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Jeske R, Becker N, Kroeller L, Mentzer AJ, Brenner N, Guy E, Waterboer T, Butt J. Advancing Toxoplasma gondii multiplex serology. Microbiol Spectr 2024; 12:e0361823. [PMID: 38385741 PMCID: PMC10986549 DOI: 10.1128/spectrum.03618-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/29/2024] [Indexed: 02/23/2024] Open
Abstract
Toxoplasma gondii is a highly prevalent pathogen causing zoonotic infections with significant public health implications. Yet, our understanding of long-term consequences, associated risk factors, and the potential role of co-infections is still limited. Seroepidemiological studies are a valuable approach to address open questions and enhance our insights into T. gondii across human populations. Here, we present substantial advancements to our previously developed T. gondii multiplex serology assay, which is based on the immunodominant antigens SAG1 and P22. While our previous bead-based assay quantified antibody levels against multiple targets in a high-throughput fashion requiring only a small sample volume, impaired assay characteristics emerged in sample dilutions beyond 1:100 and when being transferred to magnetic beads. Both are now critical for inclusion in large-scale seroprevalence studies. Using the truncated versions, SAG1D1 and P22trunc, significantly enhanced signal-to-noise ratios were achieved with almost perfect concordance with the gold-standard Sabin-Feldman dye test. In sample dilutions of 1:100, the diagnostic accuracy of SAG1D1 and P22trunc reached sensitivities (true positive rates) of 98% and 94% and specificities (true negative rates) of 93% and 95%, respectively. Importantly, performance metrics were reproducible in a 1:1,000 sample dilution, using both magnetic and nonmagnetic beads. Thresholds for seropositivity were derived from finite mixture models and performed equally well as thresholds by receiver operating characteristic analysis. Our improved multiplex serology assay is therefore able to generate robust and reproducible performance metrics under various assay conditions. Inclusion of T. gondii antibody measurements with other pathogens, in multiplex serology panels will allow for large-scale seroepidemiological research. IMPORTANCE Toxoplasma gondii is a pathogen of significant public health concern due to its widespread prevalence and zoonotic potential. However, our understanding of key aspects, such as risk factors for infection and disease, potential outcomes, and their trends, remains limited. Seroepidemiological studies in large cohorts are invaluable for addressing these questions but remain scarce. Our revised multiplex serology assay equips researchers with a powerful tool capable of delivering T. gondii serum antibody measurements with high sensitivity and specificity under diverse assay conditions. This advancement paves the way for the integration of T. gondii antibody measurements into multi-pathogen multiplex serology panels, promising valuable insights into public health and pathogen interactions.
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Affiliation(s)
- Rima Jeske
- Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Nico Becker
- Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biotechnology, Mannheim University of Applied Sciences, Mannheim, Germany
| | - Lea Kroeller
- Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | | | - Nicole Brenner
- Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Edward Guy
- Toxoplasma Reference Unit, Public Health Wales Microbiology, Swansea, United Kingdom
| | - Tim Waterboer
- Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Julia Butt
- Division of Infections and Cancer Epidemiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
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Naghi Vishteh M, Javadi Mamaghani A, Rashidi S, Seyyed Tabaei SJ, Jeddi-Tehrani M. Peptide-Based Monoclonal Antibody Production Against SAG1 (P30) Protein of Toxoplasma gondii. Monoclon Antib Immunodiagn Immunother 2020; 39:51-56. [DOI: 10.1089/mab.2019.0041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Affiliation(s)
- Mohadeseh Naghi Vishteh
- Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Amirreza Javadi Mamaghani
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Parasitology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sama Rashidi
- Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seyyed Javad Seyyed Tabaei
- Department of Parasitology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahmood Jeddi-Tehrani
- Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
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Javadi Mamaghani A, Fathollahi A, Spotin A, Ranjbar MM, Barati M, Aghamolaie S, Karimi M, Taghipour N, Ashrafi M, Tabaei SJS. Candidate antigenic epitopes for vaccination and diagnosis strategies of Toxoplasma gondii infection: A review. Microb Pathog 2019; 137:103788. [DOI: 10.1016/j.micpath.2019.103788] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/05/2019] [Accepted: 10/08/2019] [Indexed: 12/28/2022]
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Hannachi E, Bouratbine A, Mousli M. Enhancing the detection of Toxoplasma gondii via an anti-SAG1 scFv-alkaline phosphatase immunoconjugate. BIOTECHNOLOGY REPORTS (AMSTERDAM, NETHERLANDS) 2019; 23:e00360. [PMID: 31341791 PMCID: PMC6630058 DOI: 10.1016/j.btre.2019.e00360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 06/29/2019] [Accepted: 06/30/2019] [Indexed: 12/11/2022]
Abstract
The purpose of this study was to implement a fluorometric method for enhancing the detection sensitivity of Toxoplasma gondii in biological fluids. To address this challenge, we designed and produced a recombinant immunoconjugate tool based on a single-chain antibody fragment anti-T. gondii SAG1 antigen (scFvSG15) genetically fused to the bacterial alkaline phosphatase (AP) using 4-methyl-umbelliferyl-phosphate as fluorogenic substrate. The anti-SAG1 scFv-AP conjugate was fully bifunctional and was used successfully in different assays including immunoblot, fluorometric ELISA and direct immunofluorescence. The fluorometric immunoassay afforded an extremely low detection limit (1 tachyzoite/well), which was in agreement with the real-time PCR control test. The immunofluorescence imaging has provided captivating visual evidence of T. gondii detection. These results strongly suggest that the recombinant anti-SAG1-AP conjugate generated here might serve as useful and highly sensitive immunoassay probe to direct detect T. gondii in a one-step procedure, opening up new perspectives for diagnosis of toxoplasmosis.
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Affiliation(s)
| | | | - Mohamed Mousli
- Laboratoire de Parasitologie Médicale, Biotechnologies et Biomolécules, LR11-IPT06, Institut Pasteur de Tunis, Université Tunis El-Manar, 13 Place Pasteur -BP74, 1002 Tunis-Belvédère, Tunisia
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5
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Sánchez-López EF, Corigliano MG, Albarracín RM, Sander VA, Legarralde A, Bengoa-Luoni SA, Clemente M. Plant Hsp90 is a novel adjuvant that elicits a strong humoral and cellular immune response against B- and T-cell epitopes of a Toxoplasma gondii SAG1 peptide. Parasit Vectors 2019; 12:140. [PMID: 30909938 PMCID: PMC6434815 DOI: 10.1186/s13071-019-3362-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 02/26/2019] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The 90-kDa heat-shock protein (Hsp90) from Nicotiana benthamiana (NbHsp90.3) is a promising adjuvant, especially for those vaccines that require a T cell-mediated immune response. Toxoplasma gondii SAG1 is considered one of the most important antigens for the development of effective subunit vaccines. Some epitopes located in the SAG1 C-terminus region have showed a strong humoral and cellular immune response. In the present study, we aimed to assess the efficacy of NbHsp90.3 as carrier/adjuvant of SAG1-derived peptide (SAG1HC) in a T. gondii infection murine model. METHODS In the present study, C57BL/6 mice were intraperitoneal immunized with the NbHsp90.3-SAG1HC fusion protein (NbHsp90.3-SAG1HC group), mature SAG1 (SAG1m group), NbHsp90.3 (NbHsp90.3 group) or PBS buffer 1× (PBS group). The levels of IgG antibodies and the cytokine profile were determined by ELISA. Two weeks after the last immunization, all mice were orally challenged with 20 cysts of T. gondii Me49 strain and the number of brain cysts was determined. In addition, both humoral and cellular immune responses were also evaluated during the acute and chronic phase of T. gondii infection by ELISA. RESULTS The characterization of the immune response generated after vaccination with NbHsp90.3 as an adjuvant showed that NbHsp90.3-SAG1HC-immunized mice produced antibodies that were able to recognize not only rSAG1m but also the native SAG1 present in the total lysate antigen extract (SAG1TLA) from T. gondii tachyzoites, while control groups did not. Furthermore, anti-rSAG1m IgG2a/2b antibodies were significantly induced. In addition, only the spleen cell cultures from NbHsp90.3-SAG1HC-immunized mice showed a significantly increased production of IFN-γ. During the chronic phase of T. gondii infection, the antibodies generated by the infection were unable to detect the recombinant protein, but they did react with TLA extract. In addition, splenocytes from all groups showed a high production of IFN-γ when stimulated with rGRA4, but only those from NbHsp90.3-SAG1HC group stimulated with rSAG1m showed high production of IFN-γ. Finally, NbHsp90.3-SAG1HC-immunized mice exhibited a significant reduction in the cyst load (56%) against T. gondii infection. CONCLUSIONS We demonstrated that NbHsp90.3 enhances the humoral and cell-mediated immune response through a Th1 type cytokine production. Mice vaccinated with NbHsp90.3-SAG1HC exhibited a partial protection against T. gondii infection and it was correlated with the induction of memory immune response. We developed and validated a vaccine formulation which, to our knowledge, for the first time includes the NbHsp90.3 protein covalently fused to a peptide from T. gondii SAG1 protein that contains T- and B-cell epitopes.
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Affiliation(s)
- Edwin F. Sánchez-López
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
| | - Mariana G. Corigliano
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
| | - Romina M. Albarracín
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
| | - Valeria A. Sander
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
| | - Ariel Legarralde
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
| | - Sofía A. Bengoa-Luoni
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
| | - Marina Clemente
- Unidad de Biotecnología 6-UB6, IIB-INTECH, CONICET-UNSAM, Intendente Marino Km 8.2, B7130IWA Chascomús, Buenos Aires Province Argentina
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Wu Z, Wang L, Li J, Wang L, Wu Z, Sun X. Extracellular Vesicle-Mediated Communication Within Host-Parasite Interactions. Front Immunol 2019; 9:3066. [PMID: 30697211 PMCID: PMC6340962 DOI: 10.3389/fimmu.2018.03066] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 12/11/2018] [Indexed: 12/21/2022] Open
Abstract
Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells) in vivo and in vitro that contain large amounts of important substances (such as lipids, proteins, metabolites, DNA, RNA, and non-coding RNA (ncRNA), including miRNA, lncRNA, tRNA, rRNA, snoRNA, and scaRNA) in an evolutionarily conserved manner. EVs, including exosomes, play a role in the transmission of information, and substances between cells that is increasingly being recognized as important. In some infectious diseases such as parasitic diseases, EVs have emerged as a ubiquitous mechanism for mediating communication during host-parasite interactions. EVs can enable multiple modes to transfer virulence factors and effector molecules from parasites to hosts, thereby regulating host gene expression, and immune responses and, consequently, mediating the pathogenic process, which has made us rethink our understanding of the host-parasite interface. Thus, here, we review the present findings regarding EVs (especially exosomes) and recognize the role of EVs in host-parasite interactions. We hope that a better understanding of the mechanisms of parasite-derived EVs may provide new insights for further diagnostic biomarker, vaccine, and therapeutic development.
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Affiliation(s)
- Zhenyu Wu
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control (SYSU), Ministry of Education, Guangzhou, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, China
| | - Lingling Wang
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control (SYSU), Ministry of Education, Guangzhou, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, China
| | - Jiaying Li
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control (SYSU), Ministry of Education, Guangzhou, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, China
| | - Lifu Wang
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control (SYSU), Ministry of Education, Guangzhou, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, China
| | - Zhongdao Wu
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control (SYSU), Ministry of Education, Guangzhou, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, China
| | - Xi Sun
- Department of Parasitology of Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.,Key Laboratory of Tropical Disease Control (SYSU), Ministry of Education, Guangzhou, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, China
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Lakhrif Z, Moreau A, Hérault B, Di-Tommaso A, Juste M, Moiré N, Dimier-Poisson I, Mévélec MN, Aubrey N. Targeted Delivery of Toxoplasma gondii Antigens to Dendritic Cells Promote Immunogenicity and Protective Efficiency against Toxoplasmosis. Front Immunol 2018. [PMID: 29515595 PMCID: PMC5826183 DOI: 10.3389/fimmu.2018.00317] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Toxoplasmosis is a major public health problem and the development of a human vaccine is of high priority. Efficient vaccination against Toxoplasma gondii requires both a mucosal and systemic Th1 immune response. Moreover, dendritic cells play a critical role in orchestrating the innate immune functions and driving specific adaptive immunity to T. gondii. In this study, we explore an original vaccination strategy that combines administration via mucosal and systemic routes of fusion proteins able to target the major T. gondii surface antigen SAG1 to DCs using an antibody fragment single-chain fragment variable (scFv) directed against DEC205 endocytic receptor. Our results show that SAG1 targeting to DCs by scFv via intranasal and subcutaneous administration improved protection against chronic T. gondii infection. A marked reduction in brain parasite burden is observed when compared with the intranasal or the subcutaneous route alone. DC targeting improved both local and systemic humoral and cellular immune responses and potentiated more specifically the Th1 response profile by more efficient production of IFN-γ, interleukin-2, IgG2a, and nasal IgA. This study provides evidence of the potential of DC targeting for the development of new vaccines against a range of Apicomplexa parasites.
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8
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Li Y, Liu Y, Xiu F, Wang J, Cong H, He S, Shi Y, Wang X, Li X, Zhou H. Characterization of exosomes derived from Toxoplasma gondii and their functions in modulating immune responses. Int J Nanomedicine 2018; 13:467-477. [PMID: 29403276 PMCID: PMC5783023 DOI: 10.2147/ijn.s151110] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Introduction Exosomes are nanograde membrane-bound vesicles secreted from most cell types through the fusion of multivesicular bodies with plasma membranes. Some of these exosomes are well defined, and are known to have immunomodulatory properties as well as play critical roles in intercellular communications. In this study, we characterized the exosomes derived from Toxoplasma gondii and their functions in aspect of immune responses. Methods T. gondii exosomes were isolated and identified using electron microscopy, nanoparticle tracking analysis, and Western blotting. The viability of macrophage RAW264.7 cells affected by exosomes was evaluated using a Cell Counting Kit (CCK-8). Then the uptake of T. gondii exosomes by RAW264.7 cells was detected by labeling with fluorescent dye PKH67. After exosomes stimulation, in vitro the production of interleukin (IL)-12, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10 in RAW264.7 cells were investigated using enzyme-linked immunosorbent assay (ELISA). In immunized BALB/c mice, the antibodies, cytokines as well as the percentage of CD4+ and CD8+ T cells were determined using ELISA and flow cytometric analysis. Protective efficacy was evaluated by challenging intraperitoneally with tachyzoites of T. gondii. Results We successfully isolated and characterized the exosomes derived from T. gondii. Functionally, the viability of macrophage RAW264.7 cells was significantly affected by exosomes at a high concentration (160 μg/mL). The production of IL-12, TNF-α and IFN-γ in macrophage cells were increased, and the level of IL-10 was decreased. Furthermore, BALB/c mice immunized with T. gondii exosomes showed both humoral and cellular immune responses and also exhibited a prolonged survival time. Conclusion T. gondii exosomes could modulate macrophage activation in vitro and trigger humoral and cellular immune responses and partial protection against acute parasite infection in mice, which suggested that exosomes may serve as a potential candidate against toxoplasmosis.
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Affiliation(s)
- Yawen Li
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
| | - Yuan Liu
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China.,Clinical Laboratory, The People's Hospital of Changle, Shandong, People's Republic of China
| | - Fangming Xiu
- Translational Medicine, SickKids Research Institute, the Hospital for Sick Children Toronto, OT, Canada
| | - Jianing Wang
- Department of Immunology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
| | - Hua Cong
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
| | - Shenyi He
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
| | - Yongyu Shi
- Department of Immunology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
| | - Xiaoyan Wang
- Department of Immunology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
| | - Xun Li
- Department of Medicinal Chemistry, School of Pharmaceutical Sciences, Shandong University, Shandong, People's Republic of China
| | - Huaiyu Zhou
- Department of Pathogen Biology, School of Basic Medical Sciences, Shandong University, Shandong, People's Republic of China
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Yañuk JG, Alomar ML, Gonzalez MM, Alonso AM, Angel SO, Coceres VM, Cabrerizo FM. A comprehensive analysis of direct and photosensitized attenuation of Toxoplasma gondii tachyzoites. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2017; 177:8-17. [PMID: 29031212 DOI: 10.1016/j.jphotobiol.2017.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 09/26/2017] [Accepted: 10/05/2017] [Indexed: 12/11/2022]
Abstract
In the present work, we have evaluated the effect of three different types of radiation: UVC (254±5nm), UVA (365±20nm) and visible (420±20nm) on different morphological and biological functions of Toxoplasma gondii tachyzoites. Briefly, UVC and UVA showed an inhibitory effect on parasite invasion in a dose-dependent manner. UVC showed the strongest effect inducing both structural damage (antigens) and functional inhibition (i.e., invasion and replication). On its own, visible light induces a quite distinctive and selective pattern of parasite-attenuation. This type of incident radiation inhibits the replication of the parasite affecting neither the capability of invasion/attachment nor the native structure of proteins (antigens) on parasites. Such effects are a consequence of photosensitized processes where phenol red might act as the active photosensitizer. The potential uses of the methodologies investigated herein are discussed.
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Affiliation(s)
- Juan G Yañuk
- Laboratorio de Fotoquímica y Fotobiología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina
| | - M Lis Alomar
- Laboratorio de Fotoquímica y Fotobiología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina
| | - M Micaela Gonzalez
- Laboratorio de Fotoquímica y Fotobiología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina
| | - Andrés M Alonso
- Laboratorio de Parasitología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina
| | - Sergio O Angel
- Laboratorio de Parasitología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina
| | - Verónica M Coceres
- Laboratorio de Parasitología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina
| | - Franco M Cabrerizo
- Laboratorio de Fotoquímica y Fotobiología Molecular, Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad Nacional de San Martín (UNSAM) - Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Intendente Marino Km. 8.2, C.C 164, B7130IIWA Chascomús, Prov. Buenos Aires, Argentina.
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Review on the identification and role of Toxoplasma gondii antigenic epitopes. Parasitol Res 2015; 115:459-68. [PMID: 26581372 DOI: 10.1007/s00436-015-4824-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/10/2015] [Indexed: 12/12/2022]
Abstract
Toxoplasma gondii is an obligate intracellular protozoan parasite with a broad range of hosts, and it causes severe toxoplasmasis in both humans and animals. It is well known that the progression and severity of a disease depend on the immunological status of the host. Immunological studies on antigens indicate that antigens do not exert their functions through the entire protein molecule, but instead, specific epitopes are responsible for the immune response. Protein antigens not only contain epitope structures used by B, T, cytotoxic T lymphocyte (CTL), and NK cells to mediate immunological responses but can also contain structures that are unfavorable for protective immunity. Therefore, the study of antigenic epitopes from T. gondii has not only enhanced our understanding of the structure and function of antigens, the reactions between antigens and antibodies, and many other aspects of immunology but it also plays a significant role in the development of new diagnostic reagents and vaccines. In this review, we summarized the immune mechanisms induced by antigen epitopes and the latest advances in identifying T. gondii antigen epitopes. Particular attention was paid to the potential clinical usefulness of epitopes in this context. Through a critical analysis of the current state of knowledge, we elucidated the latest data concerning the biological effects of epitopes and the immune results aimed at the development of future epitope-based applications, such as vaccines and diagnostic reagents.
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Albarracín RM, Becher ML, Farran I, Sander VA, Corigliano MG, Yácono ML, Pariani S, López ES, Veramendi J, Clemente M. The fusion of Toxoplasma gondii SAG1 vaccine candidate to Leishmania infantum heat shock protein 83-kDa improves expression levels in tobacco chloroplasts. Biotechnol J 2015; 10:748-59. [PMID: 25823559 DOI: 10.1002/biot.201400742] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 02/12/2015] [Accepted: 03/25/2015] [Indexed: 11/12/2022]
Abstract
Chloroplast transformation technology has emerged as an alternative platform offering many advantages over nuclear transformation. SAG1 is the main surface antigen of the intracellular parasite Toxoplasma gondii and a promising candidate to produce an anti-T. gondii vaccine. The aim of this study was to investigate the expression of SAG1 using chloroplast transformation technology in tobacco plants. In order to improve expression in transplastomic plants, we also expressed the 90-kDa heat shock protein of Leishmania infantum (LiHsp83) as a carrier for the SAG1 antigen. SAG1 protein accumulation in transplastomic plants was approximately 0.1-0.2 μg per gram of fresh weight (FW). Fusion of SAG1 to LiHsp83 significantly increased the level of SAG1 accumulation in tobacco chloroplasts (by up to 500-fold). We also evaluated the functionality of the chLiHsp83-SAG1. Three human seropositive samples reacted with SAG1 expressed in transplastomic chLiHsp83-SAG1 plants. Oral immunization with chLiHsp83-SAG1 elicited a significant reduction of the cyst burden that correlated with an increase of SAG1-specific antibodies. We propose the fusion of foreign proteins to LiHsp83 as a novel strategy to increase the expression level of the recombinant proteins using chloroplast transformation technology, thus addressing one of the current challenges for this approach in antigen protein production.
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Affiliation(s)
- Romina M Albarracín
- Laboratorio de Biotecnología Vegetal, IIB-INTECH, CONICET-UNSAM, Chascomús, Provincia de Buenos Aires, Argentina
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12
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Hegazy S, Farid A, Rabae I, El-Amir A. Novel IMB-ELISA Assay for Rapid Diagnosis of Human Toxoplasmosis Using SAG1 Antigen. Jpn J Infect Dis 2015; 68:474-80. [DOI: 10.7883/yoken.jjid.2014.444] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
| | - Alyaa Farid
- Zoology Department, Science Faculty, Cairo University
| | | | - Azza El-Amir
- Zoology Department, Science Faculty, Cairo University
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13
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Allahyari M, Mohabati R, Babaie J, Amiri S, Siavashani ZJ, Zare M, Sadeghiani G, Golkar M. Production of in-vitro refolded and highly antigenic SAG1 for development of a sensitive and specific Toxoplasma IgG ELISA. J Immunol Methods 2014; 416:157-66. [PMID: 25437069 DOI: 10.1016/j.jim.2014.11.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/20/2014] [Accepted: 11/21/2014] [Indexed: 01/23/2023]
Abstract
Recombinant antigens are increasingly applied to replace native antigens in serological tests. Surface antigen 1 (SAG1) is a highly immunogenic antigen and probably represents the most explored and used antigen of Toxoplasma gondii for development of serological test kits. The presence of six disulfide bridges in its structure makes SAG1 a highly conformational protein. In fact, antigenicity of SAG1 is greatly dependent on proper disulfide bonding and folding. In-vitro refolding of SAG1 inclusion bodies, produced in Escherichia coli, was reported to result in soluble and antigenic protein. We produced SAG1 in E. coli and highly purified it by a single denaturing immobilized metal affinity chromatography. Refolding of denatured SAG1 was performed by (a) dialysis in the presence of reduced/oxidized glutathione, (b) drop-wise dilution and (c) drop-wise dilution in the presence of CuSo4. Refolding in the presence of oxido-shuffling reagent was much more efficient in producing presumably correctly-folded and highly antigenic SAG1 as demonstrated by non-reducing SDS-gel electrophoresis, ELISA, Western blotting and reversed-phase HPLC. An IgG ELISA developed using SAG1 refolded in the presence of oxido-shuffling reagent displayed high sensitivity and specificity for detection of Toxoplasma IgG antibodies in pregnant women.
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Affiliation(s)
- Mojgan Allahyari
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran; Recombinant Protein Production Department, Research and Production Complex, Pasteur Institute of Iran, Karaj, Iran
| | - Reyhaneh Mohabati
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Jalal Babaie
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Samira Amiri
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Zahra Jafari Siavashani
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Mehrak Zare
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Ghazaleh Sadeghiani
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Majid Golkar
- Molecular Parasitology Laboratory, Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran.
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14
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Research progress on surface antigen 1 (SAG1) of Toxoplasma gondii. Parasit Vectors 2014; 7:180. [PMID: 24726014 PMCID: PMC3989796 DOI: 10.1186/1756-3305-7-180] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/04/2014] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is an obligate intracellular parasitic protozoan that has a wide host range and causes a zoonotic parasitosis called toxoplasmosis. This infection causes significant morbidity, costs for care and loss of productivity and suffering. The most effective measures to minimize this parasite’s harm to patients are prompt diagnosis and treatment and preventing infection. A parasite surface antigen, SAG1, is considered an important antigen for the development of effective diagnostic tests or subunit vaccines. This review covers several aspects of this antigen, including its gene structure, contribution to host invasion, mechanisms of the immune responses and its applications for diagnosis and vaccine development. This significant progress on this antigen provides foundations for further development of more effective and precise approaches to diagnose toxoplasmosis in the clinic, and also have important implications for exploring novel measures to control toxoplasmosis in the near future.
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15
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Wang Y, Wang G, Zhang D, Yin H, Wang M. Screening and identification of novel B cell epitopes of Toxoplasma gondii SAG1. Parasit Vectors 2013; 6:125. [PMID: 23631709 PMCID: PMC3655890 DOI: 10.1186/1756-3305-6-125] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 04/26/2013] [Indexed: 11/24/2022] Open
Abstract
Background The identification of protein epitopes is useful for diagnostic purposes and for the development of peptide vaccines. In this study, the epitopes of Toxoplasma gondii SAG1 were identified using synthetic peptide techniques with the aid of bioinformatics. Findings Eleven peptides derived from T. gondii SAG1 were assessed by ELISA using pig sera from different time points after infection. Four (PS4, PS6, PS10 and PS11), out of the eleven peptides tested were recognized by all sera. Then, shorter peptides that were derived from PS4, PS6, PS10 and PS11 were predicted using bioinformatics and tested by experimentation. Four out of nine shorter peptides were identified successfully (amino acids 106–120, 166–180, 289–300 and 313–332). Conclusions We have precisely located the epitopes of T. gondii SAG1 using pig sera collected at different time points after infection. The identified epitopes may be useful for the further study of epitope-based vaccines and diagnostic reagents.
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Affiliation(s)
- Yanhua Wang
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou, 730046, China.
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16
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Cardona N, de-la-Torre A, Siachoque H, Patarroyo MA, Gomez-Marin JE. Toxoplasma gondii: P30 peptides recognition pattern in human toxoplasmosis. Exp Parasitol 2009; 123:199-202. [PMID: 19567250 DOI: 10.1016/j.exppara.2009.06.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 06/20/2009] [Accepted: 06/23/2009] [Indexed: 11/30/2022]
Abstract
In this study, human sera reactivity against nine peptides derived from the Toxoplasma gondii P30 protein was assessed by ELISA in patients with different clinical forms of toxoplasmosis. Same as has been reported in mice, sera from congenital, ocular and chronic asymptomatic toxoplasmosis patients recognized more strongly peptides from the protein's carboxy-terminus, being peptide 2017 (amino acids 301-320) the one most strongly recognized by sera from patients with ocular toxoplasmosis. Serum samples collected from 13 patients without ocular infection, 13 with inactive chorioretinal scars, 6 with active ocular infection and 10 seronegative individuals were then screened for anti-2017 IgG. Peptide 2017 was recognized by all patients' samples but not by sera from T. gondii-seronegative individuals. No statistically significant differences were found between the absorbance levels of groups with and without lesions or with active or inactive ocular lesions, as determined by ANOVA.
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Affiliation(s)
- Nestor Cardona
- Centro de Investigaciones Biomedicas, Universidad del Quindio, Armenia, Colombia
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17
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Liu S, Shi L, Cheng YB, Fan GX, Ren HX, Yuan YK. Evaluation of protective effect of multi-epitope DNA vaccine encoding six antigen segments of Toxoplasma gondii in mice. Parasitol Res 2009; 105:267-74. [PMID: 19288132 DOI: 10.1007/s00436-009-1393-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Accepted: 03/03/2009] [Indexed: 11/28/2022]
Abstract
To investigate the vaccine potential of multi-epitope vaccines against toxoplasmosis, a multi-epitope DNA vaccine, eukaryotic plasmid pcDNA3.1/T-ME expressing six antigen segments (SAG1(238-256), SAG1(281-320), GRA1(170-193), GRA4(331-345), GRA4(229-245), and GRA2(171-185)) of Toxoplasma gondii was constructed. We investigated the efficacy of pcDNA3.1/T-ME with or without co-administration of a CpG-oligodeoxynucleotide (CpG-ODN) as an adjuvant to protect mice (BALB/c and C57BL/6) against toxoplasmosis. High survival rates were observed in mice immunized with pcDNA3.1/T-ME when challenged with T. gondii RH strain. Lymphocyte proliferation assays, cytokine, and antibody determinations show that mice immunized with pcDNA3.1/T-ME produced stronger humoral and Th1-type cellular immune responses compared to untreated mice or those immunized with empty plasmids. However, co-immunization with CpG-ODN resulted in impaired immune responses. Our data demonstrates that multi-epitope DNA vaccination is a potential strategy for the control of toxoplasmosis and paves the way for further investigations into producing a multi-epitope anti-T. gondii DNA vaccine.
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Affiliation(s)
- Shan Liu
- Department of Immunology and Microbiology, Xi'an Jiaotong University, China
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18
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Gatkowska J, Hiszczynska-Sawicka E, Kur J, Holec L, Dlugonska H. Toxoplasma gondii: An evaluation of diagnostic value of recombinant antigens in a murine model. Exp Parasitol 2006; 114:220-7. [DOI: 10.1016/j.exppara.2006.03.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 03/15/2006] [Accepted: 03/25/2006] [Indexed: 11/16/2022]
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19
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van Dijk ADJ, de Vries SJ, Dominguez C, Chen H, Zhou HX, Bonvin AMJJ. Data-driven docking: HADDOCK's adventures in CAPRI. Proteins 2006; 60:232-8. [PMID: 15981252 DOI: 10.1002/prot.20563] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have shown previously that given high-resolution structures of the unbound molecules, structure determination of protein complexes is possible by including biochemical and/or biophysical data as highly ambiguous distance restraints in a docking approach. We applied this method, implemented in the HADDOCK (High Ambiguity Driven DOCKing) package (Dominguez et al., J Am Chem Soc 2003;125:1731-1737), to the targets in the fourth and fifth rounds of CAPRI. Here we describe our results and analyze them in detail. Special attention is given to the role of flexibility in our docking method and the way in which this improves the docking results. We describe extensions to our approach that were developed as a direct result of our participation in CAPRI. In addition to experimental information, we also included interface residue predictions from PPISP (Protein-Protein Interaction Site Predictor; Zhou and Shan, Proteins 2001;44:336-343), a neural network method. Using HADDOCK we were able to generate acceptable structures for 6 of the 8 targets, and to submit at least 1 acceptable structure for 5 of them. Of these 5 submissions, 3 were of medium quality (Targets 10, 11, and 15) and 2 of high quality (Targets 13 and 14). In all cases, predictions were obtained containing at least 40% of the correct epitope at the interface for both ligand and receptor simultaneously.
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Affiliation(s)
- A D J van Dijk
- Department of NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, The Netherlands
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20
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Daily MD, Masica D, Sivasubramanian A, Somarouthu S, Gray JJ. CAPRI rounds 3-5 reveal promising successes and future challenges for RosettaDock. Proteins 2006; 60:181-6. [PMID: 15981262 DOI: 10.1002/prot.20555] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
CAPRI Rounds 3, 4, and 5 are the first public test of the published RosettaDock algorithm. The targets cover a wide range of sizes and shapes. For most targets, published biological information indicated the region of the binding site on at least one docking partner. The RosettaDock algorithm produced high accuracy predictions for three targets, medium-accuracy predictions for two targets, and an acceptable prediction for one target. RosettaDock predicted all five targets with less than 450 residues to high or medium accuracy, but it predicted only one of seven targets with above 450 residues to acceptable accuracy. RosettaDock's high-accuracy predictions for small to moderately large targets reveal the predictive power and fidelity of the algorithm, especially the high-resolution refinement and scoring protocol. In addition, RosettaDock can predict complexes from at least one homology-modeled docking partner with comparable accuracy to unbound cases of similar size. Larger targets present a more intensive sampling problem, and some large targets present repulsive barriers to entering the binding site. Ongoing improvements to RosettaDock's low-resolution search may alleviate this problem. This first public test suggests that RosettaDock can be useful in a significant range of applications in biochemistry and cell biology.
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Affiliation(s)
- Michael D Daily
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA
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21
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Graille M, Stura EA, Bossus M, Muller BH, Letourneur O, Battail-Poirot N, Sibaï G, Gauthier M, Rolland D, Le Du MH, Ducancel F. Crystal Structure of the Complex between the Monomeric Form of Toxoplasma gondii Surface Antigen 1 (SAG1) and a Monoclonal Antibody that Mimics the Human Immune Response. J Mol Biol 2005; 354:447-58. [PMID: 16242717 DOI: 10.1016/j.jmb.2005.09.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 09/01/2005] [Accepted: 09/02/2005] [Indexed: 11/21/2022]
Abstract
Toxoplasma gondii, the intracellular parasite responsible for toxoplasmosis infects more than one-third of the world population and can be life-threatening for fetuses and immunocompromised patients. The surface protein SAG1 is an important immune target, which provides a strong immune response against the invasive tachyzoite while the other forms of the parasite, devoid of SAG1 at their surface, are multiplying. In addition to this role as a "hot spot" decoy, SAG1 is predicted to act as an adhesin during host-cell attachment through its binding to proteoglycans. To begin to understand the relationships between SAG1 epitopes and the ligand-binding site, we have solved the crystal structure of the monomeric form of T.gondii SAG1 complexed to a Fab derived from a monoclonal antibody raised against tachyzoite particles. This antibody competes strongly with human Toxoplasma-specific sera, suggesting that its epitope is part of an immunodominant region present on the surface of SAG1. The structure reveals that this conformational epitope, located within the SAG1 N-terminal domain, does not overlap with the proposed ligand-binding pocket. This study provides the first structural description of the monomeric form of SAG1, and significant insights into its dual role of adhesin and immune target during parasite infection.
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Affiliation(s)
- Marc Graille
- Département d'Ingénierie et d'Etudes des Protéines, Centre d'Etudes de Saclay, 91191 Gif-sur-Yvette, France
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22
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Smith GR, Fitzjohn PW, Page CS, Bates PA. Incorporation of flexibility into rigid-body docking: Applications in rounds 3-5 of CAPRI. Proteins 2005; 60:263-8. [PMID: 15981258 DOI: 10.1002/prot.20568] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We have submitted models for all 9 targets in Rounds 3-5 of CAPRI and have predicted at least 30% of the correct contacts for 4 of the targets and at least 10% of the correct contacts for another 4 targets. We have employed a variety of techniques but have had the greatest success by combining established rigid-body docking with a variety of initial conformations generated by molecular dynamics.
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Affiliation(s)
- Graham R Smith
- Biomolecular Modelling Laboratory, Cancer Research U.K. London Research Institute, Lincoln's Inn Fields Laboratories, London, United Kingdom
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23
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Pinitkiatisakul S, Mattsson JG, Wikman M, Friedman M, Bengtsson KL, Ståhl S, Lundén A. Immunisation of mice against neosporosis with recombinant NcSRS2 iscoms. Vet Parasitol 2005; 129:25-34. [PMID: 15817199 DOI: 10.1016/j.vetpar.2004.12.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 11/26/2004] [Accepted: 12/02/2004] [Indexed: 10/25/2022]
Abstract
The coccidian parasite Neospora caninum is an intracellular protozoan, causing abortion in cattle in many countries around the world. In this study, the protective potential of the major N. caninum surface antigen NcSRS2, expressed in Escherichia coli and formulated into immunostimulating complexes (iscoms), was investigated in an experimental mouse model. The recombinant protein was specially designed for binding to iscoms via biotin-streptavidin interaction. Two groups of 10 BALB/c mice were immunised twice, on days 0 and 28 with iscoms containing either the recombinant NcSRS2 (NcSRS2 iscoms) or similar iscoms with NcSRS2 substituted by an unrelated recombinant malaria peptide (M5) as a control (M5 iscoms). A third group of 10 age-matched BALB/c mice served as an uninfected control group. Immunisation with recombinant NcSRS2 iscoms resulted in production of substantial antibody titres against N. caninum antigen, while the mice immunised with M5 iscoms produced only very low levels of antibodies reacting with N. caninum antigen. After challenge infection with N. caninum tachyzoites on day 69, mice immunised with NcSRS2 iscoms showed only mild and transient symptoms, whereas the group immunised with M5 iscoms showed clinical symptoms until the end of the experiment at 31 days post inoculation. A competitive PCR assay detecting Nc5-repeats was applied to evaluate the level of parasite DNA in the brain. The amount of Nc5-repeats in the group vaccinated with NcSRS2 iscoms was significantly lower than in the control group given M5 iscoms. In conclusion, it was found that the recombinant NcSRS2 iscoms induced specific antibodies to native NcSRS2 and immunity sufficient to reduce the proliferation of N. caninum in the brains of immunised mice.
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Affiliation(s)
- Sunan Pinitkiatisakul
- Department of Parasitology (SWEPAR), National Veterinary Institute and Swedish University of Agricultural Sciences, SE-751 89 Uppsala, Sweden.
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24
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Nigro M, Gutierrez A, Hoffer AM, Clemente M, Kaufer F, Carral L, Martin V, Guarnera EA, Angel SO. Evaluation of Toxoplasma gondii recombinant proteins for the diagnosis of recently acquired toxoplasmosis by an immunoglobulin G analysis. Diagn Microbiol Infect Dis 2004; 47:609-13. [PMID: 14711483 DOI: 10.1016/s0732-8893(03)00156-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The value of T. gondii recombinant antigens rRop2, rGra4, rGra7 and rSAG1m (mature version) or rSAG1ct (C-terminal version) in differentiating recently acquired from chronic infections was determined by IgG-ELISA. The general highest sensitivity was observed with rRop2 whereas rSAG1m was not recognized by any of the serum samples, suggesting an incorrect folding. rGra4 and rGra7 showed significant higher sensitivity and absorbance values with serum samples from recently infected individuals compared to those with chronic infection. In contrast, rRop2 and rSAG1ct did not show differences in the reactivity pattern between both groups of serum samples.
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Affiliation(s)
- Monica Nigro
- Departamento de Parasitología, ANLIS Dr. Carlos G. Malbran, Av. Velez Sarsfield 563, 1281-Ciudad Autónoma de, Buenos Aires, Argentina
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25
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Meek B, Diepersloot RJ, van Gool T, Speijer D, Peek R. Igm recognition of recombinant Toxoplasma gondii antigens by sera of acutely or latently infected humans. Diagn Microbiol Infect Dis 2003; 45:45-52. [PMID: 12573550 DOI: 10.1016/s0732-8893(02)00476-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Clinical non-relevant (CNR) IgM specific for Toxoplasma gondii is responsible for false-positive results in commercially available IgM assays. Using IgM immunoblotting, it is possible to distinguish between IgM in sera of acutely infected (AI) patients and CNR IgM. Especially the combination of staining of a 55 and 30 kD antigen in T.gondii lysate proved useful in this respect. The 55 kD antigen was identified as Rop1, while the 30 kD antigen was confirmed to be Sag1. However, the use of recombinant antigens instead of lysates for diagnostic assays would improve reproducibility. IgM recognized recombinant Rop1, but most CNR sera also had low anti-Rop1 titers. Although purified native Sag1 separated AI and CNR sera very well on immunoblot, IgM did not recognize recombinant Sag1 at all. Clearly, it is difficult to produce a recombinant Sag1 that can be recognized by IgM. Recombinant Rop1 might be suitable as one of the recombinant antigens in an IgM immunoblot assay, but has to be combined with at least one other immunogenic antigen.
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Affiliation(s)
- Bob Meek
- Department of Molecular Immunology, The Netherlands Ophthalmic Research Institute, Amsterdam, The Netherlands
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26
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Gupta GD, Lakritz J, Kim JH, Kim DY, Kim JK, Marsh AE. Seroprevalence of Neospora, Toxoplasma gondii and Sarcocystis neurona antibodies in horses from Jeju island, South Korea. Vet Parasitol 2002; 106:193-201. [PMID: 12062508 DOI: 10.1016/s0304-4017(02)00064-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Parasite-specific antibody responses to Neospora spp. and Toxoplasma gondii, antigens were detected using the indirect fluorescent antibody test (IFAT) and immunoblot analysis in a korean equine population located on Jeju island, South Korea (126 degrees 12' E and 33 degrees 34' N). For comparison, a naturally infected Neospora hughesi horse and an experimentally inoculated T. gondii equid (pony) were used. In addition, all samples were tested for antibodies to Sarcocystis neurona by immunoblot analysis. A total of 191 serum samples from clinically normal horses were evaluated. Only 2% (4 out of 191) and 2.6% (5 out of 191) of the samples had showed reactivity at 1:100 using the IFAT for Neospora spp. and T. gondii, respectively. For T. gondii, two samples matched the antigen banding pattern of the positive control by immunoblot analysis. No sample was positive for N. hughesi by immunoblot analysis in this study. Overall, there was a 1% seroprevalence for T. gondii antibodies in the horses tested based on immunoblot analysis. The seroprevalence for S. neurona and N. hughesi antibodies was 0%. We concluded that these horses are either not routinely exposed to these parasites or antibody titers are not sufficiently elevated to be detectable. It is most likely the former explanation since Jeju island equine farms are isolated from the main land, and the horses were all less than 3 years of age. This naïve population of horses could be useful when evaluating S. neurona serodiagnostic tests or evaluating potential S. neurona vaccines since exposure risks to S. neurona and closely related parasites are negligible.
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Affiliation(s)
- G D Gupta
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Connaway Hall, 1600 East Rollins Dr., Columbia, MO 65211, USA
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27
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Chen XG, Gong Y, Lun ZR, Fung MC. High-level expression and purification of immunogenic recombinant SAG1 (P30) of Toxoplasma gondii in Escherichia coli. Protein Expr Purif 2001; 23:33-7. [PMID: 11570843 DOI: 10.1006/prep.2001.1483] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Surface antigen 1 (SAG1) of Toxoplasma gondii is a good candidate for diagnosis and vaccine development, but recombinant SAG1 produced in Escheichia coli often loses its specific immunogenicity due to the incorrect folding. In the present study, a truncated SAG1 was highly expressed in E. coli as a fusion protein, about 30% of the total protein of the cell lysate. After a simple purification and refolding procedure, purified rSAG1 can be recognized by human Toxoplasma-infective serum, and ELISA kits constructed by rSAG1 can sensitively and specifically detect toxoplasma infection.
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Affiliation(s)
- X G Chen
- Department of Parasitology, First Military Medical University, Guang ZhoU, 510515, People's Republic of China
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28
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Velge-Roussel F, Dimier-Poisson I, Buzoni-Gatel D, Bout D. Anti-SAG1 peptide antibodies inhibit the penetration of Toxoplasma gondii tachyzoites into enterocyte cell lines. Parasitology 2001; 123:225-33. [PMID: 11578086 DOI: 10.1017/s0031182001008460] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The initial attachment of Toxoplasma tachyzoites to the target host cell is an important event in the life-cycle of the parasite and a critical stage in infection. Previous studies have shown that polyclonal antibodies directed against the major surface antigen of Toxoplasma gondii (SAG1) inhibit the infection of enterocyte cell lines. Here, we demonstrate that antibodies raised against a central peptide (V41T) of SAG1 and the SAGI protein itself are able to inhibit the infection of various cell lines by the tachyzoites. Antibodies directed against SAG1 peptides were used to define a site on the SAGI antigen that interacts with the host cell. The epitope carried by V41T was identified on the tachyzoite surface by immunofluorescence. The peptide sequence seems to be conserved in all the members of the SAGI Related Sequence family (SRS). Using undifferentiated and differentiated Caco-2 cells, we found that tachyzoites enter preferentially via the basolateral side of the cell. These findings highlight the role of the SRS family members in the mediation of host cell invasion.
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Affiliation(s)
- F Velge-Roussel
- UMR UNIVERSITE-INRA d'Immunologie Parasitaire, UFR des Sciences Pharmaceutiques, Tours, France.
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Chaves-Borges FA, Souza MA, Silva DA, Kasper LH, Mineo JR. Detection of Toxoplasma gondii soluble antigen, SAG-1(p30), antibody and immune complex in the cerebrospinal fluid of HIV positive or negative individuals. Rev Inst Med Trop Sao Paulo 1999; 41:329-38. [PMID: 10671285 DOI: 10.1590/s0036-46651999000600001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Active infection by T. gondii was evaluated by immunoassay for soluble SAG-1 (p30), the major surface antigen from T. gondii, specific antibodies and immune complexes in human cerebrospinal fluid (CSF) samples. A total of 263 samples of CSF were collected from hospitalized patients presenting neurological disorders and analyzed for antibodies to HIV. Patients were divided into two groups: HIV positive (n = 96) or HIV negative (n =167). The results of the assays showed that 45% of all samples were positive for soluble SAG-1. Toxoplasma Ag/Ab immune complexes were detected in 19% of the CSF samples and 62% were positive for T. gondii- specific IgG. A combination of these assays in the presence of clinical findings consistent with active Toxoplasma infection may predict the presence of toxoplasmic encephalitis. Moreover, detection of soluble SAG-1 in the CSF of these individuals appears consistent with active infection.
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Affiliation(s)
- F A Chaves-Borges
- Laboratory of Immunology, Department of Pathology, Universidade Federal de Uberlândia, Uberlândia, MG, 38400-902, Brazil
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30
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Hunter S, Ashbaugh L, Hair P, Bozic CM, Milhausen M. Baculovirus-directed expression and secretion of a truncated version of Toxoplasma SAG1. Mol Biochem Parasitol 1999; 103:267-72. [PMID: 10551369 DOI: 10.1016/s0166-6851(99)00119-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- S Hunter
- Heska Corporation, Ft. Collins, CO 80525, USA
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Villavedra M, Battistoni J, Nieto A. IgG recognizing 21-24 kDa and 30-33 kDa tachyzoite antigens show maximum avidity maturation during natural and accidental human toxoplasmosis. Rev Inst Med Trop Sao Paulo 1999; 41:297-303. [PMID: 10602544 DOI: 10.1590/s0036-46651999000500006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We describe the avidity maturation of IgGs in human toxoplasmosis using sequential serum samples from accidental and natural infections. In accidental cases, avidity increased continuously throughout infection while naturally infected patients showed a different profile. Twenty-five percent of sera from chronic patients having specific IgM positive results could be appropriately classified using exclusively the avidity test data. To take advantage of the potentiality of this technique, antigens recognized by IgG showing steeper avidity maturation were identified using immunoblot with KSCN elution. Two clusters of antigens, in the ranges of 21-24 kDa and 30-33 kDa, were identified as the ones that fulfill the aforementioned avidity characteristics.
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Affiliation(s)
- M Villavedra
- Facultad de Química, Cátedra de Inmunología, Montevideo, Uruguay.
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Jacobs D, Vercammen M, Saman E. Evaluation of recombinant dense granule antigen 7 (GRA7) of Toxoplasma gondii for detection of immunoglobulin G antibodies and analysis of a major antigenic domain. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 1999; 6:24-9. [PMID: 9874659 PMCID: PMC95655 DOI: 10.1128/cdli.6.1.24-29.1999] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dense granule protein 7 (GRA7) of Toxoplasma gondii was expressed in Escherichia coli as a fusion protein. The leader peptide contained a 25-amino-acid mouse tumor necrosis factor fragment and six histidyl residues. After purification by metal chelate affinity chromatography, the antigen was evaluated in an enzyme-linked immunosorbent assay for detection of immunoglobulin G (IgG). For two sets of IgG-positive human serum samples, obtained from routine screening, an overall sensitivity of 81% was obtained. For chronic-phase sera, the sensitivity of detection was 79%, but chronic-phase sera with low titers were more difficult to detect (65% sensitivity for sera with immunofluorescence titer of 1/64). When GRA7 was combined with Tg34AR (rhoptry protein 2 C-terminal fragment), the sensitivity rose to 96%. For a set of acute-phase serum samples tested on GRA7, the sensitivity of detection was 94%, and high-titer IgM-positive sera were detected at an especially high rate. In contrast, when Tg34AR was used, the sensitivity was only 85% for this latter set of serum samples. Three truncated GRA7 fragments containing the same leader peptide as that of recombinant GRA7 were produced. The shortest fragment (97 N-terminal amino acids) was not reactive with human sera or with a specific anti-GRA7 monoclonal antibody, while the two larger fragments were reactive. The most important antigenic domain of GRA7 for human sera was localized between residues 97 and 146. The epitope for the specific monoclonal antibody could be further narrowed down by the use of synthetic peptides, but this epitope is not recognized by sera from T. gondii-infected humans. These results indicate that GRA7 may be considered as an additional tool for studying the immune response to T. gondii.
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Affiliation(s)
- D Jacobs
- Innogenetics NV, Ghent B-9052, Belgium.
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Feng S, Woo PT. Biochemical characterisation of an epitope on the surface membrane antigen (Cs-gp200) of the pathogenic piscine haemoflagellate Cryptobia salmositica Katz 1951. Exp Parasitol 1998; 88:3-10. [PMID: 9501843 DOI: 10.1006/expr.1998.4202] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A protective surface antigen (200 kDa) on C. salmositica was detected using a monoclonal antibody (mAb-001). Enzymatic studies on the epitope indicated that it was sensitive to nonspecific protease K and to site-specific trypsin and protease V8 but not to alpha-chymotrypsin. The reactivity of the epitope with mAb-001 was not affected when the antigen was denatured with 8 M urea; however, reduction of the antigen with dithiothreitol destroyed the epitope. The epitope was susceptible to sodium m-periodate oxidation and N-glycosidase F, but not to O-glycosidase or neuraminidase. It was also sensitive to mild potassium hydrochloride hydrolysis and to phospholipase C, which is specific for phosphatidylinositol. These results suggest that the epitope consists of a polypeptide, a carbohydrate, and probably a phospholipid. The asparagine-bound N-glycosidically linked hybrid-type carbohydrate chain has the minimum length of a chitobiose core unit. There is probably a phosphatidylinositol residue which anchors the polypeptide to the surface membrane. The antigen is extensively posttranslationally modified.
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Affiliation(s)
- S Feng
- Department of Zoology, University of Guelph, Ontario, Canada
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Velge-Roussel F, Moretto M, Buzoni-Gatel D, Dimier-Poisson I, Ferrer M, Hoebeke J, Bout D. Differences in immunological response to a T. gondii protein (SAG1) derived peptide between two strains of mice: effect on protection in T. gondii infection. Mol Immunol 1997; 34:1045-53. [PMID: 9519763 DOI: 10.1016/s0161-5890(97)00133-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This study presents the analysis of the immunogenicity, antigenicity and protective effects of a peptide derived from the major surface antigen of Toxoplasma gondii, SAG1. This synthetic peptide carrying three predicted H-2k restricted T cell epitopes was used to immunize mice. The protective effect of the peptide was evaluated in CBA/J and C57BL/6 mice using the decrease in brain cyst load as evidence of protection. Immunization of C57BL/6 mice yielded high antibody titres but had no protective effect after oral challenge. Immunized CBA/J, mice which responded with a lower titre, showed a 35% reduction in cyst burden after oral challenge. Both strains yielded antibodies which recognized the cognate SAG1 protein on immunoblot assay. Using the BIAcore, system, it was shown that at lower titres the CBA/J mouse sera recognized the native SAG1 protein more effectively than the C57BL/6 mouse sera, yielding much higher anti-peptide titres. Lymphoproliferation assays using the peptide experimentally confirmed the predicted T-cell epitopes and showed that they were also recognized by cells of T. gondii infected mice. The anti-peptide subclass analysis suggested a Th1 orientation in CBA/J mice, whereas a Th2 orientation was observed in C57BL/6 mice. Finally, fine analysis of sequences recognized under MHC class I indicated the existence of a T-cell epitope in the H-2k haplotype (CBA/J mice) but not in the H-2b haplotype (C57BL/6 mice). This study provides a structural basis to the understanding of the vaccination response to one of the T. gondii antigens in different strains of mice.
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Affiliation(s)
- F Velge-Roussel
- CJF INSERM 93-09 Immunologie des Maladies Infectieuses, Equipe associée INRA d'Immunologie Parasitaire, UFR des Sciences Pharmaceutiques, Tours, France.
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Saavedra R, Becerril MA, Dubeaux C, Lippens R, De Vos MJ, Hérion P, Bollen A. Epitopes recognized by human T lymphocytes in the ROP2 protein antigen of Toxoplasma gondii. Infect Immun 1996; 64:3858-62. [PMID: 8751939 PMCID: PMC174303 DOI: 10.1128/iai.64.9.3858-3862.1996] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The ROP2 protein of Toxoplasma gondii possesses immunological and biological properties which have led to its proposal as a vaccine candidate. To identify epitopes recognized by human T cells in the ROP2 antigen, we submitted the sequence of this protein to three reported T-cell epitope prediction algorithms. Three sequences that were predicted by all three methods were selected (sequences 197 to 216, 393 to 410, and 501 to 524), and the corresponding peptides were synthesized. The peptides were first tested in a proliferation assay with a DPw4-restricted, ROP2-specific human T-cell clone, and the peptide corresponding to residues 197 to 216 was shown to stimulate the T-cell clone. The three peptides were further tested in proliferation assays with peripheral blood mononuclear cells from a panel of T. gondii-seropositive and -seronegative individuals. We found that cells from a high proportion of the seropositive donors (64%) recognized at least one of the three peptides. The most frequently recognized ones were peptides 197 to 216 (45%) and 501 to 524 (36%). None of the seronegative donors responded to any peptide. These results show that the ROP2 antigen of T. gondii contains T-cell epitopes recognized by a high percentage of the immune population and further strengthen its potential as a vaccine candidate.
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Affiliation(s)
- R Saavedra
- Departmento de Inmunologia, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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Nam HW, Im KS, Baek EJ, Choi WY, Cho SY. Analysis of antigenic domain of GST fused major surface protein (p30) fragments of Toxoplasma gondii. THE KOREAN JOURNAL OF PARASITOLOGY 1996; 34:135-41. [PMID: 8925246 DOI: 10.3347/kjp.1996.34.2.135] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Antigenic domain of major surface protein (p30) of Toxoplasma gondii was analyzed after polymerase chain reaction (PCR) of its gene fragments. Hydrophilic or hydrophobic moiety of amino acid sequences were expressed as glutathione S-transferase (GST) fusion proteins. Fragments of p30 gene were as follows: T37, total p30 open reading frame (ORF); S28, total ORF excluding N-terminal signal sequence and C-terminal hydrophobic sequence: A19, N-terminal 2/3 parts of S28; P19, C-terminal 2/3 of S28; X9, N-terminal 1/3 part of S28; Y10, middle 1/3 of S28; and Z9, C-terminal 1/3 of S28, respectively. Primer of each fragment was synthesized to include clamp sequence of EcoR I restriction site. PCR amplified DNA was inserted into GST (26 kDa) expression vector, pGEX-4T-1 to transform into Escherichia coli (JM105 strain). GST fusion proteins were expressed with IPTG induction as 63, 54, 45, 45, 35, 36, and 35 kDa proteins measured by SDS-PAGE. Each fusion protein was confirmed with GST detection kit. Western blot analysis with the serum of a toxoplasmosis patient revealed antigenicity in proteins expressed by T37, S28, and A19 but not those by P18, X9, Y10, and Z9. Antigenicity of p30 seems to be located either in N-terminal 1/3 part in the presence of middle 1/3 part or in the oligopeptides between margins of the first and second 1/3 parts.
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Affiliation(s)
- H W Nam
- Department of Parasitology, Catholic University of Korea, School of Medicine, Seoul, Korea
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Harning D, Spenter J, Metsis A, Vuust J, Petersen E. Recombinant Toxoplasma gondii surface antigen 1 (P30) expressed in Escherichia coli is recognized by human Toxoplasma-specific immunoglobulin M (IgM) and IgG antibodies. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 1996; 3:355-7. [PMID: 8705683 PMCID: PMC170346 DOI: 10.1128/cdli.3.3.355-357.1996] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The immunodominant surface antigen of Toxoplasma gondii, surface antigen 1 (SAG1), was expressed in Escherichia coli as a fusion protein containing a majority of the SAG1 protein supplied with six histidyl residues in the N-terminal end. The recombinant protein was purified on a Ni-chelate column and then on a fast-performance liquid chromatography column and was in a nonreduced condition. It was recognized by T. gondii-specific human immunoglobulin G (IgG) and IgM antibodies as well as by a mouse monoclonal antibody (S13) recognizing only nonreduced native SAG1. Antibodies induced in mice by the recombinant SAG1 recognized native SAG1 from the T. gondii RH isolate in culture. Recombinant SAG1 is suitable for use in diagnostic systems for detecting anti-SAG1-specific IgG and IgM antibodies.
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Affiliation(s)
- D Harning
- Laboratory of Molecular Biology, Statens Seruminstitut, Copenhagen, Denmark
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