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Preclinical Assessment of Viral Vectored and Protein Vaccines Targeting the Duffy-Binding Protein Region II of Plasmodium Vivax.

de Cassan SC, Shakri AR, Llewellyn D, Elias SC, Cho JS, Goodman AL, Jin J, Douglas AD, Suwanarusk R, Nosten FH, Rénia L, Russell B, Chitnis CE, Draper SJ - Front Immunol (2015)

Bottom Line: The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax.We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants).Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay.

View Article: PubMed Central - PubMed

Affiliation: The Jenner Institute, University of Oxford , Oxford , UK.

ABSTRACT
Malaria vaccine development has largely focused on Plasmodium falciparum; however, a reawakening to the importance of Plasmodium vivax has spurred efforts to develop vaccines against this difficult to treat and at times severe form of relapsing malaria, which constitutes a significant proportion of human malaria cases worldwide. The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax. Here, we generated both preclinical and clinically compatible adenoviral and poxviral vectored vaccine candidates expressing the Salvador I allele of PvDBP_RII - including human adenovirus serotype 5 (HAdV5), chimpanzee adenovirus serotype 63 (ChAd63), and modified vaccinia virus Ankara (MVA) vectors. We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants). Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay. In recent years, recombinant ChAd63 and MVA vectors have been quickly translated into human clinical trials for numerous antigens from P. falciparum as well as a growing number of other pathogens. The vectors reported here are immunogenic in small animals, elicit antibodies against PvDBP_RII, and have recently entered clinical trials, which will provide the first assessment of the safety and immunogenicity of the PvDBP_RII antigen in humans.

No MeSH data available.


Related in: MedlinePlus

T cell responses induced by viral vectored and protein vaccines targeting PvDBP_RII. (A) BALB/c mice (n = 4–5/group) were immunized with AP and PPP regimes against PvDBP_RII as described in Figure 1C. Ten weeks after the last immunization, spleens were harvested and T cell responses were measured from frozen spleen samples by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL recombinant PvDBP_RII protein (rDBP). Median and individual data points are shown. (B) BALB/c mice (n = 6) were immunized with HAdV5-PvDBP_RII and boosted 8 weeks later with MVA-PvDBP_RII using doses as in Figure 1B. Two weeks after the last immunization, splenic T cell responses were measured by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL rDBP or 2 μg/mL OLP. Median and individual responses are shown. (C) Splenic T cell responses were measured from frozen samples in the mice reported in Figure 1B 2 weeks after the boost immunization and using OLP. Median and individual responses are shown. (D) BALB/c mice were immunized with 1.5 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII (GFP). Splenic T cell responses were measured from frozen spleen samples harvested 2 weeks post-boost and following re-stimulation with 5 μg/mL individual peptides (1–32) or the OLP pool control. Results from a representative mouse are shown. (E) BALB/c mice were immunized with 1 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII. Spleens were harvested 15 days post-boost. Intracellular cytokine staining followed by flow cytometric analysis showed the IFN-γ responses induced to the OLP pool and the three strongest peptides (Table 1) were from CD4+ cells. Cells were gated on lymphocytes, and then (top row) singlets by forward scatter height (FSC-H) versus area (FSC-A), then live cells (dead cell marker versus side scatter area, SSC-A), and then CD4 versus CD8. Representative plots (bottom row) of IFN-γ versus SSC-A from CD4+ gated cells are shown from one mouse following no stimulation (Unstim) or re-stimulation with the OLP pool or peptide 14 (P14).
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Figure 3: T cell responses induced by viral vectored and protein vaccines targeting PvDBP_RII. (A) BALB/c mice (n = 4–5/group) were immunized with AP and PPP regimes against PvDBP_RII as described in Figure 1C. Ten weeks after the last immunization, spleens were harvested and T cell responses were measured from frozen spleen samples by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL recombinant PvDBP_RII protein (rDBP). Median and individual data points are shown. (B) BALB/c mice (n = 6) were immunized with HAdV5-PvDBP_RII and boosted 8 weeks later with MVA-PvDBP_RII using doses as in Figure 1B. Two weeks after the last immunization, splenic T cell responses were measured by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL rDBP or 2 μg/mL OLP. Median and individual responses are shown. (C) Splenic T cell responses were measured from frozen samples in the mice reported in Figure 1B 2 weeks after the boost immunization and using OLP. Median and individual responses are shown. (D) BALB/c mice were immunized with 1.5 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII (GFP). Splenic T cell responses were measured from frozen spleen samples harvested 2 weeks post-boost and following re-stimulation with 5 μg/mL individual peptides (1–32) or the OLP pool control. Results from a representative mouse are shown. (E) BALB/c mice were immunized with 1 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII. Spleens were harvested 15 days post-boost. Intracellular cytokine staining followed by flow cytometric analysis showed the IFN-γ responses induced to the OLP pool and the three strongest peptides (Table 1) were from CD4+ cells. Cells were gated on lymphocytes, and then (top row) singlets by forward scatter height (FSC-H) versus area (FSC-A), then live cells (dead cell marker versus side scatter area, SSC-A), and then CD4 versus CD8. Representative plots (bottom row) of IFN-γ versus SSC-A from CD4+ gated cells are shown from one mouse following no stimulation (Unstim) or re-stimulation with the OLP pool or peptide 14 (P14).

Mentions: The induction of CD4+ T cell responses is also an important consideration in the context of antibody-inducing vaccination. Such responses are necessary to help B cell responses, and drive class-switching and somatic hypermutation within the germinal centers (56). We therefore undertook an assessment of the ability of the different immunization regimes to induce PvDBP_RII-specific T cell responses. Initially, responses were assessed using an ex vivo IFN-γ ELISpot assay. Spleens were harvested from mice previously immunized with the AP and PPP PvDBP_RII regimes, during the resting memory phase (10 weeks after the final immunization). Splenocytes were re-stimulated for 18 h with rDBP and IFN-γ secretion assessed (Figure 3A). At this late memory time-point, moderate-to-low T cell responses were observed with a comparable magnitude irrespective of immunization regime or adjuvant. Median responses of 328 and 199 SFU/million splenocytes were induced by PPP immunization using Abisco®100 and Montanide®ISA720, respectively, while the AP regimes using the same adjuvants showed median responses of 184 and 297 SFU/million splenocytes.


Preclinical Assessment of Viral Vectored and Protein Vaccines Targeting the Duffy-Binding Protein Region II of Plasmodium Vivax.

de Cassan SC, Shakri AR, Llewellyn D, Elias SC, Cho JS, Goodman AL, Jin J, Douglas AD, Suwanarusk R, Nosten FH, Rénia L, Russell B, Chitnis CE, Draper SJ - Front Immunol (2015)

T cell responses induced by viral vectored and protein vaccines targeting PvDBP_RII. (A) BALB/c mice (n = 4–5/group) were immunized with AP and PPP regimes against PvDBP_RII as described in Figure 1C. Ten weeks after the last immunization, spleens were harvested and T cell responses were measured from frozen spleen samples by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL recombinant PvDBP_RII protein (rDBP). Median and individual data points are shown. (B) BALB/c mice (n = 6) were immunized with HAdV5-PvDBP_RII and boosted 8 weeks later with MVA-PvDBP_RII using doses as in Figure 1B. Two weeks after the last immunization, splenic T cell responses were measured by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL rDBP or 2 μg/mL OLP. Median and individual responses are shown. (C) Splenic T cell responses were measured from frozen samples in the mice reported in Figure 1B 2 weeks after the boost immunization and using OLP. Median and individual responses are shown. (D) BALB/c mice were immunized with 1.5 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII (GFP). Splenic T cell responses were measured from frozen spleen samples harvested 2 weeks post-boost and following re-stimulation with 5 μg/mL individual peptides (1–32) or the OLP pool control. Results from a representative mouse are shown. (E) BALB/c mice were immunized with 1 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII. Spleens were harvested 15 days post-boost. Intracellular cytokine staining followed by flow cytometric analysis showed the IFN-γ responses induced to the OLP pool and the three strongest peptides (Table 1) were from CD4+ cells. Cells were gated on lymphocytes, and then (top row) singlets by forward scatter height (FSC-H) versus area (FSC-A), then live cells (dead cell marker versus side scatter area, SSC-A), and then CD4 versus CD8. Representative plots (bottom row) of IFN-γ versus SSC-A from CD4+ gated cells are shown from one mouse following no stimulation (Unstim) or re-stimulation with the OLP pool or peptide 14 (P14).
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Figure 3: T cell responses induced by viral vectored and protein vaccines targeting PvDBP_RII. (A) BALB/c mice (n = 4–5/group) were immunized with AP and PPP regimes against PvDBP_RII as described in Figure 1C. Ten weeks after the last immunization, spleens were harvested and T cell responses were measured from frozen spleen samples by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL recombinant PvDBP_RII protein (rDBP). Median and individual data points are shown. (B) BALB/c mice (n = 6) were immunized with HAdV5-PvDBP_RII and boosted 8 weeks later with MVA-PvDBP_RII using doses as in Figure 1B. Two weeks after the last immunization, splenic T cell responses were measured by ex vivo IFN-γ ELISpot following re-stimulation with 5 μg/mL rDBP or 2 μg/mL OLP. Median and individual responses are shown. (C) Splenic T cell responses were measured from frozen samples in the mice reported in Figure 1B 2 weeks after the boost immunization and using OLP. Median and individual responses are shown. (D) BALB/c mice were immunized with 1.5 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII (GFP). Splenic T cell responses were measured from frozen spleen samples harvested 2 weeks post-boost and following re-stimulation with 5 μg/mL individual peptides (1–32) or the OLP pool control. Results from a representative mouse are shown. (E) BALB/c mice were immunized with 1 × 108 ifu HAdV5-PvDBP_RII and 8 weeks later were boosted with 107 pfu MVA-PvDBP_RII. Spleens were harvested 15 days post-boost. Intracellular cytokine staining followed by flow cytometric analysis showed the IFN-γ responses induced to the OLP pool and the three strongest peptides (Table 1) were from CD4+ cells. Cells were gated on lymphocytes, and then (top row) singlets by forward scatter height (FSC-H) versus area (FSC-A), then live cells (dead cell marker versus side scatter area, SSC-A), and then CD4 versus CD8. Representative plots (bottom row) of IFN-γ versus SSC-A from CD4+ gated cells are shown from one mouse following no stimulation (Unstim) or re-stimulation with the OLP pool or peptide 14 (P14).
Mentions: The induction of CD4+ T cell responses is also an important consideration in the context of antibody-inducing vaccination. Such responses are necessary to help B cell responses, and drive class-switching and somatic hypermutation within the germinal centers (56). We therefore undertook an assessment of the ability of the different immunization regimes to induce PvDBP_RII-specific T cell responses. Initially, responses were assessed using an ex vivo IFN-γ ELISpot assay. Spleens were harvested from mice previously immunized with the AP and PPP PvDBP_RII regimes, during the resting memory phase (10 weeks after the final immunization). Splenocytes were re-stimulated for 18 h with rDBP and IFN-γ secretion assessed (Figure 3A). At this late memory time-point, moderate-to-low T cell responses were observed with a comparable magnitude irrespective of immunization regime or adjuvant. Median responses of 328 and 199 SFU/million splenocytes were induced by PPP immunization using Abisco®100 and Montanide®ISA720, respectively, while the AP regimes using the same adjuvants showed median responses of 184 and 297 SFU/million splenocytes.

Bottom Line: The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax.We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants).Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay.

View Article: PubMed Central - PubMed

Affiliation: The Jenner Institute, University of Oxford , Oxford , UK.

ABSTRACT
Malaria vaccine development has largely focused on Plasmodium falciparum; however, a reawakening to the importance of Plasmodium vivax has spurred efforts to develop vaccines against this difficult to treat and at times severe form of relapsing malaria, which constitutes a significant proportion of human malaria cases worldwide. The almost complete dependence of P. vivax red blood cell invasion on the interaction of the P. vivax Duffy-binding protein region II (PvDBP_RII) with the human Duffy antigen receptor for chemokines (DARC) makes this antigen an attractive vaccine candidate against blood-stage P. vivax. Here, we generated both preclinical and clinically compatible adenoviral and poxviral vectored vaccine candidates expressing the Salvador I allele of PvDBP_RII - including human adenovirus serotype 5 (HAdV5), chimpanzee adenovirus serotype 63 (ChAd63), and modified vaccinia virus Ankara (MVA) vectors. We report on the antibody and T cell immunogenicity of these vaccines in mice or rabbits, either used alone in a viral vectored prime-boost regime or in "mixed-modality" adenovirus prime - protein-in--adjuvant boost regimes (using a recombinant PvDBP_RII protein antigen formulated in Montanide(®)ISA720 or Abisco(®)100 adjuvants). Antibodies induced by these regimes were found to bind to native parasite antigen from P. vivax infected Thai patients and were capable of inhibiting the binding of PvDBP_RII to its receptor DARC using an in vitro binding inhibition assay. In recent years, recombinant ChAd63 and MVA vectors have been quickly translated into human clinical trials for numerous antigens from P. falciparum as well as a growing number of other pathogens. The vectors reported here are immunogenic in small animals, elicit antibodies against PvDBP_RII, and have recently entered clinical trials, which will provide the first assessment of the safety and immunogenicity of the PvDBP_RII antigen in humans.

No MeSH data available.


Related in: MedlinePlus