A new study by team of Scandinavian scientists has revealed how blood group O protects against malaria and suggests that the selective pressure imposed by malaria may contribute to the variable global distribution of ABO blood groups in the human population.
Previous studies have shown that people with blood type O are protected against severe malaria, while those with other types, such as A, often fall into a coma and die. Scientists led from Karolinska Institutet in Sweden have now identified the key part played by the RIFIN protein.
Using data from different kinds of experiment on cell cultures and animals, the scientists have shown how the Plasmodium falciparum parasite secretes RIFIN, and how the protein makes its way to the surface of the blood cell, where it acts like glue. The research team also demonstrates how it bonds strongly with the surface of type A blood cells, but only weakly to type O.
Principal investigator Mats Wahlgren said, "The finding is conceptually simple. However, since RIFIN is found in many different variants, it has taken us a lot of time to isolate exactly which variant is responsible for this mechanism. Our study ties together previous findings, and we can explain the mechanism behind the protection that blood group O provides against severe malaria, which can, in turn, explain why the blood type is so common in the areas where malaria is common. In Nigeria, for instance, more than half of the population belongs to blood group O, which protects against malaria."
The study is published in Nature Medicine.