Seeking “a cheap and effective way to eliminate malaria from entire regions,” a team at Imperial College London’s Department of Life Sciences have modified mosquitos to produce sperm that creates 95 percent male offspring, leading to hopes that Malaria–which still kills 627,000 people per year, according to World Health Organization estimates–will be completely eradicated.

The report, “A synthetic sex ratio distortion system for the control of the human malaria mosquito,” was published in Nature Communications Tuesday. The report represents six years of research.

The Imperial College team tested their proceedure in five labratory cages. Genetically modified mosquitoes were introduced into the cages already inhabited by regular mosquito populations. In four of the five cages, all mosquitoes were eliminated within six generations due to lack of females.

“What is most promising about our results is that they are self-sustaining,” said lead researcher Dr. Nikolai Windbichler. “Once modified mosquitoes are introduced, males will start to produce mainly sons, and their sons will do the same, so essentially the mosquitoes carry out the work for us.”

The process of genetic modification used involves inserting a DNA cutting enzyme called l-Ppol into the mosquitoes. The enzyme cuts the DNA of the X chromosome during sperm production. Therefore, during mating, almost no X chromosomes exist to pass on, so offspring usually bear the XY pair, and are born female.

The Imperial College team explain the process this way: “We combine structure-based protein engineering and molecular genetics to restrict the activity of the potentially toxic endonuclease to spermatogenesis. Shredding of the paternal X chromosome prevents it from being transmitted to the next generation, resulting in fully fertile mosquito strains that produce [greater than] 95% male offspring.”

The idea put in practice by the Imperial College team is not new, but experiments in the area were previously hampered by lack of knowledge of the genetic makeup and mode of action of naturally occurring sex distorters and the incidence of co-evolving suppressors.

Nature Communications

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The IHR Emergency Committee of the World Health Organization met last week on the “extraordinary” international spread of wild polioviruses in 2014, and voted unanimously on measures to stem the resurgence of endemic and internationally exported polioviruses, which were thought to have been nearly eradicated in 2013.

In the informational session of the meeting, affected States Parties presented information on developments in their nations, including Afghanistan, Cameroon, Equatorial Guinea, Ethiopia, Israel, Nigeria, Pakistan, Somalia and the Syrian Arab Republic, after which the Committee called the public health risk to thus-far unaffected States an “extraordinary event” and warned that a coordinated international response was essential.

Wild poliovirus was nearly stopped through the transmission season between January to April, 2012, but eradication of the disease may fail if the current situation continues. During 2013, most wild poliovirus cases were spread internationally, and in 2014–during the low transmission season–the virus has already spread from three of the 10 infected States–from Pakistan to Afghanistan, Syria to Iraq, and Cameroon to Equatorial Guinea. These three States pose the highest risk of further exportations as well.

Polio is one of the world’s most serious vaccine-preventable diseases. Prevention measures focus largely on oral vaccination and routine immunization. The Committee called for the three highest-risk States to vaccinate all residents and visitors prior to international travel. The Committee encouraged the eight non-exporting States to take similar measures.

The high transmission season for wild poliovirus–between May and June–has already started, and unilateral measures called for at by Committee face the challenge posed by compromised immunization services and high re-infection risks in polio-free but conflict-torn States.

The Committee was requested to reassess the situation in three months.

Source:

WHO

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