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Immunogenicity of the Plasmodium falciparum PfEMP1-VarO Adhesin: Induction of Surface-Reactive and Rosette-Disrupting Antibodies to VarO Infected Erythrocytes.

Guillotte M, Juillerat A, Igonet S, Hessel A, Petres S, Crublet E, Le Scanf C, Lewit-Bentley A, Bentley GA, Vigan-Womas I, Mercereau-Puijalon O - PLoS ONE (2015)

Bottom Line: High levels of rosette-disrupting and rosette-preventing antibodies are induced by DBL1 and the Head domain.Reduced-alkylated or denatured proteins fail to induce surface-reacting and rosette-disrupting antibodies, indicating that surface epitopes are conformational.These results highlight the high immunogenicity of the individual domains in outbred animals and provide a strong basis for a rational vaccination strategy targeting rosetting.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2581, Paris, France.

ABSTRACT
Adhesion of Plasmodium falciparum-infected red blood cells (iRBC) to human erythrocytes (i.e. rosetting) is associated with severe malaria. Rosetting results from interactions between a subset of variant PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1) adhesins and specific erythrocyte receptors. Interfering with such interactions is considered a promising intervention against severe malaria. To evaluate the feasibility of a vaccine strategy targetting rosetting, we have used here the Palo Alto 89F5 VarO rosetting model. PfEMP1-VarO consists of five Duffy-Binding Like domains (DBL1-5) and one Cysteine-rich Interdomain Region (CIDR1). The binding domain has been mapped to DBL1 and the ABO blood group was identified as the erythrocyte receptor. Here, we study the immunogenicity of all six recombinant PfEMP1-VarO domains and the DBL1- CIDR1 Head domain in BALB/c and outbred OF1 mice. Five readouts of antibody responses are explored: ELISA titres on the recombinant antigen, VarO-iRBC immunoblot reactivity, VarO-iRBC surface-reactivity, capacity to disrupt VarO rosettes and the capacity to prevent VarO rosette formation. For three domains, we explore influence of the expression system on antigenicity and immunogenicity. We show that correctly folded PfEMP1 domains elicit high antibody titres and induce a homogeneous response in outbred and BALB/c mice after three injections. High levels of rosette-disrupting and rosette-preventing antibodies are induced by DBL1 and the Head domain. Reduced-alkylated or denatured proteins fail to induce surface-reacting and rosette-disrupting antibodies, indicating that surface epitopes are conformational. We also report limited cross-reactivity between some PfEMP1 VarO domains. These results highlight the high immunogenicity of the individual domains in outbred animals and provide a strong basis for a rational vaccination strategy targeting rosetting.

No MeSH data available.


Related in: MedlinePlus

Influence of the expression system on the antibody response of animals immunised with PfEMP1-VarO DBL1 recombinant constructs.(A and B) Titration curves of individual bleed 2 sera collected from five outbred (OF1-1 to -5) (A) or five inbred (BALB/c-1 to -5) mice immunised with bDBL1 (B) on the immunising antigen (bDBL1). OF1 mice responded poorly. (C) Titration curves of serum from a rabbit immunised with bDBL1 compared to the pool of bleed 4 sera from OF1 mice immunised with bDBL1; antigen used in the ELISA: bDBL1. (D) Titration curve of rabbit IgG purified from the serum shown in (C); antigen used in the ELISA: bDBL1. (E to H) Cross-checking on the homologous and heterologous expression product: titration curves of individual bleed 4 sera from OF1 mice immunised with bDBL1 on bDBL1 (E) and eDBL1 (G); titration curves of individual bleed 4 sera from OF1 mice immunised with eDBL1 on eDBL1 (F) and bDBL1 (H).
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pone.0134292.g003: Influence of the expression system on the antibody response of animals immunised with PfEMP1-VarO DBL1 recombinant constructs.(A and B) Titration curves of individual bleed 2 sera collected from five outbred (OF1-1 to -5) (A) or five inbred (BALB/c-1 to -5) mice immunised with bDBL1 (B) on the immunising antigen (bDBL1). OF1 mice responded poorly. (C) Titration curves of serum from a rabbit immunised with bDBL1 compared to the pool of bleed 4 sera from OF1 mice immunised with bDBL1; antigen used in the ELISA: bDBL1. (D) Titration curve of rabbit IgG purified from the serum shown in (C); antigen used in the ELISA: bDBL1. (E to H) Cross-checking on the homologous and heterologous expression product: titration curves of individual bleed 4 sera from OF1 mice immunised with bDBL1 on bDBL1 (E) and eDBL1 (G); titration curves of individual bleed 4 sera from OF1 mice immunised with eDBL1 on eDBL1 (F) and bDBL1 (H).

Mentions: Two injections with bDBL1 were sufficient to elicit an antibody response in OF1 and BALB/c mice, although titres were dispersed over a wide range. After three injections, all inbred and outbred animals produced high antibody titres, although titres remained scattered particularly in OF1 mice (Fig 3A and 3B, respectively). The recombinant bDBL1 was highly immunogenic in the rabbit as well, with 50% titres of 1/2,560,000 and endpoint titres below 1/107 for the serum after 4 doses (Fig 3C), and less than 0.5 ng.mL-1 for purified IgG (Fig 3D). These responses are higher responses than those observed in mice (Fig 3C).


Immunogenicity of the Plasmodium falciparum PfEMP1-VarO Adhesin: Induction of Surface-Reactive and Rosette-Disrupting Antibodies to VarO Infected Erythrocytes.

Guillotte M, Juillerat A, Igonet S, Hessel A, Petres S, Crublet E, Le Scanf C, Lewit-Bentley A, Bentley GA, Vigan-Womas I, Mercereau-Puijalon O - PLoS ONE (2015)

Influence of the expression system on the antibody response of animals immunised with PfEMP1-VarO DBL1 recombinant constructs.(A and B) Titration curves of individual bleed 2 sera collected from five outbred (OF1-1 to -5) (A) or five inbred (BALB/c-1 to -5) mice immunised with bDBL1 (B) on the immunising antigen (bDBL1). OF1 mice responded poorly. (C) Titration curves of serum from a rabbit immunised with bDBL1 compared to the pool of bleed 4 sera from OF1 mice immunised with bDBL1; antigen used in the ELISA: bDBL1. (D) Titration curve of rabbit IgG purified from the serum shown in (C); antigen used in the ELISA: bDBL1. (E to H) Cross-checking on the homologous and heterologous expression product: titration curves of individual bleed 4 sera from OF1 mice immunised with bDBL1 on bDBL1 (E) and eDBL1 (G); titration curves of individual bleed 4 sera from OF1 mice immunised with eDBL1 on eDBL1 (F) and bDBL1 (H).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519321&req=5

pone.0134292.g003: Influence of the expression system on the antibody response of animals immunised with PfEMP1-VarO DBL1 recombinant constructs.(A and B) Titration curves of individual bleed 2 sera collected from five outbred (OF1-1 to -5) (A) or five inbred (BALB/c-1 to -5) mice immunised with bDBL1 (B) on the immunising antigen (bDBL1). OF1 mice responded poorly. (C) Titration curves of serum from a rabbit immunised with bDBL1 compared to the pool of bleed 4 sera from OF1 mice immunised with bDBL1; antigen used in the ELISA: bDBL1. (D) Titration curve of rabbit IgG purified from the serum shown in (C); antigen used in the ELISA: bDBL1. (E to H) Cross-checking on the homologous and heterologous expression product: titration curves of individual bleed 4 sera from OF1 mice immunised with bDBL1 on bDBL1 (E) and eDBL1 (G); titration curves of individual bleed 4 sera from OF1 mice immunised with eDBL1 on eDBL1 (F) and bDBL1 (H).
Mentions: Two injections with bDBL1 were sufficient to elicit an antibody response in OF1 and BALB/c mice, although titres were dispersed over a wide range. After three injections, all inbred and outbred animals produced high antibody titres, although titres remained scattered particularly in OF1 mice (Fig 3A and 3B, respectively). The recombinant bDBL1 was highly immunogenic in the rabbit as well, with 50% titres of 1/2,560,000 and endpoint titres below 1/107 for the serum after 4 doses (Fig 3C), and less than 0.5 ng.mL-1 for purified IgG (Fig 3D). These responses are higher responses than those observed in mice (Fig 3C).

Bottom Line: High levels of rosette-disrupting and rosette-preventing antibodies are induced by DBL1 and the Head domain.Reduced-alkylated or denatured proteins fail to induce surface-reacting and rosette-disrupting antibodies, indicating that surface epitopes are conformational.These results highlight the high immunogenicity of the individual domains in outbred animals and provide a strong basis for a rational vaccination strategy targeting rosetting.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, Paris, France; Centre National de la Recherche Scientifique, Unité de recherche associée 2581, Paris, France.

ABSTRACT
Adhesion of Plasmodium falciparum-infected red blood cells (iRBC) to human erythrocytes (i.e. rosetting) is associated with severe malaria. Rosetting results from interactions between a subset of variant PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1) adhesins and specific erythrocyte receptors. Interfering with such interactions is considered a promising intervention against severe malaria. To evaluate the feasibility of a vaccine strategy targetting rosetting, we have used here the Palo Alto 89F5 VarO rosetting model. PfEMP1-VarO consists of five Duffy-Binding Like domains (DBL1-5) and one Cysteine-rich Interdomain Region (CIDR1). The binding domain has been mapped to DBL1 and the ABO blood group was identified as the erythrocyte receptor. Here, we study the immunogenicity of all six recombinant PfEMP1-VarO domains and the DBL1- CIDR1 Head domain in BALB/c and outbred OF1 mice. Five readouts of antibody responses are explored: ELISA titres on the recombinant antigen, VarO-iRBC immunoblot reactivity, VarO-iRBC surface-reactivity, capacity to disrupt VarO rosettes and the capacity to prevent VarO rosette formation. For three domains, we explore influence of the expression system on antigenicity and immunogenicity. We show that correctly folded PfEMP1 domains elicit high antibody titres and induce a homogeneous response in outbred and BALB/c mice after three injections. High levels of rosette-disrupting and rosette-preventing antibodies are induced by DBL1 and the Head domain. Reduced-alkylated or denatured proteins fail to induce surface-reacting and rosette-disrupting antibodies, indicating that surface epitopes are conformational. We also report limited cross-reactivity between some PfEMP1 VarO domains. These results highlight the high immunogenicity of the individual domains in outbred animals and provide a strong basis for a rational vaccination strategy targeting rosetting.

No MeSH data available.


Related in: MedlinePlus