scholarly journals Design and Immunogenicity of a Novel Synthetic Antigen Based on the Ligand Domain of the Plasmodium vivax Duffy Binding Protein

2011 ◽  
Vol 19 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Francis B. Ntumngia ◽  
John H. Adams
Keyword(s):  
Amino Acids ◽  
Plasmodium Vivax ◽  
Binding Protein ◽  
Cell Epitope ◽  
Binding Motif ◽  
Duffy Binding Protein ◽  
Asexual Blood Stage ◽  
Content Type ◽  
Specific Immunity ◽  
Erythrocyte Binding

ABSTRACTThe Duffy binding protein is considered a leading vaccine candidate against asexual blood-stagePlasmodium vivax. The interaction ofP. vivaxmerozoites with human reticulocytes through Duffy binding protein (DBP) and its cognate receptor is vital for parasite infection. The ligand domain of DBP (DBPII) is polymorphic, showing a diversity characteristic of selective immune pressure that tends to compromise vaccine efficacy associated with strain-specific immunity. A previous study resolved that a polymorphic region of DBPII was a dominant B-cell epitope target of human inhibitory anti-DBP antibodies, which we refer to as the DEK epitope for the amino acids in the SalI allele. We hypothesized that the polymorphic residues, which are not functionally important for erythrocyte binding but flank the receptor binding motif of DBPII, comprise variant epitopes that tend to divert the immune response away from more conserved epitopes. In this study, we designed, expressed, and evaluated the immunogenicity of a novel artificial DBPII allele, termed DEKnull, having nonpolar amino acids in the naturally occurring polymorphic charged residues of the DEK epitope. The DEKnull antigen retained erythrocyte-binding activity and elicited antibodies to shared epitopes of SalI DBPII from which it was derived. Our results confirmed that removal of the dominant variant epitope in the DEKnull vaccine lowered immunogenicity of DBPII, but inhibitory anti-DBPII antibodies were elicited against shared neutralizing epitopes on SalI. Focusing immune responses toward more conserved DBP epitopes may avoid development of a strain-specific immunity and enhance functional inhibition against broader range of DBPII variants.

scholarly journals Single-Chain Antibody Fragment Specific for Plasmodium vivax Duffy Binding Protein

2007 ◽  
Vol 14 (6) ◽  
pp. 726-731 ◽  
Author(s):  
So-Hee Kim ◽  
Seung-Young Hwang ◽  
Yong-Seok Lee ◽  
In-Hak Choi ◽  
Sae-Gwang Park ◽  
...  
Keyword(s):  
Phage Display ◽  
Plasmodium Vivax ◽  
Binding Protein ◽  
Antibody Fragment ◽  
Neutralizing Antibody ◽  
Active Immunization ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Duffy Binding Protein ◽  
Erythrocyte Binding

ABSTRACT Phage display of single-chain variable fragment (scFv) antibodies is a powerful tool for selecting important, useful, and specific human antibodies. We constructed a library from three patients infected with Plasmodium vivax. Panning on recombinant PvRII enriched a population of scFvs that recognized region II of the P. vivax Duffy binding protein (DBP). Three clones of scFvs that reacted with PvRII were selected, and their biological functions were analyzed. These scFvs inhibited erythrocyte binding to DBP. Clone SFDBII92 had the greatest affinity (dissociation constant = 3.62 × 10−8 M) and the greatest inhibition activity (50% inhibitory concentration ≈ 2.9 μg/ml) to DBP. Thus, we demonstrated that human neutralizing antibody could be made from malaria patients using phage display and that these neutralizing scFvs should prove valuable for developing both passive and active immunization strategies based on DBP.

scholarly journals Mapping Epitopes of the Plasmodium vivax Duffy Binding Protein with Naturally Acquired Inhibitory Antibodies

2009 ◽  
Vol 78 (3) ◽  
pp. 1089-1095 ◽  
Author(s):  
Patchanee Chootong ◽  
Francis B. Ntumngia ◽  
Kelley M. VanBuskirk ◽  
Jia Xainli ◽  
Jennifer L. Cole-Tobian ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Binding Protein ◽  
High Titer ◽  
Blood Stage ◽  
Duffy Binding Protein ◽  
Linear Peptide ◽  
Binding Function ◽  
Blood Stage Infection ◽  
Erythrocyte Binding ◽  
Linear Epitopes

ABSTRACT Plasmodium vivax Duffy binding protein (DBP) is a merozoite microneme ligand vital for blood-stage infection, which makes it an important candidate vaccine for antibody-mediated immunity against vivax malaria. A differential screen with a linear peptide array compared the reactivities of noninhibitory and inhibitory high-titer human immune sera to identify target epitopes associated with protective immunity. Naturally acquired anti-DBP-specific serologic responses observed in the residents of a region of Papua New Guinea where P. vivax is highly endemic exhibited significant changes in DBP-specific titers over time. The anti-DBP functional inhibition for each serum ranged from complete inhibition to no inhibition even for high-titer responders to the DBP, indicating that epitope specificity is important. Inhibitory immune human antibodies identified specific B-cell linear epitopes on the DBP (SalI) ligand domain that showed significant correlations with inhibitory responses. Affinity-purified naturally acquired antibodies on these epitopes inhibited the DBP erythrocyte binding function greatly, confirming the protective value of specific epitopes. These results represent an important advance in our understanding of part of blood-stage immunity to P. vivax and some of the specific targets for vaccine-elicited antibody protection.

scholarly journals Strain-Specific Duffy Binding Protein Antibodies Correlate with Protection against Infection with Homologous Compared to Heterologous Plasmodium vivax Strains in Papua New Guinean Children

2009 ◽  
Vol 77 (9) ◽  
pp. 4009-4017 ◽  
Author(s):  
Jennifer L. Cole-Tobian ◽  
Pascal Michon ◽  
Moses Biasor ◽  
Jack S. Richards ◽  
James G. Beeson ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Cox Regression ◽  
Binding Protein ◽  
Blood Stage ◽  
Incidence Density ◽  
High Antibody ◽  
Duffy Binding Protein ◽  
Specific Immunity ◽  
Antibody Levels ◽  
Papua New Guinean

ABSTRACT Individuals repeatedly infected with malaria acquire protection from infection and disease; immunity is thought to be primarily antibody-mediated and directed to blood-stage infection. Merozoite surface proteins involved in the invasion of host erythrocytes are likely targets of protective antibodies. We hypothesized that Papua New Guinean children (n = 206) who acquire high antibody levels to two Plasmodium vivax merozoite proteins, Duffy binding protein region II (PvDBPII) and the 19-kDa C-terminal region of P. vivax merozoite surface protein 1 (PvMSP119), would have a delay in the time to reinfection following treatment to clear all blood-stage malaria infections. Ninety-four percent of the children were reinfected with P. vivax during biweekly follow-ups for 6 months. Since PvDBPII is polymorphic, we examined whether individuals acquired strain-specific immunity to PvDBPII. Children with high antibody levels to a prevalent PvDBPII allele (O) were associated with a delay in the time to reinfection with the same variant of P. vivax by 25% compared to parasites expressing other PvDBPII alleles (age-adjusted hazard ratio, 0.75 [95% confidence interval, 0.56 to 1.00 by Cox regression]) and 39% lower incidence density parasitemia (P = 0.01). Two other prevalent alleles (AH and P) showed a similar trend of 16% and 18% protection, respectively, against parasites with the same PvDBPII allele and reduced incidence density parasitemia. Antibodies directed to PvDBPII PNG-P and -O were both associated with a 21 to 26% reduction in the risk of P. vivax infections with higher levels of parasitemia (>150 parasites/μl), respectively. There was no association with high antibody levels to PvMSP119 and a delay in the time to P. vivax reinfection. Thus, anti-PvDBPII antibodies are associated with strain-specific immunity to P. vivax and support the use of PvDBPII for a vaccine against P. vivax.

scholarly journals Conserved and Variant Epitopes of Plasmodium vivax Duffy Binding Protein as Targets of Inhibitory Monoclonal Antibodies

2012 ◽  
Vol 80 (3) ◽  
pp. 1203-1208 ◽  
Author(s):  
Francis B. Ntumngia ◽  
Jesse Schloegel ◽  
Samantha J. Barnes ◽  
Amy M. McHenry ◽  
Sanjay Singh ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Plasmodium Vivax ◽  
Vivax Malaria ◽  
Binding Protein ◽  
Blood Stage ◽  
Effective Vaccine ◽  
Enzyme Linked Immunosorbent Assay ◽  
Duffy Binding Protein ◽  
Content Type ◽  
Functional Inhibition

The Duffy binding protein (DBP) is a vital ligand forPlasmodium vivaxblood-stage merozoite invasion, making the molecule an attractive vaccine candidate against vivax malaria. Similar to other blood-stage vaccine candidates, DBP allelic variation eliciting a strain-specific immunity may be a major challenge for development of a broadly effective vaccine against vivax malaria. To understand whether conserved epitopes can be the target of neutralizing anti-DBP inhibition, we generated a set of monoclonal antibodies to DBP and functionally analyzed their reactivity to a panel of allelic variants. Quantitative analysis by enzyme-linked immunosorbent assay (ELISA) determined that some monoclonal antibodies reacted strongly with epitopes conserved on all DBP variants tested, while reactivity of others was allele specific. Qualitative analysis characterized by anti-DBP functional inhibition using anin vitroerythrocyte binding inhibition assay indicated that there was no consistent correlation between the endpoint titers and functional inhibition. Some monoclonal antibodies were broadly inhibitory while inhibition of others varied significantly by target allele. These data demonstrate a potential for vaccine-elicited immunization to target conserved epitopes but optimization of DBP epitope target specificity and immunogenicity may be necessary for protection against diverseP. vivaxstrains.

scholarly journals Identification of an Immunogenic Broadly Inhibitory Surface Epitope of thePlasmodium vivaxDuffy Binding Protein Ligand Domain

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Miriam T. George ◽  
Jesse L. Schloegel ◽  
Francis B. Ntumngia ◽  
Samantha J. Barnes ◽  
Christopher L. King ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Vivax Malaria ◽  
Vaccine Candidate ◽  
Allelic Variation ◽  
Binding Protein ◽  
Effective Vaccine ◽  
Inhibitory Antibody ◽  
Duffy Binding Protein ◽  
Content Type ◽  
Surface Receptor

ABSTRACTThePlasmodium vivaxDuffy binding protein region II (DBPII) is a vital ligand for the parasite’s invasion of reticulocytes, thereby making this molecule an attractive vaccine candidate against vivax malaria. However, strain-specific immunity due to DBPII allelic variation in Bc epitopes may complicate vaccine efficacy, suggesting that an effective DBPII vaccine needs to target conserved epitopes that are potential targets of strain-transcending neutralizing immunity. The minimal epitopes reactive with functionally inhibitory anti-DBPII monoclonal antibody (MAb) 3C9 and noninhibitory anti-DBPII MAb 3D10 were mapped using phage display expression libraries, since previous attempts to deduce the 3C9 epitope by cocrystallographic methods failed. Inhibitory MAb 3C9 binds to a conserved conformation-dependent epitope in subdomain 3, while noninhibitory MAb 3D10 binds to a linear epitope in subdomain 1 of DBPII, consistent with previous studies. Immunogenicity studies using synthetic linear peptides of the minimal epitopes determined that the 3C9 epitope, but not the 3D10 epitope, could induce functionally inhibitory anti-DBPII antibodies. Therefore, the highly conserved binding-inhibitory 3C9 epitope offers the potential as a component in a broadly inhibitory, strain-transcending DBP subunit vaccine.IMPORTANCEVivax malaria is the second leading cause of malaria worldwide and the major cause of non-African malaria. Unfortunately, efforts to develop antimalarial vaccines specifically targetingPlasmodium vivaxhave been largely neglected, and few candidates have progressed into clinical trials. The Duffy binding protein is considered a leading blood-stage vaccine candidate because this ligand’s recognition of the Duffy blood group reticulocyte surface receptor is considered essential for infection. This study identifies a new target epitope on the ligand’s surface that may serve as the target of vaccine-induced binding-inhibitory antibody (BIAb). Understanding the potential targets of vaccine protection will be important for development of an effective vaccine.

scholarly journals The Blood Stage Antigen RBP2-P1 of Plasmodium vivax Binds Reticulocytes and Is a Target of Naturally Acquired Immunity

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Anongruk Chim-Ong ◽  
Thitiporn Surit ◽  
Sittinont Chainarin ◽  
Wanlapa Roobsoong ◽  
Jetsumon Sattabongkot ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Malaria Vaccine ◽  
Vaccine Development ◽  
Binding Protein ◽  
Blood Stage ◽  
Content Type ◽  
Binding Inhibition ◽  
Erythrocyte Binding ◽  
Blood Stage Malaria

ABSTRACT The interactions between Plasmodium parasites and human erythrocytes are prime targets of blood stage malaria vaccine development. The reticulocyte binding protein 2-P1 (RBP2-P1) of Plasmodium vivax, a member of the reticulocyte binding protein family, has recently been shown to be highly antigenic in several settings endemic for malaria. Yet, its functional characteristics and the relevance of its antibody response in human malaria have not been examined. In this study, the potential function of RBP2-P1 as an invasion ligand of P. vivax was evaluated. The protein was found to be expressed in schizonts, be localized at the apical end of the merozoite, and preferentially bind reticulocytes over normocytes. Human antibodies to this protein also exhibit erythrocyte binding inhibition at physiologically relevant concentrations. Furthermore, RBP2-P1 antibodies are associated with lower parasitemia and tend to be higher in asymptomatic carriers than in patients. This study provides evidence supporting a role of RBP2-P1 as an invasion ligand and its consideration as a vaccine target.

scholarly journals Immunogenicity of a Synthetic Vaccine Based on Plasmodium vivax Duffy Binding Protein Region II

2014 ◽  
Vol 21 (9) ◽  
pp. 1215-1223 ◽  
Author(s):  
Francis B. Ntumngia ◽  
Samantha J. Barnes ◽  
Amy M. McHenry ◽  
Miriam T. George ◽  
Jesse Schloegel ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Vaccine Development ◽  
Allelic Variation ◽  
Binding Protein ◽  
Blood Stage ◽  
Duffy Binding Protein ◽  
Merozoite Invasion ◽  
Content Type ◽  
Functional Antibodies ◽  
Region Ii

ABSTRACTMolecules that play a role inPlasmodiummerozoite invasion of host red blood cells represent attractive targets for blood-stage vaccine development against malaria. InPlasmodium vivax, merozoite invasion of reticulocytes is mediated by the Duffy binding protein (DBP), which interacts with its cognate receptor, the Duffy antigen receptor for chemokines, on the surface of reticulocytes. The DBP ligand domain, known as region II (DBPII), contains the critical residues for receptor recognition, making it a prime target for vaccine development against blood-stage vivax malaria. In natural infections, DBP is weakly immunogenic and DBPII allelic variation is associated with strain-specific immunity, which may compromise vaccine efficacy. In a previous study, a synthetic vaccine termed DEKnull that lacked an immunodominant variant epitope in DBPII induced functional antibodies to shared neutralizing epitopes on the native Sal1 allele. Anti-DEKnull antibody titers were lower than anti-Sal1 titers but produced more consistent, strain-transcending anti-DBPII inhibitory responses. In this study, we further characterized the immunogenicity of DEKnull, finding that immunization with recombinant DEKnull produced an immune response comparable to that obtained with native recombinant DBP alleles. Further investigation of DEKnull is necessary to enhance its immunogenicity and broaden its specificity.

scholarly journals A Novel Erythrocyte Binding Protein of Plasmodium vivax Suggests an Alternate Invasion Pathway into Duffy-Positive Reticulocytes

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
Francis B. Ntumngia ◽  
Richard Thomson-Luque ◽  
Letícia de Menezes Torres ◽  
Karthigayan Gunalan ◽  
Luzia H. Carvalho ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Blood Group ◽  
Binding Protein ◽  
Antigen Receptor ◽  
Blood Stage ◽  
Duffy Binding Protein ◽  
Duffy Blood Group ◽  
Erythrocyte Binding ◽  
Invasion Pathway ◽  
Duffy Negative

ABSTRACT Erythrocyte invasion by malaria parasites is essential for blood-stage development and an important determinant of host range. In Plasmodium vivax , the interaction between the Duffy binding protein (DBP) and its cognate receptor, the Duffy antigen receptor for chemokines (DARC), on human erythrocytes is central to blood-stage infection. Contrary to this established pathway of invasion, there is growing evidence of P. vivax infections occurring in Duffy blood group-negative individuals, suggesting that the parasite might have gained an alternative pathway to infect this group of individuals. Supporting this concept, a second distinct erythrocyte binding protein (EBP2), representing a new member of the DBP family, was discovered in P. vivax and may be the ligand in an alternate invasion pathway. Our study characterizes this novel ligand and determines its potential role in reticulocyte invasion by P. vivax merozoites . EBP2 binds preferentially to young (CD71 high ) Duffy-positive (Fy + ) reticulocytes and has minimal binding capacity for Duffy-negative reticulocytes. Importantly, EBP2 is antigenically distinct from DBP and cannot be functionally inhibited by anti-DBP antibodies. Consequently, our results do not support EBP2 as a ligand for invasion of Duffy-negative blood cells, but instead, EBP2 may represent a novel ligand for an alternate invasion pathway of Duffy-positive reticulocytes. IMPORTANCE For decades, P. vivax infections in humans have been defined by a unique requirement for the interaction between the Duffy binding protein ligand of the parasite and the Duffy blood group antigen receptor (DARC). Recent reports of P. vivax infections in Duffy-negative individuals challenge this paradigm and suggest an alternate pathway of infection, potentially using the recently discovered EBP2. However, we demonstrate that EBP2 host cell specificity is more restricted than DBP binding and that EBP2 binds preferentially to Duffy-positive, young reticulocytes. This finding indicates that this DBP paralog does mediate a Duffy-independent pathway of infection.

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