Pathogen translocation across the blood-brain barrier

Neurological manifestations caused by neuroinvading pathogens are typically attributed to penetration of the blood-brain barrier (BBB) and invasion of the central nervous system. However, the mechanisms used by many pathogens (such as Borrelia) to traverse the BBB are still unclear. Recent studies revealed that microbial translocation across the BBB must involve a repertoire of microbial-host interactions (receptor-ligand interactions). However, the array of interacting molecules responsible for the borrelial translocation is not yet clearly known. Pathogens bind several host molecules (plasminogen, glycosaminoglycans, factor H, etc.) that might mediate endothelial interactions in vivo. This review summarizes our current understanding of the pathogenic mechanisms involved in the translocation of the BBB by neuroinvasive pathogens.