The needle assembly of the invention is a quad-partite system for use with an arc-center stereotactic headframe that allows a clinician to deliver recombinant expression vectors through the needle assembly to targeted sites at exact depths in the brain. Methods for use of the needle assembly with a rube insert for the needle cannula that does not bind proteins, as in protein viral capsids, permit delivery of precise volumes of pharmaceutical compositions containing viral recombinant expression vectors for gene therapy.
