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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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IFN-γ responses to individual peptide pools derived from PfCSP, PfSSP2/TRAP or PfLSA1. PBMC from monkey RBsG (CSLAM/PBS) collected at time points as defined in the legend to Figure 2 were assayed against pools of synthetic peptides spanning the complete sequences of PfCSP, PfSSP2/TRAP or PfLSA1 by IFN-γ ELIspot.
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Figure 5: IFN-γ responses to individual peptide pools derived from PfCSP, PfSSP2/TRAP or PfLSA1. PBMC from monkey RBsG (CSLAM/PBS) collected at time points as defined in the legend to Figure 2 were assayed against pools of synthetic peptides spanning the complete sequences of PfCSP, PfSSP2/TRAP or PfLSA1 by IFN-γ ELIspot.

Mentions: For those antigens for which synthetic peptides spanning the complete antigen were available (PfCSP, PfSSP2/TRAP, and PfLSA1), responses to multiple peptide epitopes were detected. Representative data for responses in monkey RBsG, the most reactive monkey in the CSLAM/PBS group, are presented in Figure 5. Among the three antigens (and consistent with the recombinant protein reactivity reported above), the most robust IFN-γ responses were detected to PfLSA1, with positive responses to five of the six peptide pools. The most N-terminal pool LSA1–1415 (residues 1–84) was the most immunogenic, with an average of 380 SFC/million PBMC at 4 wks post ALVAC-Pf7 boost. The magnitude of IFN-γ responses in three of the other four PfLSA1 peptide pools was comparable, and the least reactive pool was LSA1–1718 (residues 132–236). Similarly, for PfCSP, the most immunogenic peptide pool was the most N-terminal pool CSP-2526 (residues 1–184), although the magnitude of responses to PfCSP peptide pools was lower than that for the other two antigens. The frequency and magnitude of responses to the PfSSP2/TRAP peptide pools were variable; the most immunoreactive pool was residues 44–128, with an average of 277 SFC/million PBMC at 4 wks post viral boost.


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)

IFN-γ responses to individual peptide pools derived from PfCSP, PfSSP2/TRAP or PfLSA1. PBMC from monkey RBsG (CSLAM/PBS) collected at time points as defined in the legend to Figure 2 were assayed against pools of synthetic peptides spanning the complete sequences of PfCSP, PfSSP2/TRAP or PfLSA1 by IFN-γ ELIspot.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2147027&req=5

Figure 5: IFN-γ responses to individual peptide pools derived from PfCSP, PfSSP2/TRAP or PfLSA1. PBMC from monkey RBsG (CSLAM/PBS) collected at time points as defined in the legend to Figure 2 were assayed against pools of synthetic peptides spanning the complete sequences of PfCSP, PfSSP2/TRAP or PfLSA1 by IFN-γ ELIspot.
Mentions: For those antigens for which synthetic peptides spanning the complete antigen were available (PfCSP, PfSSP2/TRAP, and PfLSA1), responses to multiple peptide epitopes were detected. Representative data for responses in monkey RBsG, the most reactive monkey in the CSLAM/PBS group, are presented in Figure 5. Among the three antigens (and consistent with the recombinant protein reactivity reported above), the most robust IFN-γ responses were detected to PfLSA1, with positive responses to five of the six peptide pools. The most N-terminal pool LSA1–1415 (residues 1–84) was the most immunogenic, with an average of 380 SFC/million PBMC at 4 wks post ALVAC-Pf7 boost. The magnitude of IFN-γ responses in three of the other four PfLSA1 peptide pools was comparable, and the least reactive pool was LSA1–1718 (residues 132–236). Similarly, for PfCSP, the most immunogenic peptide pool was the most N-terminal pool CSP-2526 (residues 1–184), although the magnitude of responses to PfCSP peptide pools was lower than that for the other two antigens. The frequency and magnitude of responses to the PfSSP2/TRAP peptide pools were variable; the most immunoreactive pool was residues 44–128, with an average of 277 SFC/million PBMC at 4 wks post viral boost.

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