Immune evasion by <i>Plasmodium falciparum</i> parasites: converting a host protection mechanism for the parasite′s benefit

Abstract

Immune evasion is a strategy used by pathogenic microbes to evade the host immune system in order to ensure successful propagation. Immune evasion is particularly important for the blood stages of Plasmodium falciparum, the causative agent of the deadly disease malaria tropica. Because Plasmodium blood stage parasites require human erythrocytes for replication, their ability to evade attack by the human immune system is essential for parasite survival. In order to escape immunity-induced killing, the intraerythrocytic parasites have evolved a variety of evasion mechanisms, including expansion of plasmodial surface proteins, organ-specific sequestration of the infected red blood cells and acquisition of immune-regulatory proteins by the parasite. This review aims to highlight recent advances in the molecular understanding of the immune evasion strategies by P. falciparum, including antigenic variation, surface protein polymorphisms and invasion ligand diversification. The review will further discuss new findings on the regulatory mechanisms applied by P. falciparum to avoid lysis by the human complement as well as killing by immune factors of the mosquito vector.