Researchers have tested genetically modifying mosquitos to express antimalarial genes and pass them on to offspring as a new strategy to eliminate malaria.
Despite decades worth of research and efforts, data from 2015 onwards suggests that there has been no significant progress in reducing global malaria cases. Every year, around 400,00 people die from malaria, with over 90% of cases being within sub-Saharan Africa. The rise of mosquito resistance to pesticides as well as malaria parasite resistance to antimalarial drugs has emphasised the urgent need for the development of new tools to fight this disease.
One approach that researchers are exploring is the use of gene drives. A gene drive is a genetic modification that can spread through a population at higher inheritance rates than normal. In this context, researchers can genetically modify mosquitos that, when released into the environment, would spread genes to either reduce mosquito populations or make them less likely to spread the malaria parasite. Due to concerns regarding the safety of gene drives, it is vital that researchers prove that this approach is safe and effective before releasing the modified mosquitos into the wild. There are currently no clear pathways for safely testing these tools within endemic countries.
Eliminating malaria with gene drives
In this study, published in eLife, researchers genetically modified the malaria-transmitting mosquito Anopheles gambiae. The team showed that minimal genetic modifications of endogenous genes could create non-autonomous gene drives without disrupting gene expression. They also harnessed CRISPR-Cas9 technology to insert a gene that encodes an antimalarial protein. The team did this in a manner to ensure that the gene drive could be passed on to the mosquitos’ offspring.
The team bred the mosquitos to see whether they could successfully reproduce and remain healthy. They also explored how well the malaria parasite developed in the guts of the mosquitos. Overall, their experiments provided preliminary evidence showing that experts can use this approach to develop successful gene drives.
Nikolai Windbichler, senior author, stated:
“These genetic modifications are passive and could be tested in the field and undergo a stringent regulatory process to ensure they are safe and effective in blocking the parasite without raising concerns of accidental spread in the environment.
However, once we combine them with other mosquitoes with an active gene drive, they turn into gene drives themselves without the need for any further changes. Our approach thus brings gene drives one step closer to being tested in the field as a malaria elimination strategy.”
Image credit: By jcomp – freepik