Mankind is a giant step closer to putting the clamps on two very old and formidable diseases–yellow fever and dengue fever.

The international effort to sequence the genome of the Aedes aegypti mosquito initiated and lead by University of Notre Dame Professor of Biological Science David W. Severson has finished its work.

The announcement was made in an online journal, Science Express, on Thursday, May 17, and revealed that the mosquito’s genome of 1.3 billion base pairs was five times larger than that of Anopheles gambiae, the primary mosquito that transmits malaria. The genome of Anopheles gambiae was sequenced in 2002 in a similar collaboration led by Frank Collins, director of the Center for Global Health and Infectious Diseases.

According to the paper, what made Aedes aegypti’s genome so different than Anopheles gambiae’s was the surprisingly large number of transposable elements, or pieces of repetitive DNA sequences, cluttered throughout its genome. Transpositional elements make up 47% of Aedes aegypti’s genome.

These transposable elements accumulated in the 150 million years since Aedes aegypti radiated from its parental Aedes and Anopheles lineages. “Both the reasons for the difference in genome size and their effect on the organism are unclear,” Severson said. It's a matter for further research and discovery. "We don't really have a good answer,'' he said.

Aedes aegypti is responsible for 50 million cases of dengue fever a year. Although rarely fatal, dengue’s nickname - “break bone fever” – attests to the acute suffering it causes its victims sometimes lasting for many weeks.

About 2.5 billion people who live in the tropics are at risk for dengue fever. Yellow fever strikes 200,000 people a year, and the yearly death toll is about 30,000 people, mainly in Africa and South America.    

The sequencing of the mosquito’s genomic code means that researchers will be able to zero in on the specific mechanisms by which it transmits viruses.

Knowing this could lead to more effective control measures, either through the development of better insecticides or through genetic modification.

The genome library will be kept at VectorBase, a centralized database and resource center at Notre Dame and funded by contracts from the United States National Institutes of Health's National Institute of Allergy and Infectious Diseases (NIAID).