These Anopheles mosquitoes have been genetically modified using CRISPR-Cas9 “genetic scissors” so that they can no longer transmit the parasite responsible for malaria to humans.
- It is now possible to create genetically modified mosquitoes that can no longer transmit malaria to humans.
- Thanks to CRISPR-Cas9 genetic scissors, scientists succeeded in changing the section of DNA in the mosquito that made malaria transmissible.
- According to the WHO, malaria was responsible for 228 million infections and 405,000 deaths in 2018.
Maybe tomorrow, mosquitoes will no longer transmit malaria. In any case, this is what researchers from the University of California at Irvine (United States) are working on. Using CRISPR-Cas9 genetic scissors, they hope to modify the chromosomes of malaria-causing mosquitoes to prevent them from transmitting the parasite. The results were published on November 3, 2020 in NatureCommunications.
A serious public health problem in the affected areas
Malaria, also called malaria, is an infectious disease which is transmitted by the intermediary of a mosquito, the anopheles mosquito, of which only females are vectors. The main parasites responsible for this disease, the Plasmodium falciparum and Plasmodium vivax, need mosquitoes to breed. Once in the human bloodstream, the parasite explodes red blood cells. This disease occurs in tropical regions with high humidity. The regions most affected by malaria are sub-Saharan Africa and the Indian subcontinent. According to figures from the World Health Organization (WHO)malaria infected 228 million people worldwide in 2018 and killed 405,000.
Faced with a major public health problem, Adriana Adolfi, postdoctoral researcher at the University of California at Irvine and lead author of the study, decided to find a solution to stop the transmission of the parasite in humans. For this, she and her team decided to use the CRISPR-Cas9 tool, in order to make it impossible for the parasites to be transmitted from female Anopheles to humans. CRISPR-Cas9 is what is known as a genetic scissor, capable of “cutting” a piece of DNA to replace it with another sequence. By modifying the DNA of Anopheles females, it will at the same time increase the chances that their offspring will be unable to carry out parasitic transmission.
“The second-generation gene drive system described in this article can be applied to any of the thousands of genes that are essential for insect survival or reproduction.says Ethan Bier, professor at the University of California at San Diego and co-author of the study. Although developed in fruit flies, this system is readily transportable to a wide selection of insect species that serve as vectors for devastating disorders such as Chagas disease, sleeping sickness, leishmaniasis and arboviral diseases”.
A mosquito that has become harmless to humans
The researchers are not at their first attempt, since he had already carried out a first experiment in 2015 on the anopheles stephensi, the mosquito responsible for malaria in the Indian subcontinent. In their early trials, the gene block was passed on to offspring in 99% of cases when the modification was done on the male, but only 60-70% when it was done on the female. Since then, the teams have managed to solve the problem in the female.
The new mosquitoes thus produced can continue to reproduce while carrying with them the total impossibility of transmitting the parasites which inhabit them. In addition, the system put in place to change their gene having been perfected, genetic errors have become almost non-existent. However, extensive trials are needed before the team does any field testing.
.