A growing number of environmental and pharmacologic manipulations have been shown to influence adult neurogenesis. Borna disease virus (BDV) in rats causes cortical and subcortical infection with extrapyramidal motor symptoms, and hippocampal infection suppresses neurogenesis. Given the known effects of cannabinoids in promoting neural progenitor cell survival, the authors examined in vivo effects of chronic BDV infection in rats on BrdU-positive progenitor cells in striatum, together with neuroprotective actions of cannabinoids. Birth and survival of BrdU-positive progenitor cells in striatum of BDV-infected rats treated with a general cannabinoid agonist (WIN 55,212 1 mg/kg i.p. b.i.d. x 7 days) were examined, as well as anti-inflammatory, antiviral, and nutritional effects of cannabinoids. Cannabinoid treatment protected BrdU-positive progenitor cells in striatum that were susceptible to virus-induced injury (p < .01) through suppression of microglia activation (p < .001). As a consequence of their anti-inflammatory actions and support of neural progenitor cell survival, cannabinoids may be adjunctive treatment for encephalitides with microglial inflammation and neurodegeneration.