Exploring the Sialomes of Ticks

Abstract

Ticks (Acarina) are obligate blood-feeding arthopods that vector human and animal pathogens, causing typhus, Lyme disease, Rocky Mountain spotted fever, tick-borne relapsing fever, babesiosis, Q fever, arboviruses, anaplasmosis, and ehrlichiosis. Among the specializations required for this peculiar diet, tick saliva, a fluid once believed to be relevant only for lubrication of mouthparts and water balance, is now well known to be a cocktail of potent antihemostatic, anti-inflammatory, and immunomodulatory molecules that helps these arthropods obtain a blood meal from their vertebrate hosts. The repertoire of pharmacologically active components in this cocktail is impressive as well as the number of targets they specifically affect. These salivary components change the physiology of the host at the bite site, and, consequently, some pathogens transmitted by ticks take advantage of this change and become more infective. Tick salivary proteins have therefore become an attractive target to control tick-borne diseases. Recent advances in molecular biology, protein chemistry, and computational biology are accelerating the isolation, sequencing, and analysis of a large number of transcripts and proteins from the saliva of different ticks. Many of these newly isolated genes code for proteins with homology to known proteins allowing identification or prediction of their function. These and other molecules from genome and proteome sequences offer an exciting possibility to identify new vaccine antigens, potential biopharmaceuticals, antimicrobial peptides, and other novel human therapeutics.