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Sunday, October 16, 2011

Dengue fever under attack through smart mosquito control

Posted: 25 August 2011

The dengue virus is primarily transmitted by Aedes mosquitoes
PARIS - Scientists say they've found on a new way of controlling dengue fever by weakening populations of mosquitoes carrying the virus which causes the deadly disease.

"The results show we can completely transform local (mosquito) populations in a few months," said Michael Turelli, a biologist at the University of California at Davis. "It's natural selection on steroids."

Dengue which affects between 50 and 100 million people in the tropics and subtropics each year, is caused by four strains of virus that are spread by the mosquito Aedes aegypti.

There is no vaccine, which is why scientists are focussing so intensely on mosquito control.

In 2009, Turelli and others hit on the idea of inserting a naturally-occurring bacterial parasite called Wolbachia to shorten the mosquito's lifespan so that the virus would not have enough time to develop.

After initial setbacks, the team of scientists found a non-virulent strain of Wolbachia in the fruitfly Drosphila.

Introduced into the mosquito, the germ prevented the insect from becoming infected by the dengue virus.

At the same time, the Wolbachia which is a symbiotic bacterium, it was also harmless to the mosquito as it exists by living in harmony with its host.

As it lives inside cells and is maternally inherited, this raises the possibility that after a few generations, the introduced dengue-free mosquitoes eventually outnumber dengue-carrying counterparts.

After long consultations with the government and regulators, the scientists released Wolbachia-infected mosquitoes in two locations in Queensland, Australia, this year.

Early results suggest that the introduced mosquitoes have thrived, and "herald the beginning of a new era in the control of mosquito-borne diseases," said Jason Rasgon, a specialist at the Johns Hopkins Malaria Research Institute, Maryland, in a commentary also carried by Nature.

"The advantage of population-replacement approaches is that, once established, they are self-propagating. And because the mosquito population is simply changed rather than eliminated, effects on the ecosystem should be minimal."

The paper appears in Nature, the weekly British science journal.

- AFP/sf

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Dengue fever under attack through smart mosquito control

NTU scientists achieve bacterium breakthrough

Posted: 25 August 2011

A German health official testing for the pathogenic agent in the virulent E. coli bacteria (EHEC) (AFP Photo/Caroline Seidel)
SINGAPORE: Scientists from Nanyang Technological University (NTU) have for the first time re-engineered a common bacterium to seek out and kill other dangerous bacteria, to target a superbug which is naturally resistant to a wide range of antibiotics.

The breakthrough could change the way medical treatment is currently done in hospitals, as it targets only harmful bacteria, unlike the existing broad-spectrum antibiotics which kill both good and bad bacteria.

In a media release on Wednesday, NTU said its scientists were able to modify a harmless strain of Escherichia coli - also known as E. coli - found naturally in the human digestive system, to target a superbug which causes infections such as upper respiratory tract infection, gastrointestinal tract infection and urinary tract infection.

The biochemically engineered E. coli, upon detection of the other bacterium, will generate "killing molecules", and then self-destruct to release these molecules to kill the superbug, while remaining harmless to the human body.

The results have generated interest in the biomedical industry, which is looking for ways to combat infection - one of the world's leading causes of death, said NTU.

The researchers, Assistant Professor Matthew Chang and Assistant Professor Poh Chueh Loo from NTU's School of Chemical and Biomedical Engineering, said the idea for the project came about after they observed that bacteria secrete toxins to kill other bacteria in their bid for survival under adverse competition.

They plan to refine the efficiency of the killing molecules and to find other possible targets, and expect to soon move into animal trials. - TODAY

Taken from; source article is below:
NTU scientists achieve bacterium breakthrough