title: The Plasmodium vivax merozoite surface protein 1 paralog is a novel erythrocyte-binding ligand of P. vivax.
abstract: Merozoite surface protein 1 of Plasmodium vivax (PvMSP1), a glycosylphosphatidylinositol-anchored protein (GPI-AP), is a malaria vaccine candidate for P. vivax. The paralog of PvMSP1, named P. vivax merozoite surface protein 1 paralog (PvMSP1P; PlasmoDB PVX_099975), was recently identified and predicted as a GPI-AP. The similarities in genetic structural characteristics between PvMSP1 and PvMSP1P (e.g., size of open reading frames, two epidermal growth factor-like domains, and GPI anchor motif in the C terminus) led us to study this protein. In the present study, different regions of the PvMSP1P protein, demarcated based on the processed forms of PvMSP1, were expressed successfully as recombinant proteins [i.e., 83 (A, B, and C), 30, 38, 42, 33, and 19 fragments]. We studied the naturally acquired immune response against each fragment of recombinant PvMSP1P and the potential ability of each fragment to bind erythrocytes. The N-terminal fragment (83A) and two C-terminal fragments (33 and 19) reacted strongly with sera from P. vivax-infected patients, with 50 to 68% sensitivity and 95 to 96% specificity, respectively. Due to colocalization of PvMSP1P with PvMSP1, we supposed that PvMSP1P plays a similar role as PvMSP1 during erythrocyte invasion. An in vitro cytoadherence assay showed that PvMSP1P, especially the 19-kDa C-terminal region, could bind to erythrocytes. We also found that human sera from populations naturally exposed to vivax malaria and antisera obtained by immunization using the recombinant molecule PvMSP1P-19 inhibited in vitro binding of human erythrocytes to PvMSP1P-19. These results provide further evidence that the PvMSP1P might be an essential parasite adhesion molecule in the P. vivax merozoite and is a potential vaccine candidate against P. vivax.
authors: Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea.
authors: Yang
authors: Y
authors: Cheng
authors: Yue
authors: Y
authors: Wang
authors: Daisuke
authors: D
authors: Ito
authors: Deok-Hoon
authors: DH
authors: Kong
authors: Kwon-Soo
authors: KS
authors: Ha
authors: Jun-Hu
authors: JH
authors: Chen
authors: Feng
authors: F
authors: Lu
authors: Jian
authors: J
authors: Li
authors: Bo
authors: B
authors: Wang
authors: Eizo
authors: E
authors: Takashima
authors: Jetsumon
authors: J
authors: Sattabongkot
authors: Takafumi
authors: T
authors: Tsuboi
authors: Eun-Taek
authors: ET
authors: Han
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology*; D005260:Female; D005455:Fluorescent Antibody Technique; D006790:Host-Parasite Interactions; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D017780:Malaria Vaccines / Q000276:immunology; D016780:Malaria, Vivax / Q000276:immunology*; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D010966:Plasmodium vivax / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D017780:Malaria Vaccines; D020066:Merozoite Surface Protein 1; D011994:Recombinant Proteins