Emerging tools for identification of arthropod vectors

COVID-19 Management at IHU Méditerranée Infection: A One-Year Experience

BACKGROUND

The Hospital-University Institute (IHU) Méditerranée Infection features a 27,000 square meter building hosting 700 employees and 75 hospitalized patients in the center of Marseille, France.

METHOD

Previous preparedness in contagious disease management allowed the IHU to manage the COVID-19 outbreak by continuing adaptation for optimal diagnosis, care and outcome. We report here the output of this management.

RESULTS

From 5 March 2020, and 26 April 2021, 608,313 PCR tests were provided for 424,919 patients and 44,089 returned positive. A total of 23,390 patients with COVID-19 were followed at IHU with an overall case fatality ratio of 1.7%. Of them 20,270 were followed as outpatients with an overall CFR of 0.17%. We performed 24,807 EKG, 5759 low dose CT Scanner, and 18,344 serology. Of the 7643 nasopharyngeal samples inoculated in cell cultures 3317 (43.3%) yielded SARS-Cov-2 isolates. Finally, 7370 SARS-Cov-2 genomes were analyzed, allowing description of the first genetic variants and their implication in the epidemiologic curves. Continuous clinical care quality evaluation provided the opportunity for 155 publications allowing a better understanding of the disease and improvement of care and 132 videos posted on the IHU Facebook network, totaling 60 million views and 390,000 followers, and dealing with COVID-19, outbreaks, epistemology, and ethics in medicine.

CONCLUSIONS

During this epidemic, IHU Méditerranée Infection played the role for which it has been created; useful clinical research to guarantee a high-quality diagnostic and care for patient and a recognized expertise.

Identification of Lice Stored in Alcohol Using MALDI-TOF MS

Lice pose major public and veterinary health problems with economic consequences. Their identification is essential and requires the development of an innovative strategy. MALDI-TOF MS has recently been proposed as a quick, inexpensive, and accurate tool for the identification of arthropods. Alcohol is one of the most frequently used storage methods and makes it possible to store samples for long periods at room temperature. Several recent studies have reported that alcohol alters protein profiles resulting from MS analysis. After preliminary studies on frozen lice, the purpose of this research was to evaluate the influence of alcohol preservation on the accuracy of lice identification by MALDI-TOF MS. To this end, lice stored in alcohol for variable periods were submitted for MS analysis and sample preparation protocols were optimized. The reproducibility and specificity of the MS spectra obtained on both these arthropod families allowed us to implement the reference MS spectra database (DB) with protein profiles of seven lice species stored in alcohol. Blind tests revealed a correct identification of 93.9% of Pediculus humanus corporis (Linnaeus, 1758) and 98.4% of the other lice species collected in the field. This study demonstrated that MALDI-TOF MS could be successfully used for the identification of lice stored in alcohol for different lengths of time.

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.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: an emerging tool for studying the vectors of human infectious diseases

Arthropod vectors have historically been identified morphologically, and more recently using molecular biology methods. However, both of these methods are time-consuming and require specific expertise and equipment. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, which has revolutionized the routine identification of microorganisms in clinical microbiology laboratories, was recently successfully applied to the identification of arthropod vectors. Since then, the robustness of this identification technique has been confirmed, extended to a large panel of arthropod vectors, and assessed for detecting blood feeding behavior and identifying the infection status in regard to certain pathogenic agents. In this study, we summarize the state-of-the-art of matrix-assisted laser desorption ionization time-of-flight mass spectrometry applied to the identification of arthropod vectors (ticks, mosquitoes, phlebotomine sand-flies, fleas, triatomines, lice and Culicoides), their trophic preferences and their ability to discriminate between infection statuses.

Entomological study in an anthroponotic cutaneous leishmaniasis focus in Morocco: Fauna survey, Leishmania infection screening, molecular characterization and MALDI-TOF MS protein profiling of relevant Phlebotomus species

In Morocco, leishmaniases are a major public health problem due to their genetic diversity and geographical distribution. Cutaneous leishmaniasis (CL) is an infectious disease caused by various species of Leishmania and transmitted typically by bite of phlebotomine sand flies. This study identifies sand fly fauna in Ibaraghen village, province of Azilal, which is a focus of CL, by combination of morphological and molecular methods (sequencing of COI gene, MALDI-TOF MS protein profiling). Nested-kDNA PCR was used to detect and identify Leishmania species within potential vector species. 432 CDC light traps were placed at different heights above ground level at four capture sites during a whole year. Traps at 1.5 m above the ground yielded capture of sand flies almost double compared to above ground level (29.33%), while the collection reached 55.09% when the traps were placed 2.5 m above ground. A total of 2,830 sand flies were collected, 2,213 unfed specimens were morphologically identified, 990 males (44.73%) and 1,223 females (55.26%) of 13 species; ten Phlebotomus species and three Sergentomyia species. Six species were analysed by MALDI-TOF MS protein profiling (4 Phlebotomus and 2 Sergentomiya species), and their identification was confirmed by COI sequencing. 1,375 unfed females were screened for the presence of Leishmania by nested-kDNA PCR in pools, 11/30 pools of P. sergenti showing a single band of 750 bp corresponding to L. tropica. Our results confirm the role of P. sergenti as a proven vector in Azilal focus of cutaneous leishmaniasis; however, the relative abundance of other species known as vectors of Leishmania species emphasizes the risk of introduction of L. infantum and L. major in this province. For the first time in Morocco, a combined approach to identify sand flies by both morphology and molecular methods based on DNA barcoding and MALDI-TOF MS protein profiling was applied.

New assessment of Anopheles vector species identification using MALDI-TOF MS

Background

Anopheles species identification is essential for an effective malaria vector control programme. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has been developed to identify adult Anopheles species, using the legs or the cephalothorax. The protein repertoire from arthropods can vary according to compartment, but there is no general consensus regarding the anatomic part to be used.

Methods

To determine the body part of the Anopheles mosquitoes best suited for the identification of field specimens, a mass spectral library was generated with head, thorax with wings and legs of Anopheles gambiae, Anopheles arabiensis and Anopheles funestus obtained from reference centres. The MSL was evaluated using two independent panels of 52 and 40 An. gambiae field-collected in Mali and Guinea, respectively. Geographic variability was also tested using the panel from Mali and several databases containing added specimens from Mali and Senegal.

Results

Using the head and a database without specimens from the same field collection, the proportion of interpretable and correct identifications was significantly higher than using the other body parts at a threshold value of 1.7 (p < 0.0001). The thorax of engorged specimens was negatively impacted by the blood meal after frozen storage. The addition of specimens from Mali into the database significantly improved the results of Mali panel (p < 0.0001), which became comparable between head and legs. With higher identification scores, the using of the head will allow to decrease the number of technical replicates of protein extract per specimen, which represents a significant improvement for routine use of MALDI-TOF MS.

Conclusions

The using of the head of Anopheles may improve the performance of MALDI-TOF MS. Region-specific mass spectrum databases will have to be produced. Further research is needed to improve the standardization in order to share online spectral databases.

An integrative approach to identify sand fly vectors of leishmaniasis in Ethiopia by morphological and molecular techniques

Background

Ethiopia is affected by human leishmaniasis caused by several Leishmania species and transmitted by a variety of sand fly vectors of the genus Phlebotomus. The sand fly fauna in Ethiopia is highly diverse and some species are closely related and similar in morphology, resulting in difficulties with species identification that requires deployment of molecular techniques. DNA barcoding entails high costs, requires time and lacks reference sequences for many Ethiopian species. Yet, proper species identification is pivotal for epidemiological surveillance as species differ in their actual involvement in transmission cycles. Recently, protein profiling using MALDI-TOF mass spectrometry has been introduced as a promising technique for sand fly identification.

Methods

In our study, we used an integrative taxonomic approach to identify most of the important sand fly vectors of leishmaniasis in Ethiopia, applying three complementary methods: morphological assessment, sequencing analysis of two genetic markers, and MALDI-TOF MS protein profiling.

Results

Although morphological assessment resulted in some inconclusive identifications, both DNA- and protein-based techniques performed well, providing a similar hierarchical clustering pattern for the analyzed species. Both methods generated species-specific sequences or protein patterns for all species except for Phlebotomus pedifer and P. longipes, the two presumed vectors of Leishmania aethiopica, suggesting that they may represent a single species, P. longipes Parrot & Martin. All three approaches also revealed that the collected specimens of Adlerius sp. differ from P. (Adlerius) arabicus, the only species of Adlerius currently reported in Ethiopia, and molecular comparisons indicate that it may represent a yet undescribed new species.

Conclusions

Our study uses three complementary taxonomical methods for species identification of taxonomically challenging and yet medically import Ethiopian sand flies. The generated MALDI-TOF MS protein profiles resulted in unambiguous identifications, hence showing suitability of this technique for sand fly species identification. Furthermore, our results contribute to the still inadequate knowledge of the sand fly fauna of Ethiopia, a country severely burdened with human leishmaniasis.

Sand fly fauna of Crete and the description of Phlebotomus (Adlerius) creticus n. sp. (Diptera: Psychodidae)

BACKGROUND

The Greek island of Crete is endemic for both visceral leishmaniasis (VL) and recently increasing cutaneous leishmaniasis (CL). This study summarizes published data on the sand fly fauna of Crete, the results of new sand fly samplings and the description of a new sand fly species.

METHODS

All published and recent samplings were carried out using CDC light traps, sticky traps or mouth aspirators. The specific status of Phlebotomus (Adlerius) creticus n. sp., was assessed by morphological analysis, cytochrome b (cytb) sequencing and MALDI-TOF protein profiling.

RESULTS

Published data revealed the presence of 10 Phlebotomus spp. and 2 Sergentomyia spp. During presented field work, 608 specimens of 8 species of Phlebotomus and one species of Sergentomyia were collected. Both published data and present samplings revealed that the two most common and abundant species were Phlebotomus neglectus, a proven vector of Leishmania infantum causing VL, and Ph. similis, a suspected vector of L. tropica causing CL. In addition, the field surveys revealed the presence of a new species, Ph. (Adlerius) creticus n. sp.

CONCLUSIONS

The identification of the newly described species is based on both molecular and morphological criteria, showing distinct characters of the male genitalia that differentiate it from related species of the subgenus Adlerius as well as species-specific sequence of cytb and protein spectra generated by MALDI-TOF mass spectrometry.

Fleas and flea-borne diseases of North Africa

North Africa has an interesting and rich wildlife including hematophagous arthropods, and specifically fleas, which constitute a large part of the North African fauna, and are recognised vectors of several zoonotic bacteria. Flea-borne organisms are widely distributed throughout the world in endemic disease foci, where components of the enzootic cycle are present. Furthermore, flea-borne diseases could re-emerge in epidemic form because of changes in the vector-host ecology due to environmental and human behaviour modifications. We need to know the real incidences of flea-borne diseases in the world due to this incidence could be much greater than are generally recognized by physicians and health authorities. As a result, diagnosis and treatment are often delayed by health care professionals who are unaware of the presence of these infections and thus do not take them into consideration when attempting to determine the cause of a patient's illness. In this context, this bibliographic review aims to summarise the main species of fleas present in North Africa, their geographical distribution, flea-borne diseases, and their possible re-emergence.

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.

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

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.

MALDI-TOF MS: optimization for future uses in entomological surveillance and identification of mosquitoes from New Caledonia

Background

Mosquito 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.

Methods

Aedes 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.

Results

This 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.

Conclusions

MALDI-TOF MS allows accurate species identification with high sensitivity and specificity and is a promising tool in public health for mosquito vector surveillance.

Prediction of malaria transmission drivers in Anopheles mosquitoes using artificial intelligence coupled to MALDI-TOF mass spectrometry

Vector control programmes are a strategic priority in the fight against malaria. However, vector control interventions require rigorous monitoring. Entomological tools for characterizing malaria transmission drivers are limited and are difficult to establish in the field. To predict Anopheles drivers of malaria transmission, such as mosquito age, blood feeding and Plasmodium infection, we evaluated artificial neural networks (ANNs) coupled to matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) and analysed the impact on the proteome of laboratory-reared Anopheles stephensi mosquitoes. ANNs were sensitive to Anopheles proteome changes and specifically recognized spectral patterns associated with mosquito age (0–10 days, 11–20 days and 21–28 days), blood feeding and P. berghei infection, with best prediction accuracies of 73%, 89% and 78%, respectively. This study illustrates that MALDI-TOF MS coupled to ANNs can be used to predict entomological drivers of malaria transmission, providing potential new tools for vector control. Future studies must assess the field validity of this new approach in wild-caught adult Anopheles. A similar approach could be envisaged for the identification of blood meal source and the detection of insecticide resistance in Anopheles and to other arthropods and pathogens.

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.

A Novel Rapid Sample Preparation Method for MALDI-TOF MS Permits Borrelia burgdorferi Sensu Lato Species and Isolate Differentiation

The genus Borrelia comprises vector-borne bacterial pathogens that can severely affect human and animal health. Members of the Borrelia burgdorferi sensu lato species complex can cause Lyme borreliosis, one of the most common vector-borne diseases in the Northern hemisphere. Besides, members of the relapsing fever group of spirochetes can cause tick-borne relapsing fever in humans and various febrile illnesses in animals in tropical, subtropical and temperate regions. Borrelia spp. organisms are fastidious to cultivate and to maintain in vitro, and therefore, difficult to work with in the laboratory. Currently, borrelia identification is mainly performed using PCR and DNA sequencing methods, which can be complicated/frustrating on complex DNA templates and may still be relatively expensive. Alternative techniques such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) are not well established for Borrelia spp., although this technique is currently one of the most used techniques for rapid identification of bacteria in microbiological diagnostic laboratories. This is mainly due to unsatisfactory results obtained by use of simple sample preparation techniques and medium-contamination obscuring the mass spectra. In addition, comprehensive libraries for Borrelia spp. MALDI-TOF MS have yet to be established. In this study, we developed a new filter-based chemical extraction technique that allows measurement of high quality Borrelia spp. spectra from less than 100,000 bacteria per spot in MALDI-TOF MS. We used 49 isolates of 13 different species to produce the largest mass-library for Borrelia spp. so far and to validate the protocol. The library was successfully established and identifies >96% of used isolates correctly to species level. Cluster analysis on the sum spectra was applied to all the different isolates, which resulted in tight cluster generation for most species. Comparative analysis of the generated cluster to a phylogeny based on concatenated multi-locus sequence typing genes provided a surprising homology. Our data demonstrate that the technique described here can be used for fast and reliable species and strain typing within the borrelia complex.

Concurrent Proteomic Fingerprinting and Molecular Analysis of Cyathostomins

Rapid, cost-effective, efficient, and reliable helminth species identification is of considerable importance to understand host-parasite interactions, clinical disease, and drug resistance. Cyathostomins (Nematoda: Strongylidae) are considered to be the most important equine parasites, yet research on this group is hampered by the large number of 50 morphologically differentiated species, their occurrence in mixed infections with often more than 10 species and the difficulties associated with conventional identification methods. Here, MALDI-TOF MS, previously successfully applied to identify numerous organisms, is evaluated and compared with conventional and molecular genetic approaches. A simple and robust protocol for protein extraction and subsequent DNA isolation allowing molecular confirmation of proteomic findings is developed, showing that MALDI-TOF MS can discriminate adult stages of the two closely related cyathostomin species Cylicostephanus longibursatus and Cylicostephanus minutus. Intraspecific variability of proteomic profiles within morphospecies demonstrated an identification of morphospecies with an accuracy of close to 100%. In contrast, three genospecies within C. minutus and sex-specific profiles within both morphospecies could not be reliably discriminated using MALDI-TOF MS. In conclusion, MALDI-TOF MS complemented by the molecular protocol is a reliable and efficient approach for cyathostomin species identification.

Identification of Aedes mosquitoes by MALDI-TOF MS biotyping using protein signatures from larval and pupal exuviae

BACKGROUND

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) biotyping is an innovative strategy, applied successfully for the identification of numerous arthropod families including mosquitoes. The effective mosquito identification using this emerging tool was demonstrated possible at different steps of their life-cycle, including eggs, immature and adult stages. Unfortunately, for species identification by MS, the euthanasia of the mosquito specimen is required.

METHODS

To avoid mosquito euthanasia, the present study assessed whether aedine mosquitoes could be identified by MALDI-TOF MS biotyping, using their respective exuviae. In this way, exuviae from the fourth-instar and pupal stages of Aedes albopictus and Aedes aegypti were submitted to MALDI-TOF MS analysis.

RESULTS

Reproducible and specific MS spectra according to aedine species and stage of exuviae were observed which were objectified by cluster analyses, composite correlation index (CCI) tool and principal components analysis (PCA). The query of our reference MS spectra database (DB) upgraded with MS spectra of exuviae from fourth-instar larvae and pupae of both Aedes species revealed that 100% of the samples were correctly classified at the species and stage levels. Among them, 93.8% (135/144) of the MS profiles reached the threshold log score value (LSV > 1.8) for reliable identification.

CONCLUSIONS

The extension of reference MS spectra DB to exuviae from fourth-instar and pupal stages made now possible the identification of mosquitoes throughout their life-cycle at aquatic and aerial stages. The exuviae presenting the advantage to avoid specimen euthanasia, allowing to perform complementary analysis on alive mosquitoes.

Upscaling the Surveillance of Tick-borne Pathogens in the French Caribbean Islands

Despite the high burden of vector-borne disease in (sub)tropical areas, few information are available regarding the diversity of tick and tick-borne pathogens circulating in the Caribbean. Management and control of vector-borne disease require actual epidemiological data to better assess and anticipate the risk of (re)emergence of tick-borne diseases in the region. To simplify and reduce the costs of such large-scale surveys, we implemented a high-throughput microfluidic real-time PCR system suitable for the screening of the main bacterial and parasitic genera involved in tick-borne disease and potentially circulating in the area. We used the new screening tool to perform an exploratory epidemiological study on 132 adult specimens of Amblyomma variegatum and 446 of Rhipicephalus microplus collected in Guadeloupe and Martinique. Not only the system was able to detect the main pathogens of the area-Ehrlichia ruminantium, Rickettsia africae, Anaplasma marginale, Babesia bigemina and Babesia bovis-but the system also provided evidence of unsuspected microorganisms in Caribbean ticks, belonging to the Anaplasma, Ehrlichia, Borrelia and Leishmania genera. Our study demonstrated how high-throughput microfluidic real-time PCR technology can assist large-scale epidemiological studies, providing a rapid overview of tick-borne pathogen and microorganism diversity, and opening up new research perspectives for the epidemiology of tick-borne pathogens.

Proteomic Investigation on Anopheles gambiae in Burkina Faso Related to Insecticide Pressures from Different Climatic Regions

In Sub-Saharan Africa, An. gambiae sensu lato (s.l.) Giles 190, largely contributes to malaria transmission. Therefore, the authors carry out a proteomic analysis to compare its metabolic state, depending on different pesticide pressures by selecting areas with/without cotton crops. The proteomes data are available via ProteomeXchange with identifier PXD016300. From a total of 1.182 identified proteins, 648 are retained for further statistical analysis and are attributed to biological functions, the most important of which being energy metabolism (120 proteins) followed by translation-biogenesis (74), cytoskeleton (71), stress response (62), biosynthetic process (60), signalling (44), cellular respiration (38), cell redox homeostasis (25), DNA processing (17), pheromone binding (10), protein folding (9), RNA processing (9), other proteins (26) and unknown functions (83). In the Sudano-Sahelian region, 421 (91.3%) proteins are found in samples from areas both with and without cotton crops. By contrast, in the Sahelian region, only 271 (55.0%) are common to both crop areas, and 233 proteins are up-regulated from the cotton area. The focus is placed on proteins with putative roles in insecticide resistance, according to literature. This study provides the first whole-body proteomic characterisation of An. gambiae s.l. in Burkina Faso, as a framework to strengthen vector control strategies.

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.

Use of MALDI-TOF MS for the Identification of Chad Mosquitoes and the Origin of Their Blood Meal

Matrix-assisted desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a clinical microbiology tool for the systematic identification of microorganisms. It has recently been presented as an innovative tool for the rapid and accurate identification of mosquitoes and their blood meal. To evaluate the capacity of this tool to identify mosquitoes collected in a tropical environment and preserved with silica gel, we analyzed 188 mosquitoes of different species collected in Chad, which were preserved with silica gel for 2 months. The MALDI-TOF MS analysis correctly identified 96% of the mosquitoes and 37.5% of their blood meals. Using MALDI-TOF MS and molecular biology, eight mosquito species were identified, including Anopheles gambiae s.l., Anopheles rufipes, Culex quinquefasciatus, Culex neavei, Culex pipiens, Culex perexiguus, Culex rima, and Culex watti. Blood meal identification revealed that mosquitoes fed mainly on humans, birds, and cows. Matrix-assisted desorption/ionization time-of-flight mass spectrometry appears to be a promising, fast, and reliable tool to identify mosquitoes and the origin of their blood meal for samples stored with silica gel.

Identification of closely related Ixodes species by protein profiling with MALDI-TOF mass spectrometry

Ticks are vectors of infectious diseases of major importance in human and veterinary medicine. For epidemiological studies, accurate identification of ticks is crucial to define their potential role as vectors and to develop control and prevention strategies. Although morphological and molecular methods are widely used to identify ticks, an innovative approach using MALDI-TOF MS technology recently emerged as an alternative tool. Previous works showed that MALDI-TOF MS was highly effective in identifying ticks, but these works mainly tested tick specimens of different genera. To confirm the accuracy of this new tool for tick identification, nine closely related tick species belonging to the Ixodes genus were analysed, specimens of the Dermacentor reticulatus species were also included in the analysis as an outer group. Three of the species used for the present study belonged to the I. ricinus species complex, which are known to transmit Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis. A total of 246 tick specimens were submitted to MALDI-TOF MS analysis, and two body parts (half-idiosoma and four legs) were individually investigated. For each body part, intraspecies reproducibility and interspecies specificity of the MS profiles were determined. The profile analysis revealed that the main determinant for spectra clustering was the tick species for both legs and half-idiosoma. For each body part, a reference database of spectra was set up including 2 to 5 specimens per species randomly selected, and genotyped using 16s rDNA and COI genes to confirm their morphological identification. Both created spectral databases were individually blind tested with their respective body part using the remaining specimens, which were correctly identified in 98.5% of the cases. MALDI-TOF MS is a reliable tool for tick identification, including specimens belonging to closely related species and hardly distinguishable using morphology. The 4-legs as well as the half-idiosoma of ticks can now be applied for specimen identification using two different databases. The combined use of these two body parts improves the rate of tick identification and their confidence level.

A novel MALDI-TOF MS-based method for blood meal identification in insect vectors: A proof of concept study on phlebotomine sand flies

Background

Identification of blood sources of hematophagous arthropods is crucial for understanding the transmission cycles of vector-borne diseases. Many different approaches towards host determination were proposed, including precipitin test, ELISA, DNA- and mass spectrometry-based methods; yet all face certain complications and limitations, mostly related to blood degradation. This study presents a novel method for blood meal identification, peptide mass mapping (PMM) analysis of host-specific hemoglobin peptides using MALDI-TOF mass spectrometry.

Methodology/Principal findings

To identify blood meal source, proteins from abdomens of engorged sand fly females were extracted, cleaved by trypsin and peptide fragments of host hemoglobin were sequenced using MALDI-TOF MS. The method provided correct host identification of 100% experimentally fed sand flies until 36h post blood meal (PBM) and for 80% samples even 48h PBM. In females fed on two hosts, both blood meal sources were correctly assigned for 60% of specimens until 36h PBM. In a validation study on field-collected females, the method yielded unambiguous host determination for 96% of specimens. The suitability of PMM-based MALDI-TOF MS was proven experimentally also on lab-reared Culex mosquitoes.

Conclusions/Significance

PMM-based MALDI-TOF MS analysis targeting host specific hemoglobin peptides represents a sensitive and cost-effective method with a fast and simple preparation protocol. As demonstrated here on phlebotomine sand flies and mosquitoes, it allows reliable and rapid blood source determination even 48h PBM with minimal material input and provides more robust and specific results than other currently used methods. This approach was also successfully tested on field-caught engorged females and proved to be a promising useful tool for large-scale screening of host preferences studies. Unlike other methods including MALDI-TOF protein profiling, it allows correct identification of mixed blood meals as was demonstrated on both experimentally fed and field-collected sand flies.

Leishmaniases belong among the most important and yet neglected vector-borne diseases, transmitted mostly by bite of female phlebotomine sand flies. To understand role of different reservoir hosts in the transmission cycles, it is important to determine blood meal sources of bloodfeeding females. Most of currently used methods face challenges due to tiny volumes of engorged blood, in case of mammals also enucleated, as well as quick progress of blood digestion which leads to rapid DNA and protein degradation. New approach towards blood source determination presented in this study is based on MALDI-TOF mass spectrometry that identifies unique peptide sequences of host hemoglobins, showing high precision and sensitivity together with a longer time period for successful host determination when compared to nowadays standardly used DNA sequencing. It was tested and verified on engorged phlebotomine sand flies from both laboratory colonies and natural endemic areas and also on Culex mosquitoes and shall be universal to hematophagous insects. Beside blood meal identification, it allows also the use of both morphological and molecular methods (DNA- or protein-based) for the species identification of the analysed specimen.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry as a useful tool for the rapid identification of wild flea vectors preserved in alcohol

Flea identification is a significant issue because some species are considered as important vectors of several human pathogens that have emerged or re-emerged recently, such as Bartonella henselae (Rhizobiales: Bartonellaceae) and Rickettsia felis (Rickettsiales: Rickettsiaceae). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been evaluated in recent years for the identification of multicellular organisms, including arthropods. A preliminary study corroborated the usefulness of this technique for the rapid identification of fleas, creating a preliminary database containing the spectra of five species of flea. However, longterm flea preservation in ethanol did not appear to be an adequate method of storage in the context of specimen identification by MALDI-TOF MS profiling. The goal of the present work was to assess the performance of MALDI-TOF MS in the identification of seven flea species [Ctenocephalides felis (Siphonaptera: Pulicidae), Ctenocephalides canis, Pulex irritans (Siphonaptera: Pulicidae), Archaeopsylla erinacei (Siphonaptera: Pulicidae), Leptopsylla taschenbergi (Siphonaptera: Ceratophyllidae), Stenoponia tripectinata (Siphonaptera: Stenoponiidae) and Nosopsyllus fasciatus (Siphonaptera: Ceratophyllidae)] collected in the field and stored in ethanol for different periods of time. The results confirmed that MALDI-TOF MS can be used for the identification of wild fleas stored in ethanol. Furthermore, this technique was able to discriminate not only different flea genera, but also the two congeneric species C. felis and C. canis.

Identification of phlebotomine sand flies through MALDI-TOF mass spectrometry and in-house reference database

Phlebotomine sand flies are vectors for many pathogens responsible for human and animal diseases worldwide. Their identification at species level is of importance in epidemiological studies and control programmes. MALDI-TOF MS has been increasingly investigated as an alternative approach to the conventional identification of arthropods species. To establish an in-house protein spectra database for a quick and reliable species identification of phlebotomine sand flies, 166 field-caught sand fly specimens, morphologically identified as Phlebotomus perniciosus (no = 56; 26 males and 30 females), Phlebotomus neglectus (no = 4 males), Phlebotomus sergenti (no = 6; 4 males and 2 females) and Sergentomyia minuta (no = 100; 45 males and 55 females), were subjected to MALDI-TOF MS analyses. Out of 166, 149 specimens (89.8%) produced consistent species-specific protein spectra. Good quality database for P. perniciosus and S. minuta were generated; no databases have yet constructed for P. neglectus and P. sergenti due to the low number of specimens examined. The identification of 80 sand flies (no = 20 P. perniciosus; no = 60 S. minuta) were confirmed using the new generated SuperSpectra as validation test. The results reported support the use of MALDI-TOF MS for rapid, simple and reliable phlebotomine sand fly species identification suggesting its usefulness in accurate survey studies, ultimately improving biological and epidemiological knowledge on these important vectors of pathogens.

High infestation of invasive Aedes mosquitoes in used tires along the local transport network of Panama

BACKGROUND

The long-distance dispersal of the invasive disease vectors Aedes aegypti and Aedes albopictus has introduced arthropod-borne viruses into new geographical regions, causing a significant medical and economic burden. The used-tire industry is an effective means of Aedes dispersal, yet studies to determine Aedes occurrence and the factors influencing their distribution along local transport networks are lacking. To assess infestation along the primary transport network of Panama we documented all existing garages that trade used tires on the highway and surveyed a subset for Ae. aegypti and Ae. albopictus. We also assess the ability of a mass spectrometry approach to classify mosquito eggs by comparing our findings to those based on traditional larval surveillance.

RESULTS

Both Aedes species had a high infestation rate in garages trading used tires along the highways, providing a conduit for rapid dispersal across Panama. However, generalized linear models revealed that the presence of Ae. aegypti is associated with an increase in road density by a log-odds of 0.44 (0.73 ± 0.16; P = 0.002), while the presence of Ae. albopictus is associated with a decrease in road density by a log-odds of 0.36 (0.09 ± 0.63; P = 0.008). Identification of mosquito eggs by mass spectrometry depicted similar occurrence patterns for both Aedes species as that obtained with traditional rearing methods.

CONCLUSIONS

Garages trading used tires along highways should be targeted for the surveillance and control of Aedes-mosquitoes and the diseases they transmit. The identification of mosquito eggs using mass spectrometry allows for the rapid evaluation of Aedes presence, affording time and cost advantages over traditional vector surveillance; this is of importance for disease risk assessment.

MALDI-TOF mass spectrometry as a diagnostic tool in human and veterinary helminthology: a systematic review

BACKGROUND

Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has become a widely used technique for the rapid and accurate identification of bacteria, mycobacteria and certain fungal pathogens in the clinical microbiology laboratory. Thus far, only few attempts have been made to apply the technique in clinical parasitology, particularly regarding helminth identification.

METHODS

We systematically reviewed the scientific literature on studies pertaining to MALDI-TOF MS as a diagnostic technique for helminths (cestodes, nematodes and trematodes) of medical and veterinary importance. Readily available electronic databases (i.e. PubMed/MEDLINE, ScienceDirect, Cochrane Library, Web of Science and Google Scholar) were searched from inception to 10 October 2018, without restriction on year of publication or language. The titles and abstracts of studies were screened for eligibility by two independent reviewers. Relevant articles were read in full and included in the systematic review.

RESULTS

A total of 84 peer-reviewed articles were considered for the final analysis. Most papers reported on the application of MALDI-TOF for the study of Caenorhabditis elegans, and the technique was primarily used for identification of specific proteins rather than entire pathogens. Since 2015, a small number of studies documented the successful use of MALDI-TOF MS for species-specific identification of nematodes of human and veterinary importance, such as Trichinella spp. and Dirofilaria spp. However, the quality of available data and the number of examined helminth samples was low.

CONCLUSIONS

Data on the use of MALDI-TOF MS for the diagnosis of helminths are scarce, but recent evidence suggests a potential role for a reliable identification of nematodes. Future research should explore the diagnostic accuracy of MALDI-TOF MS for identification of (i) adult helminths, larvae and eggs shed in faecal samples; and (ii) helminth-related proteins that are detectable in serum or body fluids of infected individuals.

Tissue-specific signatures in tick cell line MS profiles

Background

The availability of tick in vitro cell culture systems has facilitated many aspects of tick research, including proteomics. However, certain cell lines have shown a tissue-specific response to infection. Thus, a more thorough characterization of tick cell lines is necessary. Proteomic comparative studies of various tick cell lines will contribute to more efficient application of tick cell lines as model systems for investigation of host-vector-pathogen interactions.

Results

Three cell lines obtained from a hard tick, Ixodes ricinus, and two from I. scapularis were investigated. A cell mass spectrometry approach (MALDI-TOF MS) was applied, as well as classical proteomic workflows. Using PCA, tick cell line MS profiles were grouped into three clusters comprising IRE/CTVM19 and ISE18, IRE11 and IRE/CTVM20, and ISE6 cell lines. Two other approaches confirmed the results of PCA: in-solution digestion followed by nanoLC-ESI-Q-TOF MS/MS and 2D electrophoresis. The comparison of MS spectra of the cell lines and I. ricinus tick organs revealed 29 shared peaks. Of these, five were specific for ovaries, three each for gut and salivary glands, and one for Malpighian tubules. For the first time, characteristic peaks in MS profiles of tick cell lines were assigned to proteins identified in acidic extracts of corresponding cell lines.

Conclusions

Several organ-specific MS signals were revealed in the profiles of tick cell lines.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3460-5) contains supplementary material, which is available to authorized users.

Advances and challenges in barcoding of microbes, parasites, and their vectors and reservoirs

DNA barcoding is now a common tool in parasitology and epidemiology, which require good methods for identification not only of parasites and pathogens but vectors and reservoirs. This special issue presents some advances and challenges in barcoding of microbes, parasites, and their vectors and reservoirs. DNA barcoding found new applications in disease ecology, conservation parasitology, environmental parasitology and in paleoparasitology. New technologies such as next-generation sequencing and matrix-assisted laser desorption-ionization time-of-flight have made it now possible to investigate large samples of specimens. By allowing the investigation of parasites at the interface between environment, biodiversity, animal and human health, barcoding and biobanking have important policy outcomes as well as ethics and legal implications. The special issue 'Advances and challenges in the barcoding of parasites, vectors and reservoirs' illustrates some recent advances and proposes new avenues for research in barcoding in parasitology.

Longitudinal monitoring of environmental factors at Culicidae larval habitats in urban areas and their association with various mosquito species using an innovative strategy

BACKGROUND

To prevent the risk of mosquito-borne disease outbreaks, larval source management remains the most sustainable and effective mosquito control strategy. The present study aimed to determine the influence of environmental characteristics of mosquito larval habitats in an urban area of Marseille, France. Fourteen sites containing water were monitored every 2 weeks from May to October 2015 for mosquito species occurrence and larval density, and environmental parameters were measured at each visit. Rapid and accurate species identification of mosquito larvae was performed using an innovative MALDI-TOF MS method.

RESULTS

A total of 6753 larvae (L1-L4) and pupae were collected, of which 35.8% (n = 2418) were speciated using MALDI-TOF MS. Correct identifications were obtained for 2259 specimens (93.4%). A total of five mosquito species were found, including Aedes (Ae.) albopictus, Culex (Cx.) p. pipiens, Cx. hortensis, Cx. impudicus, and Culiseta (Cs.) longiareolata. Larvae of the Culex genus were predominant in both density and distribution. Small, shaded pools of shallow water favored Ae. albopictus colonization, whereas the wide distribution of Cx. p. pipiens demonstrated that this species was weakly influenced by environmental changes.

CONCLUSIONS

The present work confirms that MALDI-TOF MS is a useful tool for mosquito speciation and suggests that understanding the environmental factors associated with the occurrence and density of mosquito species at the larval stage in Marseille may aid in the future implementation of mosquito control programs. © 2018 Society of Chemical Industry.

Detection of Bartonella spp. in Cimex lectularius by MALDI-TOF MS

Bed bugs are small hematophagous insects. They are found in temperate and tropical climates around the world. Their vectorial capacity for several pathogens, including Bartonella spp., has been suspected. An experimental study of artificial infection of Cimex lectularius with Bartonella quintana and Bartonella henselae bacteria was developed to evaluate the ability of MALDI-TOF MS to simultaneously identify bed bugs and their infectious status. This experimental study confirmed the ability of MALDI-TOF MS to identify bed bugs. In addition, it was able to differentiate between control bed bugs, bed bugs infected with Bartonella quintana and bed bugs infected with Bartonella henselae, with an identification percentage above 90%.

Identification of French Guiana sand flies using MALDI-TOF mass spectrometry with a new mass spectra library

Phlebotomine sand flies are insects that are highly relevant in medicine, particularly as the sole proven vectors of leishmaniasis. Accurate identification of sand fly species is an essential prerequisite for eco-epidemiological studies aiming to better understand the disease. Traditional morphological identification is painstaking and time-consuming, and molecular methods for extensive screening remain expensive. Recent studies have shown that matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a promising tool for rapid and cost-effective identification of arthropod vectors, including sand flies. The aim of this study was to validate the use of MALDI-TOF MS for the identification of Northern Amazonian sand flies. We constituted a MALDI-TOF MS reference database comprising 29 species of sand flies that were field-collected in French Guiana, which are expected to cover many of the more common species of the Northern Amazonian region, including known vectors of leishmaniasis. Carrying out a blind test, all the sand flies tested (n = 157) with a log (score) threshold greater than 1.7 were correctly identified at the species level. We confirmed that MALDI-TOF MS protein profiling is a useful tool for the study of sand flies, including neotropical species, known for their great diversity. An application that includes the spectra generated here will be available to the scientific community in the near future via an online platform.

Phlebotomine sand flies are small insects, mostly known for their role in the transmission of Leishmania parasites to humans and other mammals. In French Guiana, the main clinical form of the disease manifests as cutaneous lesions also called American cutaneous leishmaniasis. The transmission of Leishmania from wild mammals to humans depends on the species of sand fly involved in the transmission. To better understand the mechanism of disease transmission, it is essential to accurately identify sand flies, including both vector and non-vector species. Until now, sand flies have mainly been identified using morphological and molecular methods. Recent studies have shown that a new tool based on protein profiling compiled in a library of spectra may be useful for the identification of arthropod vectors. This tool has the advantage of being less time-consuming, less expensive and does not require technical skills. The aim of this study was to assess the usefulness and accuracy of this new tool in identifying Northern Amazonian sand flies.

Improvement of mosquito identification by MALDI-TOF MS biotyping using protein signatures from two body parts

Background

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry technology (MALDI-TOF MS) is an innovative tool that has been shown to be effective for the identification of numerous arthropod groups including mosquitoes. A critical step in the implementation of MALDI-TOF MS identification is the creation of spectra databases (DB) for the species of interest. Mosquito legs were the body part most frequently used to create identification DB. However, legs are one of the most fragile mosquito compartments, which can put identification at risk. Here, we assessed whether mosquito thoraxes could also be used as a relevant body part for mosquito species identification using a MALDI-TOF MS biotyping strategy; we propose a double DB query strategy to reinforce identification success.

Methods

Thoraxes and legs from 91 mosquito specimens belonging to seven mosquito species collected in six localities from Guadeloupe, and two laboratory strains, Aedes aegypti BORA and Aedes albopictus Marseille, were dissected and analyzed by MALDI-TOF MS. Molecular identification using cox1 gene sequencing was also conducted on representative specimens to confirm their identification.

Results

MS profiles obtained with both thoraxes and legs were highly compartment-specific, species-specific and species-reproducible, allowing high identification scores (log-score values, LSVs) when queried against the in-house MS reference spectra DB (thorax LSVs range: 2.260–2.783, leg LSVs range: 2.132–2.753).

Conclusions

Both thoraxes and legs could be used for a double DB query in order to reinforce the success and accuracy of MALDI-TOF MS identification.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3157-1) contains supplementary material, which is available to authorized users.

MALDI-TOF MS and point of care are disruptive diagnostic tools in Africa

We review reviewing our experience of point-of-care and mass spectrometry in Senegal as two disruptive technologies promoting the rapid diagnosis of infection, permitting better medical management of patients.

Accurate identification of Australian mosquitoes using protein profiling

Australian mosquito species significantly impact human health through nuisance biting and the transmission of endemic and exotic pathogens. Surveillance programmes designed to provide an early warning of mosquito-borne disease risk require reliable identification of mosquitoes. This study aimed to investigate the viability of Matrix-Assisted Laser Desorption/Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) as a rapid and inexpensive approach to the identification of Australian mosquitoes and was validated using a three-step taxonomic approach. A total of 300 mosquitoes representing 21 species were collected from south-eastern New South Wales and morphologically identified. The legs from the mosquitoes were removed and subjected to MALDI-TOF MS analysis. Fifty-eight mosquitoes were sequenced at the cytochrome c oxidase subunit I (cox1) gene region and genetic relationships were analysed. We create the first MALDI-TOF MS spectra database of Australian mosquito species including 19 species. We clearly demonstrate the accuracy of MALDI-TOF MS for identification of Australian mosquitoes. It is especially useful for assessing gaps in the effectiveness of DNA barcoding by differentiating closely related taxa. Indeed, cox1 DNA barcoding was not able to differentiate members of the Culex pipiens group, Cx. quinquefasciatus and Cx. pipiens molestus, but these specimens were correctly identified using MALDI-TOF MS.

Effect of trapping method on species identification of phlebotomine sandflies by MALDI-TOF MS protein profiling

Sandflies (Diptera: Psychodidae) (Newstead, 1911) are blood-feeding insects that transmit human pathogens including Leishmania (Trypanosomatida: Trypanosomatidae) parasites, causative agents of the leishmaniases. To elucidate Leishmania transmission cycles, conclusive identification of vector species is essential. Molecular approaches including matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) protein profiling have recently emerged to complement morphological identification. The aim of this study was to evaluate the effect of the trap type used to collect sandflies, specifically Centers for Disease Control (CDC) light or sticky traps, the two most commonly used in sandfly surveys, on subsequent MALDI-TOF MS protein profiling. Specimens of five species (Phlebotomus ariasi, Phlebotomus papatasi, Phlebotomus perniciosus, Phlebotomus sergenti, Sergentomyia minuta) collected in periurban and agricultural habitats in southeast Spain were subjected to protein profiling. Acquired protein spectra were queried against an in-house reference database and their quality assessed to evaluate the trap type effect. The results indicate that trap choice can substantially affect the quality of protein spectra in collected sandflies. Whereas specimens retrieved from light traps produced intense and reproducible spectra that allowed reliable species determination, profiles of specimens from sticky traps were compromised and often did not enable correct identification. Sticky traps should therefore not be used in surveys that deploy MALDI-TOF MS protein profiling for species identification.

Neglected vector-borne bacterial diseases and arboviruses in the Mediterranean area

Arthropod vectors can transmit pathogenic microorganisms from one vertebrate to another during their blood meal. Although some vector-borne diseases have been eradicated in the Mediterranean area, such as malaria and dengue, recent endemic microorganisms (Toscana virus, Rickettsia spp.) remain neglected even though they cause many more cases. New diagnostic tools and innovative tools for the identification and characterization of vector species and microorganisms have been developed at IHU Méditerranée Infection, either internally or through collaborative and integrated projects. We have detected Rickettsia slovaca as a human pathogen and have described the disease; we have shown that Rickettsia felis can be transmitted by Anopheles mosquitoes; we have emphasized the increasing importance of bedbug (Cimex lectularius) as a potential vector of Bartonella quintana; and we have described the Toscana virus, a major agent of meningitis and meningoencephalitis which was disseminated in North Africa and Central and Eastern Europe, where it frequently cocirculates with a large number of newly described phleboviruses transmitted by sand flies.

Studies of nonhuman primates: key sources of data on zoonoses and microbiota

The genetic and morphologic similarities between primates and humans means that much information obtained from primates may be applied to humans, and vice versa. However, habitat loss, hunting and the continued presence of humans have a negative effect on the biology and behaviour of almost all nonhuman primates. Noninvasive methods such as stool collection are among the safest alternative ways to study the multiple aspects of the biology of primates. Many epidemiologic issues (e.g. pathogen detection, microbiota studies) may be easily studied using stool samples from primates. Primates are undoubtedly among the first candidates suspected of becoming the source of one of the next emerging epidemic of zoonotic origin, as has already been observed with HIV, malaria and monkeypox. The Institut Hospitalo-Universitaire Méditerranée Infection in Marseille actively participates in the study, mostly epidemiologic, of nonhuman primates, using mostly stool samples.

Evaluation of standard field and laboratory methods to compare protection times of the topical repellents PMD and DEET

Mosquitoes are important vectors of pathogens, and travellers to disease endemic countries are advised to avoid bites by applying topical repellents. Topical repellents are typically tested either in the arm-in-cage (AIC) test under laboratory conditions or in the field, but not often under both conditions. We, therefore, investigated how two topical repellents, 15% para-menthane-3,8-diol (PMD) and 15% N,N-diethyl-3-methylbenzamide (DEET) compare against each other both in the AIC test against three species recommended by the World Health Organization (i.e. Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus) and at two field sites in Switzerland, while using the same study participants in all experiments. In the field, the median complete protection time (CPT) was at least 6 hours for both PMD and DEET, while in the AIC test DEET slightly outperformed PMD. CPTs for DEET in the AIC test were 0.5, 2 and 2 hours against Ae. aegypti, An. stephensi and Cx. quinquefasciatus, respectively, and the corresponding median CPTs for PMD were 0.5, 1 and 0.5 hours. In conclusion, DEET slightly outperformed PMD in the AIC test, while the observed landing rates suggest the AIC test to underestimate efficacy of topical repellents in areas with lower landing pressure.

Mosquitoes (Diptera: Culicidae) and mosquito-borne diseases in Mali, West Africa

Mosquito-borne diseases cause major human diseases in almost every part of the world. In West Africa, and notably in Mali, vector control measures help reduce the impact of mosquito-borne diseases, although malaria remains a threat to both morbidity and mortality. The most recent overview article on mosquitoes in Mali was published in 1961, with a total of 88 species. Our present review focuses on mosquitoes of medical importance among which the Anopheles vectors of Plasmodium and filaria, as well as the Culex and Aedes vectors of arboviruses. It aims to provide a concise update of the literature on Culicidae, covering the ecological areas in which the species are found but also the transmitted pathogens and recent innovative tools for vector surveys. This review highlights the recent introduction of invasive mosquito species, including Aedes albopictus and Culex neavei. The comprehensive list of mosquito species currently recorded includes 106 species (28 species of the Anophelinae and 78 species of the Culicinae). There are probable gaps in our knowledge concerning mosquitoes of the subfamily Culicinae and northern half of Mali because most studies have been carried out on the genus Anopheles and have taken place in the southern part of the country. It is hoped that this review may be useful to decision makers responsible for vector control strategies and to researchers for future surveys on mosquitoes, particularly the vectors of emerging arboviruses.

Blood meal identification in the cryptic species Anopheles gambiae and Anopheles coluzzii using MALDI-TOF MS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently emerged in entomology as a technique to identify arthropods and their blood meal source. In this study, female Anopheles gambiae were fed on five host blood sources: ocelot (Leopardus pardalis), binturong (Arctictis binturong), springbok (Antidorcas marsupialis), jaguar (Panthera onca) and Hamadryas baboon (Papio hamadryas), while Anopheles coluzzii were fed on three hosts: dromedary (Camelus dromedarius), Barbary sheep (Ammotragus lervia) and pig (Sus scrofa). We obtained the MS spectra from 240 engorged mosquito abdomens and selected high quality ones from 72 mosquito abdomens to upgrade our home-made database. We excluded from the analysis any spectra of low quality (n = 80), and the remaining 88 specimens were subjected to a blind test analysis against the home-made database. We obtained 100% correct identification of the blood meal source for the specimens collected, 1, 12 and 24 h post-feeding, whereas for the specimens collected 36 h post-feeding, the correct identification rate decreased dramatically. We confirm here that MALDI-TOF MS can be used to identify the blood meal origin of freshly engorged mosquitoes, which opens new perspectives for further studies, including the impact of the mosquito species on blood meal identification.

Malaria, tuberculosis and HIV: what's new? Contribution of the Institut Hospitalo-Universitaire Méditerranée Infection in updated data

The Institut Hospitalo-Universitaire Méditerranée Infection is positioned for the diagnosis, prevention and treatment of the ‘big three’ killer diseases: malaria, tuberculosis and HIV. We implemented the use of new diagnostic samples such as stools and new diagnostic tests such as mass spectrometry for the dual identification of vectors and pathogens. Furthermore, advances in the prevention and treatment of malaria and tuberculosis are reviewed, along with advances in the understanding of the role of microbiota in the resistance to HIV infection. These achievements represent a major step towards a better management of the ‘big three’ diseases worldwide.

MALDI-TOF MS identification of ticks of domestic and wild animals in Algeria and molecular detection of associated microorganisms

Recent studies have reported the reliability of MALDI-TOF MS for arthropod identification, including fresh or alcohol-preserved ticks based on leg-derived mass spectra. The aim of this study was to evaluate the performance of MALDI-TOF MS for the identification of alcohol-preserved Algerian ticks collected from different domestic and wild hosts. Secondly, we conducted a molecular survey to detect the presence of bacterial DNA in all ticks that were previously subjected to MALDI-TOF MS. A total of 2635 ixodid and 1401 argasid ticks belonging to 9 distinct species were collected in nine different regions of northeastern Algeria. The legs of 230 specimens were subjected to MALDI-TOF MS assays. Spectral analysis revealed intra-species similarity and inter-species specificity for the MS spectra, which was consistent with the morphological identification. Blind tests against the in-lab database revealed that 93.48% of the tested specimens were correctly identified. The accuracy of the morphological and MALDI-TOF MS identifications was validated by sequencing the 12S ribosomal RNA gene (rRNA) for 33 specimens and all the ticks were correctly identified. The quantitative PCR screening showed that for 219 tested ticks, 15 were positive for Rickettsia spp., 8 for Borrelia spp. and 17 for Anaplasmataceae. The PCR tests were negative for Coxiella burnetii and Bartonella spp. This study supports MALDI-TOF MS being a reliable tool for the identification of arthropods and brings new data that sheds light on tick species diversity and tick-borne diseases in Algeria.

Rapid identification of medically important mosquitoes by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Background

Accurate and rapid identification of dipteran vectors is integral for entomological surveys and is a vital component of control programs for mosquito-borne diseases. Conventionally, morphological features are used for mosquito identification, which suffer from biological and geographical variations and lack of standardization. We used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for protein profiling of mosquito species from North India with the aim of creating a MALDI-TOF MS database and evaluating it.

Methods

Mosquito larvae were collected from different rural and urban areas and reared to adult stages. The adult mosquitoes of four medically important genera, Anopheles, Aedes, Culex and Armigerus, were morphologically identified to the species level and confirmed by ITS2-specific PCR sequencing. The cephalothoraces of the adult specimens were subjected to MALDI-TOF analysis and the signature peak spectra were selected for creation of database, which was then evaluated to identify 60 blinded mosquito specimens.

Results

Reproducible MALDI-TOF MS spectra spanning over 2–14 kDa m/z range were produced for nine mosquito species: Anopheles (An. stephensi, An. culicifacies and An. annularis); Aedes (Ae. aegypti and Ae. albopictus); Culex (Cx. quinquefasciatus, Cx. vishnui and Cx. tritaenorhynchus); and Armigerus (Ar. subalbatus). Genus- and species-specific peaks were identified to create the database and a score of > 1.8 was used to denote reliable identification. The average numbers of peaks obtained were 55–60 for Anopheles, 80–100 for Aedes, 30–60 for Culex and 45–50 peaks for Armigeres species. Of the 60 coded samples, 58 (96.67%) were correctly identified by MALDI-TOF MS with a score > 1.8, while there were two unreliable identifications (both Cx. quinquefasciatus with scores < 1.8).

Conclusions

MALDI-TOF MS appears to be a pragmatic technique for accurate and rapid identification of mosquito species. The database needs to be expanded to include species from different geographical regions and also different life-cycle stages to fully harness the technique for entomological surveillance programs.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2854-0) contains supplementary material, which is available to authorized users.

Medical Entomology: A Reemerging Field of Research to Better Understand Vector-Borne Infectious Diseases

In the last decade, the Chikungunya and Zika virus outbreaks have turned public attention to the possibility of the expansion of vector-borne infectious diseases worldwide. Medical entomology is focused on the study of arthropods involved in human health. We review here some of the research approaches taken by the medical entomology team of the University Hospital Institute (UHI) Méditerranée Infection of Marseille, France, with the support of recent or representative studies. We propose our approaches to technical innovations in arthropod identification and the detection of microorganisms in arthropods, the use of arthropods as epidemiological or diagnostic tools, entomological investigations around clinical cases or within specific populations, and how we have developed experimental models to decipher the interactions between arthropods, microorganisms, and humans.

Detection of Bartonella spp. in fleas by MALDI-TOF MS

Background

Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has recently emerged in the field of entomology as a promising method for the identification of arthropods and the detection of associated pathogens.

Methodology/Principal findings

An experimental model of Ctenocephalides felis (cat fleas) infected with Bartonella quintana and Bartonella henselae was developed to evaluate the efficacy of MALDI-TOF MS in distinguishing infected from uninfected fleas, and its ability to distinguish fleas infected with Bartonella quintana from fleas infected with Bartonella henselae. For B. quintana, two groups of fleas received three successive blood meals, infected or not. A total of 140 fleas (100 exposed fleas and 40 control fleas) were engorged on human blood, infected or uninfected with B. quintana. Regarding the second pathogen, two groups of fleas (200 exposed fleas and 40 control fleas) were fed in the same manner with human blood, infected or not with Bartonella henselae. Fleas were dissected longitudinally; one-half was used for assessment of B. quintana and B. henselae infectious status by real-time PCR, and the second half was subjected to MALDI-TOF MS analysis. Comparison of MS spectra from infected fleas and uninfected fleas revealed distinct MS profiles. Blind queries against our MALDI-TOF MS arthropod database, upgraded with reference spectra from B. quintana and B. henselae infected fleas but also non-infected fleas, provided the correct classification for 100% of the different categories of specimens tested on the first model of flea infection with Bartonella quintana. As for Bartonella henselae, 81% of exposed qPCR-positive fleas, 96% of exposed qPCR-negative fleas and 100% of control fleas were correctly identified on the second model of flea infection.

MALDI-TOF MS successfully differentiated Bartonella spp.-infected and uninfected fleas and was also able to correctly differentiate fleas infected with Bartonella quintana and fleas infected with Bartonella henselae. MALDI-TOF MS correctly identified flea species as well as their infectious status, consistent with the results of real-time PCR.

Conclusions/Significance

MALDI-TOF is a promising tool for identification of the infection status of fleas infected with Bartonella spp., which allows new possibilities for fast and accurate diagnosis in medical entomology and vector surveillance.

Fleas are known vectors of human infectious diseases. Identification of fleas and their associated pathogens is essential for the prevention of flea-borne diseases. Currently, the morphological identification of arthropods based on dichotomous keys, as well as molecular techniques, are the most common approaches for arthropod identification and entomological surveillance. In recent years, MALDI-TOF MS has revolutionized clinical microbiology in enabling the rapid identification of bacteria and fungi by comparing the protein profiles obtained to a database. This proteomic approach has recently been used for arthropod identification and pathogen detection. Here, we developed an experimental model to test MALDI-TOF's ability to differentiate fleas infected with human pathogens, Bartonella quintana and Bartonella henselae, from uninfected fleas.

Using MALDI-TOF MS to identify mosquitoes collected in Mali and their blood meals

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been recently described as an innovative and effective tool for identifying arthropods and mosquito blood meal sources. To test this approach in the context of an entomological survey in the field, mosquitoes were collected from five ecologically distinct areas of Mali. We successfully analysed the blood meals from 651 mosquito abdomens crushed on Whatman filter paper (WFPs) in the field using MALDI-TOF MS. The legs of 826 mosquitoes were then submitted for MALDI-TOF MS analysis in order to identify the different mosquito species. Eight mosquito species were identified, including Anopheles gambiae Giles, Anopheles coluzzii, Anopheles arabiensis, Culex quinquefasciatus, Culex neavei, Culex perexiguus, Aedes aegypti and Aedes fowleri in Mali. The field mosquitoes for which MALDI-TOF MS did not provide successful identification were not previously available in our database. These specimens were subsequently molecularly identified. The WFP blood meal sources found in this study were matched against human blood (n = 619), chicken blood (n = 9), cow blood (n = 9), donkey blood (n = 6), dog blood (n = 5) and sheep blood (n = 3). This study reinforces the fact that MALDI-TOF MS is a promising tool for entomological surveys.