Blockade of Plasmodium falciparum erythrocyte invasion: New assessment of anti-Plasmodium falciparum reticulocyte-binding protein homolog 5 antibodies

There is great interest in any new discoveries in malaria vaccine research. Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) shows promise in this area and may be used together with other merozoite antigens as a potential vaccine. In the present study, a bioinformatics prediction approach was applied to a PfRH5 B-cell epitope, and two B-cell epitope distributions were selected. Antibodies against the two PfRH5 distributions were obtained and the growth activity inhibition was measured. No inhibition of the P. falciparum CY strain was found, but the growth of the P. falciparum 3D7 strain was inhibited by all of the antibodies, in contrast to the results of other studies. It was additionally found that certain quantities of protein led to the inhibition of the parasitic invasion. Equally noteworthy was that the survival time of the group immunized with a portion of PfRH5 was significantly longer than that of the group immunized with the full-length protein, following infection by P. berghei ANKA. The present study produced conflicting results in in vitro and in vivo experiments, although the accuracy of the evaluation may be lessened due to the use of a murine malaria model. The findings of the present study may indicate that PfRH5 may not be suitable in malaria vaccine research.