Differential Astrocyte Response to Theiler’s Murine Encephalomyelitis Virus Infection

Objectives: We aimed to address if selective astrocyte apoptosis is involved in the lack of murine demyelinating disease following infection by the L*-1 variant of Theiler’s virus. In addition, we investigated whether L*-1-infected astrocytes were able to selectively express molecules whose effects would play a role as pathogenic factors. Methods: Murine cultured astrocytes were infected with two Theiler viruses, the DA strain and the mutated DA variant L*-1, which does not synthesize the out of frame L* protein. Results: Neither DA nor L*-1 provoked apoptosis, although they replicated in astrocytes inducing GFAP and iNOS expression, as well as subsequent nitric oxide production. In addition, both viruses caused an enhanced expression of ICAM-1, VCAM-1 and decay accelerating factor (DAF). In this connection, values of VCAM-1 and DAF induced by L*-1 were higher and lower, respectively, than those induced by DA. Conclusions: Since no apoptosis was found, such mechanism would not be involved in the lack of TMEV-induced demyelinating disease by L*-1. In contrast, selective expression of VCAM-1 and DAF molecules induced by L*-1 could have a role in virus clearance from the central nervous system.