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Rabies virus phosphoprotein induces mitochondrial dysfunction, oxidative stress, and neuronal process degeneration: Implications for future therapy of human rabies

      Background: Our previous studies in a mouse model of experimental rabies showed neuronal process (dendrites and axons) degeneration in association with severe clinical disease. Cultured adult rodent (mouse and rat) dorsal root ganglion neurons infected with the challenge virus standard-11 (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.
      Objective: To understand basic mechanisms important in rabies pathogenesis.
      Materials and methods: We have studied interactions of the RABV and Complex I using immunoblotting, immunoprecipitation, and immunofluorescence. We have expressed rabies virus proteins in cells after transfection of plasmids, including alanine mutagenesis of the RABV phosphoprotein (P), and evaluated Complex I activity and ROS generation.
      Results: RABV P was detected by immunoblotting in RABV-infected purified mitochondrial extracts and in Complex I immunoprecipitates from the extracts. A plasmid expressing P in cells increased Complex I activity and increased ROS generation, whereas expression of other RABV proteins did not. Expression of a peptide from amino acid 139–172 of the P increased Complex I activity and ROS generation similar to expression of the entire P protein. Mutational analysis suggests particular importance of the 157 to 169 region of P.
      Conclusion: Rabies virus infection is a mitochondrial disorder initiated by interaction of the RABV P and Complex I. This information will be important for the future development of novel therapies for rabies.