No idle chatter: Study finds malaria parasites ‘talk’ to each other – It Changes everything

Contact: Liz Williams williams@wehi.edu.au 61-405-279-095 Walter and Eliza Hall Institute

Melbourne scientists have made the surprise discovery that malaria parasites can ‘talk’ to each other – a social behaviour to ensure the parasite’s survival and improve its chances of being transmitted to other humans.

The finding could provide a niche for developing antimalarial drugs and vaccines that prevent or treat the disease by cutting these communication networks.

Professor Alan Cowman, Dr Neta Regev-Rudzki, Dr Danny Wilson and colleagues from the Walter and Eliza Hall Institute in collaboration with Professor Andrew Hill from the University of Melbourne’s Bio21 Institute and Department of Biochemistry and Molecular Biology showed that malaria parasites are able to send out messages to communicate with other malaria parasites in the body. The study was published today in the journal Cell.

Professor Cowman said the researchers were shocked to discover that malaria parasites work in unison to enhance ‘activation’ into sexually mature forms that can be picked up by mosquitoes, which are the carriers of this deadly disease.

“When Neta showed me the data, I was absolutely amazed, I couldn’t believe it,” Professor Cowman said. “We repeated the experiments many times in many different ways before I really started to believe that these parasites were signalling to each other and communicating. But we came to appreciate why the malaria parasite really needs this mechanism – it needs to know how many other parasites are in the human to sense when is the right time to activate into sexual forms that give it the best chance of being transmitted back to the mosquito.”

Malaria kills about 700,000 people a year, mostly children aged under five and pregnant women. Every year, hundreds of millions of people are infected with the malaria parasite, Plasmodium, which is transmitted through mosquito bites. It is estimated that half the world’s population is at risk of contracting malaria, with the disease being concentrated in tropical and subtropical regions including many of Australia’s near neighbours.

Dr Regev-Rudzki said the malaria parasites inside red blood cells communicate by sending packages of DNA to each other during the blood stage of infection. “We showed that the parasites inside infected red blood cells can send little packets of information from one parasite to another, particularly in response to stress,” she said.

The communication network is a social behaviour that has evolved to signal when the parasites should complete their lifecycle and be transmitted back to a mosquito, Dr Regev-Rudzki said. “Once they receive this information, they change their fate – the signals tell the parasites to become sexual forms, which are the forms of the malaria parasite that can live and replicate in the mosquito, ensuring the parasites survives and is transmitted to another human.”

Professor Cowman said he hopes to see the discovery pave the way to new antimalarial drugs or vaccines for preventing malaria. “This discovery has fundamentally changed our view of the malaria parasite and is a big step in understanding how the malaria parasite survives and is transmitted,” he said. “The next step is to identify the molecules involved in this signalling process, and ways that we could block these communication networks to block the transmission of malaria from the human to the mosquito. That would be the ultimate goal.”

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This project was supported by the National Health and Medical Research Council of Australia, Howard Hughes Medical Research Institute and the Victorian Government.

Scores at risk as new breed of mosquito foils malaria prevention methods: There is NO KNOWN DNA match

Published: 16 September, 2012, 21:14

Annual deaths could jump by the hundreds of thousands because of a new species of mosquito, which bites people in the early evening rather than at night, making bed nets useless in the battle against malaria.

The new strain of mosquito, which was discovered in the highlands of western Kenya by scientists from the London School of Hygiene and Tropical Medicine, feeds while people are outside in the early evening, according to a Sunday report by the Independent.

Malaria is already one of the world’s top killers, with nearly one million people a year dying from the disease.

And if not for mosquito nets that number would be much higher, as nets prevent the insects from biting at night, when the female anopheles mosquito sucks blood as part of its egg-production cycle. As many as one million people are thought to have dodged death by sleeping under mosquito nets covered with insecticide over the last 12 years.

Even more distressing is that scientists have as yet been unable to match the DNA of the new species to that of any existing variety.

Jennifer Stevenson, a scientist in the London School research group, told the Independent, “We observed that many mosquitos we caught – including those infected with malaria – did not physically resemble other known malaria mosquitoes.”

Stevenson, whose team set up outdoor and indoor traps to catch the species, added, “the main difference that came through from this study is that we caught 70 per cent of these species A – which is what we named them because we don’t know exactly what they are – outdoors before 10:30pm, which is the time when people in the village usually go indoors.”

Jo Lines, a colleague of Stevenson and a former co-coordinator for the World Health Organization’s global malaria program, also said, “we do not yet know what these unidentified specimens are, or whether they are acting as vectors [transmitters] on a wider scale, but in the study area they are clearly playing a major and previously unsuspected role.”

Scientists are now calling for wider controls to deal with the outdoor transmission of the disease.

Andrew Griffiths, from the children’s charity World Vision, said the findings are a setback in the fight against the disease. “It’s concerning because bed nets are one of the important tools in combating malaria and we’ve seen deaths go down dramatically. It would mean that one of the important parts in the response to malaria would be taken away. We have to be talking about protecting yourself at different times of the day and put even more focus on the community and other systems,” he said.

In a separate development, scientists in the UK and the US are developing genetically-modified mosquitos, which could prove effective in the battle against mosquito borne-diseases like malaria

http://rt.com/news/health-malaria-mosquito-africa-270/

Pheromone from the summer cypress Killed Mosquitoes (West Nile virus) in trials Everytime

*Reposted at Request, data known since 1999….  The government will not justify the expense in regards to human life and the environment…Engineering Evil

Contact: Claire Bowles claire.bowles@rbi.co.uk 44-171-331-2751 New Scientist

A burning bush could smite New York’s mosquitoes

An ornamental bush prized by gardeners in Europe and the US contains a surprise weapon against the mosquitoes spreading West Nile virus, the brain disease that has broken out in New York (p 13). The bush might also provide a cheap way for the world’s poorest countries to fight filariasis, a disfiguring parasitic disease that affects 15 million people in Africa alone.

Oil from the summer cypress, better known as the burning bush because it blushes a deep red in autumn, contains a substance which, when converted into a pheromone, can be used to lure mosquitoes to their deaths.

New Yorkers could have used this trick to combat the mosquitoes spreading the West Nile virus. The virus attacks the central nervous system and 3 of the 12 people with the illness have already died. Another 102 suspectedcases are being investigated. New York health officials are fighting the outbreak by killing mosquitoes with conventional sprays of the powerful insecticides malathion and pyrethroid.

Burning bush oil might have provided a more benign solution. Researchers from Britain and Nigeria have turned oil from the plant’s seeds into a pheromone. This biological messenger, which is odourless to humans, could lure female mosquitoes away from the places where people live.

A team from the Rothamsted site of the Institute of Arable Crops Research in Harpenden, Hertfordshire, struck lucky when team leader John Pickett noticed that the burning bush makes a fatty acid strikingly similar to the pheromone that attracts the mosquitoes (Journal of Agricultural Food Chemistry, vol 47, p 3411).

The pheromone is produced naturally when rafts of eggs are laid in stagnant water by Culex quinquefasciatus, the mosquito species which spreads filariasis and is suspected of spreading West Nile virus. “It’s a cue for female mosquitoes, telling them that there’s a safe place where they can lay their eggs,” says Mike Birkett, a member of the Rothamsted team.

The pheromone from the burning bush could have been used in New York to lure mosquitoes to their death in drums of water laced with pesticide, says Birkett. Pickett is confident that the pheromone attracts females of all Culex species.

The team at Rothamsted has tested synthetic versions of the same pheromone, called (5R,6S)-6-acetoxy-5-hexadecanolide. “It’s been tested in field trials in Africa, Japan and the US, and it works every time,” says Birkett. The problem is that the synthetic version is too expensive to manufacture. So instead, the team screened plants for substances which could be turned into the pheromone much more cheaply.

It doesn’t need to be purified from the oil, making it cheap and easy to handle. When Jenny Mordue of the University of Aberdeen tested the oil-based pheromone in the laboratory, she found that it attracted female mosquitoes as powerfully as the natural substance.

###Author: Andy Coghlan

Issue 2nd October 99

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