Author: Emerson Fuller,
Microbiology scholar, classical literature lover, plant-mom, and aspiring science communicator
Genetically modified spider venom-producing fungus could prevent the spread of Malaria
Malaria is a deadly disease; of the 219 million recorded cases it killed an estimated 435,000 in 2017, 70% of whom are children under five. While this number is down since 2010 with a concentrated effort by groups like Target Malaria, it is an uphill battle. The reported cases have increased in the last few years — up from 217 million in 2015.1
In fact, some Malaria-causing Plasmodium parasites are beginning to show resistance to the drug combination therapies used to treat infected people, and equally worrying, the disease vectors - the females of various Anopheles species of mosquitoes - are growing resistant to the insecticides used on the treated bed-nets that have formed a primary defense against the spread of this disease since their implementation in the 1980s.2
A new solution is desperately needed and a group of researchers in Burkina Faso in West Africa may have hit upon a clever one.
In a closed, near-natural environment that the researchers called the MosquitoSphere, they exposed native insecticide-resistant mosquitoes to their specially engineered version of Metarhizium pingshaense, a fungus and known pathogen of the Malaria-carrying Anopheles mosquitoes. The wild-type fungus has been used to control mosquito populations before but is not lethal or fast-acting enough to prevent the spread of Malaria by infected insects3. So the researchers juiced up a strain of Metarhizium to produce an insect-specific neuro-toxin derived from spider venom4. The toxin activates once it comes in contact with the mosquito’s hemolymph (the insect-version of blood). In 45 days 75% of the mosquitoes inside the MosquitoSpere were infected, and the population collapsed.3
Foolproof, right? Well, maybe. There are still a fair number of hurdles before this method can really get off the ground.
Genetically modified organisms (GMOs) are not a new development in the fight against Malaria. Several experiments in the last five years aim to use the CRISPR gene splicing tool to create gene drives that introduce population-curbing mutations to the malaria-carrying mosquito population. Though the UN’s 2018 Convention on Biological Diversity quietly decided against a moratorium on field releases of gene drive organisms at the 2018 meeting5, the politics remains fraught. Many people, including government officials, anti-GMO lobbyists, and average, everyday citizens, are cautious about making fundamental changes to entire populations of organisms when we have no way to determine the potential fallout. And no way to take it back once the modified organism is out there reproducing.
However, this fungus experiment aims to change the insecticides instead of the insects, and though genetically modified spider venom-producing fungus is straight out of science fiction, there is some precedent for it passing out of the testing phase. Transgenic pest-control methods are already widely used in human-safe food crops (NCBI 2000), and furthermore, this specific toxin is already on the market as an EPA-approved pest-control product (Lovett et al. 2019).
So, while it remains to be seen whether successful initial trials of the fungus among us will be proof enough against the anti-GMO advocates, as well as enough to pass on to the next experimental phase, it certainly looks hopeful.
World Health Organization. (2019). This year's World malaria report at a glance. [online] Available at: https://www.who.int/malaria/media/world-malaria-report-2018/en/
Cdc.gov. (2018). CDC - Malaria - Malaria Worldwide - How Can Malaria Cases and Deaths Be Reduced? - Insecticide-Treated Bed Nets. [online] Available at: https://www.cdc.gov/malaria/malaria_worldwide/reduction/itn.html
Vogel, G. (2019). Fungus with a venom gene could be new mosquito killer. Science, [online] 364(6443), p.817. Available at: https://www.sciencemag.org/news/2019/05/fungus-venom-gene-could-be-new-mosquito-killer
Transgenic Metarhizium rapidly kills mosquitoes in a malaria-endemic region of Burkina Faso
B Lovett, E Bilgo, S Millogo, A Ouattarra, I Sare, E Gnambani, R Dabire, A Diabate, R St. Leger, 2019
Matthews, D. (Dec 7, 2018). Gene drives could end malaria. And they just escaped a UN ban. [online] Vox. Available at: https://www.vox.com/future-perfect/2018/12/7/18126123/gene-drive-malaria-convention-biological-diversity
National Research Council (US) Committee on Genetically Modified Pest-Protected Plants. Genetically Modified Pest-Protected Plants: Science and Regulation. Washington (DC): National Academies Press (US); 2000. Available from: https://www.ncbi.nlm.nih.gov/books/NBK208345/