Spread and pathogenic characteristics of a G-deficient rabies virus recombinant: an in vitro and in vivo study

Rabies Unit, Virology Department, Pasteur Institute, 25 rue du Dr Roux, 75724 Paris Cedex 15, France 1 Max-von-Pettenkofer Institute, Munich, Germany 2 Veterans Administration Medical Center, East Orange, Newark, NJ, USA 3 Author for correspondence: Pierre-Emmanuel Ceccaldi. Fax +33 1 40 61 30 15. e-mail ceccaldi{at}pasteur.fr Rabies virus (RV), a highly neurotropic enveloped virus, is known to spread within the CNS by means of axonal transport. Although the envelope spike glycoprotein (G) of cell-free virions is required for attachment to neuronal receptors and for virus entry, its necessity for transsynaptic spread remains controversial. In this work, a G gene-deficient recombinant RV (SAD G) complemented phenotypically with RV G protein (SAD G+G) has been used to demonstrate the absolute requirement for G in virus transfer from one neuron to another, both in vitro , in neuronal cell cultures (cell line and primary cultures), and in vivo , in murine animal models. By using a model of stereotaxic inoculation into the rat striatum, infection is shown to be restricted to initially infected cells and not transferred to secondary neurons. In mouse as in rat models of infection, the limited infection did not cause any detectable symptoms, suggesting that G-deficient RV recombinants might be valuable as non-pathogenic, single-round vectors for expression of foreign genes.