Plasmodium falciparum MSP3 Exists in a Complex on the Merozoite Surface and Generates Antibody Response during Natural Infection

Abstract

merozoite surface protein 3 (MSP3) is an abundantly expressed secreted merozoite surface protein and a leading malaria vaccine candidate antigen. However, it is unclear how MSP3 is retained on the surface of merozoites without a glycosylphosphatidylinositol (GPI) anchor or a transmembrane domain. In the present study, we identified an MSP3-associated network on the merozoite surface by immunoprecipitation of merozoite lysate using antibody to the N terminus of MSP3 (anti-MSP3N) followed by mass spectrometry analysis. The results suggested the association of MSP3 with other merozoite surface proteins: MSP1, MSP6, MSP7, RAP2, and SERA5. Protein-protein interaction studies by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) analysis showed that MSP3 complex consists of MSP1, MSP6, and MSP7 proteins. Immunological characterization of MSP3 revealed that MSP3N is strongly recognized by hyperimmune serum from African and Asian populations. Furthermore, we demonstrate that human antibodies, affinity purified against recombinant MSP3N (rMSP3N), promote opsonic phagocytosis of merozoites in cooperation with monocytes. At nonphysiological concentrations, anti-MSP3N antibodies inhibited the growth of Together, the data suggest that MSP3 and especially its N-terminal region containing known B/T cell epitopes are targets of naturally acquired immunity against malaria and also comprise an important candidate for a multisubunit malaria vaccine.

A Random Forest Classifier Uses Antibody Responses to Plasmodium Antigens to Reveal Candidate Biomarkers of the Intensity and Timing of Past Exposure to Plasmodium falciparum

“…Two of the top 30 antigens, Plasmodium exported protein (PHISTc), and serine repeat antigen 4(SERA4) overlap with published markers of exposure from Kobayashi and others (2019) and Helb and others (2015). Additionally, certain proteins have been characterized in other studies related to human antibody response to P. falciparum infection including: clustered-asparagine-rich protein which has been shown to be recognized by human T-cells and antibodies in recently exposed individuals (Wahlgren and others , 1991); merzoite surface protien 3 (MSP3) which has been shown to generate antibody response during natural P. falciparum infection (Deshmukh and others , 2018); erythrocyte binding antigen 175 (EBA175), which has been shown to elicit antibody responses in children that are protective against clinical malaria (Mccarra and others , 2011); and an erythrocyte membrane protein1, PfEMP1 (VAR), which appears as different proteins in the same family among the lists of biomarkers identified by Helb and others (2015) and Kobayashi and others (2019). Aside from these, several proteins in the list of 30 most important antigens for classification (Table 3) could be novel biomarkers of the intensity and timing past exposure to P. falciparum , and considering the list of 65 most important antigens (Table S4) reveals an expanded set of such candidate markers.…”

Sistemas de expresión de proteínas recombinantes para el análisis funcional de antígenos de Plasmodium falciparum y Plasmodium vivax: una revisión

“…Así, el uso de este sistema con cepas modificadas, ha permitido la identificación de asociaciones entre las proteínas de superficie del merozoito de P. falciparum (MSP1, MSP3, MSP6, MSP7) con proteínas asociadas con roptrias (RAP2) y con el antígeno de repeticiones de serina ubicado en micronemas (SERA5), implicadas en el contacto inicial del parásito al eritrocito, resultando ser futuros componentes de vacunas anti-maláricas (55). De esta forma, la obtención del antígeno de unión a eritrocitos EBA-175 de forma recombinante, permitió profundizar en la interacción de alta afinidad con el receptor Glicoforina A en la superficie de eritrocitos y determinar las diferentes rutas de invasión en las que participa este parasito (56).…”

Plasmodium falciparum Blood Stage Antimalarial Vaccines: An Analysis of Ongoing Clinical Trials and New Perspectives Related to Synthetic Vaccines

“…The P. falciparum MSP3, secreted and translocated to a parasite membrane, has ∼43-kDa molecular weight (Deshmukh et al, 2018). An LSP has been chemically synthesized from the 95-aa- long MSP3 fragment in its C-terminal extreme’s conserved region, including the ( 181 RKTKEYAEKAKNAYEKAKNA YQKANQAVLKAKEASS YDYILGWEFGGGVPEHKKEENMLSHLYVSSKDKENISKENDDVLDEKEEEAEETEEEELE 276 ) aa sequence (Audran et al, 2005; Sirima et al, 2007).…”