Identification of phlebotomine sand flies (Diptera: Psychodidae) by matrix-assisted laser desorption/ionization time of flight mass spectrometry

Abstract

BackgroundPhlebotomine sand flies are incriminated in the transmission of several human and veterinary pathogens. To elucidate their role as vectors, proper species identification is crucial. Since traditional morphological determination is based on minute and often dubious characteristics on their head and genitalia, which require certain expertise and may be damaged in the field-collected material, there is a demand for rapid, simple and cost-effective molecular approaches.MethodsSix laboratory-reared colonies of phlebotomine sand flies belonging to five species and four subgenera (Phlebotomus, Paraphlebotomus, Larroussius, Adlerius) were used to evaluate the discriminatory power of matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Various storage conditions and treatments, including the homogenization in either distilled water or given concentrations of formic acid, were tested on samples of both sexes.ResultsSpecimens of all five analysed sand fly species produced informative, reproducible and species-specific protein spectra that enabled their conclusive species identification. The method also distinguished between two P. sergenti colonies originating from different geographical localities. Protein profiles within a species were similar for specimens of both sexes. Tested conditions of specimen storage and sample preparation give ground to a standard protocol that is generally applicable on analyzed sand fly specimens.ConclusionsSpecies identification of sand flies by MALDI-TOF MS is feasible and represents a novel promising tool to improve biological and epidemiological studies on these medically important insects.

Effects of Sample Fixation on Specimen Identification in Biodiversity Assemblies Based on Proteomic Data (MALDI-TOF)

“…A negative effect caused by higher concentrations of ethanol as reported by Dvorak et al (2014) could not be confirmed since our chilled treatments showed very similar results. After 3 months of storage, no striking differences in peak intensity or peak resolution were found.…”

“…After 3 months of storage, no striking differences in peak intensity or peak resolution were found. In this context, Dvorak et al (2014) mentioned an influence of higher ethanol concentrations on co-crystallization of the matrix because of a higher content of organic solvent. This might also have resulted from an incomplete evaporation of ethanol from the samples, rather than from the absolute ethanol content.…”

“…However, alongside former studies on Metazoa (Karger et al, 2012;Dieme et al, 2014;Yssouf et al, 2014;Mathis et al, 2015), authors reported a possible impact of short storage periods at room temperature, as the number of peaks between groups from different fixation methods differed strongly. Furthermore, Dvorak et al (2014) suggested an effect of different ethanol concentrations on resulting mass spectra quality.…”

Accurate identification of Culicidae at aquatic developmental stages by MALDI-TOF MS profiling

“…Based on the introduction of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as an economic, rapid, and highly informative tool for bacterial identification and classification [14], this proteomic approach was explored as a taxonomic tool for insects. Since a pioneering study that evaluated MALDI-TOF MS for the discrimination of fruit fly species a decade ago [15], this technique has proven to be applicable for the identification of different arthropod groups, including Drosophila [16], Culicoides [17][18][19][20], Ixodidae [21,22], Glossina [23,24], Phlebotominae [25] and Siphonaptera [26]. MALDI-TOF MS was also successfully applied for the identification of adult mosquitoes allowing the discrimination of cryptic species such as the An.…”

European Network for Neglected Vectors and Vector-Borne Infections COST Action Guidelines: What Is This About and What Is This For?

“…Recently, MALDI-TOF (matrix-assisted laser desorption/ ionization time-of-flight) mass spectrometry was used for identification of sand fly species using the thorax/wings/legs of the specimen (Dvorak et al 2014, Mathis et al 2015, Lafri et al 2016. Interestingly, since arbovirus replication in the vector is prominent in salivary glands attached to the head, it is possible to separate body parts used for MALDI-TOF identification from body parts used for virus isolation and detection.…”