Identification of phlebotomine sand flies using one MALDI-TOF MS reference database and two mass spectrometer systems

Background: rapid,accurate and high-throughput identification of vector arthropods is of paramount importance in surveillance programmes that are becoming more common due to the changing geographic occurrence and extent of many arthropod-borne diseases. protein profiling by maldi-tof mass spectrometry fulfils these requirements for identification,and reference databases have recently been established for several vector taxa,mostly with specimens from laboratory colonies. methods: we established and validated a reference database containing 20 phlebotomine sand fly (diptera: psychodidae,phlebotominae) species by using specimens from colonies or field-collections that had been stored for various periods of time. results: identical biomarker mass patterns ('superspectra') were obtained with colony- or field-derived specimens of the same species. in the validation study,high quality spectra (i.e. more than 30 evaluable masses) were obtained with all fresh insects from colonies,and with 55/59 insects deep-frozen (liquid nitrogen/-80 °c) for up to 25 years. in contrast,only 36/52 specimens stored in ethanol could be identified. this resulted in an overall sensitivity of 87 % (140/161); specificity was 100 %. duration of storage impaired data counts in the high mass range,and thus cluster analyses of closely related specimens might reflect their storage conditions rather than phenotypic distinctness. a major drawback of maldi-tof ms is the restricted availability of in-house databases and the fact that mass spectrometers from 2 companies (bruker,shimadzu) are widely being used. we have analysed fingerprints of phlebotomine sand flies obtained by automatic routine procedure on a bruker instrument by using our database and the software established on a shimadzu system. the sensitivity with 312 specimens from 8 sand fly species from laboratory colonies when evaluating only high quality spectra was 98.3 %; the specificity was 100 %. the corresponding diagnostic values with 55 field-collected specimens from 4 species were 94.7 % and 97.4 %,respectively. conclusions: a centralized high-quality database (created by expert taxonomists and experienced users of mass spectrometers) that is easily amenable to customer-oriented identification services is a highly desirable resource. as shown in the present work,spectra obtained from different specimens with different instruments can be analysed using a centralized database,which should be available in the near future via an online platform in a cost-efficient manner. © 2015 mathis et al.; licensee biomed central.