Rabies Virus Causes Acute Neurological Disease by Inducing Mitochondrial Dysfunction and Oxidative Stress: Critical Role of the Rabies Virus Phosphoprotein

Objective: To understand basic mechanisms involved in rabies pathogenesis. Background: Our previous studies in a mouse model of experimental rabies showed neuronal process degeneration in association with severe clinical disease. Cultured dorsal root ganglion neurons infected with the challenge virus standard (CVS) strain of rabies virus (RABV) showed axonal swellings and reduced axonal growth with evidence of oxidative stress. We have shown that CVS infection alters a variety of mitochondrial parameters and increases mitochondrial Complex I activity and reactive oxygen species (ROS) production. Design/Methods: We have studied interactions of the RABV and mitochondrial Complex I. We have expressed rabies virus proteins in cells after transfection of plasmids, including mutational analyses of the RABV phosphoprotein (P), and evaluated Complex I activity and ROS generation. We have studied recombinant RABVs with point mutations in P. Results: RABV P was detected in Complex I immunoprecipitates from infected mitochondrial extracts. A plasmid expressing P in cells increased Complex I activity and ROS generation. Expression of a peptide from amino acid 139–172 of the P increased Complex I activity/ROS generation similar to expression of the entire P protein. Mutational analysis suggested importance of the 157–169 region of P; serine residues at 162 and 166 were important. The P of two street RABV variants and Mokola virus (all with conserved serine residues at positions 162 and 166) also increased Complex I activities and ROS levels in transfected cells. Two CVS recombinants with serine to alanine mutations at positions 162 and 166 did not increase Complex I activity/ROS generation. Conclusions: RABV infection is a mitochondrial disorder initiated by interaction of the RABV P and Complex I. The resulting mitochondrial dysfunction produces oxidative stress in neurons causing acute degenerative changes affecting neuronal processes resulting in severe clinical disease. This information will be important for the future development of novel therapies for rabies. Study Supported by: Canadian Institutes of Health Research, Research Manitoba, and the Department of Internal Medicine at the University of Manitoba Disclosure: Dr. Jackson has nothing to disclose. Dr. Kammouni has nothing to disclose. Dr. Wood has nothing to disclose. Dr. Fernyhough has received royalty, license fees, or contractual rights payments from WinSanTor Inc.