Qld scientists breakthrough in battle against insect-transmitted diseases

Scientists at the University of Queensland have made a discovery which could lead to a breakthrough in the battle against insect-transmitted diseases.

The researchers have found a certain type of the bacteria Wolbachia, protects flies from dying from viruses - using a bacterial infection to ward off an infection from a deadly virus is a surprising discovery.

Dr Karyn Johnson, an insect virologist, and her colleagues from UQ's School of Integrative Biology, say when flies were infected with deadly viruses, the flies that also had an infection of Wolbachia bacterium lived significantly longer than those without the bacterial infection - this is the first time such an interaction has been found and is the opposite of what would be expected.

The team carried out a study using Wolbachia infected vinegar flies and injected them with a virus that is fatal to the insects - they say a bacterial infection would be expected to make the fly more susceptible to other pathogens, but they found that the Wolbachia protected the insects.

Dr Johnson says the interaction is particularly interesting as Wolbachia is very common in insects and if this type of interaction is wide-spread there could be significant implications for the way viruses are maintained in insect populations.

Dr Johnson says the potential impact of this research on the transmission of insect borne disease is exciting and the next stage of the research will be to find how the bacteria protects the flies from the virus.

She says they will initially be looking at whether this effect extends to different insects, and whether it works on different viruses, but long term, if the mechanism can be understood and then harnessed, it might offer a new range of control strategies for insect-transmitted diseases.

The researchers say Wolbachia bacteria are found in about 20% of insect species and are best known for their ability to increase their prevalence in populations by manipulating the host reproductive systems but there are Wolbachia that exist in nature that seem to induce no reproductive parasitism trait and yet are able to invade populations.

They say flies infected with Wolbachia are less susceptible to death induced by a range of RNA viruses and they believe the antiviral protection associated with Wolbachia infection might be exploited in future strategies to reduce transmission of pathogens by insects.

The study was published in the scientific journal Science on 30 October 2008.