Herpes simplex viral and amplicon vector-mediated gene transfer into glia and neurons in organotypic spinal cord and dorsal root ganglion cultures

The progression of neurodegenerative diseases and secondary consequences of spinal cord injury may be diminished by introducing transgenes to glia, sp inal neurons, and/or sensory neurons. Organotypic cultures of spinal cord s lices and dorsal root ganglia proved to be an excellent system in which to compare the relative neurotropism of a replication-defective recombinant he rpes simplex virus and herpes virus-derived amplicon vectors. Hundreds of b eta -galactosidase-expressing cells, transduced by the viral vectors, were observed in spinal cord slices 3 and 8 days postinfection. Immunostaining t o identify the infected cell type indicated that: oligodendrocytes were per missive for viral vector transduction of beta -galactosidase in the spinal cord slice, whereas neurons were not. Heparan sulfate proteoglycan, the ini tial receptor for herpes contact with cells, was highly expressed in the wh ite matter of the spinal cord slice, but was negligible in the gray matter. In contrast to the spinal cord, many fewer cells were infected in the dors al root ganglia (DRG) by these vectors, but a majority of infected cells we re identified as sensory neurons. Heparan sulfate proteoglycan expression w as abundant in the sensory fibers emanating from the DRG and also surrounde d each neuron within the ganglion. Our results demonstrate HSV-induced tran sgene expression that is amenable to ex vivo assessment of its physiologica l impact.