A VACCINE that targets the malaria parasite at a vulnerable point in its development could form part of a strategy to eradicate the disease.
Unlike other vaccines in the pipeline, which are designed to protect individuals who have been bitten, this one aims to sabotage the life cycle of the malaria parasite, Plasmodium, by stopping it from passing back from humans to mosquitoes.
While preventing this transmission wouldn鈥檛 help an infected individual directly, it would benefit the population as a whole, says the study鈥檚 lead author of Johns Hopkins Malaria Research Institute in Baltimore, Maryland. 鈥淚f you are living in a village and the mosquito that bites you gets infected from you, it can transmit the malaria parasite to other people in the village,鈥� he says.
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To create the vaccine, Kumar鈥檚 group used genetically modified bacteria to make proteins identical to some of those involved in the parasite鈥檚 sexual development. They injected the proteins into mice and baboons, which generated antibodies. When the team added Plasmodium gametes to blood samples from these animals, the antibodies bound to and blocked the proteins. If a mosquito sucked up some of this blood it would still get a bellyful of the gametes, but they would be unable to combine and spawn new adult parasites.
One shot of the vaccine led to a 93 per cent reduction in malaria transmission, and the figure went up to 98 per cent after a booster shot ().
鈥淥ne shot of the vaccine led to a 93 per cent reduction in malaria transmission鈥�
This could be used alongside another vaccine being developed by GlaxoSmithKline, called RTS,S/AS02A, which blocks Plasmodium transmission from mosquitoes to humans. By attacking the parasite鈥檚 life cycle at two points, it may even be possible to wipe out malaria. 鈥淚f this vaccine is as promising in clinical trials as it has been in this study, then it may prove to be an important part of an integrated disease-control strategy aimed at eradicating Plasmodium,鈥� says of Pennsylvania State University in University Park, who works on the ecology of infectious diseases.
Kumar admits that getting the vaccine approved will be a long process, but hopes that human trials can start by 2012. Vaccine approval is a priority as existing methods of controlling the disease are under threat. In May, researchers reported that some Plasmodium strains in Cambodia are developing resistance to our best antimalarial drug, artemisinin, while mosquitoes are becoming resistant to pesticides.
Economics may prove the biggest obstacle to any eradication strategy. It is not clear who would pay for a vaccine that does not protect individuals 鈥� although a by the World 午夜福利1000集合 Organization says that this type of vaccine could be one of the most cost-effective ways to fight the disease in the world鈥檚 poorest countries.
