MIF and infection: WNV crosses the blood-brain barrier via multiple mechanisms including: (1) the “Trojan horse” model (intracellular transport within macrophages or neutrophils), (2) loss of integrity of the blood-brain barrier, cytokine-mediated (TNF-α, MIF) or matrix metalloproteinases disruption of tight junctions and basement membranes, (3) direct infection of brain microvascular endothelial cells with basolateral spread of the virus, (4) infection of choroid plexus epithelial cells, or (5) direct infection of olfactory neurons adjacent to the cribriform plate [102].