Merozoite Surface Protein 1 from Plasmodium falciparum Is a Major Target of Opsonizing Antibodies in Individuals with Acquired Immunity against Malaria

ABSTRACT Naturally acquired immunity against malaria is largely mediated by serum antibodies controlling levels of blood-stage parasites. A limited understanding of the antigenic targets and functional mechanisms of protective antibodies has hampered the development of efficient malaria vaccines. Besides directly inhibiting the growth of Plasmodium parasites, antibodies can opsonize merozoites and recruit immune effector cells such as monocytes and neutrophils. Antibodies against the vaccine candidate merozoite surface protein 1 (MSP-1) are acquired during natural infections and have been associated with protection against malaria in several epidemiological studies. Here we analyzed serum antibodies from semi-immune individuals from Burkina Faso for their potential (i) to directly inhibit the growth of P. falciparum blood stages in vitro and (ii) to opsonize merozoites and to induce the antibody-dependent respiratory burst (ADRB) activity of neutrophils. While a few sera that directly inhibited the growth of P. falciparum blood stages were identified, immunoglobulin G (IgG) from all individuals clearly mediated the activation of neutrophils. The level of neutrophil activation correlated with levels of antibodies to MSP-1, and affinity-purified MSP-1-specific antibodies elicited ADRB activity. Furthermore, immunization of nonhuman primates with recombinant full-size MSP-1 induced antibodies that efficiently opsonized P. falciparum merozoites. Reversing the function by preincubation with recombinant antigens allowed us to quantify the contribution of MSP-1 to the antiparasitic effect of serum antibodies. Our data suggest that MSP-1, especially the partially conserved subunit MSP-183, is a major target of opsonizing antibodies acquired during natural exposure to malaria. Induction of opsonizing antibodies might be a crucial effector mechanism for MSP-1-based malaria vaccines.

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Peripheral Merozoite Surface Proteins Are Targets of Naturally Acquired Immunity against Malaria in both India and Ghana

Infection and Immunity ◽

10.1128/iai.00778-19 ◽

2020 ◽

Vol 88 (4) ◽

Cited By ~ 1

Author(s):

Asier Garcia-Senosiain ◽

Ikhlaq Hussain Kana ◽

Susheel Kumar Singh ◽

Bishwanath Kumar Chourasia ◽

Manoj Kumar Das ◽

...

Keyword(s):

Protein Complexes ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Epidemiological Studies ◽

Surface Proteins ◽

Acquired Immunity ◽

Lasso Regression ◽

Content Type ◽

The Individual ◽

Antigenic Targets

ABSTRACT Development of a successful blood-stage vaccine against Plasmodium falciparum malaria remains a high priority. Immune-epidemiological studies are effective tools for the identification of antigenic targets of naturally acquired immunity (NAI) against malaria. However, differences in study design and methodology may compromise interstudy comparisons. Here, we assessed antibody responses against intact merozoites and a panel of 24 recombinant merozoite antigens in longitudinal cohort studies of Ghanaian (n = 115) and Indian (n = 121) populations using the same reagents and statistical methods. Anti-merozoite antibodies were associated with NAI in both the Indian (hazard ratio [HR] = 0.41, P = 0.020) and the Ghanaian (HR = 0.17, P < 0.001) participants. Of the 24 antigen-specific antibodies quantified, 12 and 8 were found to be protective in India and Ghana, respectively. Using least absolute shrinkage and selection operator (LASSO) regression, a powerful variable subselection technique, we identified subsets of four (MSP6, MSP3.7, MSPDBL2, and Pf12) and five (cMSP33D7, MSP3.3, MSPDBL1, GLURP-R2, and RALP-1) antigens that explained NAI better than the individual antibodies in India (HR = 0.18, P < 0.001) and Ghana (HR = 0.31, P < 0.001), respectively. IgG1 and/or IgG3 subclasses against five antigens from these subsets were associated with protection. Through this comparative study, maintaining uniformity of reagents and methodology, we demonstrate that NAI across diverse geographic regions may result from antibodies to multiple antigenic targets that constitute the peripheral merozoite surface protein complexes.

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The Plasmodium vivax Merozoite Surface Protein 1 Paralog Is a Novel Erythrocyte-Binding Ligand of P. vivax

Infection and Immunity ◽

10.1128/iai.01117-12 ◽

2013 ◽

Vol 81 (5) ◽

pp. 1585-1595 ◽

Cited By ~ 33

Author(s):

Yang Cheng ◽

Yue Wang ◽

Daisuke Ito ◽

Deok-Hoon Kong ◽

Kwon-Soo Ha ◽

...

Keyword(s):

Plasmodium Vivax ◽

Vaccine Candidate ◽

Structural Characteristics ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Open Reading Frames ◽

Content Type ◽

Merozoite Surface Protein 1 ◽

Human Sera

ABSTRACTMerozoite surface protein 1 ofPlasmodium vivax(PvMSP1), a glycosylphosphatidylinositol-anchored protein (GPI-AP), is a malaria vaccine candidate forP. vivax. The paralog of PvMSP1, namedP. vivaxmerozoite 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 fromP. 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. Anin vitrocytoadherence 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 inhibitedin vitrobinding of human erythrocytes to PvMSP1P-19. These results provide further evidence that the PvMSP1P might be an essential parasite adhesion molecule in theP. vivaxmerozoite and is a potential vaccine candidate againstP. vivax.

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Merozoite Surface Protein 1 of Plasmodium vivax Induces a Protective Response against Plasmodium cynomolgi Challenge in Rhesus Monkeys

Infection and Immunity ◽

10.1128/iai.73.9.5936-5944.2005 ◽

2005 ◽

Vol 73 (9) ◽

pp. 5936-5944 ◽

Cited By ~ 35

Author(s):

Sheetij Dutta ◽

Deep C. Kaushal ◽

Lisa A. Ware ◽

Sunil K. Puri ◽

Nuzhat A. Kaushal ◽

...

Keyword(s):

Plasmodium Vivax ◽

Protective Efficacy ◽

High Titer ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Control Group ◽

Merozoite Surface Protein 1 ◽

Significant Difference ◽

Peak Parasitemia

ABSTRACT The 42-kDa fragment of the merozoite surface protein 1 (MSP-142) is a leading candidate for the development of a vaccine to control malaria. We previously reported a method for the production of Plasmodium vivax MSP-142 (PvMSP-142) as a soluble protein (S. Dutta, L. W. Ware, A. Barbosa, C. F. Ockenhouse, and D. E. Lanar, Infect. Immun. 69:5464-5470, 2001). We report here a process to manufacture the same PvMSP-142 protein but as an insoluble inclusion body-derived protein which was then refolded in vitro. We compared the immunogenicity and protective efficacy of the soluble and refolded forms of PvMSP-142 protein by using a heterologous but closely related P. cynomolgi-rhesus monkey challenge model. As comparative controls we also expressed, purified, and immunized rhesus with the soluble and refolded forms of the P. cynomolgi MSP-142 (PcMSP-142) proteins. All proteins induced equally high-titer, cross-reacting antibodies. Upon challenge with P. cynomolgi, none of the MSP-142-vaccinated groups demonstrated sterile protection or a delay in the prepatent period. However, following an initial rise in parasitemia, all MSP-1-vaccinated animals had significantly lower parasite burdens as indicated by lower cumulative parasitemia, lower peak parasitemia, lower secondary peak parasitemia, and lower average daily parasitemia compared to the adjuvant control group (P < 0.05). Except the soluble PcMSP-142 group, monkeys in all other groups had fewer numbers of days with parasitemia of >10,000 parasites mm−3. Interestingly, there was no significant difference in the level of partial protection observed in the homologous and heterologous groups in this challenge model. The soluble and refolded forms of PcMSP-142 and PvMSP-142 proteins also appeared to have a similar partially protective effect.

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The carboxy-terminus of merozoite surface protein 1: structure, specific antibodies and immunity to malaria

Parasitology ◽

10.1017/s0031182009990515 ◽

2009 ◽

Vol 136 (12) ◽

pp. 1445-1456 ◽

Cited By ~ 87

Author(s):

A. A. HOLDER

Keyword(s):

Protective Immunity ◽

First Generation ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Carboxy Terminus ◽

Vaccine Candidates ◽

Merozoite Surface Protein 1 ◽

Early Results ◽

Experimental Approaches

SUMMARYOver the last 30 years, evidence has been gathered suggesting that merozoite surface protein 1 (MSP1) is a target of protective immunity against malaria. In a variety of experimental approaches usingin vitromethodology, animal models and sero-epidemiological techniques, the importance of antibody against MSP1 has been established but we are still finding out what are the mechanisms involved. Now that clinical trials of MSP1 vaccines are underway and the early results have been disappointing, it is increasingly clear that we need to know more about the mechanisms of immunity, because a better understanding will highlight the limitations of our current assays and identify the improvements required. Understanding the structure of MSP1 will help us design and engineer better antigens that are more effective than the first generation of vaccine candidates. This review is focused on the carboxy-terminus of MSP1.

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Plasmodium falciparum Merozoite Surface Protein 1 (MSP-1)-MSP-3 Chimeric Protein: Immunogenicity Determined with Human-Compatible Adjuvants and Induction of Protective Immune Response

Infection and Immunity ◽

10.1128/iai.00427-09 ◽

2009 ◽

Vol 78 (2) ◽

pp. 872-883 ◽

Cited By ~ 19

Author(s):

Suman Mazumdar ◽

Paushali Mukherjee ◽

Syed Shams Yazdani ◽

S. K. Jain ◽

Asif Mohmmed ◽

...

Keyword(s):

Immune Response ◽

Plasmodium Falciparum ◽

Fusion Protein ◽

Malaria Vaccine ◽

Chimeric Protein ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Protective Immune Response ◽

Merozoite Surface Protein 1

ABSTRACT A chimeric gene, MSP-Fu24 , was constructed by genetically coupling immunodominant, conserved regions of the two leading malaria vaccine candidates, Plasmodium falciparum merozoite surface protein 1 (C-terminal 19-kDa region [PfMSP-119]) and merozoite surface protein 3 (11-kDa conserved region [PfMSP-311]). The recombinant MSP-Fu24 protein was produced in Escherichia coli cells and purified to homogeneity by a two-step purification process with a yield of ∼30 mg/liter. Analyses of conformational properties of MSP-Fu24 using PfMSP-119-specific monoclonal antibody showed that the conformational epitopes of PfMSP-119 that may be critical for the generation of the antiparasitic immune response remained intact in the fusion protein. Recombinant MSP-Fu24 was highly immunogenic in mice and in rabbits when formulated with two different human-compatible adjuvants and induced an immune response against both PfMSP-119 and PfMSP-311. Purified anti-MSP-Fu24 antibodies showed invasion inhibition of P. falciparum 3D7 and FCR parasites, and this effect was found to be dependent on antibodies specific for the PfMSP-119 component. The protective potential of MSP-Fu24 was demonstrated by in vitro parasite growth inhibition using an antibody-dependent cell inhibition (ADCI) assay with anti-MSP-Fu24 antibodies. Overall, the antiparasitic activity was mediated by a combination of growth-inhibitory antibodies generated by both the PfMSP-119 and PfMSP-311 components of the MSP-Fu24 protein. The antiparasitic activities elicited by anti-MSP-Fu24 antibodies were comparable to those elicited by antibodies generated with immunization with a physical mixture of two component antigens, PfMSP-119 and PfMSP-311. The fusion protein induces a protective immune response with human-compatible adjuvants and may form a part of a multicomponent malaria vaccine.

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Diversity Covering AMA1-MSP119Fusion Proteins as Malaria Vaccines

Infection and Immunity ◽

10.1128/iai.01267-12 ◽

2013 ◽

Vol 81 (5) ◽

pp. 1479-1490 ◽

Cited By ~ 31

Author(s):

Bart W. Faber ◽

Sumera Younis ◽

Edmond J. Remarque ◽

Roberto Rodriguez Garcia ◽

Vanessa Riasat ◽

...

Keyword(s):

Growth Inhibition ◽

Fusion Proteins ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Immunological Study ◽

Growth Inhibition Assay ◽

Content Type ◽

Apical Membrane Antigen 1 ◽

Malaria Vaccines ◽

Order Of Magnitude

ABSTRACTTo overcome polymorphism in the malaria vaccine candidatePlasmodium falciparumapical membrane antigen 1 (PfAMA1), fusion protein chimeras comprised of three diversity-covering (DiCo) PfAMA1 molecules (D1, D2, and D3) and two allelic variants of the C-terminal 19-kDa region of merozoite surface protein 1 (MSP119) (variants M1 and M2) were generated. A mixture of fusion proteins (D1M1/D2M2D3) and the D1M1D2M2D3 fusion were compared to a single-unit mixture (D1/D2/D3/M1) in an immunological study in groups of rabbits. Following immunization, titers of antibodies (Abs) against four naturally occurring PfAMA1 alleles were high for all groups, as were growth inhibition assay (GIA) levels against two antigenically distinct laboratory parasite strains. Fusion of AMA1 to MSP119did not suppress levels of antibodies against the AMA1 component. In addition, the breadth of antibody responses was unaffected. Anti-AMA1 antibodies were largely responsible for parasite growth inhibition, as shown in reversal-of-inhibition experiments by adding competing AMA1 antigen. For all groups, titration of the MSP119antigen into the GIA led to only a small decrease in parasite inhibition, although titers of antibodies against MSP119were increased 15-fold for the groups immunized with fusion proteins. GIA with affinity-purified anti-MSP119antibodies showed that the 50% inhibitory concentrations of the anti-MSP119antibody preparations were in the same order of magnitude for all animals tested, leading to the conclusion that fusing MSP119to PfAMA1 leads to a small but significant increase in functional antibody levels. This study shows that combination of multiple vaccine candidates in fusion proteins may lead to improved characteristics of the vaccine.

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Novel antimalarial antibodies highlight the importance of the antibody Fc region in mediating protection

Blood ◽

10.1182/blood-2003-02-0583 ◽

2003 ◽

Vol 102 (13) ◽

pp. 4424-4430 ◽

Cited By ~ 30

Author(s):

Richard J. Pleass ◽

Solabomi A. Ogun ◽

David H. McGuinness ◽

Jan G. J. van de Winkel ◽

Anthony A. Holder ◽

...

Keyword(s):

Passive Immunization ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Plasmodium Yoelii ◽

Single Chain ◽

Parasite Drug Resistance ◽

Parasite Challenge ◽

Major Target

Abstract Parasite drug resistance and difficulties in developing effective vaccines have precipitated the search for alternative therapies for malaria. The success of passive immunization suggests that immunoglobulin (Ig)-based therapies are effective. To further explore the mechanism(s) by which antibody mediates its protective effect, we generated human chimeric IgG1 and IgA1 and a single-chain diabody specific for the C-terminal 19-kDa region of Plasmodium yoelii merozoite surface protein 1 (MSP119), a major target of protective immune responses. These novel human reagents triggered in vitro phagocytosis of merozoites but, unlike their parental mouse IgG2b, failed to protect against parasite challenge in vivo. Therefore, the Fc region appears critical for mediating protection in vivo, at least for this MSP119 epitope. Such antibodies may serve as prototype therapeutic agents, and as useful tools in the development of in vitro neutralization assays with Plasmodium parasites. (Blood. 2003;102:4424-4430)

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Plasmodium vivaxMerozoite Surface Protein 1 Paralog as a Mediator of Parasite Adherence to Reticulocytes

Infection and Immunity ◽

10.1128/iai.00239-18 ◽

2018 ◽

Vol 86 (9) ◽

Cited By ~ 6

Author(s):

Jin-Hee Han ◽

Jee-Sun Cho ◽

Yang Cheng ◽

Fauzi Muh ◽

Won Gi Yoo ◽

...

Keyword(s):

Surface Protein ◽

Merozoite Surface Protein ◽

Binding Activity ◽

Binding Motif ◽

Dependent Manner ◽

Human Beings ◽

Content Type ◽

C Terminus ◽

Significant Difference

ABSTRACTPlasmodium vivaxparasites preferentially invade reticulocytes in human beings.P. vivaxmerozoite surface protein 1 (PvMSP1) and PvMSP1 paralog (PvMSP1P) may have important functions in reticulocyte adherence during invasion. These proteins share similar structures, including the presence of two epidermal growth factor (EGF)-like and glycosylphosphatidylinositol (GPI)-anchored domains at the C terminus. However, there have been no reports concerning the functional activity of PvMSP1P in reticulocyte adherence duringP. vivaxinvasion. In this study, the ability of PvMSP1P-19 to bind to reticulocytes and normocytes was analyzed. The reticulocyte binding activity of PvMSP1P-19 was 4.0-fold higher than its normocyte binding activity. The binding of PvMSP1P-19 to reticulocytes and normocytes was inhibited in a dose-dependent manner by antibodies from immunized rabbits and by antibodies from vivax parasite-infected patients. Consistently, antibodies against PvMSP1P inhibited parasite invasion during short-termin vitrocultivation. Similar to the case for PvDBPII binding activity, PvMSP1P-19 binding activity was reduced in chymotrypsin-treated reticulocytes. However, no significant difference between the binding of PvMSP1P-19 to Duffy-positive and Duffy-negative erythrocytes was found. The minimal binding motif of PvMSP1P-19 was characterized using synthetic peptides. The results showed that the residues at amino acid positions 1791 to 1808 may have an important function in mediating merozoite adherence to reticulocytes. The positively charged residues within the EGF-like domain were shown to constitute a key binding motif. This work presents strong evidence supporting the role of PvMSP1P in host target cell selection and invasion of Duffy-independent pathway inP. vivax. Moreover, PvMSP1P-19-specific antibodies may confer protection againstP. vivaxreinvasion.

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Analysis of Antibodies Directed against Merozoite Surface Protein 1 of the Human Malaria Parasite Plasmodium falciparum

Infection and Immunity ◽

10.1128/iai.74.2.1313-1322.2006 ◽

2006 ◽

Vol 74 (2) ◽

pp. 1313-1322 ◽

Cited By ~ 47

Author(s):

Ute Woehlbier ◽

Christian Epp ◽

Christian W. Kauth ◽

Rolf Lutz ◽

Carole A. Long ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Surface Protein ◽

Merozoite Surface Protein ◽

Merozoite Surface Protein 1 ◽

Erythrocyte Invasion ◽

Parasite Plasmodium ◽

Parasite Plasmodium Falciparum ◽

Parasite Multiplication ◽

Parasite Replication

ABSTRACT The 190-kDa merozoite surface protein 1 (MSP-1) of Plasmodium falciparum, an essential component in the parasite's life cycle, is a primary candidate for a malaria vaccine. Rabbit antibodies elicited by the heterologously produced MSP-1 processing products p83, p30, p38, and p42, derived from strain 3D7, were analyzed for the potential to inhibit in vitro erythrocyte invasion by the parasite and parasite growth. Our data show that (i) epitopes recognized by antibodies, which inhibit parasite replication, are distributed throughout the entire MSP-1 molecule; (ii) when combined, antibodies specific for different regions of MSP-1 inhibit in a strictly additive manner; (iii) anti-MSP-1 antibodies interfere with erythrocyte invasion as well as with the intraerythrocytic growth of the parasite; and (iv) antibodies raised against MSP-1 of strain 3D7 strongly cross-inhibit replication of the heterologous strain FCB-1. Accordingly, anti-MSP-1 antibodies appear to be capable of interfering with parasite multiplication at more than one level. Since the overall immunogenicity profile of MSP-1 in rabbits closely resembles that found in sera of Aotus monkeys immunized with parasite-derived MSP-1 and of humans semi-immune to malaria from whom highly inhibiting antigen-specific antibodies were recovered, we consider the findings reported here to be relevant for the development of MSP-1-based vaccines against malaria.

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