Thursday, April 2, 2015

New way to block dengue transmission using bacteria modeled on computer

Researchers working on a way to block dengue transmission using the insect bacterium Wolbachia to infect mosquitoes, have also produced a computer model that predicts how effective the method might be in different scenarios.

Describing their work in the journal Science Translational
Medicine, the international team hopes it will lead to better
ways to tackle the spread of dengue, a mosquito-borne virus
that is a leading cause of illness and death in the tropics and subtropics.

As many as 400 million people are infected with dengue every
year. The virus - which spreads among humans via Aedes aegypti mosquitoes - causes flu-like symptoms, including intense headache and joint pains.

Wolbachia bacteria reside naturally in around 60% of insect species and are probably the most prevalent infectious bacteria on Earth. They live inside the cells of insects - and are passed to the next generation through the host's eggs.

For many years, scientists have been studying Wolbachia, to see if they can use it to control the mosquitoes that spread
human diseases.

So far, this research has found A. aegypti mosquitoes stably
infected with strains of Wolbachia are resistant to dengue virus infection and field trials are currently being done to find out how effective this is.

'Real world' results primed model of Wolbachia effectiveness in reducing dengue spread

In this new study, the researchers carried out a "real world" experiment where they allowed mosquitoes infected with
Wolbachia and uninfected mosquitoes to feed on the blood of Vietnamese dengue patients.

They measured how efficiently the bacterium blocked dengue
virus infection of the mosquito body and saliva, which in turn
steps stops them spreading the virus among humans.

The team then developed a computer-based model of dengue virus transmission and primed it with the results of the experiment to predict how well the use of Wolbachia might reduce the intensity of dengue transmission in various scenarios.

Senior author Cameron Simmons, professor in the microbiology and immunology department at the University of Melbourne in Australia, describes the results: "We found that Wolbachia could eliminate dengue transmission in locations where the intensity of transmission is low or moderate. In high transmission settings, Wolbachia would also cause a significant reduction in transmission."

Model should help make 'informed decisions' about use of Wolbachia in dengue control

Prof. Simmons says their findings are important because they give realistic projections of how effective Wolbachia might be in blocking dengue virus transmission.

For example, he says that based on the study results, the recent
introduction of Wolbachia in Cairns and Townsville should
reduce the severity of future outbreaks of dengue. During the
wet season of 2008-09, Australia saw the worst dengue epidemic in over 50 years in these two cities.

Prof. Simmons, who is also of the Peter Doherty Institute for
Infection and Immunity in Melbourne, says: In December 2014, Medical News Today reported another study that Prof. Simmons co-authored about the discovery of a new class of antibody that could lead to the development of a universal vaccine against dengue. The antibody can neutralize all four types of dengue virus when it is produced from human or mosquito cells. The hope is that the discovery will also improve laboratory tests for dengue.