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  • 1.
    Accoti, Anastasia
    et al.
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States.
    Engdahl, Cecilia
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States.
    Dimopoulos, George
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States.
    Discovery of Novel Entomopathogenic Fungi for Mosquito-Borne Disease Control2021In: Frontiers in Fungal Biology, E-ISSN 2673-6128, Vol. 2, article id 637234Article in journal (Refereed)
    Abstract [en]

    The increased application of chemical control programs has led to the emergence and spread of insecticide resistance in mosquitoes. Novel environmentally safe control strategies are currently needed for the control of disease vectors. The use of entomopathogenic fungi could be a suitable alternative to chemical insecticides. Currently, Beauveria spp. and Metarhizium spp. are the most widely used entomopathogenic fungi for mosquito control, but increasing the arsenal with additional fungi is necessary to mitigate the emergence of resistance. Entomopathogenic fungi are distributed in a wide range of habitats. We have performed a comprehensive screen for candidate mosquitocidal fungi from diverse outdoor environments in Maryland and Puerto Rico. An initial screening of 22 fungi involving exposure of adult Anopheles gambiae to 2-weeks-old fungal cultures identified five potent pathogenic fungi, one of which is unidentified and the remaining four belonging to the three genera Galactomyces sp., Isaria sp. and Mucor sp. These fungi were then screened against Aedes aegypti, revealing Isaria sp. as a potent mosquito killer. The entomopathogenic effects were confirmed through spore-dipping assays. We also probed further into the killing mechanisms of these fungi and investigated whether the mosquitocidal activities were the result of potential toxic fungus-produced metabolites. Preliminary assays involving the exposure of mosquitoes to sterile filtered fungal liquid cultures showed that Galactomyces sp., Isaria sp. and the unidentified isolate 1 were the strongest producers of factors showing lethality against An. gambiae. We have identified five fungi that was pathogenic for An. gambiae and one for Ae. aegypti, among these fungi, four of them (two strains of Galactomyces sp., Mucor sp., and the unidentified isolate 1) have never previously been described as lethal to insects. Further characterization of these entomopathogenic fungi and their metabolites needs to be done to confirm their potential use in biologic control against mosquitoes.

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  • 2.
    Andersson, C. David
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Forsgren, Nina
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Akfur, Christine
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Allgardsson, Anders
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Berg, Lotta
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engdahl, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Qian, Weixing
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratories for Chemical Biology Umeå (LCBU), Umeå University,.
    Ekström, Fredrik
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå.
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Divergent Structure-Activity Relationships of Structurally Similar Acetylcholinesterase Inhibitors2013In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 56, no 19, p. 7615-7624Article in journal (Refereed)
    Abstract [en]

    The molecular interactions between the enzyme acetylcholinesterase (AChE) and two compound classes consisting of N-[2-(diethylamino)ethyl]benzenesulfonamides and N-[2-(diethylamino)ethyl]benzenemethanesulfonamides have been investigated using organic synthesis, enzymatic assays, X-ray crystallography, and thermodynamic profiling. The inhibitors' aromatic properties were varied to establish structure activity relationships (SAR) between the inhibitors and the peripheral anionic site (PAS) of AChE. The two structurally similar compound classes proved to have distinctly divergent SARs in terms of their inhibition capacity of AChE. Eight X-ray structures revealed that the two sets have different conformations in PAS. Furthermore, thermodynamic profiles of the binding between compounds and AChE revealed class-dependent differences of the entropy/enthalpy contributions to the free energy of binding. Further development of the entropy-favored compound class resulted in the synthesis of the most potent inhibitor and an extension beyond the established SARs. The divergent SARs will be utilized to develop reversible inhibitors of AChE into reactivators of nerve agent-inhibited AChE.

  • 3.
    Bergqvist, Joakim
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Forsman, Oscar
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Larsson, Pär
    Umeå University, Faculty of Medicine, Department of Medical Biosciences.
    Näslund, Jonas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Lilja, Tobias
    Engdahl, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindström, Anders
    Gylfe, Åsa
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Evander, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Arctic Research Centre at Umeå University.
    Bucht, Göran
    [ 1 ] CBRN Def & Secur, Swedish Def Res Agcy, SE-90182 Umea, Sweden.
    Detection and Isolation of Sindbis Virus from Mosquitoes Captured During an Outbreak in Sweden, 20132015In: Vector Borne and Zoonotic Diseases, ISSN 1530-3667, E-ISSN 1557-7759, Vol. 15, no 2, p. 133-140Article in journal (Refereed)
    Abstract [en]

    Mosquito-borne alphaviruses have the potential to cause large outbreaks throughout the world. Here we investigated the causative agent of an unexpected Sindbis virus (SINV) outbreak during August-September, 2013, in a previously nonendemic region of Sweden. Mosquitoes were collected using carbon dioxide-baited CDC traps at locations close to human cases. The mosquitoes were initially screened as large pools by SINV-specific quantitative RT-PCR, and the SINV-positive mosquitoes were species determined by single-nucleotide polymorphism (SNP) analysis, followed by sequencing the barcoding region of the cytochrome oxidase I gene. The proportion of the collected mosquitoes was determined by a metabarcoding strategy. By using novel strategies for PCR screening and genetic typing, a new SINV strain, Lovanger, was isolated from a pool of 1600 mosquitoes composed of Culex, Culiseta, and Aedes mosquitoes as determined by metabarcoding. The SINV-positive mosquito Culiseta morsitans was identified by SNP analysis and sequencing. After whole-genome sequencing and phylogenetic analysis, the SINV Lovanger isolate was shown to be most closely similar to recent Finnish SINV isolates. In conclusion, within a few weeks, we were able to detect and isolate a novel SINV strain and identify the mosquito vector during a sudden SINV outbreak.

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  • 4.
    Engdahl, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Selective inhibition of acetylcholinesterase 1 from disease-transmitting mosquitoes: design and development of new insecticides for vector control2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Acetylcholinesterase (AChE) is an essential enzyme with an evolutionary conserved function: to terminate nerve signaling by rapid hydrolysis of the neurotransmitter acetylcholine. AChE is an important target for insecticides. Vector control by the use of insecticide-based interventions is today the main strategy for controlling mosquito-borne diseases that affect millions of people each year. However, the efficiency of many insecticides is challenged by resistant mosquito populations, lack of selectivity and off-target toxicity of currently used compounds. New selective and resistance-breaking insecticides are needed for an efficient vector control also in the future. In the work presented in this thesis, we have combined structural biology, biochemistry and medicinal chemistry to characterize mosquito AChEs and to develop selective and resistance-breaking inhibitors of this essential enzyme from two disease-transmitting mosquitoes.We have identified small but important structural and functional differences between AChE from mosquitoes and AChE from vertebrates. The significance of these differences was emphasized by a high throughput screening campaign, which made it evident that the evolutionary distant AChEs display significant differences in their molecular recognition. These findings were exploited in the design of new inhibitors. Rationally designed and developed thiourea- and phenoxyacetamide-based non-covalent inhibitors displayed high potency on both wild type and insecticide insensitive AChE from mosquitoes. The best inhibitors showed over 100-fold stronger inhibition of mosquito than human AChE, and proved insecticide potential as they killed both adult and larvae mosquitoes.We show that mosquito and human AChE have different molecular recognition and that non-covalent selective inhibition of AChE from mosquitoes is possible. We also demonstrate that inhibitors can combine selectivity with sub-micromolar potency for insecticide resistant AChE.

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  • 5.
    Engdahl, Cecilia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Knutsson, Sofie
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ekström, Fredrik
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Discovery of selective inhibitors targeting acetylcholinesterase 1 from disease-transmitting mosquitoes2016In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 59, no 20, p. 9409-9421Article in journal (Other academic)
    Abstract [en]

    Vector control of disease-transmitting mosquitoes is increasingly important due to the re-emergence and spread of infections such as malaria and dengue. We have conducted a high throughput screen (HTS) of 17,500 compounds for inhibition of the essential AChE1 enzymes from the mosquitoes Anopheles gambiae and Aedes aegypti. In a differential HTS analysis including the human AChE, several structurally diverse, potent, and selective noncovalent AChE1 inhibitors were discovered. For example, a phenoxyacetamide-based inhibitor was identified with a 100-fold selectivity for the mosquito over the human enzyme. The compound also inhibited a resistance conferring mutant of AChE1. Structure-selectivity relationships could be proposed based on the enzymes' 3D structures; the hits' selectivity profiles appear to be linked to differences in two loops that affect the structure of the entire active site. Noncovalent inhibitors of AChE1, such as the ones presented here, provide valuable starting points toward insecticides and are complementary to existing and new covalent inhibitors.

  • 6.
    Engdahl, Cecilia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Knutsson, Sofie
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fredriksson, Sten-Åke
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bucht, Göran
    Ekström, Fredrik
    Acetylcholinesterases from the Disease Vectors Aedes aegypti and Anopheles gambiae: Functional Characterization and Comparisons with Vertebrate Orthologues2015In: PLOS ONE, E-ISSN 1932-6203, Vol. 10, no 10, article id e0138598Article in journal (Refereed)
    Abstract [en]

    Mosquitoes of the Anopheles (An.) and Aedes (Ae.) genus are principal vectors of human diseases including malaria, dengue and yellow fever. Insecticide-based vector control is an established and important way of preventing transmission of such infections. Currently used insecticides can efficiently control mosquito populations, but there are growing concerns about emerging resistance, off-target toxicity and their ability to alter ecosystems. A potential target for the development of insecticides with reduced off-target toxicity is the cholinergic enzyme acetylcholinesterase (AChE). Herein, we report cloning, baculoviral expression and functional characterization of the wild-type AChE genes (ace-1) from An. gambiae and Ae. aegypti, including a naturally occurring insecticide-resistant (G119S) mutant of An. gambiae. Using enzymatic digestion and liquid chromatography-tandem mass spectrometry we found that the secreted proteins were post-translationally modified. The Michaelis-Menten constants and turnover numbers of the mosquito enzymes were lower than those of the orthologous AChEs from Mus musculus and Homo sapiens. We also found that the G119S substitution reduced the turnover rate of substrates and the potency of selected covalent inhibitors. Furthermore, non-covalent inhibitors were less sensitive to the G119S substitution and differentiate the mosquito enzymes from corresponding vertebrate enzymes. Our findings indicate that it may be possible to develop selective non-covalent inhibitors that effectively target both the wild-type and insecticide resistant mutants of mosquito AChE.

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  • 7.
    Engdahl, Cecilia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Larsson, Pär
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå, Sweden.
    Näslund, Jonas
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå, Sweden.
    Bravo, Mayra
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå, Sweden.
    Evander, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology.
    Lundström, Jan O.
    Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Bucht, Göran
    Swedish Defense Research Agency, CBRN Defense and Security, Umeå, Sweden.
    Identification of Swedish mosquitoes based on molecular barcoding of the COI gene and SNP analysis2014In: Molecular Ecology Resources, ISSN 1755-098X, E-ISSN 1755-0998, Vol. 14, no 3, p. 478-488Article in journal (Refereed)
    Abstract [en]

    Mosquito-borne infectious diseases are emerging in many regions of the world. Consequently, surveillance of mosquitoes and concomitant infectious agents is of great importance for prediction and prevention of mosquito-borne infectious diseases. Currently, morphological identification of mosquitoes is the traditional procedure. However, sequencing of specified genes or standard genomic regions, DNA barcoding, has recently been suggested as a global standard for identification and classification of many different species. Our aim was to develop a genetic method to identify mosquitoes and to study their relationship. Mosquitoes were captured at collection sites in northern Sweden and identified morphologically before the cytochrome c oxidase subunit I (COI) gene sequences of 14 of the most common mosquito species were determined. The sequences obtained were then used for phylogenetic placement, for validation and benchmarking of phenetic classifications and finally to develop a hierarchical PCR-based typing scheme based on single nucleotide polymorphism sites (SNPs) to enable rapid genetic identification, circumventing the need for morphological characterization. The results showed that exact phylogenetic relationships between mosquito taxa were preserved at shorter evolutionary distances, but at deeper levels, they could not be inferred with confidence using COI gene sequence data alone. Fourteen of the most common mosquito species in Sweden were identified by the SNP/PCR-based typing scheme, demonstrating that genetic typing using SNPs of the COI gene is a useful method for identification of mosquitoes with potential for worldwide application.

  • 8.
    Engdahl, Cecilia
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Näslund, Jonas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Lindgren, Lena
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Bucht, Göran
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    The Rift Valley Fever virus protein NSm and putative cellular protein interactions2012In: Virology Journal, E-ISSN 1743-422X, Vol. 9, p. 139-Article in journal (Refereed)
    Abstract [en]

    Rift Valley Fever is an infectious viral disease and an emerging problem in many countries of Africa and on the Arabian Peninsula. The causative virus is predominantly transmitted by mosquitoes and high mortality and abortion rates characterize outbreaks in animals while symptoms ranging from mild to life-threatening encephalitis and hemorrhagic fever are noticed among infected humans. For a better prevention and treatment of the infection, an increased knowledge of the infectious process of the virus is required. The focus of this work was to identify protein-protein interactions between the non-structural protein (NSm), encoded by the M-segment of the virus, and host cell proteins. This study was initiated by screening approximately 26 million cDNA clones of a mouse embryonic cDNA library for interactions with the NSm protein using a yeast two-hybrid system. We have identified nine murine proteins that interact with NSm protein of Rift Valley Fever virus, and the putative protein-protein interactions were confirmed by growth selection procedures and beta-gal activity measurements. Our results suggest that the cleavage and polyadenylation specificity factor subunit 2 (Cpsf2), the peptidyl-prolyl cistrans isomerase (cyclophilin)-like 2 protein (Ppil2), and the synaptosome-associated protein of 25 kDa (SNAP-25) are the most promising targets for the NSm protein of the virus during an infection.

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  • 9.
    Knutsson, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engdahl, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kumari, Rashmi
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Forsgren, Nina
    Lindgren, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kitur, Stanley
    Kamau, Luna
    Ekström, Fredrik
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Binding Mode of Reversible Inhibitors in Mosquito Acetylcholinesterase 1 Governs their Selective and Resistance-Breaking PotencyManuscript (preprint) (Other academic)
  • 10.
    Knutsson, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engdahl, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kumari, Rashmi
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Forsgren, Nina
    Lindgren, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kitur, Stanley
    Wachira, Lucy
    Kamau, Luna
    Ekstöm, Fredrik
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Noncovalent Inhibitors of Mosquito Acetylcholinesterase 1 with Resistance-Breaking Potency2018In: Journal of Medicinal Chemistry, ISSN 0022-2623, E-ISSN 1520-4804, Vol. 61, no 23, p. 10545-10557Article in journal (Refereed)
    Abstract [en]

    Resistance development in insects significantly threatens the important benefits obtained by insecticide usage in vector control of disease-transmitting insects. Discovery of new chemical entities with insecticidal activity is highly desired in order to develop new insecticide candidates. Here, we present the design, synthesis, and biological evaluation of phenoxyacetamide-based inhibitors of the essential enzyme acetylcholinesterase 1 (AChE1). AChE1 is a validated insecticide target to control mosquito vectors of, e.g., malaria, dengue, and Zika virus infections. The inhibitors combine a mosquito versus human AChE selectivity with a high potency also for the resistance-conferring mutation G122S; two properties that have proven challenging to combine in a single compound. Structure activity relationship analyses and molecular dynamics simulations of inhibitor protein complexes have provided insights that elucidate the molecular basis for these properties. We also show that the inhibitors demonstrate in vivo insecticidal activity on disease-transmitting mosquitoes. Our findings support the concept of noncovalent, selective, and resistance-breaking inhibitors of AChE1 as a promising approach for future insecticide development.

  • 11.
    Knutsson, Sofie
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engdahl, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nikjoo, Dariush
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Forsgren, Nina
    Kitur, Stanley
    Ekström, Fredrik
    Kamau, Luna
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    N-Aryl-N'-ethyleneaminothioureas effectively inhibit acetylcholinesterase 1 from disease-transmitting mosquitoes2017In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 134, p. 415-427Article in journal (Refereed)
    Abstract [en]

    Vector control of disease-transmitting mosquitoes by insecticides has a central role in reducing the number of parasitic- and viral infection cases. The currently used insecticides are efficient, but safety concerns and the development of insecticide-resistant mosquito strains warrant the search for alternative compound classes for vector control. Here, we have designed and synthesized thiourea-based compounds as non-covalent inhibitors of acetylcholinesterase 1 (AChE1) from the mosquitoes Anopheles gambiae (An. gambiae) and Aedes aegypti (Ae. aegypti), as well as a naturally occurring resistant-conferring mutant. The N-aryl-N'-ethyleneaminothioureas proved to be inhibitors of AChE1; the most efficient one showed submicromolar potency. Importantly, the inhibitors exhibited selectivity over the human AChE (hAChE), which is desirable for new insecticides. The structure-activity relationship (SAR) analysis of the thioureas revealed that small changes in the chemical structure had a large effect on inhibition capacity. The thioureas showed to have different SAR when inhibiting AChE1 and hAChE, respectively, enabling an investigation of structure-selectivity relationships. Furthermore, insecticidal activity was demonstrated using adult and larvae An. gambiae and Ae. aegypti mosquitoes.

  • 12.
    Mutsaers, Maud
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Engdahl, Cecilia
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Wilkman, Lukas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Ahlm, Clas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Evander, Magnus
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Lwande, Olivia Wesula
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology.
    Vector competence of Anopheles stephensi for O'nyong-nyong virus: a risk for global virus spread2023In: Parasites & Vectors, E-ISSN 1756-3305, Vol. 16, no 1, article id 133Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: O'nyong-nyong virus (ONNV) is a mosquito-borne alphavirus causing sporadic outbreaks of febrile illness with rash and polyarthralgia. Up to now, ONNV has been restricted to Africa and only two competent vectors have been found, Anopheles gambiae and An. funestus, which are also known malaria vectors. With globalization and invasive mosquito species migrating to ONNV endemic areas, there is a possible risk of introduction of the virus to other countries and continents. Anopheles stephensi, is closely related to An. gambiae and one of the invasive mosquito species of Asian origin that is now present in the Horn of Africa and spreading further east. We hypothesize that An. stephensi, a known primary urban malaria vector, may also serve as a new possible vector for ONNV.

    METHODS: One-week-old female adult An. stephensi were exposed to ONNV-infected blood, and the vector competence for ONNV, i.e. infection rates (IRs), dissemination rates (DRs), transmission rates (TRs), dissemination efficiency (DEs) and transmission efficiency (TEs), were evaluated. Infection (IRs), dissemination efficiency (DEs) and transmission efficiency (TEs) were determined. Detection of ONNV RNA was analysed by RT-qPCR in the thorax and abdomen, head, wings, legs and saliva of the infected mosquitoes at four different time points, day 7, 14, 21 and 28 after blood meal. Infectious virus in saliva was assessed by infection of Vero B4 cells.

    RESULTS: The mean mortality across all sampling times was 27.3% (95 confidence interval [CI] 14.7-44.2%). The mean rate of infection across all sampling periods was 89.5% (95% CI 70.6-95.9). The mean dissemination rate across sampling intervals was 43.4% (95% CI 24.3-64.2%). The mean TR and TE across all mosquito sampling time intervals were 65.3 (95% CI 28.6-93.5) and 74.6 (95% CI 52.1-89.4). The IR was 100%, 79.3%, 78.6% and 100% respectively at 7, 14, 21 and 28 dpi. The DR was the highest at 7 dpi with 76.0%, followed by 28 dpi at 57.1%, 21 dpi at 27.3% and 14 dpi at the lowest DR of 13.04%. DE was 76%, 13.8%, 25%, 57.1% and TR was 79%, 50%, 57.1% and 75% at 7, 14, 21 and 28 dpi respectively. The TE was the highest at 28 dpi, with a proportion of 85.7%. For 7, 14 and 21 dpi the transmission efficiency was 72.0%, 65.5% and 75.0% respectively.

    CONCLUSION: Anopheles stephensi is a competent vector for ONNV and being an invasive species spreading to different parts of the world will likely spread the virus to other regions.

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  • 13.
    S. Engdahl, Cecilia
    et al.
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
    Tikhe, Chinmay V.
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
    Dimopoulos, George
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
    Discovery of novel natural products for mosquito control2022In: Parasites & Vectors, E-ISSN 1756-3305, Vol. 15, no 1, article id 481Article in journal (Refereed)
    Abstract [en]

    Vector control plays a key role in reducing the public health burden of mosquito-borne diseases. Today’s vector control strategies largely rely on synthetic insecticides that can have a negative environmental impact when applied outdoors and often become inefficient because of the mosquitoes’ ability to develop resistance. An alternative and promising approach to circumvent these challenges involves the implementation of insecticides derived from nature (biopesticides) for vector control. Biopesticides can constitute naturally occurring organisms or substances derived from them that have lifespan-shortening effects on disease vectors such as mosquitoes. Here we present the discovery and evaluation of natural product-based biological control agents that can potentially be developed into biopesticides for mosquito control. We screened a natural product collection comprising 390 compounds and initially identified 26 molecules with potential ability to kill the larval stages of the yellow fever mosquito Aedes aegypti, which is responsible for transmitting viruses such as dengue, Zika, chikungunya and yellow fever. Natural products identified as hits in the screen were further evaluated for their suitability for biopesticide development. We show that a selection of the natural product top hits, bactobolin, maytansine and ossamycin, also killed the larval stages of the malaria-transmitting mosquito Anopheles gambiae as well as the adult form of both species. We have further explored the usefulness of crude extracts and preparations from two of the best candidates’ sources (organisms of origin) for mosquitocidal activity, that is extracts from the two bacteria Burkholderia thailandensis and Streptomyces hygroscopicus var. ossamyceticus.

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  • 14.
    Springer Engdahl, Cecilia
    et al.
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
    Caragata, Eric P.
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA; Florida Medical Entomology Laboratory, Department of Entomology & Nematology, Institute of Food & Agricultural Sciences, University of Florida, Vero Beach, Florida, USA.
    Tavadia, Mihra
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
    Dimopoulos, George
    W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
    Chromobacterium biopesticide exposure does not select for resistance in Aedes mosquitoes2023In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 14, no 2, article id e00480-23Article in journal (Refereed)
    Abstract [en]

    Developing effective tools to control mosquito populations is essential for reducing the incidence of diseases like malaria and dengue. Biopesticides of microbial origin are a rich, underexplored source of mosquitocidal compounds. We previously developed a biopesticide from the bacterium Chromobacterium sp. Panama that rapidly kills vector mosquito larvae, including Aedes aegypti and Anopheles gambiae. Here, we demonstrate that two independent Ae. aegypti colonies exposed to a sublethal dose of that biopesticide over consecutive generations persistently exhibited high mortality and developmental delays, indicating that resistance did not develop during the study period. Critically, the descendants of biopesticide-exposed mosquitoes experienced decreased longevity and did not display increased susceptibility to dengue virus or decreased susceptibility to common chemical insecticides. Through RNA sequencing, we observed no link between biopesticide exposure and the increased activity of xenobiotic metabolism and detoxification genes typically associated with insecticide resistance. These findings indicate that the Chromobacterium biopesticide is an exciting, emerging mosquito control tool.

    IMPORTANCE: Vector control is an essential part of mitigating diseases caused by pathogens that mosquitoes spread. Modern vector control is highly reliant on using synthetic insecticides to eliminate mosquito populations before they can cause disease. However, many of these populations have become resistant to commonly used insecticides. There is a strong need to explore alternative vector control strategies that aim to mitigate disease burden. Biopesticides, insecticides of biological origin, can have unique mosquitocidal activities, meaning they can effectively kill mosquitoes that are already resistant to other insecticides. We previously developed a highly effective mosquito biopesticide from the bacterium Chromobacterium sp. Csp_P. Here, we investigate whether exposure to a sublethal dose of this Csp_P biopesticide over 9 to 10 generations causes resistance to arise in Aedes aegypti mosquitoes. We find no evidence of resistance at the physiological or molecular levels, confirming that the Csp_P biopesticide is a highly promising new tool for controlling mosquito populations.

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