Evolution of the immune response in the central nervous system following infection with Borna disease virus.

Borna disease virus infection of Lewis rats results in an immune-mediated disease associated with transient meningoencephalitis and persistent viral infection. In the acute phase of disease, perivascular immune cell infiltrates consisted of CD4 + and CD8 + T cells, macrophages and NK cells with peak expression of mRNAs encoding the cytokines IL1alpha, IL2, IL6, TNFalpha, and IFNgamma. In the chronic phase of disease, numbers of NK cells, B cells and activated microglia increased in the brain parenchyma with peak expression of IL4 mRNA. These data were consistent with a switch from a Th1-like, cellular immune response to a Th2-like, humoral immune response.