Neurologic Alterations Due to Respiratory Virus Infections

Bohmwald, Karen; Gálvez, Nicolás M. S.; Ríos, Mariana; Kalergis, Alexis M.

For the proper functioning of the CNS, it is essential to maintain homeostasis. Both, the blood-brain and the blood-CSF barriers play an important role in protecting the brain of free passage of unwanted molecules, pathogens and cells (McGavern and Kang, 2011) . The blood-brain barrier (BBB) is the first line of defense that prevents the entry of pathogens into the brain, and it is composed by cerebral microvascular endothelium, astrocytes, pericytes and extracellular matrix (McGavern and Kang, 2011; Swanson and McGavern, 2015a) . Importantly, the brain microvascular endothelium cells (BMECs) are a cell type found in significant proportions in the BBB; in between these cells are tight junctions (TJ), which controls the barrier permeability (Koyuncu et al., 2013; Miner and Diamond, 2016) . Several routes of CNS invasion can be used by viral pathogens, among these are included the hematogenous route-which is the infection of the endothelium or the ''Trojan Horse'' mechanism-and the peripheral nerves or olfactory sensory neurons (McGavern and Kang, 2011; Swanson and McGavern, 2015b; Dahm et al., 2016) .