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Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults

BACKGROUND: To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their va...

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Autores principales: Dodoo, Daniel, Hollingdale, Michael R, Anum, Dorothy, Koram, Kwadwo A, Gyan, Ben, Akanmori, Bartholomew D, Ocran, Josephine, Adu-Amankwah, Susan, Geneshan, Harini, Abot, Esteban, Legano, Jennylyn, Banania, Glenna, Sayo, Renato, Brambilla, Donald, Kumar, Sanjai, Doolan, Denise L, Rogers, William O, Epstein, Judith, Richie, Thomas L, Sedegah, Martha
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132199/
https://www.ncbi.nlm.nih.gov/pubmed/21689436
http://dx.doi.org/10.1186/1475-2875-10-168
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author Dodoo, Daniel
Hollingdale, Michael R
Anum, Dorothy
Koram, Kwadwo A
Gyan, Ben
Akanmori, Bartholomew D
Ocran, Josephine
Adu-Amankwah, Susan
Geneshan, Harini
Abot, Esteban
Legano, Jennylyn
Banania, Glenna
Sayo, Renato
Brambilla, Donald
Kumar, Sanjai
Doolan, Denise L
Rogers, William O
Epstein, Judith
Richie, Thomas L
Sedegah, Martha
author_facet Dodoo, Daniel
Hollingdale, Michael R
Anum, Dorothy
Koram, Kwadwo A
Gyan, Ben
Akanmori, Bartholomew D
Ocran, Josephine
Adu-Amankwah, Susan
Geneshan, Harini
Abot, Esteban
Legano, Jennylyn
Banania, Glenna
Sayo, Renato
Brambilla, Donald
Kumar, Sanjai
Doolan, Denise L
Rogers, William O
Epstein, Judith
Richie, Thomas L
Sedegah, Martha
author_sort Dodoo, Daniel
collection PubMed
description BACKGROUND: To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays. METHODS: In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant Plasmodium falciparum CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by ex vivo IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart. RESULTS: In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of ex vivo ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants. CONCLUSIONS: All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals.
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spelling pubmed-31321992011-07-10 Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults Dodoo, Daniel Hollingdale, Michael R Anum, Dorothy Koram, Kwadwo A Gyan, Ben Akanmori, Bartholomew D Ocran, Josephine Adu-Amankwah, Susan Geneshan, Harini Abot, Esteban Legano, Jennylyn Banania, Glenna Sayo, Renato Brambilla, Donald Kumar, Sanjai Doolan, Denise L Rogers, William O Epstein, Judith Richie, Thomas L Sedegah, Martha Malar J Research BACKGROUND: To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays. METHODS: In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant Plasmodium falciparum CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by ex vivo IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart. RESULTS: In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of ex vivo ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants. CONCLUSIONS: All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals. BioMed Central 2011-06-20 /pmc/articles/PMC3132199/ /pubmed/21689436 http://dx.doi.org/10.1186/1475-2875-10-168 Text en Copyright ©2011 Dodoo et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Dodoo, Daniel
Hollingdale, Michael R
Anum, Dorothy
Koram, Kwadwo A
Gyan, Ben
Akanmori, Bartholomew D
Ocran, Josephine
Adu-Amankwah, Susan
Geneshan, Harini
Abot, Esteban
Legano, Jennylyn
Banania, Glenna
Sayo, Renato
Brambilla, Donald
Kumar, Sanjai
Doolan, Denise L
Rogers, William O
Epstein, Judith
Richie, Thomas L
Sedegah, Martha
Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults
title Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults
title_full Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults
title_fullStr Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults
title_full_unstemmed Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults
title_short Measuring naturally acquired immune responses to candidate malaria vaccine antigens in Ghanaian adults
title_sort measuring naturally acquired immune responses to candidate malaria vaccine antigens in ghanaian adults
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132199/
https://www.ncbi.nlm.nih.gov/pubmed/21689436
http://dx.doi.org/10.1186/1475-2875-10-168
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