The immunosuppresive tick salivary protein, Salp15.

The interaction between Ixodid ticks and their mammalian hosts is a complex relationship. While the mammalian host tries to avoid the completion of the feeding process, the tick has devised strategies to counteract these attempts. Tick saliva contains a vast array of pharmacological activities that presumably aid the tick to evade host responses, including anticomplement, oxidative and innate and adaptive immune responses. The characterization of these activities has gained momentum in the last several years. One of the best studied activities present in tick saliva corresponds to the antigen known as Salp15, which binds specifically to the T-cell coreceptor CD4 resulting in the specific repression of CD4+ T-cell activation. We discuss here the current state of our knowledge of the mode of action of this salivary protein.