Pathogen-tick-host interactions: Borrelia burgdorferi and TBE virus.

Both tick-borne encephalitis (TBE) virus and Borrelia burgdorferi depend for their survival on a tick-borne transmission cycle involving diverse vertebrate hosts and ixodid (primarily Ixodes) tick species. Increasing evidence strongly suggests that a key factor in successful transmission is the ability of these pathogens to exploit the pharmacological properties of their vector tick's saliva. Proteins and other chemicals, secreted in tick saliva, control the vertebrate hosts' haemostatic, inflammatory and immune responses in order to facilitate blood-feeding. Such bioactive saliva molecules include immunoglobulin-binding proteins, histamine-binding proteins, natural killer cell and interferon regulators, and complement inhibitors. By unravelling the contents of tick saliva and understanding their interactions with host and pathogen, we may identify new strategies for disease control.