Jang et al. showed that (1) the influenza A virus H5N1 traveled to the brain (of mice) through the vagus nerve, induced alpha-synuclein phosphorylation and aggregation, and persistent microglial activation (neuroinflammation), which triggered neurodegeneration, dopaminergic neuronal loss in the substantia nigra and parkinsonism, and (2) the spread of the influenza virus in the brain was similar to the alpha-synuclein progression pattern described in the Braak staging in sporadic PD (5). Here, SNCA is linked to Parkinson disease.