Expression And Function Analysis Of Plasmodium Falciparum New Merozoite Protein PF3D7₁361800

Malaria is an obligate intracellular parasite disease caused by Plasmodium, which is still a serious public health problem that can not be ignored. The World Health Organization estimates that nearly half of the world’s population lives in malaria endemic areas. 190-311 million of the global population is infected by malaria annually, resulting in nearly 1,000,000 death, most of them are African children under the age of ?ve. Five Plasmodium species are known to infect humans with Plasmodium falciparum being the most virulent causing the majority of death. Clinical manifestation and mortality in malaria is directly associated with the blood stage of the parasite life cycle.Heparin and heparan sulfate were considered to be candidate drugs which could treat various diseases. Previous studies showed that heparin could inhibit the merozoites to invade erythrocytes, block the attachment between infected and uninfected red blood cells, and also disrupt the formation of rosettes. Although PF3D7₁361800 was a heparin-binding protein that identified by affinity chromatography and high-through-put technology, the study on this protein has not been reported. In this study, we aimed to elucidate the mechanism of PF3D7₁361800 among the invasion process by investigating the transcription, expression, subcellular localization and function of PF3D7₁361800 in Plasmodium falciparum 3D7 clone.Here, the transcription of PF3D7₁361800 gene in the P. falciparum 3D7 clone was performed by q PCR, with the seryl-t RNA synthetase as the internal control. Based on the analysis of water-soluble, we choosed three segments from the hydrophilic region, expressed and purified the recombinant proteins, and then immuned rabbits to obtain the specific antibodies. The expression and subcellular localization of PF3D7₁361800 were analyzed by western blot, indirect immunofluorescence（IFA） and immune electron microscopy. Then, segmented expression of the whole sequence, screening out the peptide which interacted with erythrocyte and heparin, aimed to elucidate the molecular mechanisms of invasion. Finally, we observated its direct invasion inhibition assays and the evaluation of vaccine feasibility.The data of this study indicated that it was transcribed from early after erythrocyte invasion to schizont, with a peak in transcription levels at 40 hours post-invasion. Consistent with it, the expression of PF3D7₁361800 was varied, also the highest of schizont in Plasmodium falciparum 3D7 clone. The result of IFA and immune electron demonstrated that PF3D7₁361800 located on the surface of the merozoite, indicating that it might be a merozoite surface protein. PF3D7₁361800（Arg1622-Val1918）,as a peptide could bind to erythrocyte and heparin specifically, it contributed to understanding the mechanism of PF3D7₁361800 among the invasion process. This protein had certain immunogenicity and could elicit immune responses. Anti-PF3D7₁361800 Ig G could inhibit parasites invasion efficiently, indicating that this protein could be a potential malaria vaccine candidate.