Discovery of Essential Molecules Involved In Severe Malaria

On the surface of infected erythrocytes, P. falciparum induces the expression of RIFINs. Proteins called RIFINs {are encoded by the rif (repetitive interspersed family)} targets on the host inhibitory receptor LILRB1; therefore it facilitates escape from the host immune system by inhibition of the immune response which causes severe malaria. Malaria is infectious disease affecting approximately 300 million individuals every year, representing around 500,000 deaths, however effective vaccine advancement has not been successful. Among malaria parasites infecting humans, Plasmodium falciparum (P. falciparum) causes particularly severe disease. Likewise, acquired immunity to malaria is inefficient, even after repeated exposures to P. falciparum; however the immune regulatory mechanisms utilized by P. falciparum remain to a large extent unclear. Thus, malaria parasites seem to have a mechanism to escape from our immune system.

Fumiji Saito, Kouyuki Hirayasu, Hisashi Arase at Osaka University, his study group found that RIFIN expressed on erythrocytes infected with P. falciparum help the parasite to suppress the host immune response, causing severe malaria. These discoveries are required to add to the development of effective vaccines and therapeutic medications against malaria. Malaria parasites infect predominantly erythrocytes in the host and multiply inside infected erythrocytes. The group found that proteins called RIFIN expressed on P falciparum-infected erythrocytes bind to a host inhibitory receptor LILRB1. Besides, RIFIN suppresses the immune response to malaria, causing severe complications of malaria. This research disclosed without precedent for the world that P. falciparum has another mechanism to suppress the host immune response by utilizing an inhibitory receptor, adding to the pathogenesis of severe malaria. The outcomes of this study expected to greatly add to the development of therapeutic medication and vaccine against malaria.


RIFIN proteins are encoded by the rif (repetitive interspersed family) genes of P. falciparum. There are around 150 rif qualities for each parasite genome. But their functions have been as yet unclear.


One of the immune inhibitory receptors that suppress the initiation of immune cells and prevent autoimmune system responses by recognizing self- molecules like major histocompatibility complex (MHC) class I. Human cytomegalovirus is additionally known to have a viral MHC class I-like molecule (UL18) that suppresses the immune response by means of LILRB1 for immune escape.


Please enter your comment!
Please enter your name here

5 × three =