Although much is known regarding the molecular mechanisms leading to neuronal cell loss in Parkinson’s disease (PD), the initiating event has not been identified. Prevailing theories including a chemical insult or infectious agent have been postulated as possible triggers, leading to neuroinflammation. We present immunohistochemical data indicating the presence of influenza A virus within the substantia nigra pars compacta (SNpc) from postmortem PD brain sections. Influenza A virus labeling was identified within neuromelanin granules as well as on tissue macrophages in the SNpc. Further supporting a role for neuroinflammation in PD was the identification of T-lymphocytes that colocalized with an antibody to caspase-cleaved Beclin-1 within the SNpc. The presence of influenza A virus together with macrophages and Tlymphocytes may contribute to the neuroinflammation associated with this disease.
Rohn, Troy T. and Catlin, Lindsey W.. (2011). "Immunolocalization of Influenza A Virus and Markers of Inflammation in the Human Parkinson’s Disease Brain". PLOS ONE, 6(5), . http://dx.doi.org/10.1371/journal.pone.0020495