INTERACTION OF NEISSERIA-MENINGITIDIS WITH THE COMPONENTS OF THE BLOOD-BRAIN-BARRIER CORRELATES WITH AN INCREASED EXPRESSION OF PILC

A fatal untreated case of fulminant meningococcemia was examined to in vestigate the crossing of the blood-brain barrier (BBB) by Neisseria m eningitidis. Microscopic examination showed bacteria in vivo adhering to the endothelium of both the choroid plexus and the meninges, Compar ison of the isolates cultivated from the blood and the cerebrospinal f luid (CSF) revealed no antigenic variation of the pilin or the class 5 protein, whereas the expression of the PilC protein was greater in th e CSF and the choroid plexus than in the blood, This was due to an inc reased activity of one of the pilC promoters, This higher expression o f PilC correlated in vitro with greater adhesiveness to endothelial ce lls, A mutation in the single pilC locus of this strain abolished in v itro pilus-mediated adhesion to endothelial cells. These data suggest that PilC plays an important role in the crossing of the BBB, likely t hrough pilus-mediated adhesion.