Localized gene transfer into organotypic hippocampal slice cultures and acute hippocampal slices

Viral vectors derived from herpes simplex virus, type-1 (HSV), can transfer and express genes into fully differentiated, post-mitotic neurons. These vectors also transduce cells effectively in organotypic hippocampal slice cultures. Nanoliter quantities of a virus stock of HSVlac, an HSV vector that directs expression of E. coli β-galactosidase (β-gal), were microapplied into stratum pyramidale or stratum granulosum of slice cultures. Twenty-four hours later, a cluster of transduced cells expressing β-gal was observed at the microapplication site. Gene transfer by microapplication was both effective and rapid. The titer of the HSVlac stocks was determined on NIH3T3 cells. Eighty-three percent of the β-gal forming units successfully transduced β-gal after microapplication to slice cultures. β-Gal expression was detected as rapidly as 4 h after transduction into cultures of fibroblasts or hippocampal slices. The rapid expression of β-gal by HSVlac allowed efficient transduction of acute hippocampal slices. Many genes have been transduced and expressed using HSV vectors; therefore, this microapplication method can be applied to many neurobiological questions.