Scientists uncover potential vaccine candidate

Researchers have discovered an antibody-generating protein that could help prevent multiplication of malaria parasites inside the body, giving new hope for a vaccine, a study said on May 22. The protein could aid scientists in their work fighting the most severe forms of malaria, a disease that kills more than 600,000 people each year, particularly young children in sub-Saharan Africa.
Named PfSEA-1, the protein, whose presence spurs the body's formation of antibodies, was linked to a reduced level of parasites in a number of children and adults in regions of Africa where malaria is endemic, according to the study published in the US journal Science.
Mice exposed to the protein in an experimental vaccine showed decreased levels of parasites in their blood.
The discovery of the protein could add to a limited pool of antigens used in potential malaria vaccines, said scientists who conducted the study at the National Institute of Allergy and Infectious Diseases.
The antibodies generated by the protein halt the malaria parasite as it leaves one red blood cell to invade the other, preventing it from multiplying.
Populations living in areas where malaria is common often develop natural immune responses that limit the number of parasites in the blood and prevent high fever and severe symptoms.
Researchers based their study on blood samples from two-year-old Tanzanian children who were either resistant or susceptible to malaria.
After performing genetic analysis and a series of laboratory tests, the researchers identified PfSEA-1 and confirmed that it stopped infection by malaria parasites after they had entered red blood cells.
The scientists then vaccinated five groups of mice with the protein and found that it lowered parasite levels and allowed the mice to survive longer than those who weren't vaccinated.
In addition, the researchers measured the level of antibodies in plasma samples from 453 Tanzanian children and found no cases of serious malaria where a detectable level of PfSEA-1 antibodies was present in the blood.
The researchers also analysed plasma samples from 138 males age 12 to 35 living in high-malaria areas in Kenya and found that those with detectable traces of the antibody had parasite levels 50 percent lower compared with those without the antibodies.