Scientists map detailed genome of malaria mosquito vector

Scientists have unveiled the detailed genome of the malaria mosquito vector, revealing thousands of new genes vital for the development of genetic control strategies of disease transmission.

The researchers, including those from Tata Institute for Genetics and Society (TIGS), and Institute of Bioinformatics and Applied Biotechnology, both in Bengaluru, noted that mosquito-transmitted malaria is the leading global killer among vector-borne diseases, claiming over 400,000 human lives in 2019.

In order to engineer advanced forms of defence against malaria transmission, including targeted CRISPR and gene drive-based strategies, scientists require intricate knowledge of the genomes of vector mosquitoes.

CRISPR technology is a gene-editing tool which allows researchers to easily alter DNA sequences and modify gene function.

Mahul Chakraborty, a project scientist at the University of California, Irvine (UCI) in the US and colleagues produced a new reference genome for the Asian malaria vector mosquito Anopheles stephensi.

"“Anopheles stephensi is a major malaria vector mosquito in urban areas of South Asia and has recently invaded the horn of Africa. It is predicted to become a major urban malaria vector in Africa, putting 126 million urban Africans at risk," said professor Ethan Bier, science director for TIGS-UC San Diego.

“The new genome assembly is a comprehensive and accurate map of genomic functional elements and will serve as a foundation for the new age of active genetics in An. stephensi," said Bier, co-author of the research paper published in the journal BMC Biology.

With the newly upgraded Anopheles stephensi genome, the team unearthed more than 3,000 genes that previously evaded scrutiny.

The newly revealed genes, which offer fresh gene-drive targets, play key roles in blood feeding and the metabolism of ingested blood meal, reproduction and immunity against microbial parasites.

"This reference genome and its excellent quality should help malaria biologists in India and the rest of the world, particularly in view of the national goal of malaria elimination in India by 2030," said TIGS Global Director Suresh Subramani, a distinguished professor in the Division of Biological Sciences at UC San Diego.

The discoveries include 29 formerly undetected genes that play crucial roles in resistance to chemical insecticides, a development that can help address the growing Asian and African An. stephensi populations with insecticide-resistant mutations, the researchers said.

The findings also offer clues suggesting that the molecular basis of insecticide resistance may differ between sexes, they said.

"This work will aid in basic studies of genome evolution and inform strategies aimed at eliminating one of the world’s long-time disease scourges," said paper co-author J.J. Emerson, an associate professor at UCI.

"Collectively, these results and resources underscore the significance of previously hidden genomic elements in the biology of malaria mosquitoes and will accelerate development of genetic control strategies of malaria transmission," Emerson added.