Comparison of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry and Molecular Biology Techniques for Identification of Culicoides (Diptera: Ceratopogonidae) Biting Midges in Senegal

Abstract

Biting midges of the genus Culicoides are implicated as vectors for a wide variety of pathogens. The morphological identification of these arthropods may be difficult because of a lack of detailed investigation of taxonomy for this species in Africa. However, matrix-assisted laser desorption ionization؊time of flight mass spectrometry (MALDI-TOF MS) profiling is efficient for arthropod identification at the species level. This study established a spectrum database of Culicoides spp. from Senegal using MALDI-TOF. Identification of Culicoides insects to the species level before mass spectrometry was performed on the basis of morphological characters. MALDI-TOF MS reference spectra were determined for 437 field-caught Culicoides of 10 species. The protein profiles of all tested Culicoides revealed several peaks with mass ranges of 2 to 20 kDa. In a validation study, 72 Culicoides specimens in the target species were correctly identified at the species level with a similarity of 95 to 99.9%. Four Culicoides protein profiles were misidentified. Nevertheless, six SuperSpectra (C. imicola, C. enderleini, C. oxystoma, C. kingi, C. magnus, and C. fulvithorax) were created. Abdomens of midges were used to amplify and sequence a portion of the mitochondrial cytochrome oxidase I gene (COI). The results obtained using the MALDI-TOF MS method were consistent with the morphological identification and similar to the genetic identification. Protein profiling using MALDI-TOF is an efficient approach for the identification of Culicoides spp., and it is economically advantageous for approaches that require detailed and quantitative information of vector species that are collected in field. The database of African Culicoides MS spectra created is the first database in Africa. The COI sequences of five Culicoides species that were previously noncharacterized using molecular methods were deposited in GenBank. Biting midges of the genus Culicoides are among the smallest hematophagous insects, and they can be a nuisance to humans and animals (1). These insects are implicated as vectors for a wide variety of viruses, such as bluetongue virus (2), African horse sickness virus (3), epizootic hemorrhagic disease virus (4), the Schmallenberg virus that recently emerged in Europe (5-7), Toggenburg orbivirus (8), and the Oropouche virus (9), which is the only human virus transmitted by Culicoides. Additionally, biting midges are involved in the transmission of various human filarial parasites, such as Mansonella perstans (10-13), Mansonella streptocerca, Mansonella ozzardi, and Mansonella rodhaini (14). Recently, Leishmania spp. and Leishmania infantum were detected in Culicoides imicola and Culicoides spp. (15).Vector identification is an important step in the epidemiology of vector-borne diseases. Information on the major vector species may provide a clearer indication of the geographic distribution of the disease or its potential distribution, the location of danger points for high risks of contact with the vector, and access to alternative...

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