A neuron-specific gene transfer by a recombinant defective Sindbis virus

We examined the possibility that Sindbis virus, an alpha virus with a single-stranded RNA genome, would be applied for neuronal gene transfer. The recombinant defective Sindbis viruses were constructed by replacing the structural genes of Sindbis virus with genes encoding β-galactosidase (rdSind-lacZ) or enhanced green fluorescent protein (rdSind-EGFP). In neuron- glia cocultures prepared from the neocortex, hippocampus, and striatum, EGFP or β-galactosidase was expressed selectively in neurons 24 h after infection with rdSind-EGFP or rdSind-lacZ. Most cortical neurons were infected with rdSind-lacZ at a multiplicity of infection (M.O.I.) of 5 while glial cells were little infected. In addition, transient neuron-specific expression of β-galactosidase was observed near injection sites over the next 3 d following administration of rdSind-lacZ in adult rat. In the cortical neurons infected with rdSind-EGFP, treatment with NMDA induced neuritic blebs and cell body swelling in a Na⁺-dependent manner. Therefore, recombinant defective Sindbis viruses can be used as an efficient and selective vector for gene transfer into neurons and applied to investigate biological role of target genes delivered into neurons in vitro and in vivo.