Viral vectors for neuronal gene expression

Transfection rates in primary neurons are notoriously low – only 1-5% of cells will be modified by any of the standard transfection techniques. However using viral vectors to deliver DNA offers the possibility of genetically modifying 80-90% of the neurons in culture, facilitating biochemical analysis. Here a cultured hippocampal neuron (labeled for the neuron-specific microtubule binding protein MAP2 in red) is overexpressing a transferrin receptor-synaptobrevin fusion protein (green) expressed from a recombinant herpes virus expression system. By immunostaining, this protein localizes to presynaptic terminals that contact the red dendrites of the neighboring cell. However biochemical analysis revealed that rather than being concentrated in synaptic vesicles, that this chimeric protein marks the location of an otherwise poorly characterized population of presynaptic recycling endosomes. West, AE (1997) J Cell Biol 139: 917.