Disturbances of mitochondrial dynamics in cultured neurons infected with human herpesvirus type 1 and type 2

Human herpesvirus types 1 and 2 (HHV-1 and HHV-2) are neurotropic viruses which remain latent for life and reactivate to cause recurrent infections. HHV-1 has been found to be involved in accumulation of β-amyloid, hyperphosphorylation of tau proteins, and inflammation in the brain, which can later result in neuronal dysfunction and neurodegeneration. The relationship between HHV-2 and events associated with neurodegeneration has not been extensively studied. Neurons, more than any other cell type, depend on mitochondrial trafficking for their survival, and many types of mitochondrial abnormalities have been described in the etiology of neurodegenerative diseases. Therefore, in this study, we concentrated on mitochondrial dysfunction associated with HHV-1 and HHV-2 infection of primary murine neurons in vitro. We showed that starting from the first stages of HHV-1 and HHV-2 infection, an interaction of viral particles with the mitochondrial network occurs. Both HHV-1 and HHV-2 infection affected mitochondrial function at multiple levels, including upregulation of mitochondrial fission, decrease of the mitochondrial membrane potential, and increase of ROS level. The changes observed in the organization of the mitochondrial network and physiology of productively infected neurons provide appropriate conditions for HHV-1 and HHV-2 replication and are required for effective viral spread.