physiologic, and behavioral abnormalities. One of the most dramatic sites of BDV-associated damage in the neonatal rat brain is the dentate gyrus, a neuroanatomic region believe d to play a major role in spatial learning and memory. The absence of a gen eralized inflammatory response to neonatal BDV infection permits direct eff ects of viral damage to the dentate gyrus to be examined. in this report, n eonatally BDV-infected rats at various stages of dentate gyrus degeneration were evaluated in the Morris water maze, a swimming test that assesses the rats' capacity to navigate by visual cues. Our data demonstrate progressiv e spatial learning and memory deficits in BDV-infected rats that coincided with a gradual decline in the estimated hippocampal dentate gyrus neuron de nsity. (C) 1999 Elsevier Science Inc.