Chapter 9: Immunology of TBEV infection

Tick-borne encephalitis (TBE) is a viral infectious disease of the central nervous system caused by the tick-borne encephalitis virus (TBEV). TBE is usually a biphasic disease and in humans the virus can only be detected during the first (unspecific) phase of the disease. Pathogenesis of TBE is not well understood, but both direct viral effects and immune-mediated tissue damage of the central nervous system may contribute to the natural course of TBE. The effect of TBEV on the innate immune system has mainly been studied in vitro and in mouse models. Characterization of human immune responses to TBEV is primarily conducted in peripheral blood and cerebrospinal fluid, due to the inaccessibility of brain tissue for sample collection. Natural killer (NK) cells and T cells are activated during the second (meningo-encephalitic) phase of TBE. The potential involvement of other cell types has not been examined to date. Immune cells from peripheral blood, in particular neutrophils, T cells, B cells and NK cells, infiltrate into the cerebrospinal fluid of TBE patients.