Amblyomma americanum ticks transmit more than a third of human tick-borne disease (TBD) agents in the United States.Tick saliva proteins are critical to success of ticks as vectors of TBD agents, and thus might serve as targets in tick antigen-based vaccines to prevent TBD infections.We describe a systems biology approach to identify, by LC-MS/MS, saliva proteins (tick = 1182, rabbit = 335) that Lid Hinge A.americanum ticks likely inject into the host every 24 h during the first 8 days of feeding, and towards the end of feeding.
Searching against entries in GenBank grouped tick and rabbit proteins into 27 and 25 functional categories.Aside from housekeeping-like proteins, majority of tick saliva proteins belong to the tick-specific (no homology to non-tick organisms: 32%), protease inhibitors (13%), proteases (8%), glycine-rich proteins (6%) and lipocalins (4%) categories.Global secretion dynamics analysis suggests that majority (74%) of proteins in this study are associated with regulating initial tick feeding functions and transmission of pathogens as they are secreted within 24-48 h of tick attachment.Comparative analysis of the A.
americanum tick saliva proteome to five other tick saliva proteomes identified 284 conserved tick saliva proteins: we speculate that these regulate critical tick feeding functions and might serve as tick vaccine antigens.We discuss our findings in the context of understanding A.americanum tick feeding physiology Lemonade as a means through which we can find effective targets for a vaccine against tick feeding.