An open source MALDI-TOF mass spectrometry database for the identification of North American tick species of medical and veterinary importance

Matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry (MALDI-TOF MS) is a fast emerging and robust method for rapid and accurate characterization of arthropod vectors. Correct identification of ticks is key in monitoring medically or veterinary relevant species and associated pathogens. It has been extensively used for tick identification based on leg proteins; however, in North America, MALDI-TOF MS has not been explored for comprehensive identification of ticks, except for a few studies focusing on a limited number of species. Herein, we have generated proteomic spectral profiles of nine North American tick species belonging to five genera obtained from laboratory-maintained colonies. From the 407 high-quality MS spectra generated in this study, 44 were deposited in our newly made database and used as reference. All remaining MS spectra were used to query and validate the database. All specimens were identified correctly to the species level using MALDI-TOF MS, with reliable Log Score Values (LSVs) ranging from 1.72 to 2.86, and median and mean values of 2.41 and 2.40, respectively. A single exception noted: an Amblyomma mixtum was misidentified as Amblyomma tenellum . As a cost-effective, user-friendly, and high-throughput method, MALDI-TOF MS can serve as an alternative for accurately identifying tick species of veterinary and public health importance in North America, thereby supporting tick-borne disease surveillance efforts.