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Identification of an Immunogenic Mimic of a Conserved Epitope on the Plasmodium falciparum Blood Stage Antigen AMA1 Using Virus-Like Particle (VLP) Peptide Display.

Crossey E, Frietze K, Narum DL, Peabody DS, Chackerian B - PLoS ONE (2015)

Bottom Line: Most of the selected VLPs failed to reliably elicit AMA1 specific antibodies.However, one VLP consistently induced antibodies that cross-reacted with AMA1.Taken together, these data demonstrate that VLP-peptide display can identify immunogenic mimics of a complex conformational epitope and illustrate the promise and challenges of this approach.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, United States of America.

ABSTRACT
We have developed a peptide display platform based on VLPs of the RNA bacteriophage MS2 that combines the high immunogenicity of VLP display with affinity selection capabilities. Random peptides can be displayed on the VLP surface by genetically inserting sequences into a surface-exposed loop of the viral coat protein. VLP-displayed peptides can then be isolated by selection using antibodies, and the VLP selectants can then be used directly as immunogens. Here, we investigated the ability of this platform to identify mimotopes of a highly conserved conformational epitope present on the Plasmodium falciparum blood-stage protein AMA1. Using 4G2, a monoclonal antibody that binds to this epitope and is a potent inhibitor of erythrocyte invasion, we screened three different VLP-peptide libraries and identified specific VLPs that bound strongly to the selecting mAb. We then tested the ability of a handful of selected VLPs to elicit anti-AMA1 antibody responses in mice. Most of the selected VLPs failed to reliably elicit AMA1 specific antibodies. However, one VLP consistently induced antibodies that cross-reacted with AMA1. Surprisingly, this VLP bound to 4G2 more weakly than the other selectants we identified. Taken together, these data demonstrate that VLP-peptide display can identify immunogenic mimics of a complex conformational epitope and illustrate the promise and challenges of this approach.

No MeSH data available.


Related in: MedlinePlus

A subset of selectant VLPs elicit AMA1-reactive antibody responses.Groups of mice were immunized with VLPs displaying the listed peptide sequences. Each group consisted of three mice, except for group H, in which six mice were immunized. Anti-AMA1 IgG responses were measured by ELISA. Mean ODs and SEM are shown for each group.
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pone.0132560.g006: A subset of selectant VLPs elicit AMA1-reactive antibody responses.Groups of mice were immunized with VLPs displaying the listed peptide sequences. Each group consisted of three mice, except for group H, in which six mice were immunized. Anti-AMA1 IgG responses were measured by ELISA. Mean ODs and SEM are shown for each group.

Mentions: Each of these VLPs was used to immunize a group of 3–6 Balb/C mice. Mice were immunized three times at two-week intervals with 10 μg of VLPs and sera were taken two weeks after the final boost. Anti-AMA1 antibody responses were measured by ELISA and compared to control mice that were immunized with wild-type MS2 VLPs (Fig 6). Most of the VLPs either failed to elicit AMA1-binding antibodies (panels C-G) or elicited antibodies that only weakly bound to AMA1 (panels B and I). However, surprisingly, the VLP that bound to 4G2 the weakest (MS2-VTHDAWRPD, panel H) elicited AMA1 cross-reactive IgG responses in all six mice that we tested.


Identification of an Immunogenic Mimic of a Conserved Epitope on the Plasmodium falciparum Blood Stage Antigen AMA1 Using Virus-Like Particle (VLP) Peptide Display.

Crossey E, Frietze K, Narum DL, Peabody DS, Chackerian B - PLoS ONE (2015)

A subset of selectant VLPs elicit AMA1-reactive antibody responses.Groups of mice were immunized with VLPs displaying the listed peptide sequences. Each group consisted of three mice, except for group H, in which six mice were immunized. Anti-AMA1 IgG responses were measured by ELISA. Mean ODs and SEM are shown for each group.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493041&req=5

pone.0132560.g006: A subset of selectant VLPs elicit AMA1-reactive antibody responses.Groups of mice were immunized with VLPs displaying the listed peptide sequences. Each group consisted of three mice, except for group H, in which six mice were immunized. Anti-AMA1 IgG responses were measured by ELISA. Mean ODs and SEM are shown for each group.
Mentions: Each of these VLPs was used to immunize a group of 3–6 Balb/C mice. Mice were immunized three times at two-week intervals with 10 μg of VLPs and sera were taken two weeks after the final boost. Anti-AMA1 antibody responses were measured by ELISA and compared to control mice that were immunized with wild-type MS2 VLPs (Fig 6). Most of the VLPs either failed to elicit AMA1-binding antibodies (panels C-G) or elicited antibodies that only weakly bound to AMA1 (panels B and I). However, surprisingly, the VLP that bound to 4G2 the weakest (MS2-VTHDAWRPD, panel H) elicited AMA1 cross-reactive IgG responses in all six mice that we tested.

Bottom Line: Most of the selected VLPs failed to reliably elicit AMA1 specific antibodies.However, one VLP consistently induced antibodies that cross-reacted with AMA1.Taken together, these data demonstrate that VLP-peptide display can identify immunogenic mimics of a complex conformational epitope and illustrate the promise and challenges of this approach.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, United States of America.

ABSTRACT
We have developed a peptide display platform based on VLPs of the RNA bacteriophage MS2 that combines the high immunogenicity of VLP display with affinity selection capabilities. Random peptides can be displayed on the VLP surface by genetically inserting sequences into a surface-exposed loop of the viral coat protein. VLP-displayed peptides can then be isolated by selection using antibodies, and the VLP selectants can then be used directly as immunogens. Here, we investigated the ability of this platform to identify mimotopes of a highly conserved conformational epitope present on the Plasmodium falciparum blood-stage protein AMA1. Using 4G2, a monoclonal antibody that binds to this epitope and is a potent inhibitor of erythrocyte invasion, we screened three different VLP-peptide libraries and identified specific VLPs that bound strongly to the selecting mAb. We then tested the ability of a handful of selected VLPs to elicit anti-AMA1 antibody responses in mice. Most of the selected VLPs failed to reliably elicit AMA1 specific antibodies. However, one VLP consistently induced antibodies that cross-reacted with AMA1. Surprisingly, this VLP bound to 4G2 more weakly than the other selectants we identified. Taken together, these data demonstrate that VLP-peptide display can identify immunogenic mimics of a complex conformational epitope and illustrate the promise and challenges of this approach.

No MeSH data available.


Related in: MedlinePlus