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Induction of multi-antigen multi-stage immune responses against Plasmodium falciparum in rhesus monkeys, in the absence of antigen interference, with heterologous DNA prime/poxvirus boost immunization.

Jiang G, Charoenvit Y, Moreno A, Baraceros MF, Banania G, Richie N, Abot S, Ganeshan H, Fallarme V, Patterson NB, Geall A, Weiss WR, Strobert E, Caro-Aquilar I, Lanar DE, Saul A, Martin LB, Gowda K, Morrissette CR, Kaslow DC, Carucci DJ, Galinski MR, Doolan DL - Malar. J. (2007)

Bottom Line: Immune responses to all components of the multi-antigen mixture were demonstrated following immunization with either DNA/PBS or DNA/CRL1005, and no antigen interference was observed in animals receiving CSLAM as compared to PfCSP alone.CRL1005 formulation had no apparent effect on vaccine-induced T cell or antibody responses, either before or after viral boost.Overall, this study demonstrates the potential for multivalent Pf vaccines based on rational antigen selection and combination, and suggests that further formulation development to increase the immunogenicity of DNA encoded antigens is warranted.

View Article: PubMed Central - HTML - PubMed

Affiliation: Malaria Program, Naval Medical Research Center, Silver Spring, MD 20910-7500, USA. jiang_george@bah.com

ABSTRACT
The present study has evaluated the immunogenicity of single or multiple Plasmodium falciparum (Pf) antigens administered in a DNA prime/poxvirus boost regimen with or without the poloxamer CRL1005 in rhesus monkeys. Animals were primed with PfCSP plasmid DNA or a mixture of PfCSP, PfSSP2/TRAP, PfLSA1, PfAMA1 and PfMSP1-42 (CSLAM) DNA vaccines in PBS or formulated with CRL1005, and subsequently boosted with ALVAC-Pf7, a canarypox virus expressing the CSLAM antigens. Cell-mediated immune responses were evaluated by IFN-gamma ELIspot and intracellular cytokine staining, using recombinant proteins and overlapping synthetic peptides. Antigen-specific and parasite-specific antibody responses were evaluated by ELISA and IFAT, respectively. Immune responses to all components of the multi-antigen mixture were demonstrated following immunization with either DNA/PBS or DNA/CRL1005, and no antigen interference was observed in animals receiving CSLAM as compared to PfCSP alone. These data support the down-selection of the CSLAM antigen combination. CRL1005 formulation had no apparent effect on vaccine-induced T cell or antibody responses, either before or after viral boost. In high responder monkeys, CD4+IL-2+ responses were more predominant than CD8+ T cell responses. Furthermore, CD8+ IFN-gamma responses were detected only in the presence of detectable CD4+ T cell responses. Overall, this study demonstrates the potential for multivalent Pf vaccines based on rational antigen selection and combination, and suggests that further formulation development to increase the immunogenicity of DNA encoded antigens is warranted.

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A. Frequency of IFN-γ ELIspot responders to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS, and PBMC collected at time points as defined in the legend to Figure 2 were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. B. Magnitude of IFN-γ ELIspot responses to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS and PBMC collected at defined time points were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. Time point number 1, 2, 3, 4, 5, and 6 represent time points pre-immunization, 4 wks post 1st DNA immunization, 4 wks post 2nd DNA immunization, 4 wks post 3rd DNA immunization, 4 wks post ALVAC-Pf7 boost, and 12 wks post ALVAC-Pf7 boost, for monkeys PH1019, ROk6, RQk6, ROa7 and RBsG, respectively.
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Figure 4: A. Frequency of IFN-γ ELIspot responders to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS, and PBMC collected at time points as defined in the legend to Figure 2 were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. B. Magnitude of IFN-γ ELIspot responses to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS and PBMC collected at defined time points were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. Time point number 1, 2, 3, 4, 5, and 6 represent time points pre-immunization, 4 wks post 1st DNA immunization, 4 wks post 2nd DNA immunization, 4 wks post 3rd DNA immunization, 4 wks post ALVAC-Pf7 boost, and 12 wks post ALVAC-Pf7 boost, for monkeys PH1019, ROk6, RQk6, ROa7 and RBsG, respectively.

Mentions: Antigen-specific responses to the other components of the CSLAM vaccine were also assessed. As shown in Figure 4A, antigen-specific IFN-γ ELIspot response to all other components of CSLAM/PBS vaccine (PfLSA1 recombinant protein and synthetic peptides, PfSSP2/TRAP synthetic peptide, PfAMA1 recombinant protein, and PfMSP1 recombinant protein) were induced by DNA immunization and were boosted by ALVAC-Pf7 (peptide data other than PfSSP2/TRAP not presented). IFN-γ responses to PfSSP2/TRAP and PfMSP1 were detected in 5/5 CSLAM/PBS immunized monkeys, and responses to PfCSP, PfLSA1 and PfAMA1 were detected in 4/5 monkeys. Positive responses to PfLSA1 and PfAMA1 were observed after the 1st DNA immunization, as noted for PfCSP, whereas positive responders to PfSSP2/TRAP and PfMSP1 were detected only after the 2nd DNA immunization. After the ALVAC-Pf7 boost, at least 3/5 monkeys met the defined criteria of positive responses for each immunogen (Figure 4A).


Induction of multi-antigen multi-stage immune responses against Plasmodium falciparum in rhesus monkeys, in the absence of antigen interference, with heterologous DNA prime/poxvirus boost immunization.

Jiang G, Charoenvit Y, Moreno A, Baraceros MF, Banania G, Richie N, Abot S, Ganeshan H, Fallarme V, Patterson NB, Geall A, Weiss WR, Strobert E, Caro-Aquilar I, Lanar DE, Saul A, Martin LB, Gowda K, Morrissette CR, Kaslow DC, Carucci DJ, Galinski MR, Doolan DL - Malar. J. (2007)

A. Frequency of IFN-γ ELIspot responders to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS, and PBMC collected at time points as defined in the legend to Figure 2 were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. B. Magnitude of IFN-γ ELIspot responses to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS and PBMC collected at defined time points were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. Time point number 1, 2, 3, 4, 5, and 6 represent time points pre-immunization, 4 wks post 1st DNA immunization, 4 wks post 2nd DNA immunization, 4 wks post 3rd DNA immunization, 4 wks post ALVAC-Pf7 boost, and 12 wks post ALVAC-Pf7 boost, for monkeys PH1019, ROk6, RQk6, ROa7 and RBsG, respectively.
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Related In: Results  -  Collection

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Figure 4: A. Frequency of IFN-γ ELIspot responders to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS, and PBMC collected at time points as defined in the legend to Figure 2 were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. B. Magnitude of IFN-γ ELIspot responses to all CSLAM antigen components in CSLAM/PBS immunized monkeys. Monkeys were immunized with CSLAM/PBS and PBMC collected at defined time points were assayed against recombinant PfCSP, PfLSA1, PfAMA1 or PfMSP1 protein and PfSSP2/TRAP peptide pools by IFN-γ ELIspot. Time point number 1, 2, 3, 4, 5, and 6 represent time points pre-immunization, 4 wks post 1st DNA immunization, 4 wks post 2nd DNA immunization, 4 wks post 3rd DNA immunization, 4 wks post ALVAC-Pf7 boost, and 12 wks post ALVAC-Pf7 boost, for monkeys PH1019, ROk6, RQk6, ROa7 and RBsG, respectively.
Mentions: Antigen-specific responses to the other components of the CSLAM vaccine were also assessed. As shown in Figure 4A, antigen-specific IFN-γ ELIspot response to all other components of CSLAM/PBS vaccine (PfLSA1 recombinant protein and synthetic peptides, PfSSP2/TRAP synthetic peptide, PfAMA1 recombinant protein, and PfMSP1 recombinant protein) were induced by DNA immunization and were boosted by ALVAC-Pf7 (peptide data other than PfSSP2/TRAP not presented). IFN-γ responses to PfSSP2/TRAP and PfMSP1 were detected in 5/5 CSLAM/PBS immunized monkeys, and responses to PfCSP, PfLSA1 and PfAMA1 were detected in 4/5 monkeys. Positive responses to PfLSA1 and PfAMA1 were observed after the 1st DNA immunization, as noted for PfCSP, whereas positive responders to PfSSP2/TRAP and PfMSP1 were detected only after the 2nd DNA immunization. After the ALVAC-Pf7 boost, at least 3/5 monkeys met the defined criteria of positive responses for each immunogen (Figure 4A).

Bottom Line: Immune responses to all components of the multi-antigen mixture were demonstrated following immunization with either DNA/PBS or DNA/CRL1005, and no antigen interference was observed in animals receiving CSLAM as compared to PfCSP alone.CRL1005 formulation had no apparent effect on vaccine-induced T cell or antibody responses, either before or after viral boost.Overall, this study demonstrates the potential for multivalent Pf vaccines based on rational antigen selection and combination, and suggests that further formulation development to increase the immunogenicity of DNA encoded antigens is warranted.

View Article: PubMed Central - HTML - PubMed

Affiliation: Malaria Program, Naval Medical Research Center, Silver Spring, MD 20910-7500, USA. jiang_george@bah.com

ABSTRACT
The present study has evaluated the immunogenicity of single or multiple Plasmodium falciparum (Pf) antigens administered in a DNA prime/poxvirus boost regimen with or without the poloxamer CRL1005 in rhesus monkeys. Animals were primed with PfCSP plasmid DNA or a mixture of PfCSP, PfSSP2/TRAP, PfLSA1, PfAMA1 and PfMSP1-42 (CSLAM) DNA vaccines in PBS or formulated with CRL1005, and subsequently boosted with ALVAC-Pf7, a canarypox virus expressing the CSLAM antigens. Cell-mediated immune responses were evaluated by IFN-gamma ELIspot and intracellular cytokine staining, using recombinant proteins and overlapping synthetic peptides. Antigen-specific and parasite-specific antibody responses were evaluated by ELISA and IFAT, respectively. Immune responses to all components of the multi-antigen mixture were demonstrated following immunization with either DNA/PBS or DNA/CRL1005, and no antigen interference was observed in animals receiving CSLAM as compared to PfCSP alone. These data support the down-selection of the CSLAM antigen combination. CRL1005 formulation had no apparent effect on vaccine-induced T cell or antibody responses, either before or after viral boost. In high responder monkeys, CD4+IL-2+ responses were more predominant than CD8+ T cell responses. Furthermore, CD8+ IFN-gamma responses were detected only in the presence of detectable CD4+ T cell responses. Overall, this study demonstrates the potential for multivalent Pf vaccines based on rational antigen selection and combination, and suggests that further formulation development to increase the immunogenicity of DNA encoded antigens is warranted.

Show MeSH
Related in: MedlinePlus