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Duran-Ahumada S, Karrer L, Cheng C, Roeske I, Pilchik J, Jimenez-Vallejo D, Smith E, Roy K, Kirstein OD, Martin-Park A, Contreras-Perera Y, Che-Mendoza A, Gonzalez-Olvera G, Puerta-Guardo HN, Uribe-Soto SI, Manrique-Saide P, Vazquez-Prokopec G. Wolbachia pipientis (Rickettsiales: Rickettsiaceae) mediated effects on the fitness and performance of Aedes aegypti (Diptera: Culicidae) under variable temperatures and initial larval densities. JOURNAL OF MEDICAL ENTOMOLOGY 2024; 61:1155-1167. [PMID: 39077840 DOI: 10.1093/jme/tjae088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 06/19/2024] [Accepted: 07/11/2024] [Indexed: 07/31/2024]
Abstract
Wolbachia pipientis (Hertig, 1936), also referred as Wolbachia, is a bacterium present across insect taxa, certain strains of which have been demonstrated to impact the fitness and capacity to transmit viruses in mosquitoes, particularly Aedes aegypti (Linnaeus, 1762). Most studies examine these impacts in limited sets of environmental regimes. Here we seek to understand the impacts of environmentally relevant conditions such as larval density, temperature, and their interaction on wAlbB-infected A. aegypti. Using a factorial design, we measured wAlbB stability (relative density, post-emergence in females, and in progeny), the ability for wAlbB to induce cytoplasmic incompatibility, and bacterial effects on mosquito fitness (fecundity, fertility, and body mass) and performance (adult survival and time to pupation) across 2 temperature regimes (fluctuating and constant) and 2 initial larval densities (low and high). Fluctuating daily regimes of temperature (27 to 40 °C) led to decreased post-emergence wAlbB density and increased wAlbB density in eggs compared to constant temperature (27 °C). An increased fecundity was found in wAlbB-carrying females reared at fluctuating temperatures compared to uninfected wild-type females. wAlbB-carrying adult females showed significantly increased survival than wild-type females. Contrarily, wAlbB-carrying adult males exhibited a significantly lower survival than wild-type males. We found differential effects of assessed treatments (Wolbachia infection status, temperature, and larval density) across mosquito sexes and life stages. Taken together, our results indicate that realistic conditions may not impact dramatically the stability of wAlbB infection in A. aegypti. Nonetheless, understanding the ecological consequence of A. aegypti-wAlbB interaction is complex due to life history tradeoffs under conditions faced by natural populations.
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Affiliation(s)
- Sebastian Duran-Ahumada
- Population Biology, Ecology, and Evolution Graduate Program Emory University Atlanta, GA, USA
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - Luiza Karrer
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - Chun Cheng
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
- Rollins School of Public Health, Emory University Atlanta, GA, USA
| | - Isabella Roeske
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - Josie Pilchik
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - David Jimenez-Vallejo
- Population Biology, Ecology, and Evolution Graduate Program Emory University Atlanta, GA, USA
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - Emily Smith
- Population Biology, Ecology, and Evolution Graduate Program Emory University Atlanta, GA, USA
| | - Kristina Roy
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - Oscar D Kirstein
- Department of Environmental Sciences, Emory University Atlanta, GA, USA
| | - Abdiel Martin-Park
- Laboratory for the Biological Control of Aedes aegypti, Collaborative Unit for Entomological Bioassays (UCBE-LCB), Autonomous University of Yucatan, Merida, Mexico
| | - Yamili Contreras-Perera
- Laboratory for the Biological Control of Aedes aegypti, Collaborative Unit for Entomological Bioassays (UCBE-LCB), Autonomous University of Yucatan, Merida, Mexico
| | - Azael Che-Mendoza
- Laboratory for the Biological Control of Aedes aegypti, Collaborative Unit for Entomological Bioassays (UCBE-LCB), Autonomous University of Yucatan, Merida, Mexico
| | - Gabriela Gonzalez-Olvera
- Laboratory for the Biological Control of Aedes aegypti, Collaborative Unit for Entomological Bioassays (UCBE-LCB), Autonomous University of Yucatan, Merida, Mexico
| | - Henry N Puerta-Guardo
- Laboratory for the Biological Control of Aedes aegypti, Collaborative Unit for Entomological Bioassays (UCBE-LCB), Autonomous University of Yucatan, Merida, Mexico
| | - Sandra I Uribe-Soto
- Sciences Faculty, National University of Colombia, Medellin Campus, Medellin, Antioquia, Colombia
| | - Pablo Manrique-Saide
- Laboratory for the Biological Control of Aedes aegypti, Collaborative Unit for Entomological Bioassays (UCBE-LCB), Autonomous University of Yucatan, Merida, Mexico
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Lau MJ, Valdez AR, Jones MJ, Aranson I, Hoffmann AA, McGraw EA. The effect of repeat feeding on dengue virus transmission potential in Wolbachia-infected Aedes aegypti following extended egg quiescence. PLoS Negl Trop Dis 2024; 18:e0012305. [PMID: 38976758 PMCID: PMC11257391 DOI: 10.1371/journal.pntd.0012305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 07/18/2024] [Accepted: 06/21/2024] [Indexed: 07/10/2024] Open
Abstract
As Wolbachia pipientis is more widely being released into field populations of Aedes aegypti for disease control, the ability to select the appropriate strain for differing environments is increasingly important. A previous study revealed that longer-term quiescence in the egg phase reduced the fertility of mosquitoes, especially those harboring the wAlbB Wolbachia strain. This infertility was also associated with a greater biting rate. Here, we attempt to quantify the effect of this heightened biting behavior on the transmission potential of the dengue virus using a combination of assays for fitness, probing behavior, and vector competence, allowing repeat feeding, and incorporate these effects in a model of R0. We show that Wolbachia-infected infertile mosquitoes are more interested in feeding almost immediately after an initial blood meal relative to wild type and Wolbachia-infected fertile mosquitoes and that these differences continue for up to 8 days over the period we measured. As a result, the infertile Wolbachia mosquitoes have higher virus prevalence and loads than Wolbachia-fertile mosquitoes. We saw limited evidence of Wolbachia-mediated blocking in the disseminated tissue (legs) in terms of prevalence but did see reduced viral loads. Using a previously published estimate of the extrinsic incubation period, we demonstrate that the effect of repeat feeding/infertility is insufficient to overcome the effects of Wolbachia-mediated blocking on R0. These estimates are very conservative, however, and we posit that future studies should empirically measure EIP under a repeat feeding model. Our findings echo previous work where periods of extensive egg quiescence affected the reproductive success of Wolbachia-infected Ae. aegypti. Additionally, we show that increased biting behavior in association with this infertility in Wolbachia-infected mosquitoes may drive greater vector competence. These relationships require further exploration, given their ability to affect the success of field releases of Wolbachia for human disease reduction in drier climates where longer egg quiescence periods are expected.
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Affiliation(s)
- Meng-Jia Lau
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Andrés R. Valdez
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Matthew J. Jones
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Igor Aranson
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Biomedical Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Ary A. Hoffmann
- Pest and Environmental Adaptation Research Group, Bio21 Institute and The School of Biosciences, University of Melbourne, Parkville, Victoria, Australia
| | - Elizabeth A. McGraw
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States of America
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Salje H, Jiggins FM. Risks of releasing imperfect Wolbachia strains for arbovirus control. THE LANCET. MICROBE 2024; 5:622-623. [PMID: 38642566 DOI: 10.1016/s2666-5247(24)00072-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 04/22/2024]
Affiliation(s)
- Henrik Salje
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK.
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
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Orozco-Gonzales JL, Dos Santos Benedito A, Cardona-Salgado D, Ferreira CP, de Oliveira Florentino H, Sepulveda-Salcedo LS, Vasilieva O. Comparing the long-term persistence of different Wolbachia strains after the release of bacteria-carrying mosquitoes. Math Biosci 2024; 372:109190. [PMID: 38631561 DOI: 10.1016/j.mbs.2024.109190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 03/18/2024] [Accepted: 04/04/2024] [Indexed: 04/19/2024]
Abstract
This paper proposes a bidimensional modeling framework for Wolbachia invasion, assuming imperfect maternal transmission, incomplete cytoplasmic incompatibility, and direct infection loss due to thermal stress. Our model adapts to various Wolbachia strains and retains all properties of higher-dimensional models. The conditions for the durable coexistence of Wolbachia-carrying and wild mosquitoes are expressed using the model's parameters in a compact closed form. When the Wolbachia bacterium is locally established, the size of the remanent wild population can be assessed by a direct formula derived from the model. The model was tested for four Wolbachia strains undergoing laboratory and field trials to control mosquito-borne diseases: wMel, wMelPop, wAlbB, and wAu. As all these bacterial strains affect the individual fitness of mosquito hosts differently and exhibit different levels of resistance to temperature variations, the model helped to conclude that: (1) the wMel strain spreads faster in wild mosquito populations; (2) the wMelPop exhibits lower resilience but also guarantees the smallest size of the remanent wild population; (3) the wAlbB strain performs better at higher ambient temperatures than others; (4) the wAu strain is not sustainable and cannot persist in the wild mosquito population despite its resistance to high temperatures.
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Hoffmann AA, Ahmad NW, Keong WM, Ling CY, Ahmad NA, Golding N, Tierney N, Jelip J, Putit PW, Mokhtar N, Sandhu SS, Ming LS, Khairuddin K, Denim K, Rosli NM, Shahar H, Omar T, Ridhuan Ghazali MK, Aqmar Mohd Zabari NZ, Abdul Karim MA, Saidin MI, Mohd Nasir MN, Aris T, Sinkins SP. Introduction of Aedes aegypti mosquitoes carrying wAlbB Wolbachia sharply decreases dengue incidence in disease hotspots. iScience 2024; 27:108942. [PMID: 38327789 PMCID: PMC10847733 DOI: 10.1016/j.isci.2024.108942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/22/2023] [Accepted: 01/15/2024] [Indexed: 02/09/2024] Open
Abstract
Partial replacement of resident Aedes aegypti mosquitoes with introduced mosquitoes carrying certain strains of inherited Wolbachia symbionts can result in transmission blocking of dengue and other viruses of public health importance. Wolbachia strain wAlbB is an effective transmission blocker and stable at high temperatures, making it particularly suitable for hot tropical climates. Following trial field releases in Malaysia, releases using wAlbB Ae. aegypti have become operationalized by the Malaysian health authorities. We report here on an average reduction in dengue fever of 62.4% (confidence intervals 50-71%) in 20 releases sites when compared to 76 control sites in high-rise residential areas. Importantly the level of dengue reduction increased with Wolbachia frequency, with 75.8% reduction (61-87%) estimated at 100% Wolbachia frequency. These findings indicate large impacts of wAlbB Wolbachia invasions on dengue fever incidence in an operational setting, with incidence expected to further decrease as wider areas are invaded.
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Affiliation(s)
- Ary A. Hoffmann
- Pest and Environmental Research Group, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Nazni Wasi Ahmad
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Wan Ming Keong
- Vector Borne Disease Control Section, Disease Control Division, Ministry of Health Malaysia, Complex E, Block E10, Persiaran Sultan Sallahuddin Abdul Aziz Shah, Presint 1, Putrajaya 62000, Malaysia
| | - Cheong Yoon Ling
- Biomedical Museum Unit, Special Resource Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Noor Afizah Ahmad
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Nick Golding
- Telethon Kids Institute, Perth Children’s Hospital, Nedlands, WA 6009, Australia
- Curtin School of Population Health, Curtin University, Bentley, WA 6845, Australia
- Melbourne School of Population and Global Health, University of Melbourne, Parkville, VIC 3052, Australia
| | - Nicholas Tierney
- Telethon Kids Institute, Perth Children’s Hospital, Nedlands, WA 6009, Australia
- Curtin School of Population Health, Curtin University, Bentley, WA 6845, Australia
| | - Jenarun Jelip
- Vector Borne Disease Control Section, Disease Control Division, Ministry of Health Malaysia, Complex E, Block E10, Persiaran Sultan Sallahuddin Abdul Aziz Shah, Presint 1, Putrajaya 62000, Malaysia
| | - Perada Wilson Putit
- Vector Borne Disease Control Section, Disease Control Division, Ministry of Health Malaysia, Complex E, Block E10, Persiaran Sultan Sallahuddin Abdul Aziz Shah, Presint 1, Putrajaya 62000, Malaysia
| | - Norhayati Mokhtar
- Vector Borne Disease Control Section, Disease Control Division, Ministry of Health Malaysia, Complex E, Block E10, Persiaran Sultan Sallahuddin Abdul Aziz Shah, Presint 1, Putrajaya 62000, Malaysia
| | - Sukhvinder Singh Sandhu
- Petaling District Health Office, Ministry of Health Malaysia, SS 6, Petaling Jaya 47301, Selangor, Malaysia
| | - Lau Sai Ming
- Petaling District Health Office, Ministry of Health Malaysia, SS 6, Petaling Jaya 47301, Selangor, Malaysia
| | - Khadijah Khairuddin
- Petaling District Health Office, Ministry of Health Malaysia, SS 6, Petaling Jaya 47301, Selangor, Malaysia
| | - Kamilan Denim
- Vector Borne Disease Control Section, Disease Control Division, Ministry of Health Malaysia, Complex E, Block E10, Persiaran Sultan Sallahuddin Abdul Aziz Shah, Presint 1, Putrajaya 62000, Malaysia
| | - Norazman Mohd Rosli
- Health Department of Federal Territory of Kuala Lumpur & Putrajaya, Jalan Cenderasari, Kuala Lumpur 50590, Malaysia
| | - Hanipah Shahar
- Health Department of Federal Territory of Kuala Lumpur & Putrajaya, Jalan Cenderasari, Kuala Lumpur 50590, Malaysia
| | - Topek Omar
- Health Department of Federal Territory of Kuala Lumpur & Putrajaya, Jalan Cenderasari, Kuala Lumpur 50590, Malaysia
| | - Muhammad Kamarul Ridhuan Ghazali
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Nur Zatil Aqmar Mohd Zabari
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Mohd Arif Abdul Karim
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Mohamad Irwan Saidin
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Muhammad Nizam Mohd Nasir
- Medical Entomology Unit, Infectious Disease Research Centre, Institute for Medical Research, Jalan Pahang, Kuala Lumpur 50588, Malaysia
| | - Tahir Aris
- Institute for Medical Research, National Institutes of Health, Ministry of Health Malaysia, Jalan Setia Murni U13/52, Seksyen U13, Shah Alam 40170, Selangor, Malaysia
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Fallon AM. Wolbachia: Advancing into a Second Century. Methods Mol Biol 2024; 2739:1-13. [PMID: 38006542 DOI: 10.1007/978-1-0716-3553-7_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
Wolbachia pipientis had its scientific debut nearly a century ago and has recently emerged as a target for therapeutic treatment of filarial infections and an attractive tool for control of arthropod pests. Wolbachia was known as a biological entity before DNA was recognized as the molecule that carries the genetic information on which life depends, and before arthropods and nematodes were grouped in the Ecdysozoa. Today, some investigators consider Wolbachia the most abundant endosymbiont on earth, given the numbers of its hosts and its diverse mutualistic, commensal, and parasitic roles in their life histories. Recent advances in molecular technologies have revolutionized our understanding of Wolbachia and its associated reproductive phenotypes. New models have emerged for its investigation, and substantial progress has been made towards Wolbachia-based interventions in medicine and agriculture. Here I introduce Wolbachia, with a focus on aspects of its biology that are covered in greater detail in subsequent chapters.
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Affiliation(s)
- Ann M Fallon
- Department of Entomology, University of Minnesota, Saint Paul, MN, USA.
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Zhang M, Xi Z. Wolbachia Transinfection Via Embryonic Microinjection. Methods Mol Biol 2024; 2739:175-188. [PMID: 38006552 DOI: 10.1007/978-1-0716-3553-7_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
The process of transferring Wolbachia from one species to another to establish a stable, maternally inherited infection in the target species is known as transinfection. The success of transinfection is primarily achieved through embryonic microinjection, which is the most direct and efficient means of delivering Wolbachia into the germline of the target species and establishing stable maternal transmission. For the fundamental studies, transinfection is often used to characterize Wolbachia-host interactions, including Wolbachia host range, the role of host or bacterial factors in symbiosis, and evolution of Wolbachia-host associations. For the applied studies, use of transinfection to generate a novel infection in the target species is the first step to build the weapon for both population replacement and population suppression for controlling insect pests or their transmitted diseases. For the primary dengue vector Aedes aegypti and Anopheles vectors of malaria, which either do not naturally carry Wolbachia or are infected with strains that lack necessary features for implementation, transinfection can be established by introducing a novel strain capable of inducing both cytoplasmic incompatibility (CI) and pathogen blocking. For A. albopictus and Culex mosquito species, which naturally harbor CI-inducing Wolbachia, transinfection can be achieved by either introducing a novel strain to generate superinfection or replacing the native infection with a different Wolbachia strain in a symbiont-free line, which is derived from antibiotic treatment of the wild type. Here, we use A. aegypti as an example to describe the Wolbachia transinfection method, which can be adapted to other insect species, such as planthoppers, according to their specific developmental requirements.
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Affiliation(s)
- Meichun Zhang
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Zhiyong Xi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA.
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Weng SC, Masri RA, Akbari OS. Advances and challenges in synthetic biology for mosquito control. Trends Parasitol 2024; 40:75-88. [PMID: 38000957 PMCID: PMC11064511 DOI: 10.1016/j.pt.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/26/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023]
Abstract
Mosquito-borne illnesses represent a significant global health peril, resulting in approximately one million fatalities annually. West Nile, dengue, Zika, and malaria are continuously expanding their global reach, driven by factors that escalate mosquito populations and pathogen transmission. Innovative control measures are imperative to combat these catastrophic ailments. Conventional approaches, such as eliminating breeding sites and using insecticides, have been helpful, but they face challenges such as insecticide resistance and environmental harm. Given the mounting severity of mosquito-borne diseases, there is promise in exploring innovative approaches using synthetic biology to bolster mosquitoes' resistance to pathogens, or even eliminate the mosquito vectors, as a means of control. This review outlines current strategies, future goals, and the importance of gene editing for global health defenses against mosquito-borne diseases.
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Affiliation(s)
- Shih-Che Weng
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Reem A Masri
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Omar S Akbari
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA.
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Zhang H, Trueman E, Hou X, Chew DX, Deng L, Liew J, Chia T, Xi Z, Tan CH, Cai Y. Different mechanisms of X-ray irradiation-induced male and female sterility in Aedes aegypti. BMC Biol 2023; 21:274. [PMID: 38012718 PMCID: PMC10683188 DOI: 10.1186/s12915-023-01757-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 11/02/2023] [Indexed: 11/29/2023] Open
Abstract
BACKGROUND Aedes aegypti (Ae. aegypti) is the major vector that transmits many diseases including dengue, Zika, and filariasis in tropical and subtropical regions. Due to the growing resistance to chemical-based insecticides, biological control methods have become an emerging direction to control mosquito populations. The sterile insect technique (SIT) deploys high doses of ionizing radiation to sterilize male mosquitoes before the release. The Wolbachia-based population suppression method of the incompatible insect technique (IIT) involves the release of Wolbachia-infected males to sterilize uninfected field females. Due to the lack of perfect sex separation tools, a low percentage of female contamination is detected in the male population. To prevent the unintentional release of these Wolbachia-infected females which might result in population replacement, a low dose of X-ray irradiation is deployed to sterilize any female escapees. However, it remains unclear whether these irradiation-induced male and female sterilizations share common mechanisms. RESULTS In this work, we set out to define the minimum dose of X-ray radiation required for complete female sterilization in Ae. aegypti (NEA-EHI strain). Further results showed that this minimum dose of X-ray irradiation for female sterilization significantly reduced male fertility. Similar results have been reported previously in several operational trials. By addressing the underlying causes of the sterility, our results showed that male sterility is likely due to chromosomal damage in the germ cells induced by irradiation. In contrast, female sterility appears to differ and is likely initiated by the elimination of the somatic supporting cells, which results in the blockage of the ovariole maturation. Building upon these findings, we identified the minimum dose of X-ray irradiation on the Wolbachia-infected NEA-EHI (wAlbB-SG) strain, which is currently being used in the IIT-SIT field trial. Compared to the uninfected parental strain, a lower irradiation dose could fully sterilize wAlbB-SG females. This suggests that Wolbachia-carrying mosquitoes are more sensitive to irradiation, consistent with a previous report showing that a lower irradiation dose fully sterilized Wolbachia-infected Ae. aegypti females (Brazil and Mexican strains) compared to those uninfected controls. CONCLUSIONS Our findings thus reveal the distinct mechanisms of ionizing X-ray irradiation-induced male or female sterility in Ae. aegypti mosquitoes, which may help the design of X-ray irradiation-based vector control methods.
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Affiliation(s)
- Heng Zhang
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore
- Present address: Institute of Infectious Disease, Shenzhen Bay Laboratory, Shenzhen, 518000, China
| | - Emma Trueman
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore
| | - Xinjun Hou
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
| | - De Xian Chew
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore
| | - Lu Deng
- Environmental Health Institute, National Environment Agency, Singapore, 138667, Singapore
| | - Jonathan Liew
- Environmental Health Institute, National Environment Agency, Singapore, 138667, Singapore
| | - Tania Chia
- Environmental Health Institute, National Environment Agency, Singapore, 138667, Singapore
| | - Zhiyong Xi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Cheong Huat Tan
- Environmental Health Institute, National Environment Agency, Singapore, 138667, Singapore.
| | - Yu Cai
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore.
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore.
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