Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax
Abstract 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...
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| Format: | Article |
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BMC
2022-11-01
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| Series: | Parasites & Vectors |
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| Online Access: | https://doi.org/10.1186/s13071-022-05561-8 |
| _version_ | 1811217689231753216 |
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| author | Jieyun Ge Qiubo Wang Gangcheng Chen Kokouvi Kassegne Hangye Zhang Jiali Yu Jianxia Tang Bo Wang Feng Lu Jun Cao Eun-Taek Han Yang Cheng |
| author_facet | Jieyun Ge Qiubo Wang Gangcheng Chen Kokouvi Kassegne Hangye Zhang Jiali Yu Jianxia Tang Bo Wang Feng Lu Jun Cao Eun-Taek Han Yang Cheng |
| author_sort | Jieyun Ge |
| collection | DOAJ |
| description | Abstract 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 |
| first_indexed | 2024-04-12T06:58:57Z |
| format | Article |
| id | doaj.art-3047f68b99b94faa8ecc8dbab9685818 |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-04-12T06:58:57Z |
| publishDate | 2022-11-01 |
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| series | Parasites & Vectors |
| spelling | doaj.art-3047f68b99b94faa8ecc8dbab96858182022-12-22T03:43:03ZengBMCParasites & Vectors1756-33052022-11-0115111210.1186/s13071-022-05561-8Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivaxJieyun Ge0Qiubo Wang1Gangcheng Chen2Kokouvi Kassegne3Hangye Zhang4Jiali Yu5Jianxia Tang6Bo Wang7Feng Lu8Jun Cao9Eun-Taek Han10Yang Cheng11Laboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan UniversityDepartment of Clinical Laboratory, Wuxi 9th People’s Hospital affiliated to Soochow UniversityKey Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasite DiseasesSchool of Global Health, Chinese Centre for Tropical Diseases Research, Shanghai Jiao Tong University School of MedicineLaboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan UniversityLaboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan UniversityKey Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasite DiseasesDepartment of Clinical Laboratory, The First Affiliated Hospital of Anhui Medical UniversityDepartment of Pathogen Biology and Immunology, School of Medicine, Yangzhou UniversityLaboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan UniversityDepartment of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National UniversityLaboratory of Pathogen Infection and Immunity, Department of Public Health and Preventive Medicine, Wuxi School of Medicine, Jiangnan UniversityAbstract 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 Abstracthttps://doi.org/10.1186/s13071-022-05561-8Plasmodium vivaxRAMAGenetic diversityImmunogenicity |
| spellingShingle | Jieyun Ge Qiubo Wang Gangcheng Chen Kokouvi Kassegne Hangye Zhang Jiali Yu Jianxia Tang Bo Wang Feng Lu Jun Cao Eun-Taek Han Yang Cheng Immunogenicity and antigenicity of a conserved fragment of the rhoptry-associated membrane antigen of Plasmodium vivax Parasites & Vectors Plasmodium vivax RAMA Genetic diversity Immunogenicity |
| 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 | Plasmodium vivax RAMA Genetic diversity Immunogenicity |
| url | https://doi.org/10.1186/s13071-022-05561-8 |
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