An Animal Model for the Study of BBB Modulators

To cause a systemic illness, a virus must first enter the host animal, undergo primary replication at a site near its portal of entry, and then ultimately spread to distant target tissues, such as the central nervous system (CNS). Viral infections of the nervous system are amongst the most severe and potentially devastating of human infections. The outcome of such infection is determined in part by the type of cells infected in the CNS, with most severe infections caused by viruses that replicate primarily in neurons. Neuroinvasiveness and neurovirulence are the crucial properties that determine the capacity of a virus to cause encephalitis. Neuroinvasiveness is defined as the ability of a neurotropic virus to invade the host CNS following its introduction by a peripheral route (Gonzalez-Scarano and Tyler, 1987; Johnson, 1982) whereas neurovirulence is the ability to establish a lethal infection within the CNS. The two major pathways mediating the spread of the virus from the periphery to the brain are via the bloodstream and via nerves (Chou and Dix, 1991).