A vector and a method are provided for delivering a nucleic acid to a
nervous system cell. The vector includes a first nucleic acid, a second
nucleic acid, inverted terminal repeats of adeno-associated virus, and a
tetracycline-off regulatable promoter system that includes a first
promoter operably linked to the first nucleic acid and a second promoter
operably linked to the second nucleic acid. The promoters drive
expression in opposite directions and away from the inverted terminal
repeats. The method includes providing a recombinant adeno-associated
viral (rAAV) vector and administering the vector to a nervous system
cell. Expression of a product from the first nucleic acid is regulatable
by the promoter system.