Th1 cytokines are upregulated by adenoviral vectors in the brains of primed mice.

A major disadvantage of first generation adenoviral vectors for gene therapy in the brain is the immune response they elicit. Human adenovirus is a common respiratory virus and earlier exposure to it has important implications for gene therapy. We show that the immune response against E1-deleted adenoviral vectors in the brain is more deleterious in animals previously exposed to the virus.