Immune evasion, a critical strategy for rabies virus.

It is intriguing to note that RABV progression is interrupted neither by destruction of the infected neuron nor by the immune response. Thus, it is likely that RABV has developed a subversive strategy to avoid functional neuron impairment, which compromises the infectious cycle. Rabies virus neuroinvasiveness results from two factors: not only does neurotropic rabies virus avoid inducing neuronal cell death, but also 'protective' T cells that migrate into the infected nervous system are killed by apoptosis or inactivated, as a result of the overexpression of immunosubversive molecules such as FasL, HLA-G or B7-H1 in the infected nervous system. This suggests that the preservation of the neuronal network and the destruction of T cells that invade the nervous system in response to the infection are crucial events for rabies virus neuroinvasion and for transmission of rabies virus to another animal. Implications of these findings for rabies treatment are discussed.