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Analysis of a Multi-component Multi-stage Malaria Vaccine Candidate--Tackling the Cocktail Challenge.

Boes A, Spiegel H, Voepel N, Edgue G, Beiss V, Kapelski S, Fendel R, Scheuermayer M, Pradel G, Bolscher JM, Behet MC, Dechering KJ, Hermsen CC, Sauerwein RW, Schillberg S, Reimann A, Fischer R - PLoS ONE (2015)

Bottom Line: To investigate the potential of such an approach we combined proteins and domains (11 in total) from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants.Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80%), blood (up to 90%) and sexual parasite stages (100%).While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy.

View Article: PubMed Central - PubMed

Affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Aachen, Germany.

ABSTRACT
Combining key antigens from the different stages of the P. falciparum life cycle in the context of a multi-stage-specific cocktail offers a promising approach towards the development of a malaria vaccine ideally capable of preventing initial infection, the clinical manifestation as well as the transmission of the disease. To investigate the potential of such an approach we combined proteins and domains (11 in total) from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants. After immunization of rabbits we determined the domain-specific antibody titers as well as component-specific antibody concentrations and correlated them with stage specific in vitro efficacy. Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80%), blood (up to 90%) and sexual parasite stages (100%). Based on the component-specific antibody concentrations we calculated the IC50 values for the pre-erythrocytic stage (17-25 μg/ml), the blood stage (40-60 μg/ml) and the sexual stage (1.75 μg/ml). While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy.

No MeSH data available.


Related in: MedlinePlus

Antigen-specific antibody titers of rabbit immune sera determined by ELISA.Three rabbits (R1, R2 and R3) were immunized six times with PlasmoMix and serum samples were collected on days 0 (pre-immune), 35, 63 and 91. (A) The antibody titer against the immunization mixture (PlasmoMix) as well as against the four protein-based components (CCT, E3, gAMA1 and F0) were determined. (B) To further dissect the immune response, the specific antibody response against each individual domain was analyzed. Therefore, the domains were C-terminaly fused to DsRed (fluorescent reporter protein), and expressed and purified as described in the methods section. Antigen domains comprising a fusion protein are connected by a bracket. Antibody titers are shown for each rabbit (R1: open black square, R2: open red circle, R3: open blue triangle) as well as the geometric mean (black line) of three rabbits.
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pone.0131456.g002: Antigen-specific antibody titers of rabbit immune sera determined by ELISA.Three rabbits (R1, R2 and R3) were immunized six times with PlasmoMix and serum samples were collected on days 0 (pre-immune), 35, 63 and 91. (A) The antibody titer against the immunization mixture (PlasmoMix) as well as against the four protein-based components (CCT, E3, gAMA1 and F0) were determined. (B) To further dissect the immune response, the specific antibody response against each individual domain was analyzed. Therefore, the domains were C-terminaly fused to DsRed (fluorescent reporter protein), and expressed and purified as described in the methods section. Antigen domains comprising a fusion protein are connected by a bracket. Antibody titers are shown for each rabbit (R1: open black square, R2: open red circle, R3: open blue triangle) as well as the geometric mean (black line) of three rabbits.

Mentions: Antibody titer analysis was performed for the cocktail (PlasmoMix), the components (CCT, F0, E3 and gAMA1) as well as the individual recombinant domains. Antibody antibody titers were monitored at day 0, 35, 63, and 91, and an increase of antibody titers over the sampling period was observed for all tested antigens and domains. We recorded a antibody titer of 3.8 x 106 against the cocktail, antibody titers of 1.9–3.3 x 106 against CCT, F0 and E3, and a antibody titer of just below 5.5 x 105 against gAMA1 (Fig 2A). For CCT, we observed a strong bias in the antibody titers against the three pre-erythrocytic stage antigens PfCeltos, PfCSP_TSR and PfTRAP_TSR, a antibody titer of 1.6 x 106 against the TSR-domain of PfCSP and 20-fold lower values for the other two domains (Fig 2B). In contrast, all five blood-stage domains within E3 induced comparable antibody titers of approximately 4.0 x 105. A two-fold difference in antibody titers was observed when we compared the transmission blocking-component F0 (2 x 106) with the individual antibody titers of the two sexual-stage antigens at 4.4 x 105 for Pfs25 and 1.8 x 105 for Pfs230_C0 (Fig 2B).


Analysis of a Multi-component Multi-stage Malaria Vaccine Candidate--Tackling the Cocktail Challenge.

Boes A, Spiegel H, Voepel N, Edgue G, Beiss V, Kapelski S, Fendel R, Scheuermayer M, Pradel G, Bolscher JM, Behet MC, Dechering KJ, Hermsen CC, Sauerwein RW, Schillberg S, Reimann A, Fischer R - PLoS ONE (2015)

Antigen-specific antibody titers of rabbit immune sera determined by ELISA.Three rabbits (R1, R2 and R3) were immunized six times with PlasmoMix and serum samples were collected on days 0 (pre-immune), 35, 63 and 91. (A) The antibody titer against the immunization mixture (PlasmoMix) as well as against the four protein-based components (CCT, E3, gAMA1 and F0) were determined. (B) To further dissect the immune response, the specific antibody response against each individual domain was analyzed. Therefore, the domains were C-terminaly fused to DsRed (fluorescent reporter protein), and expressed and purified as described in the methods section. Antigen domains comprising a fusion protein are connected by a bracket. Antibody titers are shown for each rabbit (R1: open black square, R2: open red circle, R3: open blue triangle) as well as the geometric mean (black line) of three rabbits.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4492585&req=5

pone.0131456.g002: Antigen-specific antibody titers of rabbit immune sera determined by ELISA.Three rabbits (R1, R2 and R3) were immunized six times with PlasmoMix and serum samples were collected on days 0 (pre-immune), 35, 63 and 91. (A) The antibody titer against the immunization mixture (PlasmoMix) as well as against the four protein-based components (CCT, E3, gAMA1 and F0) were determined. (B) To further dissect the immune response, the specific antibody response against each individual domain was analyzed. Therefore, the domains were C-terminaly fused to DsRed (fluorescent reporter protein), and expressed and purified as described in the methods section. Antigen domains comprising a fusion protein are connected by a bracket. Antibody titers are shown for each rabbit (R1: open black square, R2: open red circle, R3: open blue triangle) as well as the geometric mean (black line) of three rabbits.
Mentions: Antibody titer analysis was performed for the cocktail (PlasmoMix), the components (CCT, F0, E3 and gAMA1) as well as the individual recombinant domains. Antibody antibody titers were monitored at day 0, 35, 63, and 91, and an increase of antibody titers over the sampling period was observed for all tested antigens and domains. We recorded a antibody titer of 3.8 x 106 against the cocktail, antibody titers of 1.9–3.3 x 106 against CCT, F0 and E3, and a antibody titer of just below 5.5 x 105 against gAMA1 (Fig 2A). For CCT, we observed a strong bias in the antibody titers against the three pre-erythrocytic stage antigens PfCeltos, PfCSP_TSR and PfTRAP_TSR, a antibody titer of 1.6 x 106 against the TSR-domain of PfCSP and 20-fold lower values for the other two domains (Fig 2B). In contrast, all five blood-stage domains within E3 induced comparable antibody titers of approximately 4.0 x 105. A two-fold difference in antibody titers was observed when we compared the transmission blocking-component F0 (2 x 106) with the individual antibody titers of the two sexual-stage antigens at 4.4 x 105 for Pfs25 and 1.8 x 105 for Pfs230_C0 (Fig 2B).

Bottom Line: To investigate the potential of such an approach we combined proteins and domains (11 in total) from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants.Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80%), blood (up to 90%) and sexual parasite stages (100%).While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy.

View Article: PubMed Central - PubMed

Affiliation: Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Aachen, Germany.

ABSTRACT
Combining key antigens from the different stages of the P. falciparum life cycle in the context of a multi-stage-specific cocktail offers a promising approach towards the development of a malaria vaccine ideally capable of preventing initial infection, the clinical manifestation as well as the transmission of the disease. To investigate the potential of such an approach we combined proteins and domains (11 in total) from the pre-erythrocytic, blood and sexual stages of P. falciparum into a cocktail of four different components recombinantly produced in plants. After immunization of rabbits we determined the domain-specific antibody titers as well as component-specific antibody concentrations and correlated them with stage specific in vitro efficacy. Using purified rabbit immune IgG we observed strong inhibition in functional in vitro assays addressing the pre-erythrocytic (up to 80%), blood (up to 90%) and sexual parasite stages (100%). Based on the component-specific antibody concentrations we calculated the IC50 values for the pre-erythrocytic stage (17-25 μg/ml), the blood stage (40-60 μg/ml) and the sexual stage (1.75 μg/ml). While the results underline the feasibility of a multi-stage vaccine cocktail, the analysis of component-specific efficacy indicates significant differences in IC50 requirements for stage-specific antibody concentrations providing valuable insights into this complex scenario and will thereby improve future approaches towards malaria vaccine cocktail development regarding the selection of suitable antigens and the ratios of components, to fine tune overall and stage-specific efficacy.

No MeSH data available.


Related in: MedlinePlus