A semi field trial test on efficacy of transgenic antimalarial biocontrol fungi

描述（由申请人提供）：世界上大约46%的人口生活在蚊媒疾病（包括疟疾、丝虫病、病毒性脑炎、登革热和黄热病）流行的地区。最近确定，昆虫病原真菌绿僵菌具有在城市环境中控制成蚊的潜力，但如果其效力增加，效果会更好。利用两年R21资助的资源，我们比较了感染转基因绿僵菌菌株的蚊子的死亡率和疟疾子孢子的患病率，这些转基因绿僵菌菌株表达不同的杀虫蛋白和抗疟原虫蛋白的组合。使用绿僵菌传递节肢动物毒素减少了杀死时间，并使有效孢子剂量减少了150倍。我们假设，在田间条件下，这将大大增加获得致命感染的蚊子的百分比和生物农药的有效持久性。在这项应用中，我们建议与蚊子控制专家Abdoulaye Diabates及其在Center Muraz的同事密切合作，这将使我们能够评估转基因绿僵菌在布基纳法索疟疾媒介冈比亚按蚊密度非常高的地区的潜力（高达200叮咬/人/夜）和恶性疟原虫子孢子率约3%。在世界范围内，转基因生物（转基因生物）项目都要经过一个审查过程，其中包括在封闭的近自然环境中进行半实地研究，作为开放实地释放的先决条件。已从布基纳法索科学研究和创新部获得许可证，以建造和使用一个疟疾球体，该球体将包括实验小屋（模仿传统住房）、供成人使用的糖源（植物）和创造的繁殖场所（塑料容器），封闭在一个温室框架内，有蚊帐墙，使其暴露在环境气候条件下，模拟自然蚊子栖息地。为了确定修饰真菌的潜在价值，我们将使用球体来评估设计表达节肢动物毒素的病原体与对昆虫具有野生型毒力但表达抗疟疾蛋白的菌株相比所带来的功效、存活率和环境风险，所述抗疟疾蛋白可将蚊子中的寄生虫负担降低98%。我们的数据将支持可能的试验的预测数学建模，从而为设计未来的试验提供合理性。这些研究将1）开发工具并测试有可能大大降低疟疾流行率的基因工程真菌; 2）提供证据，为政策提供信息，并吸引捐助者资助开放现场释放，以测试流行病学和临床影响，和3）使发展中国家的科学家能够直接参与评估转基因微生物在未来疾病中的潜在用途和应用控制

DESCRIPTION (provided by applicant): Around 46% of the Worlds population lives in areas where mosquito-borne diseases including malaria, filariasis, viral encephalitides, dengue and yellow fever are endemic. It was recently established that the insect pathogenic fungus Metarhizium has the potential to control adult mosquitoes in an urban setting, but would work much better if its potency is increased. Using the resources of a two year R21 grant we compared mortality and malaria sporozoite prevalence in mosquitoes infected with transgenic Metarhizium strains expressing different combinations of insecticidal and anti-plasmodial proteins. Using Metarhizium to deliver arthropod toxins reduced the time it took to kill and produced a 150-fold reduction in effective spore doses. We hypothesize that under field conditions this will greatly increase the % of mosquitoes picking up a lethal infection and the effective persistence of the biopesticide. In this application, we propose a close collaboration with mosquito control expert Abdoulaye Diabates and his colleagues at Center Muraz that will enable us to evaluate the potential of transgenic Metarhizium in an area of Burkina Faso with very high densities of the malaria vector Anopheles gambiae (up to 200 bites/person/night) and Plasmodium falciparum sporozoite rates around 3%. Worldwide, GMO (genetically manipulated organisms) projects go through a review process that includes semi-field studies in a contained near-natural environment as a prerequisite for an open field release. A permit has been obtained from the Burkina Faso Ministry of Scientific Research and Innovation to build and use a malaria sphere that will consist of experimental huts (mimicking traditional housing), sugar sources (plants) for adults and created breeding sites (plastic containers), enclosed in a greenhouse frame with walls of mosquito netting to allow exposure to ambient climate conditions and simulate a natural mosquito habitat. To establish the potential value of modified fungi we will use the sphere to assess the efficacy, survivability, and environmental risk posed by pathogens engineered to express arthropod toxins in comparison with a strain with wild type virulence to insects but expressing ant-malarial proteins that reduce the parasite burden in mosquitoes by 98%. Our data will support predictive mathematical modeling of possible trials and hence provide a rational for designing future trials. These studies will 1) develop tools and test genetically engineered fungi that have the potential to greatly reduce malaria prevalence; 2) generate evidence to inform policy and attract donor funding for an open field release which will test epidemiological and clinical impact, and 3) enable scientists from a developing country to become directly involved in evaluating the potential use and application of transgenic microbes for future disease control.