New vaccine fights malaria in unique way - by trapping it in blood cells


Malaria, a potentially fatal disease that is commonly transmitted by the bite of an infected Anopheles mosquito, is attributed to over 600,000 deaths worldwide in 2012. The mortality rate of the disease and the number of individuals affected by malaria, however, may go down with a newly developed vaccine that works like the immune system cells found in children who are naturally resistant to malaria.

Malaria is caused by a parasite that invades the red blood cells. Researchers who are working on a vaccine for malaria have discovered that children who are resistant to the disease have antibodies that trap the malaria parasites inside the infected red blood cells so they do not spread and cause more serious illness.

For their study which was published in the journal Science on May 23, Jonathan Kurtis, from the Center for International Health Research at Rhode Island Hospital in Providence, and colleagues studied blood samples collected from children in Tanzania who had been sick with malaria or appeared to be resistant to the disease.

They found that the children who were protected from malaria had antibodies that fight the malaria parasite antigen known as PfSEA-1. The PfSEA-1 is allows the malaria parasite to exit from the infected red blood cells and spread but the antibodies found in the malaria-resistant children trap the parasites in the red blood cells and thus inhibit the progression of the disease.

The researchers then developed a vaccine that target the PfSEA-1 and tested it on mice. In five trials, they found that the mice that were given the vaccine and exposed to malaria had 4 times lower parasite levels than the mice that were not vaccinated. The vaccinated also survived twice longer.

By examining blood samples from over 100 individuals from Kenya, Kurtis and his colleagues also found that those with detectable levels of the antibodies to PfSEA-1 had 50 percent less parasites compared to individuals who do not have the antibodies.

"Tanzanian children with antibodies to recombinant PfSEA-1A (rPfSEA-1A) did not experience severe malaria, and Kenyan adolescents and adults with antibodies to rPfSEA-1A had significantly lower parasite densities than individuals without these antibodies," Kurtis and colleagues reported.

The researchers said that the experimental vaccine will be tested on monkeys within the next four to six and if all goes well, the vaccine will be tested on a small group of people.

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