Researchers at the Walter and Eliza Hall Institute of Medical Research, Australia, have found the evasion tactics of the malaria causing parasite Plasmodium falciparum.
James Beeson and colleagues found that Plasmodium falciparum uses various red blood cell invasion mechanisms to evade the human immune response, which eventually causes the disease.
Antibodies that prevent P. falciparum from invading red blood cells (erythrocytes) are believed to be important components of immunity against malaria.
However, the targets of these antibodies have not been well defined and there are a number of P. falciparum proteins that could be candidates because the parasite uses several different mechanisms to enter red blood cells.
Researchers said that determining the targets of the protective antibodies should help in the development of effective vaccines.
In their study, they have determined that malaria-exposed Kenyan kids and adults acquire antibodies that target P. falciparum proteins involved in different red blood cell-invasion mechanisms.
Furthermore, the ability of a given antibody to inhibit P. falciparum invasion of red blood cells depended on the parasite using the invasion mechanism dependent on the protein targeted by that antibody. Detailed analysis identified the targets of the inhibitory antibodies as various EBA and PfRh proteins.
As antibodies that target these proteins were acquired with age, the researchers suggested that P. falciparum might use various red blood cell invasion mechanisms to evade the human immune response and that protective immunity might only be engendered by a repertoire of antibodies recognizing multiple proteins involved in different invasion mechanisms.