Zap mosquitoes from the inside

Mosquitoes are not a problem during summer barbecues. In many parts of the world, they carry pathogens for Zika, dengue fever, yellow fever and the most devastating disease transmitted by mosquitoes, malaria. According to the Centers for Disease Control and Prevention, 440,000 people died of malaria in sub-Saharan Africa in 2016, as a result of the bite of an infected female Anopheles mosquito. Malaria causes severe chills, high fever, heavy sweating, and other flu-like symptoms. If untreated, it can lead to death. The protection of US military personnel who continue to serve in this part of the world is essential.

The Armed Forces Pest Management Council of the Ministry of Defense has developed a variety of repellent personal protection systems for deployed military personnel: uniforms treated with permethrin, application of insect repellents such as DEET and Picaridin, mosquito nets impregnated with permethrin and prescribed antimalarial drugs. They also oversee the research program on the protection of deployed combatants that is studying ways to mitigate various threats of insects to military personnel.

Although control measures for chemical mosquito populations have been used with some success, they are toxic to other insect populations and to human health. A different defense angle has emerged, namely the genetic modification of the mosquito itself, making it transgenic. Transgenic mosquitoes are unable to transmit a pathogen, such as malaria, because of their altered genetic makeup.

The concept of transgenic mosquitoes has existed since the 1980s, although the first laboratory laboratory was not developed before 1997, according to Dr. Marcelo Ramalho-Ortigao, Associate Professor of Preventive Medicine in the Department of Preventive Medicine and Biostatistics uniformed services. University of Bethesda, Maryland. Two methods are currently used to control mosquito-borne diseases with transgenic mosquitoes. One is the replacement of the population using a concept known as "gene drive" to spread anti-pathogen genes. The other is a population suppression strategy that reduces the number of mosquitoes that can transmit the pathogen.

Until now, the idea of ​​using transgenic mosquitoes to fight malaria has only been tested in the laboratory. However, a successful genetic modification of a particular mosquito species, Aedes aegypti – known to spread Zika virus, dengue fever, yellow fever and chikungunya – has been tested in the laboratory and in the field by Oxitec, a Kingdom-based company. -United.

"This area of ​​study and research has changed dramatically since the discovery and advent of gene modification technology called CRISPR-Cas9, as the speed and number of genes that can be targeted have increased." ", Said Ramalho-Ortigao. Field tests of modified mosquitoes using CRISPR technology are still in the research and development phase.

Because of the ethical ramifications of editing genes to alter mosquitoes or other species, this concept has always been controversial, Ramalho-Ortigao said. "Controversy and discussions about applications, and in particular ways of dealing with adverse effects, are essential for scientific progress, especially for transgenic technologies." Government regulation by the Food and Drug Administration and the United States. Environmental Protection Agency is a way to ensure that studies do not deviate from their scientific goals, he added.

In addition to potentially being a new tool for mosquito-borne disease control, "insect transgenic studies also provide essential training for the next generation of scientists who may be involved in cutting-edge research and possibly apply the techniques they learned using mosquitoes. other insects as a model for higher organisms, "Ramalho-Ortigao explained. He pointed out that insects "share many common features with vertebrates with respect to gene expression, their ability to develop an immune response to invasions of microorganisms and viruses, and certain behavioral traits." Scientists will therefore be able to apply the knowledge gained on insects to "higher organisms in evolutionary scale, including vertebrates," he said.

Although humans can not forget mosquitoes if they are eradicated, our ecosystem would do it. "Mosquitoes play an important role as pollinators," Ramalho-Ortigao said. "They are also a source of food for other insects, spiders, frogs, lizards and birds." He added that not all mosquitoes transmit disease and that only females feed on blood. In fact, out of nearly 3,000 known mosquito species, only a fraction of them transmit diseases. Complete elimination could result in the expansion of other species or an increase in the population of a species currently present in smaller areas. numbers – creating a whole new bug problem.