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Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax

BACKGROUND: Plasmodium vivax rhoptry-associated membrane antigen (RAMA) is a glycophosphatidylinositol-anchored membrane protein currently under consideration as a malaria vaccine candidate. Immunoglobulin G (IgG) antibodies induced by P. vivax RAMA (PvRAMA) have been proved to persist over 12 month...

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Autores principales: Ge, Jieyun, Wang, Qiubo, Chen, Gangcheng, Kassegne, Kokouvi, Zhang, Hangye, Yu, Jiali, Tang, Jianxia, Wang, Bo, Lu, Feng, Cao, Jun, Han, Eun-Taek, Cheng, Yang
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2022
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9664424/
https://www.ncbi.nlm.nih.gov/pubmed/36380374
http://dx.doi.org/10.1186/s13071-022-05561-8
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author Ge, Jieyun
Wang, Qiubo
Chen, Gangcheng
Kassegne, Kokouvi
Zhang, Hangye
Yu, Jiali
Tang, Jianxia
Wang, Bo
Lu, Feng
Cao, Jun
Han, Eun-Taek
Cheng, Yang
author_facet Ge, Jieyun
Wang, Qiubo
Chen, Gangcheng
Kassegne, Kokouvi
Zhang, Hangye
Yu, Jiali
Tang, Jianxia
Wang, Bo
Lu, Feng
Cao, Jun
Han, Eun-Taek
Cheng, Yang
author_sort Ge, Jieyun
collection PubMed
description BACKGROUND: Plasmodium vivax rhoptry-associated membrane antigen (RAMA) is a glycophosphatidylinositol-anchored membrane protein currently under consideration as a malaria vaccine candidate. Immunoglobulin G (IgG) antibodies induced by P. vivax RAMA (PvRAMA) have been proved to persist over 12 months in the sera of people infected with P. vivax. It has also been shown that through stimulation of peripheral blood mononuclear cells with PvRAMA in vitro, the antigen can induce CD4(+) T cells to produce interleukin-10. However, the genetic diversity of the RAMA gene in isolates of P. vivax (pvrama) and the immunogenicity of PvRAMA in animals remain unclear. METHODS: Genomic DNA was extracted from blood samples (n = 25) of patients in Jiangsu Province, China with imported infections of P. vivax from endemic countries in South and Southeast Asia. The extract genomic DNA was used as templates to amplify the P. vivax rama gene (pvrama) by PCR, and the PCR products were then sequenced and analyzed by the DnaSP, MEGA, and GeneDoc software packages. Recombinant PvRAMA (rPvRAMA) protein was expressed and purified, and then used to immunize mice. Levels of total IgG and different IgG subclasses of rPvRAMA-immunized mice were evaluated by enzyme-linked immunosorbent assay. Also, spleen cells of rPvRAMA-immunized mice were stimulated with rPvRAMA in vitro and levels of T cells were measured by flow cytometry. RESULTS: The average pairwise nucleotide diversity (π) of the pvrama gene was 0.00190, and the haplotype diversity (Hd) was 0.982. The C-terminal of PvRAMA showed lower haplotype diversity compared to the N-terminal and was completely conserved at amino acid sites related to erythrocyte binding. To further characterize immunogenicity of the C-terminal of PvRAMA, mice were immunized with rPvRAMA antigen. The rPvRAMA protein induced antibody responses, with the end-point titer ranging from 1:10,000 to 1:5,120,000. IgG1 was the predominant IgG subclass in rPvRAMA-immunized mice, followed by IgG2b. In addition, levels of CD4(+) and CD8(+) T cells in the rPvRAMA-stimulated group were significantly higher than those in the phosphate-buffered saline-stimulated group (normal control group). CONCLUSIONS: The high conservation at specific amino acid sites and the high immunogenicity of the C-terminal of PvRAMA indicate the presence of conserved epitopes able to generate broadly reactive humoral and cellular immune responses. These findings support the potential of PvRAMA to serve as a vaccine candidate against P. vivax infection. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13071-022-05561-8.
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spelling pubmed-96644242022-11-14 Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax Ge, Jieyun Wang, Qiubo Chen, Gangcheng Kassegne, Kokouvi Zhang, Hangye Yu, Jiali Tang, Jianxia Wang, Bo Lu, Feng Cao, Jun Han, Eun-Taek Cheng, Yang Parasit Vectors Research BACKGROUND: Plasmodium vivax rhoptry-associated membrane antigen (RAMA) is a glycophosphatidylinositol-anchored membrane protein currently under consideration as a malaria vaccine candidate. Immunoglobulin G (IgG) antibodies induced by P. vivax RAMA (PvRAMA) have been proved to persist over 12 months in the sera of people infected with P. vivax. It has also been shown that through stimulation of peripheral blood mononuclear cells with PvRAMA in vitro, the antigen can induce CD4(+) T cells to produce interleukin-10. However, the genetic diversity of the RAMA gene in isolates of P. vivax (pvrama) and the immunogenicity of PvRAMA in animals remain unclear. METHODS: Genomic DNA was extracted from blood samples (n = 25) of patients in Jiangsu Province, China with imported infections of P. vivax from endemic countries in South and Southeast Asia. The extract genomic DNA was used as templates to amplify the P. vivax rama gene (pvrama) by PCR, and the PCR products were then sequenced and analyzed by the DnaSP, MEGA, and GeneDoc software packages. Recombinant PvRAMA (rPvRAMA) protein was expressed and purified, and then used to immunize mice. Levels of total IgG and different IgG subclasses of rPvRAMA-immunized mice were evaluated by enzyme-linked immunosorbent assay. Also, spleen cells of rPvRAMA-immunized mice were stimulated with rPvRAMA in vitro and levels of T cells were measured by flow cytometry. RESULTS: The average pairwise nucleotide diversity (π) of the pvrama gene was 0.00190, and the haplotype diversity (Hd) was 0.982. The C-terminal of PvRAMA showed lower haplotype diversity compared to the N-terminal and was completely conserved at amino acid sites related to erythrocyte binding. To further characterize immunogenicity of the C-terminal of PvRAMA, mice were immunized with rPvRAMA antigen. The rPvRAMA protein induced antibody responses, with the end-point titer ranging from 1:10,000 to 1:5,120,000. IgG1 was the predominant IgG subclass in rPvRAMA-immunized mice, followed by IgG2b. In addition, levels of CD4(+) and CD8(+) T cells in the rPvRAMA-stimulated group were significantly higher than those in the phosphate-buffered saline-stimulated group (normal control group). CONCLUSIONS: The high conservation at specific amino acid sites and the high immunogenicity of the C-terminal of PvRAMA indicate the presence of conserved epitopes able to generate broadly reactive humoral and cellular immune responses. These findings support the potential of PvRAMA to serve as a vaccine candidate against P. vivax infection. GRAPHICAL ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13071-022-05561-8. BioMed Central 2022-11-15 /pmc/articles/PMC9664424/ /pubmed/36380374 http://dx.doi.org/10.1186/s13071-022-05561-8 Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
spellingShingle Research
Ge, Jieyun
Wang, Qiubo
Chen, Gangcheng
Kassegne, Kokouvi
Zhang, Hangye
Yu, Jiali
Tang, Jianxia
Wang, Bo
Lu, Feng
Cao, Jun
Han, Eun-Taek
Cheng, Yang
Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
title Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
title_full Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
title_fullStr Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
title_full_unstemmed Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
title_short Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
title_sort immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of plasmodium vivax
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9664424/
https://www.ncbi.nlm.nih.gov/pubmed/36380374
http://dx.doi.org/10.1186/s13071-022-05561-8
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