The principle research area of the Hooper laboratory is CNS immunity and, particularly, the balance between protective and destructive neuroinflammatory processes. CNS tissues are protected from immune mechanisms by the blood-brain barrier (BBB) and a major focus of the lab is on mechanisms that modulate BBB integrity and how these impact protective versus pathological CNS inflammatory and neurodegenerative conditions. Important questions are how does the therapeutic delivery of immune effectors across the BBB during virus clearance differ from pathological immune cell invasion into the CNS parenchyma and how are these processes regulated? We were the first to show that peroxynitrite-dependent radicals open the BBB during a CNS inflammatory response and that the sources of these radicals differ between pathological and therapeutic immune cell invasion into CNS tissues.