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 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 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.

Sign in / Sign up

Export Citation Format

Share Document