151
|
Crawford JE, Clarke DW, Criswell V, Desnoyer M, Cornel D, Deegan B, Gong K, Hopkins KC, Howell P, Hyde JS, Livni J, Behling C, Benza R, Chen W, Dobson KL, Eldershaw C, Greeley D, Han Y, Hughes B, Kakani E, Karbowski J, Kitchell A, Lee E, Lin T, Liu J, Lozano M, MacDonald W, Mains JW, Metlitz M, Mitchell SN, Moore D, Ohm JR, Parkes K, Porshnikoff A, Robuck C, Sheridan M, Sobecki R, Smith P, Stevenson J, Sullivan J, Wasson B, Weakley AM, Wilhelm M, Won J, Yasunaga A, Chan WC, Holeman J, Snoad N, Upson L, Zha T, Dobson SL, Mulligan FS, Massaro P, White BJ. Efficient production of male Wolbachia-infected Aedes aegypti mosquitoes enables large-scale suppression of wild populations. Nat Biotechnol 2020; 38:482-492. [PMID: 32265562 DOI: 10.1038/s41587-020-0471-x] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 02/10/2020] [Accepted: 02/27/2020] [Indexed: 11/09/2022]
Abstract
The range of the mosquito Aedes aegypti continues to expand, putting more than two billion people at risk of arboviral infection. The sterile insect technique (SIT) has been used to successfully combat agricultural pests at large scale, but not mosquitoes, mainly because of challenges with consistent production and distribution of high-quality male mosquitoes. We describe automated processes to rear and release millions of competitive, sterile male Wolbachia-infected mosquitoes, and use of these males in a large-scale suppression trial in Fresno County, California. In 2018, we released 14.4 million males across three replicate neighborhoods encompassing 293 hectares. At peak mosquito season, the number of female mosquitoes was 95.5% lower (95% CI, 93.6-96.9) in release areas compared to non-release areas, with the most geographically isolated neighborhood reaching a 99% reduction. This work demonstrates the high efficacy of mosquito SIT in an area ninefold larger than in previous similar trials, supporting the potential of this approach in public health and nuisance-mosquito eradication programs.
Collapse
Affiliation(s)
| | | | | | | | - Devon Cornel
- Consolidated Mosquito Abatement District, Parlier, CA, USA
| | | | - Kyle Gong
- Verily Life Sciences, South San Francisco, CA, USA
| | | | - Paul Howell
- Verily Life Sciences, South San Francisco, CA, USA
| | | | - Josh Livni
- Verily Life Sciences, South San Francisco, CA, USA
| | | | - Renzo Benza
- Verily Life Sciences, South San Francisco, CA, USA
| | - Willa Chen
- Verily Life Sciences, South San Francisco, CA, USA
| | | | | | | | - Yi Han
- Verily Life Sciences, South San Francisco, CA, USA
| | | | | | | | | | - Erika Lee
- Verily Life Sciences, South San Francisco, CA, USA
| | - Teresa Lin
- Verily Life Sciences, South San Francisco, CA, USA
| | - Jianyi Liu
- Verily Life Sciences, South San Francisco, CA, USA
| | | | | | | | | | | | - David Moore
- Verily Life Sciences, South San Francisco, CA, USA
| | | | | | | | - Chris Robuck
- Verily Life Sciences, South San Francisco, CA, USA
| | | | | | - Peter Smith
- Verily Life Sciences, South San Francisco, CA, USA
| | | | | | - Brian Wasson
- Verily Life Sciences, South San Francisco, CA, USA
| | | | - Mark Wilhelm
- Verily Life Sciences, South San Francisco, CA, USA
| | - Joshua Won
- Verily Life Sciences, South San Francisco, CA, USA
| | - Ari Yasunaga
- Verily Life Sciences, South San Francisco, CA, USA
| | | | - Jodi Holeman
- Consolidated Mosquito Abatement District, Parlier, CA, USA
| | - Nigel Snoad
- Verily Life Sciences, South San Francisco, CA, USA
| | - Linus Upson
- Verily Life Sciences, South San Francisco, CA, USA
| | - Tiantian Zha
- Verily Life Sciences, South San Francisco, CA, USA
| | - Stephen L Dobson
- MosquitoMate Inc., Lexington, KY, USA.,Department of Entomology, University of Kentucky, Lexington, KY, USA
| | | | | | | |
Collapse
|
152
|
Wang WH, Urbina AN, Chang MR, Assavalapsakul W, Lu PL, Chen YH, Wang SF. Dengue hemorrhagic fever - A systemic literature review of current perspectives on pathogenesis, prevention and control. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2020; 53:963-978. [PMID: 32265181 DOI: 10.1016/j.jmii.2020.03.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/26/2020] [Accepted: 03/08/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Dengue is an arboviral disease caused by dengue virus. Symptomatic dengue infection causes a wide range of clinical manifestations, from mild dengue fever (DF) to potentially fatal disease, such as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). We conducted a literature review to analyze the risks of DHF and current perspectives for DHF prevention and control. METHODS According to the PRISMA guidelines, the references were selected from PubMed, Web of Science and Google Scholar database using search strings containing a combination of terms that included dengue hemorrhagic fever, pathogenesis, prevention and control. Quality of references were evaluated by independent reviewers. RESULTS DHF was first reported in the Philippines in 1953 and further transmitted to the countries in the region of South-East Asia and Western Pacific. Plasma leakages is the main pathophysiological hallmark that distinguishes DHF from DF. Severe plasma leakage can result in hypovolemic shock. Various factors are thought to impact disease presentation and severity. Virus virulence, preexisting dengue antibodies, immune dysregulation, lipid change and host genetic susceptibility are factors reported to be correlated with the development of DHF. However, the exact reasons and mechanisms that triggers DHF remains controversial. Currently, no specific drugs and licensed vaccines are available to treat dengue disease in any of its clinical presentations. CONCLUSION This study concludes that antibody-dependent enhancement, cytokine dysregulation and variation of lipid profiles are correlated with DHF occurrence. Prompt diagnosis, appropriate treatment, active and continuous surveillance of cases and vectors are the essential determinants for dengue prevention and control.
Collapse
Affiliation(s)
- Wen-Hung Wang
- Division of Infectious Disease, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Center for Tropical Medicine and Infectious Disease, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
| | - Aspiro Nayim Urbina
- Program in Tropical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, 80708, Taiwan.
| | - Max R Chang
- Program in Tropical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung City, 80708, Taiwan.
| | - Wanchai Assavalapsakul
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.
| | - Po-Liang Lu
- Division of Infectious Disease, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Center for Tropical Medicine and Infectious Disease, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
| | - Yen-Hsu Chen
- Division of Infectious Disease, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Center for Tropical Medicine and Infectious Disease, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
| | - Sheng-Fan Wang
- Center for Tropical Medicine and Infectious Disease, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
| |
Collapse
|
153
|
Anderson KB, Stewart-Ibarra AM, Buddhari D, Beltran Ayala EF, Sippy RJ, Iamsirithaworn S, Ryan SJ, Fernandez S, Jarman RG, Thomas SJ, Endy TP. Key Findings and Comparisons From Analogous Case-Cluster Studies for Dengue Virus Infection Conducted in Machala, Ecuador, and Kamphaeng Phet, Thailand. Front Public Health 2020; 8:2. [PMID: 32117847 PMCID: PMC7028768 DOI: 10.3389/fpubh.2020.00002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 01/03/2020] [Indexed: 11/21/2022] Open
Abstract
Dengue viruses (DENV) pose a significant and increasing threat to human health across broad regions of the globe. Currently, prevention, control, and treatment strategies are limited. Promising interventions are on the horizon, including multiple vaccine candidates under development and a renewed and innovative focus on controlling the vector, Aedes aegypti. However, significant gaps persist in our understanding of the similarities and differences in DENV epidemiology across regions of potential implementation and evaluation. In this manuscript, we highlight and compare findings from two analogous cluster-based studies for DENV transmission and pathogenesis conducted in Thailand and Ecuador to identify key features and questions for further pursuit. Despite a remarkably similar incidence of DENV infection among enrolled neighborhood contacts at the two sites, we note a higher occurrence of secondary infection and severe illness in Thailand compared to Ecuador. A higher force of infection in Thailand, defined as the incidence of infection among susceptible individuals, is suggested by the higher number of captured Aedes mosquitoes per household, the increasing proportion of asymptomatic infections with advancing age, and the high proportion of infections identified as secondary-type infections by serology. These observations should be confirmed in long-term, parallel prospective cohort studies conducted across regions, which would advantageously permit characterization of baseline immune status (susceptibility) and contemporaneous assessment of risks and risk factors for dengue illness.
Collapse
Affiliation(s)
- Kathryn B Anderson
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States.,Armed Forces Research Institute of Medical Science, Bangkok, Thailand.,Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, NY, United States.,Institute for Global Health and Translational Science, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Anna M Stewart-Ibarra
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Montevideo, Inter-American Institute for Global Change Research (IAI), Montevideo, Uruguay
| | - Darunee Buddhari
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
| | | | - Rachel J Sippy
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Geography, University of Florida, Gainesville, FL, United States
| | | | - Sadie J Ryan
- Department of Geography, University of Florida, Gainesville, FL, United States.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, United States
| | - Stefan Fernandez
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
| | - Richard G Jarman
- Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Stephen J Thomas
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, NY, United States.,Institute for Global Health and Translational Science, SUNY Upstate Medical University, Syracuse, NY, United States
| | - Timothy P Endy
- Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, United States.,Department of Microbiology and Immunology, SUNY Upstate Medical University, Syracuse, NY, United States.,Institute for Global Health and Translational Science, SUNY Upstate Medical University, Syracuse, NY, United States
| |
Collapse
|
154
|
Genetic Variation and Potential for Resistance Development to the tTA Overexpression Lethal System in Insects. G3 (BETHESDA, MD.) 2020; 10:1271-1281. [PMID: 32019873 PMCID: PMC7144068 DOI: 10.1534/g3.120.400990] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Release of insect pests carrying the dominant lethal tetracycline transactivator (tTA) overexpression system has been proposed as a means for population suppression. High levels of the tTA transcription factor are thought to be toxic due to either transcriptional squelching or interference with protein ubiquitination. Here we utilized the Drosophila melanogaster Genetic Reference Panel (DGRP) to examine the influence of genetic variation on the efficacy of a female-specific tTA overexpression system. The level of female lethality between DGRP lines varied from 11 to 97% with a broad sense heritability of 0.89. A genome-wide association analysis identified 192 allelic variants associated with high or low lethality (P < 10-5), although none were significant when corrected for multiple testing. 151 of the variants fell within 108 genes that were associated with several biological processes including transcription and protein ubiquitination. In four lines with high female lethality, tTA RNA levels were similar or higher than in the parental tTA overexpression strain. In two lines with low lethality, tTA levels were about two fold lower than in the parental strain. However, in two other lines with low lethality, tTA levels were similar or approximately 30% lower. RNAseq analysis identified genes that were up or downregulated in the four low female lethal lines compared to the four high lethal lines. For example, genes associated with RNA processing and rRNA maturation were significantly upregulated in low lethal lines. Our data suggest that standing genetic variation in an insect population could provide multiple mechanisms for resistance to the tTA overexpression system.
Collapse
|
155
|
Felipe Ramírez-Sánchez L, Camargo C, Avila FW. Male sexual history influences female fertility and re-mating incidence in the mosquito vector Aedes aegypti (Diptera: Culicidae). JOURNAL OF INSECT PHYSIOLOGY 2020; 121:104019. [PMID: 32032591 DOI: 10.1016/j.jinsphys.2020.104019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/20/2020] [Accepted: 02/04/2020] [Indexed: 06/10/2023]
Abstract
Aedes aegypti is the primary vector of several arboviruses that impact human health including the dengue, Zika, and yellow fever viruses. The potential of Ae. aegypti females to transmit viruses is enhanced by mating-induced behavioral and physiological changes that increase female host-seeking behaviors, blood-feeding frequency and longevity. The mating-induced changes are due to female receipt of male seminal fluid proteins (SFPs) during copulation. SFPs also inhibit female re-mating-re-mating incidence is significantly reduced in the initial hours after mating and nearly absent after 24 h. Males, however, are not limited in the number of females they can inseminate and are able to mate with multiple females in succession. As successive mating depletes SFPs, we examined parameters of fertility and re-mating incidence in females after mating with recently mated males. Males of two Ae. aegypti strains (Colombian and Thai) were mated five consecutive times and fecundity, resulting larvae and hatch percentage in each female of the mating sequence was assessed. In both strains, we found that males can mate three times in succession without impacting fertility in their mates. However, significant declines in fecundity, resulting larvae, and hatch percentage were observed after a third mating. Male size influenced female fecundity and fertility as mates of small males showed further reductions compared to mates of big males after mating consecutively. Seven days after the consecutive mating assays, the re-mating rate of females mated fifth in succession was significantly increased (Colombian strain: 33%; Thai strain: 48%) compared to females mated first (0% in both strains). Re-mating incidence was further increased in small, Thai strain males where 82% of fifth mated females re-mated compared to 0% of first mated females. Finally, we show that regardless of male size, mates of experimental males were similarly fertile to mates of control males when mated for a sixth time 48 h after the consecutive mating assays, showing that males recover fertility after 2 d. Our results show that male sexual history influences fertility and re-mating incidence of Ae. aegypti females.
Collapse
Affiliation(s)
- Luis Felipe Ramírez-Sánchez
- Max Planck Tandem Group in Mosquito Reproductive Biology, Universidad de Antioquia, Medellín, Antioquia 050010, Colombia
| | - Carolina Camargo
- Max Planck Tandem Group in Mosquito Reproductive Biology, Universidad de Antioquia, Medellín, Antioquia 050010, Colombia
| | - Frank W Avila
- Max Planck Tandem Group in Mosquito Reproductive Biology, Universidad de Antioquia, Medellín, Antioquia 050010, Colombia.
| |
Collapse
|
156
|
Shelton AM, Long SJ, Walker AS, Bolton M, Collins HL, Revuelta L, Johnson LM, Morrison NI. First Field Release of a Genetically Engineered, Self-Limiting Agricultural Pest Insect: Evaluating Its Potential for Future Crop Protection. Front Bioeng Biotechnol 2020; 7:482. [PMID: 32083066 PMCID: PMC7000757 DOI: 10.3389/fbioe.2019.00482] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 12/24/2019] [Indexed: 01/26/2023] Open
Abstract
Alternative, biologically-based approaches for pest management are sorely needed and one approach is to use genetically engineered insects. Herein we describe a series of integrated field, laboratory and modeling studies with the diamondback moth, Plutella xylostella, a serious global pest of crucifers. A "self-limiting" strain of Plutella xylostella (OX4319L), genetically engineered to allow the production of male-only cohorts of moths for field releases, was developed as a novel approach to protect crucifer crops. Wild-type females that mate with these self-limiting males will not produce viable female progeny. Our previous greenhouse studies demonstrated that releases of OX4319L males lead to suppression of the target pest population and dilution of insecticide-resistance genes. We report results of the first open-field release of a non-irradiated, genetically engineered self-limiting strain of an agricultural pest insect. In a series of mark-release-recapture field studies with co-releases of adult OX4319L males and wild-type counterparts, the dispersal, persistence and field survival of each strain were measured in a 2.83 ha cabbage field. In most cases, no differences were detected in these parameters. Overall, 97.8% of the wild-type males and 95.4% of the OX4319L males recaptured dispersed <35 m from the release point. The predicted persistence did not differ between strains regardless of release rate. With 95% confidence, 75% of OX4319L males released at a rate of 1,500 could be expected to live between 3.5 and 5.4 days and 95% of these males could be expected to be detected within 25.8-34.9 m from the release point. Moth strain had no effect on field survival but release rate did. Collectively, these results suggest similar field behavior of OX4319L males compared to its wild-type counterpart. Laboratory studies revealed no differences in mating competitiveness or intrinsic growth rates between the strains and small differences in longevity. Using results from these studies, mathematical models were developed that indicate release of OX4319L males should offer efficacious pest management of P. xylostella. Further field studies are recommended to demonstrate the potential for this self-limiting P. xylostella to provide pest suppression and resistance management benefits, as was previously demonstrated in greenhouse studies.
Collapse
Affiliation(s)
- Anthony M. Shelton
- Department of Entomology, AgriTech, New York State Agricultural Experiment Station, Cornell University, Geneva, NY, United States
| | - Stefan J. Long
- Department of Entomology, AgriTech, New York State Agricultural Experiment Station, Cornell University, Geneva, NY, United States
| | | | - Michael Bolton
- Oxitec Ltd, Milton Park, Abingdon, United Kingdom
- School of Biological Sciences, Norwich Research Park, University of East Anglia, Norwich, United Kingdom
| | - Hilda L. Collins
- Department of Entomology, AgriTech, New York State Agricultural Experiment Station, Cornell University, Geneva, NY, United States
| | | | - Lynn M. Johnson
- Cornell Statistical Consulting Unit, Cornell University, Ithaca, NY, United States
| | | |
Collapse
|
157
|
Li M, Yang T, Kandul NP, Bui M, Gamez S, Raban R, Bennett J, Sánchez C HM, Lanzaro GC, Schmidt H, Lee Y, Marshall JM, Akbari OS. Development of a confinable gene drive system in the human disease vector Aedes aegypti. eLife 2020; 9:e51701. [PMID: 31960794 PMCID: PMC6974361 DOI: 10.7554/elife.51701] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 01/03/2020] [Indexed: 12/23/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Ming Li
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
| | - Ting Yang
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
| | - Nikolay P Kandul
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
| | - Michelle Bui
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
| | - Stephanie Gamez
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
| | - Robyn Raban
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
| | - Jared Bennett
- Department of BiophysicsUniversity of California, BerkeleyBerkeleyUnited States
| | - Héctor M Sánchez C
- Division of Epidemiology and Biostatistics, School of Public HealthUniversity of California, BerkeleyBerkeleyUnited States
| | - Gregory C Lanzaro
- Vector Genetics Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary MedicineUniversity of California, DavisDavisUnited States
| | - Hanno Schmidt
- Vector Genetics Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary MedicineUniversity of California, DavisDavisUnited States
| | - Yoosook Lee
- Vector Genetics Laboratory, Department of Pathology, Microbiology, and Immunology, School of Veterinary MedicineUniversity of California, DavisDavisUnited States
| | - John M Marshall
- Division of Epidemiology and Biostatistics, School of Public HealthUniversity of California, BerkeleyBerkeleyUnited States
- Innovative Genomics InstituteBerkeleyUnited States
| | - Omar S Akbari
- Section of Cell and Developmental BiologyUniversity of California, San DiegoSan DiegoUnited States
- Tata Institute for Genetics and SocietyUniversity of California, San DiegoLa JollaUnited States
| |
Collapse
|
158
|
López Del Amo V, Bishop AL, Sánchez C HM, Bennett JB, Feng X, Marshall JM, Bier E, Gantz VM. A transcomplementing gene drive provides a flexible platform for laboratory investigation and potential field deployment. Nat Commun 2020; 11:352. [PMID: 31953404 PMCID: PMC6969112 DOI: 10.1038/s41467-019-13977-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 12/11/2019] [Indexed: 12/11/2022] Open
Abstract
CRISPR-based gene drives can spread through wild populations by biasing their own transmission above the 50% value predicted by Mendelian inheritance. These technologies offer population-engineering solutions for combating vector-borne diseases, managing crop pests, and supporting ecosystem conservation efforts. Current technologies raise safety concerns for unintended gene propagation. Herein, we address such concerns by splitting the drive components, Cas9 and gRNAs, into separate alleles to form a trans-complementing split-gene-drive (tGD) and demonstrate its ability to promote super-Mendelian inheritance of the separate transgenes. This dual-component configuration allows for combinatorial transgene optimization and increases safety by restricting escape concerns to experimentation windows. We employ the tGD and a small-molecule-controlled version to investigate the biology of component inheritance and resistant allele formation, and to study the effects of maternal inheritance and impaired homology on efficiency. Lastly, mathematical modeling of tGD spread within populations reveals potential advantages for improving current gene-drive technologies for field population modification.
Collapse
Affiliation(s)
- Víctor López Del Amo
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093, USA
| | - Alena L Bishop
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093, USA
| | - Héctor M Sánchez C
- Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA, 94720, USA
| | - Jared B Bennett
- Biophysics Graduate Group, University of California, Berkeley, CA, 94720, USA
| | - Xuechun Feng
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093, USA
| | - John M Marshall
- Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA, 94720, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093, USA
- Tata Institute for Genetics and Society, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0349, USA
| | - Valentino M Gantz
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, 92093, USA.
| |
Collapse
|
159
|
Brady OJ, Hay SI. The Global Expansion of Dengue: How Aedes aegypti Mosquitoes Enabled the First Pandemic Arbovirus. ANNUAL REVIEW OF ENTOMOLOGY 2020; 65:191-208. [PMID: 31594415 DOI: 10.1146/annurev-ento-011019-024918] [Citation(s) in RCA: 145] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Dengue is an emerging viral disease principally transmitted by the Aedes (Stegomyia) aegypti mosquito. It is one of the fastest-growing global infectious diseases, with 100-400 million new infections a year, and is now entrenched in a growing number of tropical megacities. Behind this rapid rise is the simple adaptation of Ae. aegypti to a new entomological niche carved out by human habitation. This review describes the expansion of dengue and explores how key changes in the ecology of Ae. aegypti allowed it to become a successful invasive species and highly efficient disease vector. We argue that characterizing geographic heterogeneity in mosquito bionomics will be a key research priority that will enable us to better understand future dengue risk and design control strategies to reverse its global spread.
Collapse
Affiliation(s)
- Oliver J Brady
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom;
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London WC1E 7HT, United Kingdom
| | - Simon I Hay
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, Washington 98121, USA;
| |
Collapse
|
160
|
Buchman A, Gamez S, Li M, Antoshechkin I, Li HH, Wang HW, Chen CH, Klein MJ, Duchemin JB, Crowe JE, Paradkar PN, Akbari OS. Broad dengue neutralization in mosquitoes expressing an engineered antibody. PLoS Pathog 2020; 16:e1008103. [PMID: 31945137 PMCID: PMC6964813 DOI: 10.1371/journal.ppat.1008103] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 09/23/2019] [Indexed: 12/11/2022] Open
Abstract
With dengue virus (DENV) becoming endemic in tropical and subtropical regions worldwide, there is a pressing global demand for effective strategies to control the mosquitoes that spread this disease. Recent advances in genetic engineering technologies have made it possible to create mosquitoes with reduced vector competence, limiting their ability to acquire and transmit pathogens. Here we describe the development of Aedes aegypti mosquitoes synthetically engineered to impede vector competence to DENV. These mosquitoes express a gene encoding an engineered single-chain variable fragment derived from a broadly neutralizing DENV human monoclonal antibody and have significantly reduced viral infection, dissemination, and transmission rates for all four major antigenically distinct DENV serotypes. Importantly, this is the first engineered approach that targets all DENV serotypes, which is crucial for effective disease suppression. These results provide a compelling route for developing effective genetic-based DENV control strategies, which could be extended to curtail other arboviruses.
Collapse
Affiliation(s)
- Anna Buchman
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Stephanie Gamez
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Ming Li
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
| | - Igor Antoshechkin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Hsing-Han Li
- Institute of Biotechnology, National Tsing Hua University, Hsinchu, Taiwan
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
- National Mosquito-Borne Diseases Control Research Center, National Health Research Institutes, Zhunan, Taiwan
| | - Hsin-Wei Wang
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
- National Mosquito-Borne Diseases Control Research Center, National Health Research Institutes, Zhunan, Taiwan
| | - Chun-Hong Chen
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
- National Mosquito-Borne Diseases Control Research Center, National Health Research Institutes, Zhunan, Taiwan
| | - Melissa J. Klein
- CSIRO Health and Biosecurity, Australian Animal Health Laboratory, Geelong, VIC, Australia
| | - Jean-Bernard Duchemin
- CSIRO Health and Biosecurity, Australian Animal Health Laboratory, Geelong, VIC, Australia
| | - James E. Crowe
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Departments of Pediatrics, Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Prasad N. Paradkar
- CSIRO Health and Biosecurity, Australian Animal Health Laboratory, Geelong, VIC, Australia
| | - Omar S. Akbari
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, California, United States of America
- Tata Institute for Genetics and Society-UCSD, La Jolla, California, United States of America
| |
Collapse
|
161
|
Experimental population modification of the malaria vector mosquito, Anopheles stephensi. PLoS Genet 2019; 15:e1008440. [PMID: 31856182 PMCID: PMC6922335 DOI: 10.1371/journal.pgen.1008440] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 09/19/2019] [Indexed: 12/14/2022] Open
Abstract
Small laboratory cage trials of non-drive and gene-drive strains of the Asian malaria vector mosquito, Anopheles stephensi, were used to investigate release ratios and other strain properties for their impact on transgene spread during simulated population modification. We evaluated the effects of transgenes on survival, male contributions to next-generation populations, female reproductive success and the impact of accumulation of gene drive-resistant genomic target sites resulting from nonhomologous end-joining (NHEJ) mutagenesis during Cas9, guide RNA-mediated cleavage. Experiments with a non-drive, autosomally-linked malaria-resistance gene cassette showed ‘full introduction’ (100% of the insects have at least one copy of the transgene) within 8 weeks (≤ 3 generations) following weekly releases of 10:1 transgenic:wild-type males in an overlapping generation trial design. Male release ratios of 1:1 resulted in cages where mosquitoes with at least one copy of the transgene fluctuated around 50%. In comparison, two of three cages in which the malaria-resistance genes were linked to a gene-drive system in an overlapping generation, single 1:1 release reached full introduction in 6–8 generations with a third cage at ~80% within the same time. Release ratios of 0.1:1 failed to establish the transgenes. A non-overlapping generation, single-release trial of the same gene-drive strain resulted in two of three cages reaching 100% introduction within 6–12 generations following a 1:1 transgenic:wild-type male release. Two of three cages with 0.33:1 transgenic:wild-type male single releases achieved full introduction in 13–16 generations. All populations exhibiting full introduction went extinct within three generations due to a significant load on females having disruptions of both copies of the target gene, kynurenine hydroxylase. While repeated releases of high-ratio (10:1) non-drive constructs could achieve full introduction, results from the 1:1 release ratios across all experimental designs favor the use of gene drive, both for efficiency and anticipated cost of the control programs. The experimental introduction of manipulated genes into insect species has a long history in basic genetics. Recent advances in genome editing technologies have spurred considerable effort to exploit these methodologies to provide genetic solutions to some of the worst medical and agricultural problems caused by insects. Insect population suppression and population modification approaches have been proposed to control transmission of vector-borne diseases, including malaria. We used small cage trials to explore the efficacy of non-drive and gene-drive releases to deliver anti-malarial effector genes to a vector mosquito, Anopheles stephensi. We show that both approaches can work to introduce genes to high percentages, but as expected, the gene-drive approaches were more efficient in that they needed only a single release with a much lower number of released insects. The gene-drive females in our studies exhibited a significant load that resulted in some cage populations going to extinction. Furthermore, the accumulation of drive-resistant target genes prevented full introduction of the transgenes in those cages that did not go extinct. While none of the strains evaluated here are proposed for open release, these laboratory cage trials reveal features that can be used to improve next-generation gene-drive strains for population modification.
Collapse
|
162
|
Powell JR. An Evolutionary Perspective on Vector-Borne Diseases. Front Genet 2019; 10:1266. [PMID: 31921304 PMCID: PMC6929172 DOI: 10.3389/fgene.2019.01266] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 11/18/2019] [Indexed: 01/22/2023] Open
Abstract
Several aspects of the biology of the three players in a vector-borne disease that affect their evolutionary interactions are outlined. A model of the origin of a human–human cycle of vector-borne diseases is presented emphasizing the narrowing of the niche experienced by the pathogen and vector. Variation in the expected rates of evolution of the three players is discussed with the rapid rate of pathogen evolution providing them with advantages. Population sizes and fluctuations also affect the three players in very different ways. The time since the origin of a vector-borne disease likely determines how stable the interactions are and thus how easily the disease might be eliminated. Stability and variation are also linked. Human technological advances are rapidly upsetting the previously relatively slow coevolutionary adjustment of the three players. Finally, it is pointed out that development of quantitative coevolutionary models specifically addressing details of vector-borne diseases is needed to identify parameters most likely to break transmission cycles and thus control or eliminate diseases.
Collapse
|
163
|
Cryo-Electron Microscopy Reveals That Sperm Modification Coincides with Female Fertility in the Mosquito Aedes aegypti. Sci Rep 2019; 9:18537. [PMID: 31811199 PMCID: PMC6898104 DOI: 10.1038/s41598-019-54920-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 11/18/2019] [Indexed: 12/13/2022] Open
Abstract
Manipulating mosquito reproduction is a promising approach to reducing mosquito populations and the burden of diseases they carry. A thorough understanding of reproductive processes is necessary to develop such strategies, but little is known about how sperm are processed and prepared for fertilization within female mosquitoes. By employing cryo-electron microscopy for the first time to study sperm of the mosquito Aedes aegypti, we reveal that sperm shed their entire outer coat, the glycocalyx, within 24 hours of being stored in the female. Motility assays demonstrate that as their glycocalyx is shed in the female’s sperm storage organs, sperm transition from a period of dormancy to rapid motility—a critical prerequisite for sperm to reach the egg. We also show that females gradually become fertile as sperm become motile, and that oviposition behavior increases sharply after females reach peak fertility. Together, these experiments demonstrate a striking coincidence of the timelines of several reproductive events in Ae. aegypti, suggesting a direct relationship between sperm modification and female reproductive capacity.
Collapse
|
164
|
Ross PA, Lau MJ, Hoffmann AA. Does membrane feeding compromise the quality of Aedes aegypti mosquitoes? PLoS One 2019; 14:e0224268. [PMID: 31693672 PMCID: PMC6834243 DOI: 10.1371/journal.pone.0224268] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/09/2019] [Indexed: 12/26/2022] Open
Abstract
Modified Aedes aegypti mosquitoes are being mass-reared for release in disease control programs around the world. Releases involving female mosquitoes rely on them being able to seek and feed on human hosts. To facilitate the mass-production of mosquitoes for releases, females are often provided blood through artificial membrane feeders. When reared across generations there is a risk that mosquitoes will adapt to feeding on membranes and lose their ability to feed on human hosts. To test adaptation to membrane feeding, we selected replicate populations of Ae. aegypti for feeding on either human arms or membrane feeders for at least 8 generations. Membrane-selected populations suffered fitness costs, likely due to inbreeding depression arising from bottlenecks. Membrane-selected females had higher feeding rates on membranes than human-selected ones, suggesting adaptation to membrane feeding, but they maintained their attraction to host cues and feeding ability on humans despite a lack of selection for these traits. Host-seeking ability in small laboratory cages did not differ between populations selected on the two blood sources, but membrane-selected females were compromised in a semi-field enclosure where host-seeking was tested over a longer distance. Our findings suggest that Ae. aegypti may adapt to feeding on blood provided artificially, but this will not substantially compromise field performance or affect experimental assessments of mosquito fitness. However, large population sizes (thousands of individuals) during mass rearing with membrane feeders should be maintained to avoid bottlenecks which lead to inbreeding depression.
Collapse
Affiliation(s)
- Perran A. Ross
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Meng-Jia Lau
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Ary A. Hoffmann
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
165
|
Marshall JM, Raban RR, Kandul NP, Edula JR, León TM, Akbari OS. Winning the Tug-of-War Between Effector Gene Design and Pathogen Evolution in Vector Population Replacement Strategies. Front Genet 2019; 10:1072. [PMID: 31737050 PMCID: PMC6831721 DOI: 10.3389/fgene.2019.01072] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 10/07/2019] [Indexed: 12/19/2022] Open
Abstract
While efforts to control malaria with available tools have stagnated, and arbovirus outbreaks persist around the globe, the advent of clustered regularly interspaced short palindromic repeat (CRISPR)-based gene editing has provided exciting new opportunities for genetics-based strategies to control these diseases. In one such strategy, called "population replacement", mosquitoes, and other disease vectors are engineered with effector genes that render them unable to transmit pathogens. These effector genes can be linked to "gene drive" systems that can bias inheritance in their favor, providing novel opportunities to replace disease-susceptible vector populations with disease-refractory ones over the course of several generations. While promising for the control of vector-borne diseases on a wide scale, this sets up an evolutionary tug-of-war between the introduced effector genes and the pathogen. Here, we review the disease-refractory genes designed to date to target Plasmodium falciparum malaria transmitted by Anopheles gambiae, and arboviruses transmitted by Aedes aegypti, including dengue serotypes 2 and 3, chikungunya, and Zika viruses. We discuss resistance concerns for these effector genes, and genetic approaches to prevent parasite and viral escape variants. One general approach is to increase the evolutionary hurdle required for the pathogen to evolve resistance by attacking it at multiple sites in its genome and/or multiple stages of development. Another is to reduce the size of the pathogen population by other means, such as with vector control and antimalarial drugs. We discuss lessons learned from the evolution of resistance to antimalarial and antiviral drugs and implications for the management of resistance after its emergence. Finally, we discuss the target product profile for population replacement strategies for vector-borne disease control. This differs between early phase field trials and wide-scale disease control. In the latter case, the demands on effector gene efficacy are great; however, with new possibilities ushered in by CRISPR-based gene editing, and when combined with surveillance, monitoring, and rapid management of pathogen resistance, the odds are increasingly favoring effector genes in the upcoming evolutionary tug-of-war.
Collapse
Affiliation(s)
- John M. Marshall
- Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA, United States
- Innovative Genomics Institute, Berkeley, CA, United States
| | - Robyn R. Raban
- Section of Cell and Developmental Biology, University of California, San Diego, CA, United States
| | - Nikolay P. Kandul
- Section of Cell and Developmental Biology, University of California, San Diego, CA, United States
| | - Jyotheeswara R. Edula
- Section of Cell and Developmental Biology, University of California, San Diego, CA, United States
| | - Tomás M. León
- Division of Epidemiology and Biostatistics, School of Public Health, University of California, Berkeley, CA, United States
| | - Omar S. Akbari
- Section of Cell and Developmental Biology, University of California, San Diego, CA, United States
- Tata Institute for Genetics and Society, University of California, San Diego, CA, United States
| |
Collapse
|
166
|
Kittayapong P, Ninphanomchai S, Limohpasmanee W, Chansang C, Chansang U, Mongkalangoon P. Combined sterile insect technique and incompatible insect technique: The first proof-of-concept to suppress Aedes aegypti vector populations in semi-rural settings in Thailand. PLoS Negl Trop Dis 2019; 13:e0007771. [PMID: 31658265 PMCID: PMC6837763 DOI: 10.1371/journal.pntd.0007771] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 11/07/2019] [Accepted: 09/10/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Important arboviral diseases, such as dengue, chikungunya, and Zika virus infections, are transmitted mainly by the Aedes aegypti vector. So far, controlling this vector species with current tools and strategies has not demonstrated sustainable and significant impacts. Our main objective was to evaluate whether open field release of sterile males, produced from combining the sterile insect technique using radiation with the insect incompatible technique through Wolbachia-induced incompatibility (SIT/IIT), could suppress natural populations of Ae. aegypti in semi-rural village settings in Thailand. METHODOLOGY/PRINCIPAL FINDINGS Irradiated Wolbachia-infected Aedes aegypti males produced by the SIT/IIT approach were completely sterile and were able to compete with the wild fertile ones. Open field release of these sterile males was conducted in an ecologically isolated village in Chachoengsao Province, eastern Thailand. House-to-house visit and media reports resulted in community acceptance and public awareness of the technology. During intervention, approximately 100-200 sterile males were released weekly in each household. After 6 months of sterile male release, a significant reduction (p<0.05) of the mean egg hatch rate (84%) and the mean number of females per household (97.30%) was achieved in the treatment areas when compared to the control ones. CONCLUSIONS/SIGNIFICANCE Our study represents the first open field release of sterile Ae. aegypti males developed from a combined SIT/IIT approach. Entomological assessment using ovitraps, adult sticky traps, and portable vacuum aspirators confirmed the success in reducing natural populations of Ae. aegypti females in treated areas. Public awareness through media resulted in positive support for practical use of this strategy in wider areas. Further study using a systematic randomized trial is needed to determine whether this approach could have a significant impact on the diseases transmitted by Ae. aegypti vector.
Collapse
Affiliation(s)
- Pattamaporn Kittayapong
- Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Nakhon Pathom, Thailand
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand
- * E-mail:
| | - Suwannapa Ninphanomchai
- Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Nakhon Pathom, Thailand
| | - Wanitch Limohpasmanee
- Thailand Institute of Nuclear Technology, Ministry of Science and Technology, Nakhon Nayok, Thailand
| | - Chitti Chansang
- Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Uruyakorn Chansang
- Department of Medical Sciences, Ministry of Public Health, Nonthaburi, Thailand
| | - Piti Mongkalangoon
- Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| |
Collapse
|
167
|
Lwande OW, Obanda V, Lindström A, Ahlm C, Evander M, Näslund J, Bucht G. Globe-Trotting Aedes aegypti and Aedes albopictus: Risk Factors for Arbovirus Pandemics. Vector Borne Zoonotic Dis 2019; 20:71-81. [PMID: 31556813 PMCID: PMC7041325 DOI: 10.1089/vbz.2019.2486] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Introduction: Two species of Aedes (Ae.) mosquitoes (Ae. aegypti and Ae. albopictus) are primary vectors for emerging arboviruses that are a significant threat to public health and economic burden worldwide. Distribution of these vectors and the associated arboviruses, such as dengue virus, chikungunya virus, yellow fever virus, and Zika virus, was for a long time restricted by geographical, ecological, and biological factors. Presently, arbovirus emergence and dispersion are more rapid and geographically widespread, largely due to expansion of the range for these two mosquitoes that have exploited the global transportation network, land perturbation, and failure to contain the mosquito population coupled with enhanced vector competence. Ae. aegypti and Ae. albopictus may also sustain transmission between humans without having to depend on their natural reservoir forest cycles due to arthropod adaptation to urbanization. Currently, there is no single strategy that is adequate to control these vectors, especially when managing arbovirus outbreaks. Objective: This review aimed at presenting the characteristics and abilities of Ae. aegypti and Ae. albopictus, which can drive a global public health risk, and suggests strategies for prevention and control. Methods: This review presents the geographic range, reproduction and ecology, vector competence, genetic evolution, and biological and chemical control of these two mosquito species and how they have changed and developed over time combined with factors that may drive pandemics and mitigation measures. Conclusion: We suggest that more efforts should be geared toward the development of a concerted multidisciplinary approach.
Collapse
Affiliation(s)
- Olivia Wesula Lwande
- Virology Section, Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Consortium for Epidemiology and Ecology (CEER-Africa), Nairobi, Kenya.,Arctic Research Centre at Umeå University, Sweden University, Umeå, Sweden
| | - Vincent Obanda
- Consortium for Epidemiology and Ecology (CEER-Africa), Nairobi, Kenya.,Veterinary Services Department, Kenya Wildlife Service, Nairobi, Kenya
| | | | - Clas Ahlm
- Arctic Research Centre at Umeå University, Sweden University, Umeå, Sweden.,Infection and Immunology Section, Department of Clinical Microbiology, Umeå University, Umeå, Sweden
| | - Magnus Evander
- Virology Section, Department of Clinical Microbiology, Umeå University, Umeå, Sweden.,Arctic Research Centre at Umeå University, Sweden University, Umeå, Sweden
| | - Jonas Näslund
- Swedish Defence Research Agency, CBRN, Defence and Security, Umeå, Sweden
| | - Göran Bucht
- Swedish Defence Research Agency, CBRN, Defence and Security, Umeå, Sweden
| |
Collapse
|
168
|
Transgenic Aedes aegypti Mosquitoes Transfer Genes into a Natural Population. Sci Rep 2019; 9:13047. [PMID: 31506595 PMCID: PMC6736937 DOI: 10.1038/s41598-019-49660-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 08/29/2019] [Indexed: 11/08/2022] Open
Abstract
In an attempt to control the mosquito-borne diseases yellow fever, dengue, chikungunya, and Zika fevers, a strain of transgenically modified Aedes aegypti mosquitoes containing a dominant lethal gene has been developed by a commercial company, Oxitec Ltd. If lethality is complete, releasing this strain should only reduce population size and not affect the genetics of the target populations. Approximately 450 thousand males of this strain were released each week for 27 months in Jacobina, Bahia, Brazil. We genotyped the release strain and the target Jacobina population before releases began for >21,000 single nucleotide polymorphisms (SNPs). Genetic sampling from the target population six, 12, and 27-30 months after releases commenced provides clear evidence that portions of the transgenic strain genome have been incorporated into the target population. Evidently, rare viable hybrid offspring between the release strain and the Jacobina population are sufficiently robust to be able to reproduce in nature. The release strain was developed using a strain originally from Cuba, then outcrossed to a Mexican population. Thus, Jacobina Ae. aegypti are now a mix of three populations. It is unclear how this may affect disease transmission or affect other efforts to control these dangerous vectors. These results highlight the importance of having in place a genetic monitoring program during such releases to detect un-anticipated outcomes.
Collapse
|
169
|
Engineered action at a distance: Blood-meal-inducible paralysis in Aedes aegypti. PLoS Negl Trop Dis 2019; 13:e0007579. [PMID: 31479450 PMCID: PMC6719823 DOI: 10.1371/journal.pntd.0007579] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 06/26/2019] [Indexed: 11/23/2022] Open
Abstract
Background Population suppression through mass-release of Aedes aegypti males carrying dominant-lethal transgenes has been demonstrated in the field. Where population dynamics show negative density-dependence, suppression can be enhanced if lethality occurs after the density-dependent (i.e. larval) stage. Existing molecular tools have limited current examples of such Genetic Pest Management (GPM) systems to achieving this through engineering ‘cell-autonomous effectors’ i.e. where the expressed deleterious protein is restricted to the cells in which it is expressed–usually under the control of the regulatory elements (e.g. promoter regions) used to build the system. This limits the flexibility of these technologies as regulatory regions with useful spatial, temporal or sex-specific expression patterns may only be employed if the cells they direct expression in are simultaneously sensitive to existing effectors, and also precludes the targeting of extracellular regions such as cell-surface receptors. Expanding the toolset to ‘non-cell autonomous’ effectors would significantly reduce these limitations. Methodology/Principal findings We sought to engineer female-specific, late-acting lethality through employing the Ae. aegypti VitellogeninA1 promoter to drive blood-meal-inducible, fat-body specific expression of tTAV. Initial attempts using pro-apoptotic effectors gave no evident phenotype, potentially due to the lower sensitivity of terminally-differentiated fat-body cells to programmed-death signals. Subsequently, we dissociated the temporal and spatial expression of this system by engineering a novel synthetic effector (Scorpion neurotoxin–TetO-gp67.AaHIT) designed to be secreted out of the tissue in which it was expressed (fat-body) and then affect cells elsewhere (neuro-muscular junctions). This resulted in a striking, temporary-paralysis phenotype after blood-feeding. Conclusions/Significance These results are significant in demonstrating for the first time an engineered ‘action at a distance’ phenotype in a non-model pest insect. The potential to dissociate temporal and spatial expression patterns of useful endogenous regulatory elements will extend to a variety of other pest insects and effectors. A recent addition to the toolbox for controlling populations of the disease vector Aedes aegypti is the mass-release of males engineered with dominant, lethal transgenes. The lethal effect of these transgenes is activated in the progeny of these released engineered males and wild females they mate with in the field and with continuous release of males can cause population collapse. To date, these systems have relied on the use of ‘cell-autonomous’ effectors, meaning that their action is restricted to the cells in which they are expressed, limiting the flexibility of designing new, more complex systems. Here we demonstrate that it is possible to engineer ‘non-cell autonomous’ effectors–that is where the effect (e.g. the action of a toxic protein) can act on cells distant from the tissues in which they are originally expressed. To achieve this we utilised the endogenous cell secretory pathway to engineer a novel control phenotype–blood-meal inducible (i.e. late-acting, female-specific) reversible paralysis. The logic behind engineering such ‘action at a distance’ phenotypes will extend to a variety of other pest insects and control phenotypes.
Collapse
|
170
|
Bouyer J, Vreysen MJB. Concerns about the feasibility of using "precision guided sterile males" to control insects. Nat Commun 2019; 10:3954. [PMID: 31477713 PMCID: PMC6718395 DOI: 10.1038/s41467-019-11616-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 05/31/2019] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jérémy Bouyer
- Insect Pest Control Laboratory, Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture, A-1400, Vienna, Austria.
- Unité Mixte de Recherche ASTRE, CIRAD, INRA, Univ Montpellier, Montpellier, France.
| | - Marc J B Vreysen
- Insect Pest Control Laboratory, Joint FAO/IAEA Programme of Nuclear Techniques in Food and Agriculture, A-1400, Vienna, Austria
| |
Collapse
|
171
|
Kandul NP, Liu J, Sanchez C HM, Wu SL, Marshall JM, Akbari OS. Reply to 'Concerns about the feasibility of using "precision guided sterile males" to control insects'. Nat Commun 2019; 10:3955. [PMID: 31477702 PMCID: PMC6718384 DOI: 10.1038/s41467-019-11617-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/10/2019] [Indexed: 11/09/2022] Open
Affiliation(s)
- Nikolay P Kandul
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Junru Liu
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Hector M Sanchez C
- Division of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA, United States of America
| | - Sean L Wu
- Division of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA, United States of America
| | - John M Marshall
- Division of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA, United States of America
| | - Omar S Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America.
- Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA, United States of America.
| |
Collapse
|
172
|
Xia S, Baskett ML, Powell JR. Quantifying the efficacy of genetic shifting in control of mosquito-borne diseases. Evol Appl 2019; 12:1552-1568. [PMID: 31462914 PMCID: PMC6708429 DOI: 10.1111/eva.12802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 04/11/2019] [Indexed: 01/07/2023] Open
Abstract
Many of the world's most prevalent diseases are transmitted by animal vectors such as dengue transmitted by mosquitoes. To reduce these vector-borne diseases, a promising approach is "genetic shifting": selective breeding of the vectors to be more resistant to pathogens and releasing them to the target populations to reduce their ability to transmit pathogens, that is, lower their vector competence. The efficacy of genetic shifting will depend on possible counterforces such as natural selection against low vector competence. To quantitatively evaluate the potential efficacy of genetic shifting, we developed a series of coupled genetic-demographic models that simulate the changes of vector competence during releases of individuals with low vector competence. We modeled vector competence using different genetic architectures, as a multilocus, one-locus, or two-locus trait. Using empirically determined estimates of model parameters, the model predicted a reduction of mean vector competence of at least three standard deviations after 20 releases, one release per generation, and 10% of the size of the target population released each time. Sensitivity analysis suggested that release efficacy depends mostly on the vector competence of the released population, release size, release frequency, and the survivorship of the released individuals, with duration of the release program less important. Natural processes such as density-dependent survival and immigration from external populations also strongly influence release efficacy. Among different sex-dependent release strategies, releasing blood-fed females together with males resulted in the highest release efficacy, as these females mate in captivity and reproduce when released, thus contributing a greater proportion of low-vector-competence offspring. Conclusions were generally consistent across three models assuming different genetic architectures of vector competence, suggesting that genetic shifting could generally apply to various vector systems and does not require detailed knowledge of the number of loci contributing to vector competence.
Collapse
Affiliation(s)
- Siyang Xia
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenConnecticut
| | - Marissa L. Baskett
- Department of Environmental Science and PolicyUniversity of California, DavisDavisCalifornia
| | | |
Collapse
|
173
|
McLaughlin GM, Dearden PK. Invasive Insects: Management Methods Explored. JOURNAL OF INSECT SCIENCE (ONLINE) 2019; 19:5587051. [PMID: 31612947 PMCID: PMC6792099 DOI: 10.1093/jisesa/iez085] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Indexed: 04/29/2023]
Abstract
Invasive insect species can act as a plague across the globe, capable of vast expansion and rapid, proliferate reproduction. The spread of pathogens of serious diseases such as malaria and Zika virus and damages to agricultural crops number some of the afflictions invasive insects provide to humans alone. Additionally, an escape from predators can fail to keep invasive insects in check, providing potential threats such as extra resource competition to native species when insects invade. A variety of methods are employed to combat these invasive species, each with their own varying levels of success. Here, we explore the more traditional methods of invasive insect pest control, such as pesticides and biological control. In lieu of several unintended consequences resulting from such practices, we suggest some should be abandoned. We evaluate the potential of new techniques, in particular, those with a genetic component, regarding the costs, benefits and possible consequences of implementing them. And finally, we consider which techniques should be the focus of future research, if we truly wish to manage or even eradicate invasive insects in their introduced lands.
Collapse
Affiliation(s)
- Gemma M McLaughlin
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Corresponding author, e-mail:
| | - Peter K Dearden
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- Genomics Aotearoa, University of Otago, Dunedin, New Zealand
| |
Collapse
|
174
|
Staunton KM, Usher L, Prachar T, Ritchie SA, Snoad N, Johnson BJ. A Novel Methodology For Recording Wing Beat Frequencies of Untethered Male and Female Aedes aegypti. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2019; 35:169-177. [PMID: 31647706 DOI: 10.2987/18-6799.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Aedes aegypti is a vector of many significant arboviruses worldwide, including dengue, Zika, chikungunya, and yellow fever viruses. With vector control methodology pivoting toward rearing and releasing large numbers of insects for either population suppression or virus-blocking, economical remote (sentinel) surveillance methods for release tracking become increasingly necessary. Recent steps in this direction include advances in optical sensors that identify and classify insects based on their wing beat frequency (WBF). As these traps are being developed, there is a strong need to better understand the environmental and biological factors influencing mosquito WBFs. Here, we developed new untethered-subject methodology to detect changes in WBFs of male and female Ae. aegypti. This new methodology involves directing an ultrasonic transducer at a free-flying subject and measuring the Doppler shift of the reflected ultrasonic continuous wave signal. This system's utility was assessed by determining its ability to confirm previous reports on the effect of temperature, body size, and age on the WBFs generated from acoustic or optical-based experiments. The presented ultrasonic method successfully detected expected trends for each factor for both male and female Ae. aegypti without the need for subject manipulation and potential impediment of natural flight dynamics due to tethering. As a result, this ultrasonic methodology provides a new method for understanding the environmental and physiological determinants of male and female WBFs that can inform the design of remote mosquito surveillance systems.
Collapse
|
175
|
Pantoja-Sánchez H, Gomez S, Velez V, Avila FW, Alfonso-Parra C. Precopulatory acoustic interactions of the New World malaria vector Anopheles albimanus (Diptera: Culicidae). Parasit Vectors 2019; 12:386. [PMID: 31370863 PMCID: PMC6676525 DOI: 10.1186/s13071-019-3648-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Accepted: 07/25/2019] [Indexed: 12/04/2022] Open
Abstract
Background Anopheles albimanus is a malaria vector in Central America, northern South America and the Caribbean. Although a public health threat, An. albimanus precopulatory mating behaviors are unknown. Acoustics play important roles in mosquito communication, where flight tones allow males to detect and attract potential mates. The importance of sound in precopulatory interactions has been demonstrated in Toxorhynchites brevipalpis, Aedes aegypti, Culex quinquefasciatus and Anopheles gambiae; convergence in a shared harmonic of the wing beat frequency (WBF) during courtship is thought to increase the chance of copulation. To our knowledge, An. albimanus precopulatory acoustic behaviors have not been described to date. Here, we characterized An. albimanus (i) male and female flight tones; (ii) male–female precopulatory acoustic interactions under tethered and free flight conditions; and (iii) male-male acoustic interactions during free flight. Results We found significant increases in the WBFs of both sexes in free flight compared to when tethered. We observed harmonic convergence between 79% of tethered couples. In free flight, we identified a female-specific behavior that predicts mate rejection during male mating attempts: females increase their WBFs significantly faster during mate rejection compared to a successful copulation. This behavior consistently occurred during mate rejection regardless of prior mating attempts (from the same or differing male). During group flight, males of An. albimanus displayed two distinct flying behaviors: random flight and a swarm-like, patterned flight, each associated with distinct acoustic characteristics. In the transition from random to patterned flight, males converged their WBFs and significantly decreased flight area, male-male proximity and the periodicity of their trajectories. Conclusions We show that tethering of An. albimanus results in major acoustic differences compared to free flight. We identify a female-specific behavior that predicts mate rejection during male mating attempts in this species and show that male groups in free flight display distinct flying patterns with unique audio and visual characteristics. This study shows that An. albimanus display acoustic features identified in other mosquito species, further suggesting that acoustic interactions provide worthwhile targets for mosquito intervention strategies. Our results provide compelling evidence for swarming in this species and suggests that acoustic signaling is important for this behavior. Electronic supplementary material The online version of this article (10.1186/s13071-019-3648-8) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Hoover Pantoja-Sánchez
- Departamento de Ingeniería Electrónica, SISTEMIC, Universidad de Antioquia, Medellín, Antioquia, 050010, Colombia.,Programa de Estudio y Control de Enfermedades Tropicales, PECET, Universidad de Antioquia, Medellín, Antioquia, 050010, Colombia
| | - Sebastián Gomez
- Departamento de Ingeniería Electrónica, SISTEMIC, Universidad de Antioquia, Medellín, Antioquia, 050010, Colombia.,Instituto Colombiano de Medicina Tropical, Universidad CES, Sabaneta, Antioquia, 055450, Colombia
| | - Viviana Velez
- Programa de Estudio y Control de Enfermedades Tropicales, PECET, Universidad de Antioquia, Medellín, Antioquia, 050010, Colombia
| | - Frank W Avila
- Max Planck Tandem Group in Mosquito Reproductive Biology, Universidad de Antioquia, Medellín, Antioquia, 050010, Colombia.
| | - Catalina Alfonso-Parra
- Instituto Colombiano de Medicina Tropical, Universidad CES, Sabaneta, Antioquia, 055450, Colombia. .,Max Planck Tandem Group in Mosquito Reproductive Biology, Universidad de Antioquia, Medellín, Antioquia, 050010, Colombia.
| |
Collapse
|
176
|
Aldersley A, Pongsiri A, Bunmee K, Kijchalao U, Chittham W, Fansiri T, Pathawong N, Qureshi A, Harrington LC, Ponlawat A, Cator LJ. Too "sexy" for the field? Paired measures of laboratory and semi-field performance highlight variability in the apparent mating fitness of Aedes aegypti transgenic strains. Parasit Vectors 2019; 12:357. [PMID: 31324262 PMCID: PMC6642483 DOI: 10.1186/s13071-019-3617-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/13/2019] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Evaluating and improving mating success and competitive ability of laboratory-reared transgenic mosquito strains will enhance the effectiveness of proposed disease-control strategies that involve deployment of transgenic strains. Two components of the mosquito rearing process, larval diet quantity and aquatic environment - which are linked to physiological and behavioural differences in adults - are both relatively easy to manipulate. In mosquitoes, as for many other arthropod species, the quality of the juvenile habitat is strongly associated with adult fitness characteristics, such as longevity and fecundity. However, the influence of larval conditioning on mating performance is poorly understood. Here, we investigated the combined effects of larval diet amount and environmental water source on adult male mating success in a genetically modified strain of Aedes aegypti mosquitoes in competition with wild-type conspecifics. Importantly, this research was conducted in a field setting using low generation laboratory and wild-type lines. RESULTS By controlling larval diet (high and low) and rearing water source (field-collected and laboratory water), we generated four treatment lines of a genetically modified strain of Ae. aegypti tagged with fluorescent sperm. Laboratory reared mosquitoes were then competed against a low generation wild-type colony in a series of laboratory and semi-field mating experiments. While neither food quantity nor larval aquatic environment were found to affect male mating fitness, the transgenic lines consistently outperformed wild-types in laboratory competition assays, an advantage that was not conferred to semi-field tests. CONCLUSIONS Using a model transgenic system, our results indicate that differences in the experimental conditions of laboratory- and field-based measures of mating success can lead to variation in the perceived performance ability of modified strains if they are only tested in certain environments. While there are many potential sources of variation between laboratory and field lines, laboratory adaptation - which may occur over relatively few generations in this species - may directly impact mating ability depending on the context in which it is measured. We suggest that colony-hybridization with field material can potentially be used to mitigate these effects in a field setting. Release programs utilising mass-produced modified laboratory strains should incorporate comparative assessments of quality in candidate lines.
Collapse
Affiliation(s)
- Andrew Aldersley
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, UK
| | - Arissara Pongsiri
- Vector Biology and Control Section, Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Kamonchanok Bunmee
- Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Udom Kijchalao
- Vector Biology and Control Section, Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Wachiraphan Chittham
- Vector Biology and Control Section, Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Thanyalak Fansiri
- Vector Biology and Control Section, Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Nattaphol Pathawong
- Vector Biology and Control Section, Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Alima Qureshi
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, UK
| | | | - Alongkot Ponlawat
- Vector Biology and Control Section, Department of Entomology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Lauren J. Cator
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, UK
| |
Collapse
|
177
|
Breed MF, Harrison PA, Blyth C, Byrne M, Gaget V, Gellie NJC, Groom SVC, Hodgson R, Mills JG, Prowse TAA, Steane DA, Mohr JJ. The potential of genomics for restoring ecosystems and biodiversity. Nat Rev Genet 2019; 20:615-628. [PMID: 31300751 DOI: 10.1038/s41576-019-0152-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2019] [Indexed: 01/12/2023]
Abstract
Billions of hectares of natural ecosystems have been degraded through human actions. The global community has agreed on targets to halt and reverse these declines, and the restoration sector faces the important but arduous task of implementing programmes to meet these objectives. Existing and emerging genomics tools offer the potential to improve the odds of achieving these targets. These tools include population genomics that can improve seed sourcing, meta-omics that can improve assessment and monitoring of restoration outcomes, and genome editing that can generate novel genotypes for restoring challenging environments. We identify barriers to adopting these tools in a restoration context and emphasize that regulatory and ethical frameworks are required to guide their use.
Collapse
Affiliation(s)
- Martin F Breed
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia.
| | - Peter A Harrison
- School of Natural Sciences, Australian Research Council Training Centre for Forest Value, University of Tasmania, Hobart, Tasmania, Australia
| | - Colette Blyth
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia
| | - Margaret Byrne
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Western Australia, Australia
| | - Virginie Gaget
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia
| | - Nicholas J C Gellie
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia
| | - Scott V C Groom
- School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, Urrbrae, South Australia, Australia
| | - Riley Hodgson
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia
| | - Jacob G Mills
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia
| | - Thomas A A Prowse
- School of Biological Sciences and the Environment Institute, University of Adelaide, North Terrace, South Australia, Australia.,School of Mathematical Sciences, University of Adelaide, North Terrace, South Australia, Australia
| | - Dorothy A Steane
- School of Natural Sciences, Australian Research Council Training Centre for Forest Value, University of Tasmania, Hobart, Tasmania, Australia
| | - Jakki J Mohr
- College of Business, Institute on Ecosystems, University of Montana, Missoula, MT, USA
| |
Collapse
|
178
|
Resnik DB. Two unresolved issues in community engagement for field trials of genetically modified mosquitoes. Pathog Glob Health 2019; 113:238-245. [PMID: 31549925 PMCID: PMC6882470 DOI: 10.1080/20477724.2019.1670490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
There is an emerging consensus among scientists, ethicists, and public health officials that substantive and effective engagement with communities and the wider public is required prior to releasing genetically modified mosquitoes into the environment. While there is little disagreement about the need for community and public engagement prior to releasing genetically modified mosquitoes into the environment, two important issues have not been resolved, namely: defining the community and dealing with potential conflicts between the community and the wider public. This commentary addresses these unresolved issues.
Collapse
Affiliation(s)
- David B. Resnik
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| |
Collapse
|
179
|
Staunton KM, Yeeles P, Townsend M, Nowrouzi S, Paton CJ, Trewin B, Pagendam D, Bondarenco A, Devine GJ, Snoad N, Beebe NW, Ritchie SA. Trap Location and Premises Condition Influences on Aedes aegypti (Diptera: Culicidae) Catches Using Biogents Sentinel Traps During a 'Rear and Release' Program: Implications for Designing Surveillance Programs. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:1102-1111. [PMID: 30817823 DOI: 10.1093/jme/tjz018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Indexed: 06/09/2023]
Abstract
As the incidence of arboviral diseases such as dengue, Zika, chikungunya, and yellow fever increases globally, controlling their primary vector, Aedes aegypti (L.) (Diptera: Culicidae), is of greater importance than ever before. Mosquito control programs rely heavily on effective adult surveillance to ensure methodological efficacy. The Biogents Sentinel (BGS) trap is the gold standard for surveilling adult Aedes mosquitoes and is commonly deployed worldwide, including during modern 'rear and release' programs. Despite its extensive use, few studies have directly assessed environmental characteristics that affect BGS trap catches, let alone how these influences change during 'rear and release' programs. We assessed male and female Ae. aegypti spatial stability, as well as premises condition and trap location influences on BGS trap catches, as part of Debug Innisfail 'rear and release' program in northern Australia. We found similar trends in spatial stability of male and female mosquitoes at both weekly and monthly resolutions. From surveillance in locations where no males were released, reduced catches were found at premises that contained somewhat damaged houses and unscreened properties. In addition, when traps were located in areas that were unsheltered, more than 10 m from commonly used sitting areas or more visually complex catches were also negatively affected. In locations where males were released, we found that traps in treatment sites, relative to control sites, displayed increased catches in heavily shaded premises and were inconsistently influenced by differences in house sets and building materials. Such findings have valuable implications for a range of Ae. aegypti surveillance programs.
Collapse
Affiliation(s)
- Kyran M Staunton
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Smithfield, QLD, Australia
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| | - Peter Yeeles
- College of Science and Engineering, James Cook University, Smithfield, QLD, Australia
| | - Michael Townsend
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Smithfield, QLD, Australia
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| | - Somayeh Nowrouzi
- College of Science and Engineering, James Cook University, Smithfield, QLD, Australia
| | - Christopher J Paton
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Smithfield, QLD, Australia
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| | | | | | | | - Gregor J Devine
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Nigel Snoad
- Verily Life Sciences, South San Francisco, CA
| | - Nigel W Beebe
- Health and Biosecurity, CSIRO, Brisbane, QLD, Australia
- School of Biological Sciences Faculty of Science, University of Queensland, St Lucia, Brisbane, QLD, Australia
| | - Scott A Ritchie
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Smithfield, QLD, Australia
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| |
Collapse
|
180
|
Karungu S, Atoni E, Ogalo J, Mwaliko C, Agwanda B, Yuan Z, Hu X. Mosquitoes of Etiological Concern in Kenya and Possible Control Strategies. INSECTS 2019; 10:E173. [PMID: 31208124 PMCID: PMC6627689 DOI: 10.3390/insects10060173] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 06/11/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022]
Abstract
Kenya is among the most affected tropical countries with pathogen transmitting Culicidae vectors. For decades, insect vectors have contributed to the emergence and distribution of viral and parasitic pathogens. Outbreaks and diseases have a great impact on a country's economy, as resources that would otherwise be used for developmental projects are redirected to curb hospitalization cases and manage outbreaks. Infected invasive mosquito species have been shown to increasingly cross both local and global boarders due to the presence of increased environmental changes, trade, and tourism. In Kenya, there have been several mosquito-borne disease outbreaks such as the recent outbreaks along the coast of Kenya, involving chikungunya and dengue. This certainly calls for the implementation of strategies aimed at strengthening integrated vector management programs. In this review, we look at mosquitoes of public health concern in Kenya, while highlighting the pathogens they have been linked with over the years and across various regions. In addition, the major strategies that have previously been used in mosquito control and what more could be done to reduce or combat the menace caused by these hematophagous vectors are presented.
Collapse
Affiliation(s)
- Samuel Karungu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Evans Atoni
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Joseph Ogalo
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Caroline Mwaliko
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Bernard Agwanda
- Mammalogy Section, National Museum of Kenya, P.O. Box 40658, Nairobi 00100, Kenya.
| | - Zhiming Yuan
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Xiaomin Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
| |
Collapse
|
181
|
Jasper M, Schmidt TL, Ahmad NW, Sinkins SP, Hoffmann AA. A genomic approach to inferring kinship reveals limited intergenerational dispersal in the yellow fever mosquito. Mol Ecol Resour 2019; 19:1254-1264. [PMID: 31125998 PMCID: PMC6790672 DOI: 10.1111/1755-0998.13043] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/13/2019] [Accepted: 05/17/2019] [Indexed: 12/21/2022]
Abstract
Understanding past dispersal and breeding events can provide insight into ecology and evolution and can help inform strategies for conservation and the control of pest species. However, parent-offspring dispersal can be difficult to investigate in rare species and in small pest species such as mosquitoes. Here, we develop a methodology for estimating parent-offspring dispersal from the spatial distribution of close kin, using pairwise kinship estimates derived from genome-wide single nucleotide polymorphisms (SNPs). SNPs were scored in 162 Aedes aegypti (yellow fever mosquito) collected from eight close-set, high-rise apartment buildings in an area of Malaysia with high dengue incidence. We used the SNPs to reconstruct kinship groups across three orders of kinship. We transformed the geographical distances between all kin pairs within each kinship category into axial standard deviations of these distances, then decomposed these into components representing past dispersal events. From these components, we isolated the axial standard deviation of parent-offspring dispersal and estimated neighbourhood area (129 m), median parent-offspring dispersal distance (75 m) and oviposition dispersal radius within a gonotrophic cycle (36 m). We also analysed genetic structure using distance-based redundancy analysis and linear regression, finding isolation by distance both within and between buildings and estimating neighbourhood size at 268 individuals. These findings indicate the scale required to suppress local outbreaks of arboviral disease and to target releases of modified mosquitoes for mosquito and disease control. Our methodology is readily implementable for studies of other species, including pests and species of conservation significance.
Collapse
Affiliation(s)
- Moshe Jasper
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Thomas L Schmidt
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Nazni W Ahmad
- Institute for Medical Research, Ministry of Health Malaysia, Kuala Lumpur, Malaysia
| | | | - Ary A Hoffmann
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
182
|
Liu-Helmersson J, Brännström Å, Sewe MO, Semenza JC, Rocklöv J. Estimating Past, Present, and Future Trends in the Global Distribution and Abundance of the Arbovirus Vector Aedes aegypti Under Climate Change Scenarios. Front Public Health 2019; 7:148. [PMID: 31249824 PMCID: PMC6582658 DOI: 10.3389/fpubh.2019.00148] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/22/2019] [Indexed: 12/27/2022] Open
Abstract
Background:Aedes aegypti is the principal vector for several important arbovirus diseases, including dengue, chikungunya, yellow fever, and Zika. While recent empirical research has attempted to identify the current global distribution of the vector, the seasonal, and longer-term dynamics of the mosquito in response to trends in climate, population, and economic development over the twentieth and the twenty-first century remains to be elucidated. Methods: In this study, we use a process-based mathematical model to estimate global vector distribution and abundance. The model is based on the lifecycle of the vector and its dependence on climate, and the model sensitivity to socio-economic development is tested. Model parameters were generally empirically based, and the model was calibrated to global databases and time series of occurrence and abundance records. Climate data on temperature and rainfall were taken from CRU TS3.25 (1901–2015) and five global circulation models (CMIP5; 2006–2099) forced by a high-end (RCP8.5) and a low-end (RCP2.6) emission scenario. Socio-economic data on global GDP and human population density were from ISIMIP (1950–2099). Findings: The change in the potential of global abundance in A. aegypti over the last century up to today is estimated to be an increase of 9.5% globally and a further increase of 20 or 30% by the end of this century under a low compared to a high carbon emission future, respectively. The largest increase has occurred in the last two decades, indicating a tipping point in climate-driven global abundance which will be stabilized at the earliest in the mid-twenty-first century. The realized abundance is estimated to be sensitive to socioeconomic development. Interpretation: Our data indicate that climate change mitigation, i.e., following the Paris Agreement, could considerably help in suppressing risks of increased abundance and emergence of A. aegypti globally in the second half of the twenty-first century.
Collapse
Affiliation(s)
| | - Åke Brännström
- Department of Mathematics and Mathematical Statistics, Umeå University, Umeå, Sweden.,Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria
| | - Maquins Odhiambo Sewe
- Department of Public Health and Clinical Medicine, Section of Sustainable Health, Umeå University, Umeå, Sweden
| | - Jan C Semenza
- European Centre for Disease Prevention and Control, Stockholm, Sweden
| | - Joacim Rocklöv
- Department of Public Health and Clinical Medicine, Section of Sustainable Health, Umeå University, Umeå, Sweden
| |
Collapse
|
183
|
Otu A, Ebenso B, Etokidem A, Chukwuekezie O. Dengue fever - an update review and implications for Nigeria, and similar countries. Afr Health Sci 2019; 19:2000-2007. [PMID: 31656483 PMCID: PMC6794512 DOI: 10.4314/ahs.v19i2.23] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background In the last five decades, dengue has emerged as one of the most important infectious diseases, following a 30-fold increase in global incidence throughout tropical and sub-tropical regions of the world. The actual numbers of dengue cases are under-reported and many cases are misclassified. Objectives This article describes the epidemiology, pathophysiology, clinical features and management of dengue. It also explores the implications of infection with this flavivirus for Nigeria, and similar countries. Methods The literature search for publications on dengue in West Africa was performed using PubMed, African Journals Online (AJOL), Google Scholar, Web of Science, databases and grey literature to identify all published papers regarding the topic. A snowballing strategy was adopted to identify additional publications. Results Recent reports suggest that dengue is a growing public health problem in Nigeria, the magnitude of which needs to be more clearly defined. Nigeria, the most populous country in Africa has an abundance of the Aedes aegypti mosquito which is known to transmit dengue, Zika, as well as chikungunya (CHIKV) and West Nile viruses. Conclusion This article provides practical suggestions for strengthening the dengue virus control programme in Nigeria. The Nigerian health system shares similarities with health systems in many other sub-Saharan countries. Therefore, the practical suggestions provided at the end of this review are likely to be applicable to many other African countries.
Collapse
Affiliation(s)
- Akaninyene Otu
- Department of Internal Medicine, College of Medical Sciences, University of Calabar Nigeria. Tel: +2348105723133.
| | - Bassey Ebenso
- Nuffield Centre for International Health and Development, Leeds Institute for Health Sciences, University of Leeds, United Kingdom.
| | - Aniekan Etokidem
- Department of Community Medicine, College of Medical Sciences University of Calabar, Nigeria.
| | | |
Collapse
|
184
|
Reiner RC, Stoddard ST, Vazquez-Prokopec GM, Astete H, Perkins TA, Sihuincha M, Stancil JD, Smith DL, Kochel TJ, Halsey ES, Kitron U, Morrison AC, Scott TW. Estimating the impact of city-wide Aedes aegypti population control: An observational study in Iquitos, Peru. PLoS Negl Trop Dis 2019; 13:e0007255. [PMID: 31145744 PMCID: PMC6542505 DOI: 10.1371/journal.pntd.0007255] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
During the last 50 years, the geographic range of the mosquito Aedes aegypti has increased dramatically, in parallel with a sharp increase in the disease burden from the viruses it transmits, including Zika, chikungunya, and dengue. There is a growing consensus that vector control is essential to prevent Aedes-borne diseases, even as effective vaccines become available. What remains unclear is how effective vector control is across broad operational scales because the data and the analytical tools necessary to isolate the effect of vector-oriented interventions have not been available. We developed a statistical framework to model Ae. aegypti abundance over space and time and applied it to explore the impact of citywide vector control conducted by the Ministry of Health (MoH) in Iquitos, Peru, over a 12-year period. Citywide interventions involved multiple rounds of intradomicile insecticide space spray over large portions of urban Iquitos (up to 40% of all residences) in response to dengue outbreaks. Our model captured significant levels of spatial, temporal, and spatio-temporal variation in Ae. aegypti abundance within and between years and across the city. We estimated the shape of the relationship between the coverage of neighborhood-level vector control and reductions in female Ae. aegypti abundance; i.e., the dose-response curve. The dose-response curve, with its associated uncertainties, can be used to gauge the necessary spraying effort required to achieve a desired effect and is a critical tool currently absent from vector control programs. We found that with complete neighborhood coverage MoH intra-domicile space spray would decrease Ae. aegypti abundance on average by 67% in the treated neighborhood. Our framework can be directly translated to other interventions in other locations with geolocated mosquito abundance data. Results from our analysis can be used to inform future vector-control applications in Ae. aegypti endemic areas globally. Despite the growing threat of arboviruses, there is a dearth of ‘best practices’ for the primary vector control tools used in the field. In the absence of cluster randomized control trials, evidence on the utility (or lack thereof) of vector control interventions must be gleaned from ongoing control programs. Motivated by 12 years of household-level Ae. aegypti abundance surveys and neighborhood-level space-spray campaign data from Iquitos, Peru, we developed a new framework to model mosquito abundance. In spite of significant spatial and temporal heterogeneity, we identified a statistically significant and practically important impact of the local Ministry of Health space-spray campaign, specifically, a reduction of mosquito abundance of 67% when coverage was optimal. Our framework can be directly applied to other locations with geolocated mosquito abundance data and our findings can be used to both optimize resources within Iquitos as well as inform future vector-control interventions in Ae. aegypti endemic areas globally.
Collapse
Affiliation(s)
- Robert C. Reiner
- Institute for Health Metrics and Evaluation, Department of Global Health, Schools of Medicine and Public Health, University of Washington, WA, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
- * E-mail:
| | - Steven T. Stoddard
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
- School of Public Health, San Diego State University, San Diego, CA, United States of America
| | - Gonzalo M. Vazquez-Prokopec
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
- Department of Environmental Sciences, Emory University, Atlanta, GA, United States of America
| | | | - T. Alex Perkins
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | | | | | - David L. Smith
- Institute for Health Metrics and Evaluation, Department of Global Health, Schools of Medicine and Public Health, University of Washington, WA, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
| | | | | | - Uriel Kitron
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
- Department of Environmental Sciences, Emory University, Atlanta, GA, United States of America
| | - Amy C. Morrison
- U.S. Naval Medical Research Unit N0.6, Lima, Peru
- Department of Entomology, University of California, Davis, CA, United States of America
| | - Thomas W. Scott
- Fogarty International Center, National Institutes of Health, Bethesda, MD, United States of America
- Department of Entomology, University of California, Davis, CA, United States of America
| |
Collapse
|
185
|
Pleydell DRJ, Bouyer J. Biopesticides improve efficiency of the sterile insect technique for controlling mosquito-driven dengue epidemics. Commun Biol 2019; 2:201. [PMID: 31149645 PMCID: PMC6541632 DOI: 10.1038/s42003-019-0451-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 04/30/2019] [Indexed: 12/16/2022] Open
Abstract
Various mosquito control methods use factory raised males to suppress vector densities. But the efficiency of these methods is currently insufficient to prevent epidemics of arbovirus diseases such as dengue, chikungunya or Zika. Suggestions that the sterile insect technique (SIT) could be "boosted" by applying biopesticides to sterile males remain unquantified. Here, we assess mathematically the gains to SIT for Aedes control of either: boosting with the pupicide pyriproxifen (BSIT); or, contaminating mosquitoes at auto-dissemination stations. Thresholds in sterile male release rate and competitiveness are identified, above which mosquitoes are eliminated asymptotically. Boosting reduces these thresholds and aids population destabilisation, even at sub-threshold release rates. No equivalent bifurcation exists in the auto-dissemination sub-model. Analysis suggests that BSIT can reduce by over 95% the total release required to circumvent dengue epidemics compared to SIT. We conclude, BSIT provides a powerful new tool for the integrated management of mosquito borne diseases.
Collapse
Affiliation(s)
- David R. J. Pleydell
- CIRAD, INRA, University of Montpellier, UMR ASTRE, F-34398 Montpellier, France
- INRA, CIRAD, University of Montpellier, UMR ASTRE, F-97170 Petit Bourg Guadeloupe, France
| | - Jérémy Bouyer
- CIRAD, INRA, University of Montpellier, UMR ASTRE, F-34398 Montpellier, France
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, IAEA, Vienna, Austria
| |
Collapse
|
186
|
Hickner PV, Mori A, Rund SSC, Sheppard AD, Cunningham JM, Chadee DD, Duffield GE, Severson DW. QTL Determining Diel Flight Activity in Male Culex pipiens Mosquitoes. J Hered 2019; 110:310-320. [PMID: 30668763 PMCID: PMC6503456 DOI: 10.1093/jhered/esz003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 01/14/2019] [Indexed: 12/26/2022] Open
Abstract
Members of the Culex pipiens complex differ in physiological traits that facilitate their survival in diverse environments. Assortative mating within the complex occurs in some regions where autogenous (the ability to lay a batch of eggs without a blood meal) and anautogenous populations are sympatric, and differences in mating behaviors may be involved. For example, anautogenous populations mate in flight/swarms, while autogenous populations often mate at rest. Here, we characterized flight activity of males and found that anautogenous strain males were crepuscular, while autogenous strain males were crepuscular and nocturnal, with earlier activity onset times. We conducted quantitative trait locus (QTL) mapping to explore the genetic basis of circadian chronotype (crepuscular vs. crepuscular and nocturnal) and time of activity onset. One major-effect QTL was identified for chronotype, while 3 QTLs were identified for activity onset. The highest logarithm of the odds (LOD) score for the chronotype QTL coincides with a chromosome 3 marker that contains a 15-nucleotide indel within the coding region of the canonical clock gene, cryptochrome 2. Sequencing of this locus in 7 different strains showed that the C-terminus of CRY2 in the autogenous forms contain deletions not found in the anautogenous forms. Consequently, we monitored activity in constant darkness and found males from the anautogenous strain exhibited free running periods of ~24 h while those from the autogenous strain were ~22 h. This study provides novel insights into the genetic basis of flight behaviors that likely reflect adaptation to their distinct ecological niches.
Collapse
Affiliation(s)
- Paul V Hickner
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| | - Akio Mori
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| | - Samuel S C Rund
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, UK
| | - Aaron D Sheppard
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| | - Joanne M Cunningham
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| | - Dave D Chadee
- Department of Life Sciences, University of the West Indies, St. Augustine, Trinidad, West Indies
| | - Giles E Duffield
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| | - David W Severson
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| |
Collapse
|
187
|
Collins MH. Serologic Tools and Strategies to Support Intervention Trials to Combat Zika Virus Infection and Disease. Trop Med Infect Dis 2019; 4:tropicalmed4020068. [PMID: 31010134 PMCID: PMC6632022 DOI: 10.3390/tropicalmed4020068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/11/2019] [Accepted: 04/15/2019] [Indexed: 12/30/2022] Open
Abstract
Zika virus is an emerging mosquito-borne flavivirus that recently caused a large epidemic in Latin America characterized by novel disease phenotypes, including Guillain-Barré syndrome, sexual transmission, and congenital anomalies, such as microcephaly. This epidemic, which was declared an international public health emergency by the World Health Organization, has highlighted shortcomings in our current understanding of, and preparation for, emerging infectious diseases in general, as well as challenges that are specific to Zika virus infection. Vaccine development for Zika virus has been a high priority of the public health response, and several candidates have shown promise in pre-clinical and early phase clinical trials. The optimal selection and implementation of imperfect serologic assays are among the crucial issues that must be addressed in order to advance Zika vaccine development. Here, I review key considerations for how best to incorporate into Zika vaccine trials the existing serologic tools, as well as those on the horizon. Beyond that, this discussion is relevant to other intervention strategies to combat Zika and likely other emerging infectious diseases.
Collapse
Affiliation(s)
- Matthew H Collins
- Hope Clinic of the Emory Vaccine Center, Division of Infectious Diseases, Department of Medicine, School of Medicine, Emory University, Decatur, GA 30030, USA.
| |
Collapse
|
188
|
Simard F. [Next-generation vector control]. Biol Aujourdhui 2019; 212:137-145. [PMID: 30973142 DOI: 10.1051/jbio/2019006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Indexed: 11/14/2022]
Abstract
Vector control is a cornerstone of vector-borne infectious disease control, a group of emerging and re-emerging diseases of major public health concern at a global scale. The history and evolution of mosquito disease vectors control, mainly based on the use of chemical insecticides, is emblematic of the successes, failures, lessons learned and experiences gained in setting-up and implementing vector control, and of the challenges that pave the way to sustainable disease vector management. This paper provides a non-exhaustive and non-exclusive overview of some of the most promising cutting-edge technical and strategic innovations that are committed to this endeavour, assessing the strength of scientific evidences for proof of concept, perspectives for scaling-up, and expected impact and outcomes in a rapidly changing world.
Collapse
Affiliation(s)
- Frédéric Simard
- MIVEGEC (Maladies Infectieuses et Vecteurs : Écologie, Génétique, Évolution et Contrôle), UMR IRD-CNRS-Université de Montpellier, 911 avenue Agropolis, 34080 Montpellier, France
| |
Collapse
|
189
|
Lee WS, Webster JA, Madzokere ET, Stephenson EB, Herrero LJ. Mosquito antiviral defense mechanisms: a delicate balance between innate immunity and persistent viral infection. Parasit Vectors 2019; 12:165. [PMID: 30975197 PMCID: PMC6460799 DOI: 10.1186/s13071-019-3433-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 04/04/2019] [Indexed: 01/24/2023] Open
Abstract
Mosquito-borne diseases are associated with major global health burdens. Aedes spp. and Culex spp. are primarily responsible for the transmission of the most medically important mosquito-borne viruses, including dengue virus, West Nile virus and Zika virus. Despite the burden of these pathogens on human populations, the interactions between viruses and their mosquito hosts remain enigmatic. Viruses enter the midgut of a mosquito following the mosquito’s ingestion of a viremic blood meal. During infection, virus recognition by the mosquito host triggers their antiviral defense mechanism. Of these host defenses, activation of the RNAi pathway is the main antiviral mechanism, leading to the degradation of viral RNA, thereby inhibiting viral replication and promoting viral clearance. However, whilst antiviral host defense mechanisms limit viral replication, the mosquito immune system is unable to effectively clear the virus. As such, these viruses can establish persistent infection with little or no fitness cost to the mosquito vector, ensuring life-long transmission to humans. Understanding of the mosquito innate immune response enables the discovery of novel antivectorial strategies to block human transmission. This review provides an updated and concise summary of recent studies on mosquito antiviral immune responses, which is a key determinant for successful virus transmission. In addition, we will also discuss the factors that may contribute to persistent infection in mosquito hosts. Finally, we will discuss current mosquito transmission-blocking strategies that utilize genetically modified mosquitoes and Wolbachia-infected mosquitoes for resistance to pathogens.
Collapse
Affiliation(s)
- Wai-Suet Lee
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, 4215, Australia
| | - Julie A Webster
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, 4215, Australia
| | - Eugene T Madzokere
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, 4215, Australia
| | - Eloise B Stephenson
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, 4215, Australia.,Environmental Futures Research Institute, Griffith University, Gold Coast Campus, Southport, QLD, 4215, Australia
| | - Lara J Herrero
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, 4215, Australia.
| |
Collapse
|
190
|
Kauffman EB, Kramer LD. Zika Virus Mosquito Vectors: Competence, Biology, and Vector Control. J Infect Dis 2019; 216:S976-S990. [PMID: 29267910 DOI: 10.1093/infdis/jix405] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Zika virus (ZIKV) (Flaviviridae, Flavivirus) has become one of the most medically important mosquito-borne viruses because of its ability to cause microcephaly in utero and Guillain-Barré syndrome in adults. This virus emerged from its sylvatic cycle in Africa to cause an outbreak in Yap, Federated States of Micronesia in 2007, French Polynesia in 2014, and most recently South America in 2015. The rapid expansion of ZIKV in the Americas largely has been due to the biology and behavior of its vector, Aedes aegypti. Other arboviruses transmitted by Ae. aegypti include the 2 flaviviruses dengue virus and yellow fever virus and the alphavirus chikungunya virus, which are also (re)emerging viruses in the Americas. This mosquito vector is highly domesticated, living in close association with humans in urban households. Its eggs are desiccation resistant, and the larvae develop rapidly in subtropical and tropical environments. Climate warming is facilitating range expansion of Ae. aegypti, adding to the threat this mosquito poses to human health, especially in light of the difficulty controlling it. Aedes albopictus, another highly invasive arbovirus vector that has only been implicated in one country (Gabon), is an important vector of ZIKV, but because of its wide geographic distribution may become a more important vector in the future. This article discusses the historical background of ZIKV and the biology and ecology of these 2 vectors.
Collapse
Affiliation(s)
- Elizabeth B Kauffman
- Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Albany
| | - Laura D Kramer
- Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Albany.,School of Public Health, State University of New York, Albany
| |
Collapse
|
191
|
Schwab SR, Stone CM, Fonseca DM, Fefferman NH. (Meta)population dynamics determine effective spatial distributions of mosquito-borne disease control. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01856. [PMID: 30681219 DOI: 10.1002/eap.1856] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 11/19/2018] [Accepted: 12/21/2018] [Indexed: 06/09/2023]
Abstract
Recent epidemics of mosquito-borne dengue and Zika viruses demonstrate the urgent need for effective measures to control these diseases. The best method currently available to prevent or reduce the size of outbreaks is to reduce the abundance of their mosquito vectors, but there is little consensus on which mechanisms of control are most effective, or when and where they should be implemented. Although the optimal methods are likely context dependent, broadly applicable strategies for mosquito control, such as how to distribute limited resources across a landscape in times of high epidemic risk, can mitigate (re)emerging outbreaks. We used mathematical simulations to examine how the spatial distribution of larval mosquito control affects the size of disease outbreaks, and how mosquito metapopulation dynamics and demography might impact the efficacy of different spatial distributions of control. We found that the birth rate and mechanism of density-dependent regulation of mosquito populations affected the average outbreak size across all control distributions. These factors also determined whether control distributions favoring the interior or the edges of the landscape most effectively reduced human infections. Thus, understanding local mosquito population regulation and dispersion can lead to more effective control strategies.
Collapse
Affiliation(s)
- Samantha R Schwab
- Graduate Program in Ecology and Evolution, Environmental & Natural Resource Sciences Building, Room 150, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, New Jersey 08901-8551, USA
| | - Chris M Stone
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 South Oak Street, MC 652, Champaign, Illinois, 61820, USA
- Department of Ecology and Evolutionary Biology, University of Tennessee, 447 Hesler Biology Building, Knoxvillle, Tennessee, 37996-1610, USA
| | - Dina M Fonseca
- Center for Vector Biology, School of Environmental & Biological Sciences Rutgers, The State University of New Jersey, 178-180 Jones Ave, New Brunswick, New Jersey, 08901-8536, USA
| | - Nina H Fefferman
- Department of Ecology and Evolutionary Biology, University of Tennessee, 447 Hesler Biology Building, Knoxvillle, Tennessee, 37996-1610, USA
| |
Collapse
|
192
|
Somerville J, Zhou L, Raymond B. Aseptic Rearing and Infection with Gut Bacteria Improve the Fitness of Transgenic Diamondback Moth, Plutella xylostella. INSECTS 2019; 10:insects10040089. [PMID: 30925791 PMCID: PMC6523322 DOI: 10.3390/insects10040089] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 03/21/2019] [Accepted: 03/25/2019] [Indexed: 12/27/2022]
Abstract
Mass insect rearing can have a range of applications, for example in biological control of pests. The competitive fitness of released insects is extremely important in a number of applications. Here, we investigated how to improve the fitness of a transgenic diamondback moth, which has shown variation in mating ability when reared in different insectaries. Specifically we tested whether infection with a gut bacteria, Enterobacter cloacae, and aseptic rearing of larvae could improve insect growth and male performance. All larvae were readily infected with E. cloacae. Under aseptic rearing, pupal weights were reduced and there was a marginal reduction in larval survival. However, aseptic rearing substantially improved the fitness of transgenic males. In addition, under aseptic rearing, inoculation with E. cloacae increased pupal weights and male fitness, increasing the proportion of transgenic progeny from 20% to 30% relative to uninfected insects. Aseptic conditions may improve the fitness of transgenic males by excluding microbial contaminants, while symbiont inoculation could further improve fitness by providing additional protection against infection, or by normalizing insect physiology. The simple innovation of incorporating antibiotic into diet, and inoculating insects with symbiotic bacteria that are resistant to that antibiotic, could provide a readily transferable tool for other insect rearing systems.
Collapse
Affiliation(s)
- Jasmine Somerville
- Centre for Ecology and Conservation, Penryn campus, College of Life and Environmental Science, University of Exeter, TR10 9FE, UK.
| | - Liqin Zhou
- Centre for Ecology and Conservation, Penryn campus, College of Life and Environmental Science, University of Exeter, TR10 9FE, UK.
| | - Ben Raymond
- Centre for Ecology and Conservation, Penryn campus, College of Life and Environmental Science, University of Exeter, TR10 9FE, UK.
| |
Collapse
|
193
|
Shet A, Kang G. Dengue in India: Towards a better understanding of priorities and progress. Int J Infect Dis 2019; 84S:S1-S3. [PMID: 30877040 DOI: 10.1016/j.ijid.2019.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 03/06/2019] [Accepted: 03/06/2019] [Indexed: 11/28/2022] Open
Affiliation(s)
- Anita Shet
- International Vaccine Access Center, Johns Hopkins University, 415 N Washington Street, Baltimore 21231, USA.
| | - Gagandeep Kang
- Translational Health Science and Technology Institute, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana 120001, India.
| |
Collapse
|
194
|
Degner EC, Ahmed-Braimah YH, Borziak K, Wolfner MF, Harrington LC, Dorus S. Proteins, Transcripts, and Genetic Architecture of Seminal Fluid and Sperm in the Mosquito Aedes aegypti. Mol Cell Proteomics 2019; 18:S6-S22. [PMID: 30552291 PMCID: PMC6427228 DOI: 10.1074/mcp.ra118.001067] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/29/2018] [Indexed: 11/06/2022] Open
Abstract
The yellow fever mosquito, Aedes aegypti,, transmits several viruses causative of serious diseases, including dengue, Zika, and chikungunya. Some proposed efforts to control this vector involve manipulating reproduction to suppress wild populations or to replace them with disease-resistant mosquitoes. The design of such strategies requires an intimate knowledge of reproductive processes, yet our basic understanding of reproductive genetics in this vector remains largely incomplete. To accelerate future investigations, we have comprehensively catalogued sperm and seminal fluid proteins (SFPs) transferred to females in the ejaculate using tandem mass spectrometry. By excluding female-derived proteins using an isotopic labeling approach, we identified 870 sperm proteins and 280 SFPs. Functional composition analysis revealed parallels with known aspects of sperm biology and SFP function in other insects. To corroborate our proteome characterization, we also generated transcriptomes for testes and the male accessory glands-the primary contributors to Ae. aegypti, sperm and seminal fluid, respectively. Differential gene expression of accessory glands from virgin and mated males suggests that transcripts encoding proteins involved in protein translation are upregulated post-mating. Several SFP transcripts were also modulated after mating, but >90% remained unchanged. Finally, a significant enrichment of SFPs was observed on chromosome 1, which harbors the male sex determining locus in this species. Our study provides a comprehensive proteomic and transcriptomic characterization of ejaculate production and composition and thus provides a foundation for future investigations of Ae. aegypti, reproductive biology, from functional analysis of individual proteins to broader examination of reproductive processes.
Collapse
Affiliation(s)
- Ethan C Degner
- From the ‡Department of Entomology, Cornell University, Ithaca, New York
| | | | - Kirill Borziak
- Center for Reproductive Evolution, Syracuse University, Syracuse, New York
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York;.
| | - Laura C Harrington
- From the ‡Department of Entomology, Cornell University, Ithaca, New York;.
| | - Steve Dorus
- Center for Reproductive Evolution, Syracuse University, Syracuse, New York.
| |
Collapse
|
195
|
Meuti ME, Short SM. Physiological and Environmental Factors Affecting the Composition of the Ejaculate in Mosquitoes and Other Insects. INSECTS 2019; 10:E74. [PMID: 30875967 PMCID: PMC6468485 DOI: 10.3390/insects10030074] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/05/2019] [Accepted: 03/08/2019] [Indexed: 01/02/2023]
Abstract
In addition to transferring sperm, male mosquitoes deliver several proteins, hormones and other factors to females in their seminal fluid that inhibit remating, alter host-seeking behaviors and stimulate oviposition. Recently, bioinformatics, transcriptomics and proteomics have been used to characterize the genes transcribed in male reproductive tissues and the individual proteins that are delivered to females. Thanks to these foundational studies, we now understand the complexity of the ejaculate in several mosquito species. Building on this work, researchers have begun to identify the functions of various proteins and hormones in the male ejaculate, and how they mediate their effects on female mosquitoes. Here, we present an overview of these studies, followed by a discussion of an under-studied aspect of male reproductive physiology: the effects of biotic and abiotic factors on the composition of the ejaculate. We argue that future research in this area would improve our understanding of male reproductive biology from a physiological and ecological perspective, and that researchers may be able to leverage this information to study key components of the ejaculate. Furthermore, this work has the potential to improve mosquito control by allowing us to account for relevant factors when implementing vector control strategies involving male reproductive biology.
Collapse
Affiliation(s)
- Megan E Meuti
- Department of Entomology, The Ohio State University, 2001 Fyffe Rd., Room 232 Howlett Hall, Columbus, OH 43210, USA.
| | - Sarah M Short
- Department of Entomology, The Ohio State University, 2001 Fyffe Rd., Room 232 Howlett Hall, Columbus, OH 43210, USA.
| |
Collapse
|
196
|
Multerer L, Smith T, Chitnis N. Modeling the impact of sterile males on an Aedes aegypti population with optimal control. Math Biosci 2019; 311:91-102. [PMID: 30857942 DOI: 10.1016/j.mbs.2019.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 11/29/2022]
Abstract
We use partial differential equations to describe the dynamics of an Aedes aegypti mosquito population on an island, and the effects of a sterile male release. The model includes mosquito movement and an Allee effect to capture extinction events. We apply optimal control theory to identify the release strategy that eliminates the mosquitoes most rapidly, conditional on a limited availability of sterile males. The optimal solution for a single location is to initially release a substantial number of mosquitoes and to subsequently release fewer sterile males proportionally to the decreasing female population. The optimal solution for the whole island is intractable given a constraint on the total daily release of sterile males. The best approximation to the spatial optimal control strategy is to focus on the high mosquito density areas first and then move outwards (in both directions along the periphery of the island), until all areas have been covered, retaining throughout sufficient release intensity to prevent reintroduction in the already cleared areas.
Collapse
Affiliation(s)
- Lea Multerer
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
| | - Thomas Smith
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
| |
Collapse
|
197
|
Ross PA, Endersby‐Harshman NM, Hoffmann AA. A comprehensive assessment of inbreeding and laboratory adaptation in Aedes aegypti mosquitoes. Evol Appl 2019; 12:572-586. [PMID: 30828375 PMCID: PMC6383739 DOI: 10.1111/eva.12740] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 09/04/2018] [Accepted: 11/11/2018] [Indexed: 12/13/2022] Open
Abstract
Modified Aedes aegypti mosquitoes reared in laboratories are being released around the world to control wild mosquito populations and the diseases they transmit. Several efforts have failed due to poor competitiveness of the released mosquitoes. We hypothesized that colonized mosquito populations could suffer from inbreeding depression and adapt to laboratory conditions, reducing their performance in the field. We established replicate populations of Ae. aegypti mosquitoes collected from Queensland, Australia, and maintained them in the laboratory for twelve generations at different census sizes. Mosquito colonies maintained at small census sizes (≤100 individuals) suffered from inbreeding depression due to low effective population sizes which were only 25% of the census size as estimated by SNP markers. Populations that underwent full-sib mating for nine consecutive generations had greatly reduced performance across all traits measured. We compared the established laboratory populations with their ancestral population resurrected from quiescent eggs for evidence of laboratory adaptation. The overall performance of laboratory populations maintained at a large census size (400 individuals) increased, potentially reflecting adaptation to artificial rearing conditions. However, most individual traits were unaffected, and patterns of adaptation were not consistent across populations. Differences between replicate populations may indicate that founder effects and drift affect experimental outcomes. Though we find limited evidence of laboratory adaptation, mosquitoes maintained at low population sizes can clearly suffer fitness costs, compromising the success of "rear-and-release" strategies for arbovirus control.
Collapse
Affiliation(s)
- Perran A. Ross
- Bio21 Institute and the School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
| | | | - Ary A. Hoffmann
- Bio21 Institute and the School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
| |
Collapse
|
198
|
Zhou L, Alphey N, Walker AS, Travers LM, Morrison NI, Bonsall MB, Raymond B. The application of self-limiting transgenic insects in managing resistance in experimental metapopulations. J Appl Ecol 2019; 56:688-698. [PMID: 30983625 PMCID: PMC6446822 DOI: 10.1111/1365-2664.13298] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/08/2018] [Indexed: 12/24/2022]
Abstract
The mass release of transgenic insects carrying female lethal self-limiting genes can reduce pest insect populations. Substantial releases are also a novel resistance management tool, since wild type alleles conferring susceptibility to pesticides can dilute resistance alleles in target populations. However, a potential barrier is the need for large-scale area-wide releases. Here, we address whether localized releases of transgenic insects could provide an alternative means of population suppression and resistance management, without serious loss of efficacy.We used experimental mesocosms constituting insect metapopulations to explore the evolution of resistance to the Bacillus thuringiensis toxin Cry1Ac in a high-dose/refugia landscape in the insect Plutella xylostella. We ran two selection experiments, the first compared the efficacy of "everywhere" releases and negative controls to a spatially density-dependent or "whack-a-mole" strategy that concentrated release of transgenic insects in subpopulations with elevated resistance. The second experiment tested the relative efficacy of whack-a-mole and everywhere releases under spatially homogenous and heterogeneous selection pressure.The whack-a-mole releases were less effective than everywhere releases in terms of slowing the evolution of resistance, which, in the first experiment, largely prevented the evolution of resistance. In contrast to predictions, heterogeneous whack-a-mole releases were no more effective under heterogeneous selection pressure. Heterogeneous selection pressure did, however, reduce total insect population sizes.Whack-a-mole releases provided early population suppression, indistinguishable from homogeneous everywhere releases. However, insect population densities tracked the evolution of resistance in this system, as phenotypic resistance provides access to additional diet containing the toxin Cry1Ac. Thus, as resistance levels diverged between treatments, carrying capacities and population sizes increased under the whack-a-mole approach. Synthesis and applications. Spatially density-dependent releases of transgenic insects, particularly those targeting source populations at a landscape level, could suppress pest populations in the absence of blanket area-wide releases. The benefits of self-limiting transgenic insects were reduced in spatially localized releases, suggesting that they are not ideal for "spot" treatment of resistance problems. Nevertheless, spatially homogeneous or heterogeneous releases could be used to support other resistance management interventions.
Collapse
Affiliation(s)
- Liqin Zhou
- Department of Life SciencesImperial College LondonAscotUK
- Department of BiosciencesCollege of Life and Environmental SciencesUniversity of ExeterPenrynUK
| | - Nina Alphey
- Department of ZoologyMathematical Ecology Research GroupUniversity of OxfordOxfordUK
- The Pirbright InstituteSurreyUK
| | | | - Laura M. Travers
- Department of BiosciencesCollege of Life and Environmental SciencesUniversity of ExeterPenrynUK
| | | | - Michael B. Bonsall
- Department of ZoologyMathematical Ecology Research GroupUniversity of OxfordOxfordUK
| | - Ben Raymond
- Department of Life SciencesImperial College LondonAscotUK
- Department of BiosciencesCollege of Life and Environmental SciencesUniversity of ExeterPenrynUK
| |
Collapse
|
199
|
Kura K, Khamis D, El Mouden C, Bonsall MB. Optimal control for disease vector management in SIT models: an integrodifference equation approach. J Math Biol 2019; 78:1821-1839. [PMID: 30734075 PMCID: PMC6469698 DOI: 10.1007/s00285-019-01327-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 01/14/2019] [Indexed: 11/26/2022]
Abstract
Vector-borne diseases are a major public health concern inflicting high levels of disease morbidity and mortality. Vector control is one of the principal methods available to manage infectious disease burden. One approach, releasing modified vectors (such as sterile or GM mosquitoes) Into the wild population has been suggested as an effective method of vector control. However, the effects of dispersal and the spatial distribution of disease vectors (such as mosquitoes) remain poorly studied. Here, we develop a novel mathematical framework using an integrodifference equation (discrete in time and continuous in space) approach to understand the impact of releasing sterile insects into the wild population in a spatially explicit environment. We prove that an optimal release strategy exists and show how it may be characterized by defining a sensitivity variable and an adjoint system. Using simulations, we show that the optimal strategy depends on the spatially varying carrying capacity of the environment.
Collapse
Affiliation(s)
- Klodeta Kura
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK
| | - Doran Khamis
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK
| | - Claire El Mouden
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK
| | - Michael B Bonsall
- Mathematical Ecology Research Group, Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK.
| |
Collapse
|
200
|
Engineered resistance to Zika virus in transgenic Aedes aegypti expressing a polycistronic cluster of synthetic small RNAs. Proc Natl Acad Sci U S A 2019; 116:3656-3661. [PMID: 30723148 PMCID: PMC6397566 DOI: 10.1073/pnas.1810771116] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Here, we describe the generation of Aedes aegypti mosquitoes that are engineered to be resistant to Zika virus (ZIKV) transmission. Our results demonstrate that engineered mosquitoes express a polycistronic cluster of synthetic small RNAs designed to target the ZIKV genome. As a result, homozygous mosquitoes were refractory to ZIKV infection, and therefore could not transmit the virus. Additionally, mosquitoes heterozygous for the transgene showed significantly lower levels of viral infection, dissemination, and transmission compared with wild-type mosquitoes; importantly, these levels were low enough to make such mosquitoes unlikely to transmit ZIKV to a susceptible host. Finally, we discuss how such an engineering approach can be used to combat the major health burden of ZIKV, and potentially other arboviruses, in the future. Recent Zika virus (ZIKV) outbreaks have highlighted the necessity for development of novel vector control strategies to combat arboviral transmission, including genetic versions of the sterile insect technique, artificial infection with Wolbachia to reduce population size and/or vectoring competency, and gene drive-based methods. Here, we describe the development of mosquitoes synthetically engineered to impede vector competence to ZIKV. We demonstrate that a polycistronic cluster of engineered synthetic small RNAs targeting ZIKV is expressed and fully processed in Aedes aegypti, ensuring the formation of mature synthetic small RNAs in the midgut where ZIKV resides in the early stages of infection. Critically, we demonstrate that engineered Ae. aegypti mosquitoes harboring the anti-ZIKV transgene have significantly reduced viral infection, dissemination, and transmission rates of ZIKV. Taken together, these compelling results provide a promising path forward for development of effective genetic-based ZIKV control strategies, which could potentially be extended to curtail other arboviruses.
Collapse
|