Abstract
BackgroundMosquito vectors cause a significant human public health burden through the transmission of pathogens. Due to the expansion of international travel and trade, the dispersal of these mosquito vectors and the pathogens they carry is on the rise. Entomological surveillance is therefore required which relies on accurate mosquito species identification. This study aimed to optimize the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for mosquito identification.MethodsAedes aegypti of the Bora-Bora strain and 11 field-sampled mosquito species were used in this study. Analyses were performed to study the impact of the trapping duration on mosquito identification with MALDI-TOF MS. The best preservation methods to use for short, medium and long-term preservation before MALDI-TOF MS analysis were also assessed. In addition, the number of specimens per species required for MALDI-TOF MS database creation was determined. The first MALDI-TOF database of New Caledonian mosquitoes was assembled and the optimal threshold for mosquito species identification according to the sensitivity and specificity of this technique was determined.ResultsThis study showed that the identification scores decreased as the trapping duration increased. High identification scores were obtained for mosquitoes preserved on silica gel and cotton at room temperature and those frozen at − 20 °C, even after two months of preservation. In addition, the results showed that the scores increased according to the number of main spectrum patterns (MSPs) used until they reached a plateau at 5 MSPs for Ae. aegypti. Mosquitoes (n = 67) belonging to 11 species were used to create the MALDI-TOF reference database. During blind test analysis, 96% of mosquitoes tested (n = 224) were correctly identified. Finally, based on MALDI-TOF MS sensitivity and specificity, the threshold value of 1.8 was retained for a secure identification score.ConclusionsMALDI-TOF MS allows accurate species identification with high sensitivity and specificity and is a promising tool in public health for mosquito vector surveillance.
Highlights
Mosquito vectors cause a significant human public health burden through the transmission of patho‐ gens
The cox1 query and internal transcribed spacer 2 (ITS2) sequences in the GenBank database allowed us to obtain reliable species identification for all the mosquito species of which reference sequences were available (Table 1); no cox1 sequences were available on GenBank for An. bancroftii, Cx. iyengari and T. melanesiensis
The analysis showed that the log-score value (LSV) medians increased according to the number of main spectrum patterns (MSP) used until they reached a plateau (Fig. 3)
Summary
Mosquito vectors cause a significant human public health burden through the transmission of patho‐ gens. Vector-borne diseases are among the most significant public health burdens in the world. In addition to dengue fever which is responsible for 390 million infections per year, the emergence or re-emergence of yellow fever, chikungunya fever and Zika fever resulted in pandemics with significant morbidity [1,2,3]. These diseases are caused by arboviruses that are transmitted to humans through the bites of vector mosquitoes. Two vector species were recently introduced: Aedes scutellaris, a vector of dengue virus, detected in 2016 and Anopheles bancroftii, a secondary vector of Plasmodium sp., detected in 2017 [14, 15]
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