14 DAY TRIAL // A large, international effort, bringing together scientists from the Walter and Eliza Hall Institute, in Melbourne, Australia, and experts from the United States, Japan and Canada, has recently announced that it completed the first genetically engineered malaria vaccine. The serum contains a weakened version of the pathogen, and the team plans to start human trials as soon as possible. At this point, the experiments are scheduled to begin in early 2010, and the experts rely on a boosted immune system to be able to more efficiently stand up against potential infection.
According to statistics, about one million people all around the globe die every year because of the disease, which permanently disables countless others. It is estimated that about 35 million productive human years are lost annually on account of the infections. Therefore, finding ways to prevent its spread, either by devising a human vaccine, or by developing new methods of keeping mosquitoes away from prospective victims, has become a top priority in research medicine over the years. Mosquitoes are the main source of infection for humans, because the malaria-prone regions are, by definition, infested with the little insects.
The Head of the Infection and Immunity division at the Institute, Professor Alan Cowman, explains that the team managed to remove two key genes in the Plasmodium falciparum parasite, which are widely believed to be responsible for the most deadly form of the disease. The new mutation stops the parasite from moving past its liver-infection stage, and from reaching the bloodstream. When a real-life infection occurs, the pathogen slowly makes its way into the bloodstream, at which point the victim is essentially destined to die.
“Although vaccines are under development that use whole malaria parasites weakened by irradiation to protect against infection, their safety and effectiveness rely on a precise irradiation dose and trial results have been variable. We believe that our genetically attenuated parasite approach provides a safe and reproducible way of developing a whole organism malaria vaccine,” Cowman explains. “In addition, the 'one-two punch' approach of deleting two essential genes make[s] it extremely unlikely that the attenuated parasite vaccine could restore its capacity to multiply and lead to disease.”
“Although two genes have been deleted the parasite is still alive and able to stimulate the body's protective immune system to recognize and destroy incoming mosquito-transmitted deadly parasites,” he adds. Human trials are scheduled at the Walter Reed Army Institute of Research, in Maryland, the US, early next year.