High susceptibility of Mongolian gerbil (Meriones unguiculatus) to Borna disease virus

Borna disease virus (BDV) is a neurotropic enveloped virus with a nonsegmen ted, single-, negative-stranded RNA genome. This virus induced encephalitis in experimentally infected adult rats, but in newborn rats BDV established a persistent, tolerant infection with no apparent clinical signs. Here, we report evidence that newborn Mongolian gerbils (Meriones umguiculatus) are more susceptible to experimental intracranial inoculation of horse-derived BDV in persistently infected MDCK cells, compared with similar inoculation in newborn rats. All inoculated newborn gerbils, but not rats, died 30 day s after infection. Reverse transcriptase-polymerase chain reaction amplifie d BDV-specific sequences in several regions including the brain. Histopatho logical analysis revealed apparent inflammatory reactions in the brains of inoculated gerbils but not rats, although similar levels of BDV RNA were de tected in both gerbil and rat brains. BDV-specific antigen and RNA were ide ntified predominantly in neurons in the brains by immunohistochemistry with antibodies to BDV and in situ hybridization with BDV-specific riboprobes, respectively BDV in the gerbil brain was easily rescued by co-cultivation o f the brain homogenate with human oligodendroglioma cells. Thus, gerbils se em to be a useful animal model for studying BDV-induced pathogenesis in the brain. (C) 1999 Elsevier Science Ltd. All rights reserved.