Rabies Virus Glycoprotein G Variation Is Associated with Neurovirulence and Reduced Vamp2 Abundance in a Mouse Model of Direct CNS Infection.

Rabies virus causes fatal neurological disease, but the mechanisms by which its glycoprotein G influences neuronal dysfunction remain incompletely understood. In this study, we rescued two recombinant RABV LBNSE strains carrying G proteins from either the attenuated SAD-B19 strain or the virulent CVS11 strain, designated as rLBNSE-SfG and rLBNSE-CfG, respectively. Infection of primary mouse neurons and challenge experiments in mice showed that rLBNSE-CfG was associated with increased early neuronal infectivity and greater neurovirulence after intracerebral (i.c.) injection. Western blot analysis revealed that the SAD-B19-derived G protein exhibited a higher apparent molecular weight than the CVS11-derived G protein. Bioinformatic analysis identified strain-specific differences in putative post-translational modification sites, which may contribute to the observed migration difference. Quantitative proteomic analysis of mouse brain tissue showed that proteins downregulated in the rLBNSE-CfG group were enriched in synaptic vesicle cycle-related pathways and synapse-associated Gene Ontology (GO) terms. Integrated analysis identified a SNARE-associated module containing Snap25, Stx1a, and Vamp2, among which Vamp2 was significantly reduced in the rLBNSE-CfG group. In primary neurons, reduced Vamp2 abundance was associated with the extracellular domain of CVS11 G protein. These findings associate CVS11-derived G protein variation with reduced Vamp2 abundance and a presynaptic vesicle-related proteomic signature, although whether these molecular alterations directly impair synaptic vesicle release remains to be determined.