Editorial: Unravelling the genetic make-up

Published in the Hindu on June 4, 2007

Aedes aegypti
Photo: Wikimedia

The battle to eradicate Aedes aegypti, the mosquito that causes yellow fever, dengue and chikungunya, has got a shot in the arm with the successful sequencing of the mosquito’s genome.  A. aegypti mosquito figures in about 50 million cases of dengue fever in tropical countries and about 30,000 deaths from yellow fever, mainly in West and Central Africa and parts of South America every year.  Chikungunya, a menace in India last year, affected nearly 1.25 million people.  This is the second instance where scientists have been able to sequence a mosquito genome. The genome of Anopheles gambiae, the mosquito that causes malaria, was decoded in 2002.  The success was then two-fold with another team of researchers simultaneously sequencing the malaria parasite, Plasmodium falciparum.  Studying the DNA makeup of A. aegypti and comparing it with A. gambiae allowed the researchers to understand that the dengue causing mosquito diverged evolutionarily from the malaria mosquito about 150 million years ago.  That probably explains the differences in appearance and feeding habits of the two species and the different diseases that they cause although they have the same number of genes.

Sequencing the two mosquito species is important for more than one reason.  While decoding the genome of the malaria-causing mosquito was the first ever attempt to unravel the genetic makeup of a non-human organism that has a direct impact on human lives, the latest success underlines the level of maturity attained in genome sequencing.  At a time when researchers and institutions are focussing on applied research, the sequencing of the two mosquito vector species is a shining example of the importance of basic research in the advancement of science.  Though no successful strategy has been found as yet by researchers to fight the malaria-causing mosquito, sequencing the genome has opened up unprecedented opportunities and brought humanity one step closer to finding one.  The biggest advantage of having the genetic maps of the two vectors, and other mosquito species that are being sequenced, will be the ability to undertake comparative analyses to identify the common and unique genes and understand their functions, and devise new strategies and improve existing ones to tackle specific vectors.  At a time when intellectual property rights are being safeguarded in ways that deny the benefits of scientific research to a wide part of the world, large-scale basic research projects help in bringing together researchers from different institutions across the world for a common cause going beyond purely monetary considerations. The real challenge will be to make any advances in tackling the vectors and fighting the diseases available  to the needy.