GFAP and infection: Similarly, increased GFAP expression in astrocytes, as found on the ipsilateral brain side in our study, is described to be an important component of the reaction of the brain to a number of different injuries or infections (e.g., Eng and Ghirnikar 1994; Johnson et al. 1995) and thus cannot be attributed exclusively to the brain trauma or the effects of the viral vectors without further comprehensive studies addressing reactive changes in the whole brain.