Accurate identification of Australian mosquitoes using protein profiling

MALDI-TOF MS Profiling and Its Contribution to Mosquito-Borne Diseases: A Systematic Review

Mosquito-borne diseases are responsible for hundreds of thousands of deaths per year. The identification and control of the vectors that transmit pathogens to humans are crucial for disease prevention and management. Currently, morphological classification and molecular analyses via DNA barcoding are the standard methods used for vector identification. However, these approaches have several limitations. In the last decade, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) profiling has emerged as an innovative technology in biological sciences and is now considered as a relevant tool for the identification of pathogens and arthropods. Beyond species identification, this tool is also valuable for determining various life traits of arthropod vectors. The purpose of the present systematic review was to highlight the contribution of MALDI-TOF MS to the surveillance and control of mosquito-borne diseases. Published articles from January 2003 to August 2024 were retrieved, focusing on different aspects of mosquito life traits that could be determinants in disease transmission and vector management. The screening of the scientific literature resulted in the selection of 54 published articles that assessed MALDI-TOF MS profiling to study various mosquito biological factors, such species identification, life expectancy, gender, trophic preferences, microbiota, and insecticide resistance. Although a large majority of the selected articles focused on species identification, the present review shows that MALDI-TOF MS profiling is promising for rapidly identifying various mosquito life traits, with high-throughput capacity, reliability, and low cost. The strengths and weaknesses of this proteomic tool for vector control and surveillance are discussed.

Identification of Neotropical Culex Mosquitoes by MALDI-TOF MS Profiling

The mosquito (Diptera: Culicidae) fauna of French Guiana encompasses 242 species, of which nearly half of them belong to the genus Culex. Whereas several species of Culex are important vectors of arboviruses, only a limited number of studies focus on them due to the difficulties to morphologically identify field-caught females. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a promising method for the identification of mosquitoes. Culex females collected in French Guiana were morphologically identified and dissected. Abdomens were used for molecular identification using the COI (cytochrome oxidase 1) gene. Legs and thorax of 169 specimens belonging to 13 Culex species, (i.e., Cx. declarator, Cx. nigripalpus, Cx. quinquefasciatus, Cx. usquatus, Cx. adamesi, Cx. dunni, Cx. eastor, Cx. idottus, Cx. pedroi, Cx. phlogistus, Cx. portesi, Cx. rabanicolus and Cx. spissipes) were then submitted to MALDI-TOF MS analysis. A high intra-species reproducibility and inter-species specificity of MS spectra for each mosquito body part tested were obtained. A corroboration of the specimen identification was revealed between MALDI-TOF MS, morphological and molecular results. MALDI-TOF MS protein profiling proves to be a suitable tool for identification of neotropical Culex species and will permit the enhancement of knowledge on this highly diverse genus.

MALDI-TOF mass spectrometry identification of mosquitoes collected in Vietnam

BACKGROUND

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a tool that has revolutionised clinical microbiology and has recently been described as an innovative and effective approach to arthropod identification.

METHODS

In this study, mosquitoes were captured in Vietnam using four different methods (human landing catch, CDC light traps, BG-Sentinel traps, animal-baited net traps). A total of 4215 mosquitoes were captured and morphologically identified as belonging to three genera: Aedes, Anopheles and Culex. We randomly selected 1253 mosquitoes, including 662 specimens of 14 Anopheles species, 200 specimens of two Aedes species and 391 morphologically unidentified Culex specimens, for molecular and MALDI-TOF MS analysis. The DNA from 98 mosquitoes (69 Anopheles specimens, 23 Culex specimens and six Aedes sp. specimens) was subjected to molecular analysis, either to confirm our morphological identification or the MALDI-TOF MS results, as well as to identify the Culex species that were morphologically identified at the genus level and to resolve the discrepancies between the morphological identification and the MALDI-TOF MS identification.

RESULTS

High-quality MS spectra were obtained for 1058 of the 1253 specimens (84%), including 192/200 for Aedes, 589/662 for Anopheles and 277/391 for Culex. The blind test showed that 986/997 (99%) of the specimens were correctly identified by MALDI-TOF MS, with log score values ranging from 1.708 to 2.843. Eleven specimens of Culex could not be identified based on morphological features, MALDI-TOF MS or molecular analysis.

CONCLUSIONS

This study enabled us to identify several species of mosquitoes from Vietnam using MALDI-TOF MS, and to enrich our database of MALDI-TOF MS reference spectra.

Using MALDI-TOF mass spectrometry to identify ticks collected on domestic and wild animals from the Democratic Republic of the Congo

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) has recently emerged as an alternative to morphological and molecular tools to identify tick species. In this study, we set out to evaluate and confirm the ability of MALDI-TOF MS to identify different species of ticks collected in the Democratic Republic of the Congo and preserved in 70% ethanol. A total of 575 ticks, of which 530 were collected from domestic pigs and 45 from wild animals, were subjected to MALDI-TOF MS analysis to evaluate the intraspecies reproducibility and interspecies specificity of MS profiles obtained from the different species. Morphologically, the ticks belonged to seven different species, namely Rhipicephalus complanatus, Rhipicephalus congolensis, Haemaphysalis muhsamae, Ixodes cumulatimpunctatus, Amblyomma exornatum, Amblyomma compressum and an unidentified Rhipicephalus sp. A total of 535/575 (93%) of the spectra obtained were of good enough quality to be used for our analyses. Our home-made MALDI-TOF MS arthropod database was upgraded with spectra obtained from between one and five randomly selected specimens per species. For these reference specimens, molecular identification of the ticks was also made using 16S, 12S rDNA genes and the Cox1 mtDNA gene sequencing. The remaining good quality spectra were then queried against the upgraded MALDI-TOF MS database, showing that 100% were in agreement with the morphological identification, with logarithmic score values (LSVs) between 1.813 and 2.51. The consistency between our morphological, molecular and MALDI-TOF MS identification confirms the capability and precision of MALDI-TOF MS for tick identification.

Performance of MALDI-TOF Mass Spectrometry to Determine the Sex of Mosquitoes and Identify Specific Colonies from French Polynesia

Mosquitoes are the main arthropod vectors of human pathogens. The current methods for mosquito identification include morphological and molecular methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), now routinely used for bacterial identification, has recently emerged in the field of entomology. The aim of this study was to use MALDI-TOF MS to identify mosquito colonies from French Polynesia. Five hundred specimens from French Polynesia belonging to three species, Aedes aegypti, Aedes polynesiensis, and Culex quinquefasciatus, were included in the study. Testing the legs of these mosquitoes by MALDI-TOF MS revealed a 100% correct identification of all specimens at the species level. The MALDI-TOF MS profiles obtained allowed differentiation of male from female mosquitoes and the specific identification of female mosquito colonies of the same species but different geographic origin.

MALDI-TOF MS identification of Cimex lectularius and Cimex hemipterus bedbugs

Bedbugs (Cimex lectularius and C. hemipterus) have reemerged as a major public health problem around the world. Their bites cause various skin lesions as well as discomfort and anxiety. Their role as potential vectors of various infectious agents is discussed. Accordingly, all suspected cases of bedbug infestations need to be documented thoroughly, with an unequivocal identification of the arthropods involved, if any are present. Although morphological identification is easily and quickly performed by entomologists or professionals, it can be challenging otherwise. Also, distinguishing Cimex lectularius and C. hemipterus requires entomological expertise. MALDI-TOF mass spectrometry has been recently presented as an additional tool for arthropod identification. In this study, we assess the use of MALDI-TOF MS for the identification of laboratory and wild strains of C. lectularius and C. hemipterus. Several body parts of laboratory reared C. lectularius specimens were used to develop a MALDI-TOF MS protocol for bedbug identification, which was later validated using five other laboratory and wild populations of C. hemipterus and C. lectularius. A total of 167C. lectularius and C. hemipterus bedbug specimens (98 laboratory specimens and 69 wild specimens) were submitted to MALDI-TOF MS analysis. 143/167 (85.63%) provided high quality MS spectra. The in-lab database was then upgraded with a total of 20 reference spectra from all bedbug populations and the rest of the MS spectra (123 bedbugs) were blind tested. All specimens were properly identified to the species level using MALDI-TOF MS and 86,25% (69/80) were aptly identified according to their origin with LSVs ranging from 1.867 to 2.861. MALDI-TOF MS appears as a reliable additional tool for the identification of these two anthropophilic species.

Development of MALDI-TOF mass spectrometry for the identification of lice isolated from farm animals

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is now routinely used for the rapid identification of microorganisms isolated from clinical samples and has been recently successfully applied to the identification of arthropods. In the present study, this proteomics tool was used to identify lice collected from livestock and poultry in Algeria. The MALDI-TOF MS spectra of 408 adult specimens were measured for 14 species, including Bovicola bovis, B. ovis, B. caprae, Haematopinus eurysternus, Linognathus africanus, L. vituli, Solenopotes capillatus, Menacanthus stramineus, Menopon gallinae, Chelopistes meleagridis, Goniocotes gallinae, Goniodes gigas, Lipeurus caponis and laboratory reared Pediculus humanus corporis. Good quality spectra were obtained for 305 samples. Spectral analysis revealed intra-species reproducibility and inter-species specificity that were consistent with the morphological classification. A blind test of 248 specimens was performed against the in-lab database upgraded with new spectra and validated using molecular tools. With identification percentages ranging from 76% to 100% alongside high identification scores (mean = 2.115), this study proposes MALDI-TOF MS as an effective tool for discriminating lice species.

Identification of mixed and successive blood meals of mosquitoes using MALDI-TOF MS protein profiling

BACKGROUND

The accurate and rapid identification of mosquito blood meals is critical to study the interactions between vectors and vertebrate hosts and, subsequently, to develop vector control strategies. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling has been shown to be a reliable and effective tool for identifying single blood meals from mosquitoes.

METHODS

In this study, we developed MALDI-TOF MS profiling protocols to identify Anopheles gambiae Giles, Anopheles coluzzii and Aedes albopictus mosquitoes' mixed blood meals and the last of successive blood meals. The mosquitoes were either successively artificially fed with distinct host bloods or engorged with mixed bloods from distinct vertebrate hosts, such as humans, sheep and dogs.

RESULTS

Blind test analyses revealed a correct identification of mixed blood meals from mosquitoes using MALDI-TOF MS profiling. The 353 MS spectra from mixed blood meals were identified using log score values >1.8. All MS spectra (n = 244) obtained from mosquitoes' successive blood meals were reproducible and specific to the last blood meal, suggesting that the previous blood meals do not have an impact on the identification of the last one.

CONCLUSION

MALDI-TOF MS profiling approach appears to be an effective and robust technique to identify the last and mixed blood meals during medical entomological surveys.

Breeding Site Characteristics and Associated Factors of Culex pipiens Complex in Lhasa, Tibet, P. R. China

Characterizing the breeding sites of Culex pipiens complex is of major importance for the control of West Nile disease and other related diseases. However, little information is available about the characteristics and associated factors of the breeding sites of the Cx. pipiens complex in Lhasa, a representative high-altitude region in Southwestern China. In this study, a cross-sectional study concerning the breeding site characteristics and associated factors of the Cx. pipiens complex was carried out in Lhasa, Tibet from 2013–2016. Chi-square analysis and binary logistic regression analysis were applied to identify the key factors associated with the presence of Cx. pipiens complex larvae. Using a standard dipping method, 184 water bodies were examined and Cx. pipiens complex larvae were observed in 36 (19.57%) of them. There were significant differences in the composition of Cx. pipiens complex larvae among the breeding site stability (χ² = 19.08, p = 0.00) and presence or absence of predators (χ² = 6.986, p = 0.008). Binary logistic regression analysis indicated that breeding site stability and presence or absence of predators were significantly associated with the presence of Cx. pipiens complex larvae in Chengguan District, Lhasa. Relatively permanent water bodies such as water bodies along river fringes, ponds and puddles, and water bodies with no predators should be paid more attention for future Cx. pipiens complex larvae abatement campaigns in Lhasa, China.