scholarly journals Development of a Confinable Gene-Drive System in the Human Disease Vector, Aedes aegypti

2019 ◽  
Author(s):  
Ming Li ◽  
Ting Yang ◽  
Nikolay P. Kandul ◽  
Michelle Bui ◽  
Stephanie Gamez ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
High Efficiency ◽  
New Technologies ◽  
Current Control ◽  
Pathogen Transmission ◽  
Mosquito Vector ◽  
Control Methods ◽  
Split Gene ◽  
Pathogen Effector ◽  
Gene Drives

AbstractAedes aegypti, the principal mosquito vector for many arboviruses that causes yellow fever, dengue, Zika, and chikungunya, increasingly infects millions of people every year. With an escalating burden of infections and the relative failure of traditional control methods, the development of innovative control measures has become of paramount importance. The use of gene drives has recently sparked significant enthusiasm for the genetic control of mosquito populations, however no such system has been developed in Ae. aegypti. To fill this void and demonstrate efficacy in Ae. aegypti, here we develop several CRISPR-based split-gene drives for use in this vector. With cleavage rates up to 100% and transmission rates as high as 94%, mathematical models predict that these systems could spread anti-pathogen effector genes into wild Ae. aegypti populations in a safe, confinable and reversible manner appropriate for field trials and effective for controlling disease. These findings could expedite the development of effector-linked gene drives that could safely control wild populations of Ae. aegypti to combat local pathogen transmission.Significance StatementAe. aegypti is a globally distributed arbovirus vector spreading deadly pathogens to millions of people annually. Current control methods are inadequate and therefore new technologies need to be innovated and implemented. With the aim of providing new tools for controlling this pest, here we engineered and tested several split gene drives in this species. These drives functioned at very high efficiency and may provide a tool to fill the void in controlling this vector. Taken together, our results provide compelling path forward for the feasibility of future effector-linked split-drive technologies that can contribute to the safe, sustained control and potentially the elimination of pathogens transmitted by this species.

scholarly journals Development of a confinable gene drive system in the human disease vector Aedes aegypti

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Ming Li ◽  
Ting Yang ◽  
Nikolay P Kandul ◽  
Michelle Bui ◽  
Stephanie Gamez ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Field Trials ◽  
Pathogen Transmission ◽  
Control Measures ◽  
Mosquito Vector ◽  
Gene Drive ◽  
Wild Populations ◽  
Linked Gene ◽  
Pathogen Effector ◽  
Gene Drives

Aedes aegypti is the principal mosquito vector for many arboviruses that increasingly infect millions of people every year. With an escalating burden of infections and the relative failure of traditional control methods, the development of innovative control measures has become of paramount importance. The use of gene drives has sparked significant enthusiasm for genetic control of mosquitoes; however, no such system has been developed in Ae. aegypti. To fill this void, here we develop several CRISPR-based split gene drives for use in this vector. With cleavage rates up to 100% and transmission rates as high as 94%, mathematical models predict that these systems could spread anti-pathogen effector genes into wild populations in a safe, confinable and reversible manner appropriate for field trials and effective for controlling disease. These findings could expedite the development of effector-linked gene drives that could safely control wild populations of Ae. aegypti to combat local pathogen transmission.

scholarly journals Assessment of a Split Homing Based Gene Drive for Efficient Knockout of Multiple Genes

2019 ◽  
Vol 10 (2) ◽  
pp. 827-837 ◽  
Author(s):  
Nikolay P. Kandul ◽  
Junru Liu ◽  
Anna Buchman ◽  
Valentino M. Gantz ◽  
Ethan Bier ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Target Genes ◽  
High Efficiency ◽  
Population Control ◽  
Natural Populations ◽  
Pathogen Transmission ◽  
Gene Drive ◽  
Guide Rnas ◽  
Cas9 Protein ◽  
Gene Drives

Homing based gene drives (HGD) possess the potential to spread linked cargo genes into natural populations and are poised to revolutionize population control of animals. Given that host encoded genes have been identified that are important for pathogen transmission, targeting these genes using guide RNAs as cargo genes linked to drives may provide a robust method to prevent disease transmission. However, effectiveness of the inclusion of additional guide RNAs that target separate genes has not been thoroughly explored. To test this approach, we generated a split-HGD in Drosophila melanogaster that encoded a drive linked effector consisting of a second gRNA engineered to target a separate host-encoded gene, which we term a gRNA-mediated effector (GME). This design enabled us to assess homing and knockout efficiencies of two target genes simultaneously, and also explore the timing and tissue specificity of Cas9 expression on cleavage/homing rates. We demonstrate that inclusion of a GME can result in high efficiency of disruption of both genes during super-Mendelian propagation of split-HGD. Furthermore, both genes were knocked out one generation earlier than expected indicating the robust somatic expression of Cas9 driven by Drosophila germline-limited promoters. We also assess the efficiency of ‘shadow drive’ generated by maternally deposited Cas9 protein and accumulation of drive-induced resistance alleles along multiple generations, and discuss design principles of HGD that could mitigate the accumulation of resistance alleles while incorporating a GME.

scholarly journals Assessment of a split homing based gene drive for efficient knockout of multiple genes

2019 ◽  
Author(s):  
Nikolay P. Kandul ◽  
Junru Liu ◽  
Anna Buchman ◽  
Valentino M. Gantz ◽  
Ethan Bier ◽  
...  
Keyword(s):  
Target Gene ◽  
Tissue Specificity ◽  
Target Genes ◽  
High Efficiency ◽  
Population Control ◽  
Natural Populations ◽  
Pathogen Transmission ◽  
Gene Drive ◽  
Guide Rnas ◽  
Gene Drives

AbstractHoming based gene drives (HGD) possess the potential to spread linked cargo genes into natural populations and are poised to revolutionize population control of animals. Given that host-encoded genes have been identified that are important for pathogen transmission, targeting these genes using guide RNAs as cargo genes linked to drives may provide a robust method to prevent transmission. However, effectiveness of the inclusion of additional guide RNAs that target separate host encoded genes has not been thoroughly explored. To test this approach, here we generated a split-HGD in Drosophila melanogaster that encoded a drive linked effector consisting of a second gRNA engineered to target a separate host encoded gene, which we term a gRNA-mediated effector (GME). This design enabled us to assess homing and knockout efficiencies of two target genes simultaneously, and also explore the timing and tissue specificity of Cas9 expression on cleavage/homing rates. We demonstrate that inclusion of a GME can result in high efficiency of disruption of its target gene during super-Mendelian propagation of split-HGD. However, maternal deposition and embryonic expression of Cas9 resulted in the generation of drive resistant alleles which can accumulate and limit the spread of such a drive. Alternative design principles are discussed that could mitigate the accumulation of resistance alleles while incorporating a GME.

scholarly journals Integrated Control of Aedes Aegypti With Parasitic Nematodes, Biological Control Agents, Chemical Insecticides and Plant Essential Oil

2021 ◽  
Author(s):  
Jinfeng Xiong ◽  
Hui Zhang ◽  
Caixia Li ◽  
Rui Ma ◽  
Hui Ai ◽  
...  
Keyword(s):  
Biological Control ◽  
Essential Oil ◽  
Aedes Aegypti ◽  
High Efficiency ◽  
Pcr Analysis ◽  
Control Group ◽  
Mosquito Vector ◽  
Biological Control Agents ◽  
Competitive Binding Assay ◽  
Density Control

Abstract Aedes aegypti can transmit dengue fever, yellow fever, Chikungunya fever, Zika virus disease and vector density control is the most effective way to prevent these infectious diseases. However, the extensive use of chemical pesticides has caused a series of problems, such as environmental pollution, killing non-target organisms and so on. In this study, a parasitic nematode, Romanomermis wuchangensis was used in the larviciding evaluation of Ae. aegypti, while the activity of four chemical insecticides and biological control agents were tested. Besides, Mentha haplocalyx essential oil was isolated and its olfactory physiological function with OBP1 protein of Ae. aegypti antenna was measured by the prokaryotic expression and fluorescence competitive binding assay. Compared with the control group, R. wuchangensis indicated high efficiency and environmental friendliness in the control of Ae. aegypti. After the second instar larvae were parasitized, the mortality of two treatment groups exceeded 75%. Compared to control group, the quantitative real-time PCR analysis results demonstrated that SOD, POD and CAT genes had obvious high expression levels in the nematodes parasitic groups. The antioxidant enzyme test results also exhibited obvious difference of SOD, CAT and POD during the nematode parasitic period. Besides, Bacillus thuringiensis (Bti) and chemical insecticide experimental results also showed great insecticidal efficacy against mosquito larvae. Five chemical components including Menthol, Pinene, Limonene, Isopulegol and Pulegone were identified from M. haplocalyx and exhibited great binding ability with AaegOBP1 protein. Present results illustrated that the integrated application of these various mosquito vector control methods in the future has broad prospects.

scholarly journals Combating mosquito-borne diseases using genetic control technologies

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guan-Hong Wang ◽  
Stephanie Gamez ◽  
Robyn R. Raban ◽  
John M. Marshall ◽  
Luke Alphey ◽  
...  
Keyword(s):  
Disease Burden ◽  
Genome Engineering ◽  
Mosquito Control ◽  
Control Strategies ◽  
Current Control ◽  
Transmission Risk ◽  
Control Methods ◽  
Control Technologies ◽  
Health Burdens ◽  
Gene Drives

AbstractMosquito-borne diseases, such as dengue and malaria, pose significant global health burdens. Unfortunately, current control methods based on insecticides and environmental maintenance have fallen short of eliminating the disease burden. Scalable, deployable, genetic-based solutions are sought to reduce the transmission risk of these diseases. Pathogen-blocking Wolbachia bacteria, or genome engineering-based mosquito control strategies including gene drives have been developed to address these problems, both requiring the release of modified mosquitoes into the environment. Here, we review the latest developments, notable similarities, and critical distinctions between these promising technologies and discuss their future applications for mosquito-borne disease control.

A Simple PCR Assay for Discrimination of Dengue Vectors from Nsukka LGA, Nigeria

2020 ◽  
Vol 10 (1) ◽  
pp. 67-77
Author(s):  
Amos Watentena ◽  
Ikem Chris Okoye ◽  
Ikechukwu Eugene Onah ◽  
Onwude Cosmas Ogbonnaya ◽  
Emmanuel Ogudu
Keyword(s):  
Aedes Aegypti ◽  
Aedes Albopictus ◽  
Mosquito Species ◽  
Public Health Problem ◽  
Major Public Health Problem ◽  
Mosquito Vector ◽  
Aedes Mosquitoes ◽  
Allele Specific ◽  
Arboviral Diseases ◽  
Dengue Vectors

Mosquitoes of Aedes species are vectors of several arboviral diseases which continue to be a major public health problem in Nigeria. This study among other things, morphologically identified Aedes mosquitoes collected from Nsukka LGA and used an allele specific PCR amplification for discrimination of dengue vectors. Larval sampling, BG-sentinel traps and modified human landing catches were used for mosquito sampling in two selected autonomous communities of Nsukka LGA (Nsukka and Obimo). A total of 124 Aedes mosquitoes consisting of five (5) different species were collected from April to June, 2019 in a cross-sectional study that covered 126 households, under 76 distinct geographical coordinates. Larvae was mainly collected from plastic containers 73% (n=224), metallic containers 14% (n=43), earthen pots 9% (n=29) and used car tyres 3% (n=9), reared to adult stage 69.35% (n=86), and all mosquitoes were identified using standard morphological keys. Five (5) Aedes mosquito species were captured; Aedes aegypti 83(66.94%), Aedes albopictus 33(26.61%), Aedes simpsoni (4.48%), Aedes luteocephalus (≤1%) and Aedes vittatus (≤1%). Nsukka autonomous community had higher species diversity than Obimo. Allele specific amplification confirmed dengue vectors, Aedes aegypti and Aedes albopictus species on a 2% agarose gel. Since the most recent re-emergence of arboviral diseases is closely associated with Aedes species, findings of this study, therefore, give further evidence about the presence of potential arboviral vectors in Nigeria and describe the role of a simple PCR in discriminating some. Further entomological studies should integrate PCR assays in mosquito vector surveillance.

scholarly journals Temporal and Spatial Blood Feeding Patterns of Urban Mosquitoes in the San Juan Metropolitan Area, Puerto Rico

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 129
Author(s):  
Matthew W. Hopken ◽  
Limarie J. Reyes-Torres ◽  
Nicole Scavo ◽  
Antoinette J. Piaggio ◽  
Zaid Abdo ◽  
...  
Keyword(s):  
Puerto Rico ◽  
Aedes Aegypti ◽  
Metropolitan Area ◽  
Culex Quinquefasciatus ◽  
Urban Ecosystems ◽  
Life Cycles ◽  
Pathogen Transmission ◽  
San Juan ◽  
Vertebrate Species ◽  
Blood Meals

Urban ecosystems are a patchwork of habitats that host a broad diversity of animal species. Insects comprise a large portion of urban biodiversity which includes many pest species, including those that transmit pathogens. Mosquitoes (Diptera: Culicidae) inhabit urban environments and rely on sympatric vertebrate species to complete their life cycles, and in this process transmit pathogens to animals and humans. Given that mosquitoes feed upon vertebrates, they can also act as efficient samplers that facilitate detection of vertebrate species that utilize urban ecosystems. In this study, we analyzed DNA extracted from mosquito blood meals collected temporally in multiple neighborhoods of the San Juan Metropolitan Area, Puerto Rico to evaluate the presence of vertebrate fauna. DNA was collected from 604 individual mosquitoes that represented two common urban species, Culex quinquefasciatus (n = 586) and Aedes aegypti (n = 18). Culex quinquefasciatus fed on 17 avian taxa (81.2% of blood meals), seven mammalian taxa (17.9%), and one reptilian taxon (0.85%). Domestic chickens dominated these blood meals both temporally and spatially, and no statistically significant shift from birds to mammals was detected. Aedes aegypti blood meals were from a less diverse group, with two avian taxa (11.1%) and three mammalian taxa (88.9%) identified. The blood meals we identified provided a snapshot of the vertebrate community in the San Juan Metropolitan Area and have potential implications for vector-borne pathogen transmission.

scholarly journals Timing and Route of Contamination of Patient Rooms With Healthcare-Associated Pathogens

2020 ◽  
Vol 41 (S1) ◽  
pp. s412-s412
Author(s):  
Sarah Redmond ◽  
Jennifer Cadnum ◽  
Basya Pearlmutter ◽  
Natalia Pinto Herrera ◽  
Curtis Donskey
Keyword(s):  
Acute Care Hospital ◽  
Current Control ◽  
Pathogen Transmission ◽  
Control Measures ◽  
Effective Control ◽  
Portable Devices ◽  
Care Hospital ◽  
Spa Typing ◽  
Persistent Problem ◽  
Healthcare Associated

Background: Transmission of healthcare-associated pathogens such as Clostridioides difficile and methicillin-resistant Staphylococcus aureus (MRSA) is a persistent problem in healthcare facilities despite current control measures. A better understanding of the routes of pathogen transmission is needed to develop effective control measures. Methods: We conducted an observational cohort study in an acute-care hospital to identify the timing and route of transfer of pathogens to rooms of newly admitted patients with negative MRSA nares results and no known carriage of other healthcare-associated pathogens. Rooms were thoroughly cleaned and disinfected prior to patient admission. Interactions of patients with personnel and portable equipment were observed, and serial cultures for pathogens were collected from the skin of patients and from surfaces, including those observed to come in contact with personnel and equipment. For MRSA, spa typing was used to determine relatedness of patient and environmental isolates. Results: For the 17 patients enrolled, 1 or more environmental cultures became positive for MRSA in rooms of 10 patients (59%), for C. difficile in rooms of 2 patients (12%) and for vancomycin-resistant enterococci (VRE) in rooms of 2 patients (12%). The patients interacted with an average of 2.4 personnel and 0.6 portable devices per hour of observation. As shown in Figure 1, MRSA contamination of the floor occurred rapidly as personnel entered the room. In a subset of patients, MRSA was subsequently recovered from patients’ socks and bedding and ultimately from the high-touch surfaces in the room (tray table, call button, bedrail). For several patients, MRSA isolates recovered from the floor had the same spa type as isolates subsequently recovered from other sites (eg, socks, bedding, and/or high touch surfaces). The direct transfer of healthcare-associated pathogens from personnel or equipment to high-touch surfaces was not detected. Conclusions: Healthcare-associated pathogens rapidly accumulate on the floor of patient rooms and can be transferred to the socks and bedding of patients and to high-touch surfaces. Healthcare facility floors may be an underappreciated source of pathogen dissemination not addressed by current infection control measures.Funding: NoneDisclosures: None

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