Genetically Modified Mosquitos in the Fight Against Malaria
05.07.2021
Research led by the University of Padua Department Director of Molecular Medicine, Prof Andrea Crisanti and an international team from Imperial College London, North Carolina State University, University of Würzburg, and Keele University discovers how to transmit genes that fully block the transmission of malaria from mosquitoes.
Findings from the study of genetically controlled mosquitoes carrying the disease entitled, A genetically encoded anti-CRISPR protein constrains gene drive spread and prevents population suppression, was published in Nature Communications.
Malaria kills nearly 400,000 people in Africa every year, thus far control strategies such as mosquito nets, insecticides, drugs, and vaccines have worked only satisfactorily in the economically challenged countries most affected. Researchers have devised strategies promoting the spread of genes useful for blocking the transmission of malaria by causing sterility in Anopheles gambiae mosquitoes or by causing an imbalance between the sexes to reset reproduction rates in a few months.
Prof Crisanti explains, “The Mendelian mechanisms regulating heredity represent serious limitations. When a modified mosquito mates with a wild type, their combined inherited genetic modification is limited to half of its offspring, thus, only diluting the population. However, if the gene of interest is driven by a genetic drive, or by an element capable of self-propagating, the desired characteristic is passed to all its offspring. The most effective method to do this is the copy-paste method performed by CRISPR / Cas9, as the gene drives become a perpetual genome correction machine that follows generation after generation. However, hopes to control the process or stop it all together have focused on anti-CRISPR agent proteins used as a type of preventive set of genetic scissors.
Located inside a high-level biosafety laboratory, Crisanti and his team demonstrate that their work on gene drives could lead to the collapse of an experimental mosquito population. Recently adding a new piece to their work by proving that once the process is set in motion it can be interrupted and is reversible. This process would enable the presence of an anti-drive to be activated in the drive itself, making the anti-CRISPR protein AcrIIA4 native to the bacterium Listeria monocytogenes. When the technology is ready to move from closed laboratory environments to the real world, any experimental release into the environment must take place using careful risks and benefits analysis under the consent of local communities.
