Morphological, molecular and MALDI-TOF mass spectrometry identification of ixodid tick species collected in Oromia, Ethiopia

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technology has recently been reported as a promising method for arthropods identification. More recently, our laboratory reported the correct identification of tick species via the MALDI-TOF MS protein spectra profiling of legs from fresh specimens. The aim of the present study was to assess the use of MALDI-TOF MS for correct identification of ixodid tick species preserved in 70 % ethanol during field collection in Ethiopia. Following morphological identification of 12 tick species, the legs from 85 tick specimens were subjected to MALDI-TOF MS. Spectral analysis revealed an intra-species reproducibility and inter-species specificity that were consistent with the morphological classification. To support the results of the MALDI-TOF MS tick species identification, 41 tick specimens comprising 3 to 5 specimens per tick species were used to create a reference spectra database, which was evaluated using the spectra of the 44 remaining tick specimens. The blind tests revealed that 100 % of the tick specimens studied by MALDI-TOF MS were correctly identified. A relevant Log score value (LSV) of >1.8 was recorded for all of the tick species studied by MALDI-TOF MS, except for Rhipicephalus praetextatus. The morphological and MALDI-TOF MS identifications were confirmed by sequencing the 12S ribosomal RNA (rRNA) gene of 40 tick specimens belonging to 11 ixodid species. Taken together, the results of the present study indicate that MALDI-TOF MS is a reliable tool for tick species identification, even after preservation in ethanol, provided that a reference spectra database is built from specimens that represent the respective species stored under the same conditions.

Concurrent Proteomic Fingerprinting and Molecular Analysis of Cyathostomins

“…In the present study, the time between anthelmintic treatment and collection of feces was 24–60 h, during which the worms start to autolyze. The effect of appropriate sampling and storage conditions was previously described and, although preservation in 70% ethanol is frequently used, it can have a negative effect on MALDI‐TOF MS measurements, such as the identification of fewer peaks in comparison to fresh specimens …”

Comparative analysis of storage conditions and homogenization methods for tick and flea species for identification by MALDI‐TOF MS

“…to DB3) with MS spectra from ticks stored in the same condition allowed reliable and correct identification. These results confirmed, as previously described (Kumsa et al ., ), that the preservation of ticks in alcohol is compatible with future analysis by MALDI‐TOF MS, on condition that MS spectra from counterpart species that have been stored and prepared under the same conditions have been included in the reference MS spectra database. Additionally, other studies reported MS profile alterations between fresh and 70% ethanol preserved specimens for long periods (Kaufmann et al ., ; Yssouf et al ., ).…”

“…Interestingly, the storing method and its duration can also impact the reproducibility of the MS spectra, altering the reliability of MALDI-TOF MS for species identification. The principal and most common method currently used for ticks and fleas include freezing, 70% ethanol, or Carnoy's buffer (Engelthaler et al, 1999;Reis et al, 2011;Kumsa et al, 2016). Some authors have observed that unlike frozen preservation, ethanol storage for longer periods of time may be detrimental to the reproducibility of tick or flea MS spectra (Karger et al, 2012;Yssouf et al, 2013aYssouf et al, , 2014bRothen et al, 2016).…”

“…Some authors have observed that unlike frozen preservation, ethanol storage for longer periods of time may be detrimental to the reproducibility of tick or flea MS spectra (Karger et al, 2012;Yssouf et al, 2013aYssouf et al, , 2014bRothen et al, 2016). Conversely, others have reported that ethanol storage of ticks seems not to have altered their identification by MALDI-TOF MS (Kumsa et al, 2016).…”

Identification of French Guiana anopheline mosquitoes by MALDI-TOF MS profiling using protein signatures from two body parts

“…Interestingly, none of these MSP dendrograms proposed a classification comparable with those obtained using COI gene sequences for phylogenetic tree construction. The MSP dendrograms are not adapted for phylogenetic analyses as previously reported [50,51].…”