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

Abstract

In French Guiana, the malaria, a parasitic infection transmitted by Anopheline mosquitoes, remains a disease of public health importance. To prevent malaria transmission, the main effective way remains Anopheles control. For an effective control, accurate Anopheles species identification is indispensable to distinguish malaria vectors from non-vectors. Although, morphological and molecular methods are largely used, an innovative tool, based on protein pattern comparisons, the Matrix Assisted Laser Desorption / Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) profiling, emerged this last decade for arthropod identification. However, the limited mosquito fauna diversity of reference MS spectra remains one of the main drawback for its large usage. The aim of the present study was then to create and to share reference MS spectra for the identification of French Guiana Anopheline species. A total of eight distinct Anopheles species, among which four are malaria vectors, were collected in 6 areas. To improve Anopheles identification, two body parts, legs and thoraxes, were independently submitted to MS for the creation of respective reference MS spectra database (DB). This study underlined that double checking by MS enhanced the Anopheles identification confidence and rate of reliable classification. The sharing of this reference MS spectra DB should make easier Anopheles species monitoring in endemic malaria area to help malaria vector control or elimination programs.

Fig 1. Map of mosquito collection sites in French Guiana.

The different sampling sites are indicated by circles.

Fig 2

Comparison of MALDI-TOF MS spectra from legs (A) and thoraxes (B) of Anopheles mosquitoes. Representative MS spectra of An. peryassui (a, b), An. intermedius (c, d), An. oswaldoi (e, f), An. aquasalis (g, h), An. braziliensis (i, j), An. darlingi (k, l), An. nuneztovari (m, n), and An. triannulatus (o, p) are shown. MS spectra from two distinct specimens per species were selected, excepted for An. oswaldoi. As only one specimen was available for this species, MS spectra from biological replicates were presented. a.u., arbitrary units; m/z, mass-to-charge ratio.

Fig 3

MSP dendrogram of MALDI-TOF MS spectra from legs (A) and thoraxes (B) of Anopheles mosquitoes. Two specimens per species were used to construct the dendrogram, at the exception of An. oswaldoi, for which only one specimen was available. The dendrogram was created using Biotyper v3.0 software and distance units correspond to the relative similarity of MS spectra. The Anopheles and Nyssorhynchus subgenus were indicated at the right part.

Fig 4. Comparison of paired body parts LSVs from MS spectra of Anopheles species.

Dashed lines represent the threshold values (black and grey for LSV threshold of 1.8 and 2.0, respectively), for relevant identification. LSV, log score value.