HEMATOLOGIC CONSEQUENCES OF BORNA-DISEASE VIRUS-INFECTION OF RAT BONE-MARROW AND THYMUS STROMAL CELLS

Borna disease virus (BDV) was previously believed to have a strict tro pism for the nervous system. BDV has recently been identified by a rev erse transcription-polymerization chain reaction-enzyme immunosorbent assay (RT-PCR-EIA) in bone marrow cells and peripheral blood mononucle ar cells (PBMC) in BDV-infected Lewis rats. We now report the identifi cation of BDV RNA and infectious virus in thymus cells from rats infec ted either as neonates (PTI-NB) or as adults (4 weeks of age). Based o n in vitro studies, we determined that the BDV-infected cells in bone marrow and thymus tissue are fibroblastic stromal cells. Bone marrow s tromal cells are nonhematopoietic, fixed-tissue elements that support hematopoiesis, and, thus, it was not surprising that BDV infection alt ered the recovery from granulocytopenia and leukocytopenia after myelo suppressive treatment. Notably, unlike other immunotropic and neurotro pic viruses, BDV does not appear to infect cells of myeloid or lymphoi d lineages. We also report the association between BDV in the thymus w ith the lack, or loss, of encephalitis in neonatally inoculated rats o r adult-inoculated rats during the chronic stage of disease. (C) 1995 by The American Society of Hematology.