Traditional measures to prevent the spread of malaria have traditionally focused on transmission, the human-mosquito interaction represented essentially by the insect bite. They generally involve the use of a mosquito net and insecticides and repellents and a few other measures generally suggested to travelers, along with the practice of necessary vaccinations, in Travel Medicine Clinics. Those who apply them are protected and together with drug prophylaxis therefore retain their effectiveness against malaria and other diseases and are advisable. They do, however, have one flaw. They do not stop the transmission of the disease in others who have not applied them; the mosquito still continues to carry Plasmodi.
What if we could modify the mosquito so that it does not transmit malaria?
What if we could vaccinate the mosquito?
This is the logic behind so-called "gene drives": a technique that by implanting specific genetic traits releases genetically modified and essentially harmless mosquitoes into the environment.
The technology that allows us to modify the DNA of mosquitoes is the CRISPR/Cas9 system. It is a natural defense mechanism that some bacteria resort to, to defend themselves against viruses. CRISPR/Cas9 is an enzyme that acts like a pair of molecular scissors, capable of cutting sections of DNA.
At the time of reproduction, it copies and pastes the specific section into each chromosomal variant, ensuring its inheritance. "Gene drive" takes advantage of this technology and applies it to the spread of genetic modifications in mosquito populations.
This technique can install resistance genes in plants: for example, against insecticides or herbicides. They can be used to control invasive species or to prevent vector-borne diseases--such as dengue, zika or precisely as in our case malaria--by controlling the insect population.
In the context of malaria, genetic units could help drastically reduce disease transmission by targeting the Anopheles mosquito, the type of mosquito that transmits malaria. There are two ways to achieve this goal. By "vaccinating" the mosquito to increase resistance to the malaria parasite or by inhibiting its reproductive capacity.
In 2015, researchers at the University of California used gene-editing technology to vaccinate a population of Anopheles stephensi mosquitoes, the main malaria vector in India. They inserted a resistance gene to Plasmodium falciparum, the most prevalent malaria parasite. Determining the absence of the parasite in the insects and the impossibility of transmission.
More recently, researchers at Imperial College London have been thinking about inhibiting the mosquito's reproductive capabilities. They targeted a gene called doublesex, which determines the development of gender traits (male or female) in Anopheles gambiae, the main malaria vector in Africa. Their genetic modification rendered female mosquitoes infertile, but did not affect males, which could continue to transmit this genetic modification for generations.
https://blog.fightmalaria.co.uk/hot-topics/gene-drives-can-we-vaccinate-mosquitoes/
