Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) is a debilitating disorder without known causes, that affects 42/10,000 people in the US. Symptoms of CFS/ME include fatigue, muscular pain, sore throat and tender lymphadenopathy. Symptoms can be triggered by stressful events, like exercise, and coincide with symptoms of infection reactivation, as seen with Epstein-Barr virus. It is believed that a virus causes CFS/ME. Supporting fact is that antiviral drugs, such as Acyclovir ameliorate the symptoms of some patients. At a molecular level, many viruses seize host-cell functions by disrupting nucleocytoplasmic transport. This disruption prevents host activation of innate immune responses. All transport to and from the nucleus occurs via nuclear pore complexes (NPCs), which are composed of Nucleoporins (Nups). Nups commonly targeted by viruses are: Nup98, Rae1, Nup153, Nup62, Nup214 and Nup358. Antiviral Nups Rae1 and Nup98 (also responsible for mRNA export) are directly targeted by vesicular stomatitis virus, poliovirus and Influenza-A. Based on this information, we will investigate: Specific Aim I: Whether peripheral blood mononuclear cells (PBMC) from CFS/ME patients present viral reactivation characteristics at a cellular level. We will localize/quantitate total cellular mRNA distribution by in-situ hybridization paired with confocal microscopy. We will look for mRNA export blockage and compare PBMCs from CFS/ME patients carefully matched to healthy controls (HC) before, during and after exercise challenge. Specific Aim II: Compare Nucleoporins and viral proteins levels as well as integrity by Western Blots and Immunostaining. Our innovative approach examines cytopathic effects on common viral targets, in order to determine a direct presence of viral particles. Uncovering alterations of NPC function in PBMCs will not only contribute to a possible isolation of the virus, but also help to elucidate complex pathogenic viral mechanisms involving NPC transport. Furthermore, it will reveal key strategies for drug reassignment and therapeutic intervention.