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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

Homogeneity of the antibody response to bDBL2 after three immunising doses.ELISA analysis of the antibody response of inbred and outbred mice with increasing number of immunisations with PfEMP1-VarO bDBL2 domain. Sera collected from seven individual outbred mice (OF1-1 to -7) (A, C) or six BALB/c mice (BALB/c-1 to -6) (B, D) were assayed by ELISA on the cognate bDBL2 antigen. (A, B): individual sera from successive bleedings assayed at a (dilution 1/200); (C, D): titration curves of individual sera from bleed 4 (same numbering of animals for A,C and B,D). (E) Comparative titration curves of the pools prepared by mixing equal volumes of individual sera from bleed 4 of OF1 or BALB/c mice.
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pone.0134292.g002: Homogeneity of the antibody response to bDBL2 after three immunising doses.ELISA analysis of the antibody response of inbred and outbred mice with increasing number of immunisations with PfEMP1-VarO bDBL2 domain. Sera collected from seven individual outbred mice (OF1-1 to -7) (A, C) or six BALB/c mice (BALB/c-1 to -6) (B, D) were assayed by ELISA on the cognate bDBL2 antigen. (A, B): individual sera from successive bleedings assayed at a (dilution 1/200); (C, D): titration curves of individual sera from bleed 4 (same numbering of animals for A,C and B,D). (E) Comparative titration curves of the pools prepared by mixing equal volumes of individual sera from bleed 4 of OF1 or BALB/c mice.

Mentions: We first analysed the number of doses needed to achieve a homogeneous ELISA response in OF1 and BALB/c mice using the baculovirus-expressed DBL2βC2 (bDBL2) and NTS-DBL1α1 (bDBL1) domains. Three injections were necessary to elicit a response to bDBL2 in all animals. After two injections, responses were heterogeneous in OF1 and minimal in BALB/c mice (Fig 2A and 2B, respectively); they substantially increased and were quite homogeneous after the 3rd injection in both OF1 and BALB/c mice. The high response was sustained after the 4th and 5th dose. All outbred and inbred animals produced good titres of anti-bDBL2 antibodies (Fig 2C and 2D), although signal intensity was usually higher in OF1 than in BALB/c mice (Fig 2E).


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)

Homogeneity of the antibody response to bDBL2 after three immunising doses.ELISA analysis of the antibody response of inbred and outbred mice with increasing number of immunisations with PfEMP1-VarO bDBL2 domain. Sera collected from seven individual outbred mice (OF1-1 to -7) (A, C) or six BALB/c mice (BALB/c-1 to -6) (B, D) were assayed by ELISA on the cognate bDBL2 antigen. (A, B): individual sera from successive bleedings assayed at a (dilution 1/200); (C, D): titration curves of individual sera from bleed 4 (same numbering of animals for A,C and B,D). (E) Comparative titration curves of the pools prepared by mixing equal volumes of individual sera from bleed 4 of OF1 or BALB/c mice.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134292.g002: Homogeneity of the antibody response to bDBL2 after three immunising doses.ELISA analysis of the antibody response of inbred and outbred mice with increasing number of immunisations with PfEMP1-VarO bDBL2 domain. Sera collected from seven individual outbred mice (OF1-1 to -7) (A, C) or six BALB/c mice (BALB/c-1 to -6) (B, D) were assayed by ELISA on the cognate bDBL2 antigen. (A, B): individual sera from successive bleedings assayed at a (dilution 1/200); (C, D): titration curves of individual sera from bleed 4 (same numbering of animals for A,C and B,D). (E) Comparative titration curves of the pools prepared by mixing equal volumes of individual sera from bleed 4 of OF1 or BALB/c mice.
Mentions: We first analysed the number of doses needed to achieve a homogeneous ELISA response in OF1 and BALB/c mice using the baculovirus-expressed DBL2βC2 (bDBL2) and NTS-DBL1α1 (bDBL1) domains. Three injections were necessary to elicit a response to bDBL2 in all animals. After two injections, responses were heterogeneous in OF1 and minimal in BALB/c mice (Fig 2A and 2B, respectively); they substantially increased and were quite homogeneous after the 3rd injection in both OF1 and BALB/c mice. The high response was sustained after the 4th and 5th dose. All outbred and inbred animals produced good titres of anti-bDBL2 antibodies (Fig 2C and 2D), although signal intensity was usually higher in OF1 than in BALB/c mice (Fig 2E).

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