Malaria Vaccine Shows Promise

In animal studies, a new vaccine that targets the toxin instead of the malaria parasite may be a more effective and longer lasting anti-malarial vaccine than those currently available. The study was published in the August 21, 2002, issue of Nature.

Louis Schofield, Ph.D., co-leader of the study, recently discovered that, as part of its life cycle inside its human host, the malaria parasite releases an inflammatory toxin that appears to trigger the fever, convulsions, and deaths associated with malaria. Dr. Schofield and Dr. Peter H. Seeberger, also a co-leader, designed a synthetic version and attached it to a protein molecule in the hope that the complex would be large enough for the body to recognize and mount an immune response.

When a group of unvaccinated mice was injected with blood containing the malaria parasite, all died. When the toxin was injected into a group of healthy mice and they were then injected with the parasite, 65-95% survived. Dr. Schoenfield is associated with the Walter & Eliza Hall Institute of Medical Research (Melbourne, Australia; www.wehi.edu.au). Dr. Seeberger is associate professor of chemistry at the Massachusetts Institute of Technology (Cambridge, USA; www.mit.edu).

One or two shots of the vaccine are expected to provide lasting protection against the disease. If necessary, its effectiveness could be enhanced by using it in combination with other vaccines that target the malarial parasite. Although other vaccines have been developed and tested against malaria, none lasts for more than a few weeks. Most of these target proteins on the surface of the parasite, which has the ability to change its surface proteins and resist the vaccine.

"We hope that this is the answer, but we don't know yet,” said Dr. Seeberger.




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