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Chen WX, Chen YR, Peng MZ, Liu X, Cai YN, Huang ZF, Yang SY, Huang JY, Wang RH, Yi P, Liu L. Plasma Amino Acid Profile in Children with Autism Spectrum Disorder in Southern China: Analysis of 110 Cases. J Autism Dev Disord 2024; 54:1567-1581. [PMID: 36652126 PMCID: PMC10981617 DOI: 10.1007/s10803-022-05829-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2022] [Indexed: 01/19/2023]
Abstract
To retrospectively explore the characteristics of plasma amino acids (PAAs) in children with autism spectrum disorder and their clinical association via case-control study. A total of 110 autistic and 55 healthy children were recruited from 2014 to 2018. The clinical phenotypes included severity of autism, cognition, adaptability, and regression. Compared with the control group, autistic children had significantly elevated glutamate, γ-Amino-n-butyric acid, glutamine, sarcosine, δ-aminolevulinic acid, glycine and citrulline. In contrast, their plasma level of ethanolamine, phenylalanine, tryptophan, homocysteine, pyroglutamic acid, hydroxyproline, ornithine, histidine, lysine, and glutathione were significantly lower. Elevated neuroactive amino acids (glutamate) and decreased essential amino acids were mostly distinct characteristics of PAAs of autistic children. Increased level of tryptophan might be associated with severity of autism.
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Affiliation(s)
- Wen-Xiong Chen
- Department of Neurology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China.
- The Assessment and Intervention Center for Autistic Children, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China.
| | - Yi-Ru Chen
- Department of Neurology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Min-Zhi Peng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Xian Liu
- Division of Birth Cohort Study, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Yan-Na Cai
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Zhi-Fang Huang
- Department of Neurology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
- The Assessment and Intervention Center for Autistic Children, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Si-Yuan Yang
- Department of Neurology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
- The Assessment and Intervention Center for Autistic Children, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Jing-Yu Huang
- Department of Neurology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
- The Assessment and Intervention Center for Autistic Children, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Ruo-Han Wang
- Department of Neurology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Peng Yi
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
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Tarannum A, Rodríguez-Almonacid CC, Salazar-Bravo J, Karamysheva ZN. Molecular Mechanisms of Persistence in Protozoan Parasites. Microorganisms 2023; 11:2248. [PMID: 37764092 PMCID: PMC10534552 DOI: 10.3390/microorganisms11092248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/31/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Protozoan parasites are known for their remarkable capacity to persist within the bodies of vertebrate hosts, which frequently results in prolonged infections and the recurrence of diseases. Understanding the molecular mechanisms that underlie the event of persistence is of paramount significance to develop innovative therapeutic approaches, given that these pathways still need to be thoroughly elucidated. The present article provides a comprehensive overview of the latest developments in the investigation of protozoan persistence in vertebrate hosts. The focus is primarily on the function of persisters, their formation within the host, and the specific molecular interactions between host and parasite while they persist. Additionally, we examine the metabolomic, transcriptional, and translational changes that protozoan parasites undergo during persistence within vertebrate hosts, focusing on major parasites such as Plasmodium spp., Trypanosoma spp., Leishmania spp., and Toxoplasma spp. Key findings of our study suggest that protozoan parasites deploy several molecular and physiological strategies to evade the host immune surveillance and sustain their persistence. Furthermore, some parasites undergo stage differentiation, enabling them to acclimate to varying host environments and immune challenges. More often, stressors such as drug exposure were demonstrated to impact the formation of protozoan persisters significantly. Understanding the molecular mechanisms regulating the persistence of protozoan parasites in vertebrate hosts can reinvigorate our current insights into host-parasite interactions and facilitate the development of more efficacious disease therapeutics.
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Affiliation(s)
| | | | | | - Zemfira N. Karamysheva
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA; (A.T.); (C.C.R.-A.); (J.S.-B.)
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Jeffers V, Tampaki Z, Kim K, Sullivan WJ. A latent ability to persist: differentiation in Toxoplasma gondii. Cell Mol Life Sci 2018; 75:2355-2373. [PMID: 29602951 PMCID: PMC5988958 DOI: 10.1007/s00018-018-2808-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/01/2018] [Accepted: 03/26/2018] [Indexed: 01/08/2023]
Abstract
A critical factor in the transmission and pathogenesis of Toxoplasma gondii is the ability to convert from an acute disease-causing, proliferative stage (tachyzoite), to a chronic, dormant stage (bradyzoite). The conversion of the tachyzoite-containing parasitophorous vacuole membrane into the less permeable bradyzoite cyst wall allows the parasite to persist for years within the host to maximize transmissibility to both primary (felids) and secondary (virtually all other warm-blooded vertebrates) hosts. This review presents our current understanding of the latent stage, including the factors that are important in bradyzoite induction and maintenance. Also discussed are the recent studies that have begun to unravel the mechanisms behind stage switching.
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Affiliation(s)
- Victoria Jeffers
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | - Zoi Tampaki
- Departments of Medicine, Microbiology and Immunology, and Pathology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Kami Kim
- Departments of Medicine, Microbiology and Immunology, and Pathology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
| | - William J Sullivan
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
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Marques P, O’ Donovan J, Williams E, Gutierrez J, Worrall S, McElroy M, Proctor A, Brady C, Sammin D, Bassett H, Buxton D, Maley S, Markey B, Nally J. Detection of Toxoplasma gondii antigens reactive with antibodies from serum, amniotic, and allantoic fluids from experimentally infected pregnant ewes. Vet Parasitol 2012; 185:91-100. [DOI: 10.1016/j.vetpar.2011.10.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 10/12/2011] [Accepted: 10/19/2011] [Indexed: 10/15/2022]
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5
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Norose K, Naoi K, Fang H, Yano A. In vivo study of toxoplasmic parasitemia using interferon-γ-deficient mice: Absolute cell number of leukocytes, parasite load and cell susceptibility. Parasitol Int 2008; 57:447-53. [DOI: 10.1016/j.parint.2008.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 05/16/2008] [Accepted: 05/24/2008] [Indexed: 11/25/2022]
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Toxoplasma gondii induces prostaglandin E2 synthesis in macrophages via signal pathways for calcium-dependent arachidonic acid production and PKC-dependent induction of cyclooxygenase-2. Parasitol Res 2008; 102:1043-50. [DOI: 10.1007/s00436-007-0873-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Accepted: 12/23/2007] [Indexed: 10/22/2022]
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Serrano-Martínez E, Ferre I, Martínez A, Osoro K, Mateos-Sanz A, Del-Pozo I, Aduriz G, Tamargo C, Hidalgo CO, Ortega-Mora LM. Experimental neosporosis in bulls: Parasite detection in semen and blood and specific antibody and interferon-gamma responses. Theriogenology 2007; 67:1175-84. [PMID: 17316779 DOI: 10.1016/j.theriogenology.2007.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 12/22/2006] [Accepted: 01/16/2007] [Indexed: 11/17/2022]
Abstract
AIM To investigate the presence of Neospora caninum in semen and blood, and the development of specific antibody and interferon-gamma (IFN-gamma) responses in experimentally infected bulls. METHODS Eight bulls were intravenously infected with 10(8) live N. caninum tachyzoites of NC-1 isolate. The presence of N. caninum in semen and blood was assessed using a nested-PCR procedure. PCR-positive semen samples were bioassayed using a BALB/c nu/nu mouse model. Specific anti-N. caninum antibody and IFN-gamma responses were also examined. In parallel, eight seronegative bulls were studied as non-infected controls. All bulls were monitored for 26 weeks. RESULTS All eight experimentally infected bulls showed N. caninum DNA in their semen and/or blood samples at some time during the course of the study. Parasite load in semen ranged from 0.1 to 14.5 parasites/ml (mean 6.0). N. caninum could not be detected in BALB/c nu/nu mice inoculated with PCR-positive semen samples. A significant increase in mean serum specific IgM antibody response to N. caninum was detected between 10 and 28 days post-infection (p.i.). Serum specific IgG, IgG1, and IgG2 antibody levels in experimentally infected bulls were significantly different after 21, 10, and 14 days p.i. as compared to controls, respectively. Specific anti-N. caninum IgG were detected in seminal plasma from infected bulls and values obtained were different from controls after 25 days p.i. Mean specific IFN-gamma responses in experimentally infected bulls were significantly higher than controls 3 days p.i. CONCLUSIONS This is the first study to report the presence of N. caninum DNA in the semen and blood of experimentally infected bulls. Our observations indicate an intermittent presence of N. caninum in low numbers in semen and associated with chronic stage of the infection. This study is also the first to report the detection of anti-N. caninum IgG in seminal plasma of experimentally infected bulls.
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Affiliation(s)
- E Serrano-Martínez
- Grupo SALUVET, Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid (UCM), Ciudad Universitaria s/n, E-28040 Madrid, Spain
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8
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Eaton MS, Weiss LM, Kim K. Cyclic nucleotide kinases and tachyzoite-bradyzoite transition in Toxoplasma gondii. Int J Parasitol 2005; 36:107-14. [PMID: 16216248 PMCID: PMC3109623 DOI: 10.1016/j.ijpara.2005.08.014] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2005] [Revised: 08/19/2005] [Accepted: 08/29/2005] [Indexed: 11/15/2022]
Abstract
The ability of Toxoplasma gondii to cycle between the tachyzoite and bradyzoite life stages in intermediate hosts is key to parasite survival and the pathogenesis of toxoplasmosis. Studies from a number of laboratories indicate that differentiation in T. gondii is a stress-induced phenomenon. The signalling pathways or molecular mechanisms that control formation of the latent bradyzoite stage are unknown and specific effectors of differentiation have not been identified. We engineered a reporter parasite to facilitate simultaneous comparison of differentiation and replication after various treatments. Chloramphenicol acetyltransferase (CAT), expressed constitutively from the alpha-tubulin promoter (TUB1), was used to quantitate parasite number. beta-galactosidase (beta-GAL), expressed from a bradyzoite specific promoter (BAG1), was used as a measure of bradyzoite gene expression. Sodium nitroprusside, a well-known inducer of bradyzoite differentiation, reduced reporter parasite replication and caused bradyzoite differentiation. Stress-induced differentiation in many other pathogens is regulated by cyclic nucleotide kinases. Specific inhibitors of the cAMP dependent protein kinase and apicomplexan cGMP dependent protein kinase inhibited replication and induced differentiation. The beta-GAL/CAT reporter parasite provides a method to quantify and compare agents that cause differentiation in T. gondii.
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Affiliation(s)
- Michael S. Eaton
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Louis M. Weiss
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Kami Kim
- Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Corresponding author Address: Ullmann 1225, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. Tel.: +1 718 430 2611; fax: +1 718 430 8968. (K. Kim)
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Ferre I, Aduriz G, Del-Pozo I, Regidor-Cerrillo J, Atxaerandio R, Collantes-Fernández E, Hurtado A, Ugarte-Garagalza C, Ortega-Mora LM. Detection of Neospora caninum in the semen and blood of naturally infected bulls. Theriogenology 2005; 63:1504-18. [PMID: 15725454 DOI: 10.1016/j.theriogenology.2004.07.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Revised: 07/23/2004] [Accepted: 07/25/2004] [Indexed: 11/23/2022]
Abstract
A prospective study was designed to investigate the presence of Neospora caninum in semen and blood of eight bulls seropositive to N. caninum using nested-PCR procedures. Positive semen and blood samples were bioassayed in a BALB/c nu/nu mouse model. Specific anti-N. caninum serological and interferon-gamma (IFN-gamma) responses were also studied. In parallel, five seronegative bulls acted as non-infected controls. All bulls were located in a collaborating AI centre and monitored for 22 weeks. Six of eight seropositive bulls showed N. caninum DNA in their semen and/or blood samples at some time during the course of the study. In all positive semen samples, we consistently found Neospora-DNA in the cell fraction and not in seminal plasma. Parasite load, as determined by a real-time PCR in nested-PCR positive semen samples, ranged from 1 to 10 parasites/ml. We found no association between the presence of N. caninum DNA in semen and blood. N. caninum could not be detected in the BALB/c nu/nu mice inoculated with PCR-positive semen or blood samples. Specific IgG antibody levels in seropositive bulls fluctuated over time, at times falling below cut-off level. The response was predominantly IgG2, with significant differences compared to control bulls (P < 0.05). The overall mean specific IFN-gamma response in seropositive bulls was also higher than those observed in the control group (P < 0.05), although extensive variation in individual responses was observed among bulls and over time. No significant association was found between bulls showing Neospora DNA in semen, blood, or both, and specific IgG, IgG1, IgG2, IgM and IgA levels or IFN-gamma response. This study is the first to report the presence of Neospora DNA in semen and blood of naturally-infected bulls. Our observations indicate intermittent presence of N. caninum in blood and semen and shedding in semen in low numbers.
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Affiliation(s)
- Ignacio Ferre
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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10
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Caetano-da-Silva A, Ferre I, Collantes-Fernández E, Navarro V, Aduriz G, Ugarte-Garagalza C, Ortega-Mora LM. Occasional detection of Neospora caninum DNA in frozen extended semen from naturally infected bulls. Theriogenology 2005; 62:1329-36. [PMID: 15325558 DOI: 10.1016/j.theriogenology.2004.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2003] [Revised: 01/23/2004] [Accepted: 01/24/2004] [Indexed: 11/30/2022]
Abstract
Recently, the presence of Neospora caninum DNA in semen from naturally infected bulls was reported. In the present work, the presence and quantification of N. caninum by PCR techniques in frozen extended semen straws from naturally infected bulls was investigated. A total of 20 seropositive and five seronegative bulls raised for reproductive purposes in an AI centre were used. Ten extended semen straws from each bull obtained at different time-points during the previous 2 years were selected for Neospora testing. Eight of the seropositive bulls (40%) studied showed at least one positive straw to N. caninum DNA and 14 of their 180 semen straws examined (7.8%) were found to be positive. In all positive samples, N. caninum DNA was consistently detected in the cell fraction and not in the seminal plasma. However, the parasite number in each positive straw was under the detection level of real-time PCR. In parallel, 10 semen straws from each of the five seronegative bulls were also analyzed by the nested-PCR and no N. caninum DNA products were obtained. In order to check the consistent presence of N. caninum in a positive semen batch, three additional semen straws from the same batch of each positive straw from three seropositive bulls were analyzed but N. caninum DNA was only detected in one straw from one bull. In conclusion, we report the sporadic detection of N. caninum DNA in semen straws of naturally infected bulls but the low frequency of contaminated semen straws and the low parasite load observed indicate a minor chance of bovine neosporosis transmission by AI.
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Affiliation(s)
- Andrea Caetano-da-Silva
- Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
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Abstract
Recent studies indicate that Toxoplasma gondii attachment is mediated via a parasite ligand-host cell receptor interaction. Lloyd Kosper and Jose Mineo here survey factors involved in the attachment to and penetration and invasion of host cells by T. gondii.
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Affiliation(s)
- L H Kasper
- Department of Medicine (Neurology), Dartmouth Medical School, Hanover, NH 03756, USA
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12
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Garcia JL, Gennari SM, Navarro IT, Machado RZ, Sinhorini IL. Toxoplasma gondii: isolation of tachyzoites rhoptries and incorporation into Iscom. Exp Parasitol 2004; 108:40-6. [PMID: 15491547 DOI: 10.1016/j.exppara.2004.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 05/11/2004] [Accepted: 07/01/2004] [Indexed: 11/24/2022]
Abstract
Rhoptries have been isolated from Toxoplasma gondii tachyzoites by subcellular fractionation in isopynic density sucrose gradient. Five bands were observed, and transmission electron microscopy of these indicated that rhoptries were in band 3. This band had a density of 1.17 g/cm(3). Fraction 1 had membrane structures of the parasite. Fraction 2 contained membranes and mitochondria. Fraction 4 had mostly conoid structure and fraction 5 showed ghosts. The electrophoretic and Western blotting analysis of the fractions indicated the presence of a number of proteins. Iscoms were constructed from band 3, which contained the rhoptry structures. Iscom showed a only protein incorporated of 55 kDa. Isolation of the parasite organelles has got in this work is necessary to identification, characterization, and function elucidation of the organelle proteins.
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Affiliation(s)
- João Luis Garcia
- Microbiology and Immunology Laboratory, Departamento de Biologia, Universidade Estadual do Centro Oeste-Unicentro, R. Simeão Camargo Varela de Sá, 03, Bairro Cascavel, 85040-080 Guarapuava, PR, Brazil.
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13
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Seng S, Makala LHC, Yokoyama M, Lim C, Choi YH, Suzuki N, Toyoda Y, Nagasawa H. SAG1 Is a Host-Targeted Antigen for Protection against Toxoplasma gondii Infection. Pathobiology 2004; 71:144-51. [PMID: 15051927 DOI: 10.1159/000076469] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2003] [Accepted: 07/18/2003] [Indexed: 11/19/2022] Open
Abstract
We previously reported that SAG1 transgenic (tg) mice have an elevated susceptibility resulting from their inability to elicit strong Th1-based protection against Toxoplasma gondii infection. Here, we demonstrate that SAG1 tg mice were protected against T. gondii infection, characterized by a decline in IFN-gamma levels, following administration of a lethal dose of T. gondii. Moreover, immunization with T. gondii homogenate conferred protection and induced production of IgG, with IgG1 and IgG2a subclasses driven by Th2 and Th1 responses, respectively, in both SAG1 tg and wild-type (wt) mice. IgG titers were significantly higher from day 10 after immunization in wt mice compared to those in SAG1 tg mice. There were no significant differences observed in levels of IgG1 in both groups. However, significantly lower IgG2a titers were measured in the sera from SAG1 tg mice on days 10, 15 and 20. IFN-gamma levels in sera were significantly lower in SAG1 tg mice compared to those in wt mice on day 20 after immunization. When challenged with a lethal dose of the Beverley strain of T. gondii, 80 and 100% survival rates were observed in SAG1 tg and wt mice, respectively, indicating that SAG1 tg mice were protected to a lesser extent from challenge due to the decrease in protective immunity. These results suggest that SAG1 plays a critical role in eliciting protection, hence a target antigen for the development of protective Th1-based responses against T. gondii infection in mice.
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MESH Headings
- Animals
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Disease Models, Animal
- Host-Parasite Interactions
- Immunoglobulin G/biosynthesis
- Immunoglobulin G/blood
- Interferon-gamma/blood
- Mice
- Mice, Inbred Strains
- Mice, Transgenic
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Toxoplasma/immunology
- Toxoplasma/pathogenicity
- Toxoplasmosis/genetics
- Toxoplasmosis/immunology
- Toxoplasmosis/prevention & control
- Toxoplasmosis, Animal/genetics
- Toxoplasmosis, Animal/immunology
- Toxoplasmosis, Animal/prevention & control
- Vaccination
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Affiliation(s)
- S Seng
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan
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14
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Hiszczyńska-Sawicka E, Brillowska-Dabrowska A, Dabrowski S, Pietkiewicz H, Myjak P, Kur J. High yield expression and single-step purification of Toxoplasma gondii SAG1, GRA1, and GRA7 antigens in Escherichia coli. Protein Expr Purif 2003; 27:150-7. [PMID: 12509997 DOI: 10.1016/s1046-5928(02)00593-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This report describes a simple, highly efficient and reproducible method for obtaining large quantities of highly pure recombinant Toxoplasma gondii antigens, which can be used for diagnostic application. The obtained T. gondii SAG1, GRA1, and GRA7 antigens (as fusion proteins), expressed in Escherichia coli, contained polyhistidine tags at the N- and C-ends that allowed single-step isolation by metal-affinity chromatography on Ni(2+)-IDA-Sepharose columns. The immunoreactivity of the recombinant antigens was tested in an enzyme-linked immunosorbent assay (ELISA) format for potential application in the serodiagnosis of T. gondii infection.
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15
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Ribeiro ACDA, de Souza MA, Mineo JR. Detection of antibodies to the 97 kDa component of Toxoplasma gondii in samples of human serum. Mem Inst Oswaldo Cruz 2002; 97:1009-13. [PMID: 12471429 DOI: 10.1590/s0074-02762002000700014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was carried out to investigate the immune response against 97 kDa (p97) molecular marker of Toxoplasma gondii that has been characterized as a cytosolic protein and a component of the excreted-secreted antigens from this parasite. A total of 60 serum samples from patients were analyzed by enzime-linked immunosorbent assay and Western blot for toxoplasmosis. These samples were organized in three groups, based on clinical symptoms and results of serological tests. Group I: 20 samples reactive to IgG and IgM (acute phase); group II: 20 non-reactive samples (control group); and group III: 20 samples reactive only to IgG (chronic phase). Western blot was performed with total antigenic extracts or with excreted and secreted antigen from T. gondii to identify the fraction correspondent to p97. It was observed that this cytosolic component from T. gondii stimulates the immunologic system to produce both IgM and IgG antibodies in the beginning of the acute infection and IgG throughout the chronic stage of the asymptomatic toxoplasmosis.
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16
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Conde M, Caballero JM, Rodríguez-Ponce E, Ruiz A, González J. Analysis of IgG response to experimental infection with RH Toxoplasma gondii in goats. Comp Immunol Microbiol Infect Dis 2001; 24:197-206. [PMID: 11440192 DOI: 10.1016/s0147-9571(00)00027-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The IgG response of goats experimentally infected with RH Toxoplasma gondii has been analysed using an indirect ELISA and Western-blot analysis. Specific IgG antibodies were first detected at 14 days post-inoculation (p.i.), reaching a peak by day 35 p.i. and showing slight fluctuations until the end of the experiment (91 p.i.). Specific IgG showed a reactivity over a whole range of peptides (125-24 kDa approximately), but the highest reactivity was observed against a group of antigens with a molecular weight between 34 and 28 kDa, in particular against a 30 kDa fraction which is considered to represent the major surface protein of T. gondii named p30 or SAG-1.
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Affiliation(s)
- M Conde
- Departamento de Patología Animal (Parasitología y Enfermedades Parasitarias), Facultad de Veterinaria de la Universidad de Las Palmas de Gran Canaria, Spain
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17
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Zhang YW, Halonen SK, Ma YF, Wittner M, Weiss LM. Initial characterization of CST1, a Toxoplasma gondii cyst wall glycoprotein. Infect Immun 2001; 69:501-7. [PMID: 11119543 PMCID: PMC97909 DOI: 10.1128/iai.69.1.501-507.2001] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxoplasma gondii is an important protozoan pathogen of humans that can cause encephalitis in immunocompromised individuals such as those with AIDS. This encephalitis is due to reactivation of latent infection in T. gondii-seropositive patients. Latent organisms survive within tissue cysts, which are specialized parasitophorous vacuoles containing bradyzoites. The cyst wall of this structure is produced by modification of the parasitophorous vacuole by the parasite and is important in cyst survival. The components of the cyst wall have been poorly characterized. By using immunofluorescence and immunoelectron microscopy, we have identified a monoclonal antibody (MAb 93.18) that reacts with the cyst wall. This antibody recognizes a 116-kDa glycoprotein, which we have termed CST1, containing sugar residues that bind Dolichos biflorans lectin (DBA). CST1 is distinct from T. gondii antigen labeled with succinyl Triticum vulgare lectin (S-WGA) and represents the major DBA-binding component in T. gondii. The carbohydrate components of the tissue cyst, such as CST1, are probably important in both providing stability and facilitating persistence in its host. As is seen in the carbohydrate capsules of fungi, glycoproteins in the T. gondii cyst wall may protect cysts from the immune response of the host. Further characterization of the formation of the cyst wall and its components should lead to insights into the mechanism of tissue cyst persistence and may suggest novel therapeutic approaches to eliminate tissue cysts of this organism.
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Affiliation(s)
- Y W Zhang
- Department of Pathology, Division of Parasitology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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18
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Weiss LM, Kim K. The development and biology of bradyzoites of Toxoplasma gondii. FRONTIERS IN BIOSCIENCE : A JOURNAL AND VIRTUAL LIBRARY 2000; 5:D391-405. [PMID: 10762601 PMCID: PMC3109641 DOI: 10.2741/weiss] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Toxoplasma gondii is a protozoan parasite of mammals and birds that is an important human pathogen. Infection with this Apicomplexan parasite results in its dissemination throughout its host via the tachyzoite life-stage. After dissemination these tachyzoites differentiate into bradyzoites within cysts that remain latent. These bradyzoites can transform back into tachyzoites and in immunosupressed individuals this often results in symptomatic disease. Both tachyzoites and bradyzoites develop in tissue culture and thus this crucial differentiation event can be studied. Recent advances in the genetic manipulation of T. gondii have expanded the molecular tools that can be applied to studies on bradyzoite differentiation. Evidence is accumulating that this differentiation event is stress mediated and may share common pathways with other stress-induced differentiation events in other eukaryotic organisms. Study of the stress response and signaling pathways are areas of active research in this organism. In addition, characterization of unique bradyzoite-specific structures, such as the cyst wall, should lead to a further understanding of T. gondii biology. This review focuses on the biology and development of bradyzoites and current approaches to the study of the tachyzoite to bradyzoite differentiation process.
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Affiliation(s)
- Louis M. Weiss
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461
- Department of Pathology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461
| | - Kami Kim
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461
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19
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Aubert D, Maine GT, Villena I, Hunt JC, Howard L, Sheu M, Brojanac S, Chovan LE, Nowlan SF, Pinon JM. Recombinant antigens to detect Toxoplasma gondii-specific immunoglobulin G and immunoglobulin M in human sera by enzyme immunoassay. J Clin Microbiol 2000; 38:1144-50. [PMID: 10699010 PMCID: PMC86359 DOI: 10.1128/jcm.38.3.1144-1150.2000] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have evaluated the diagnostic utility of eleven Toxoplasma gondii recombinant antigens (P22 [SAG2], P24 [GRA1], P25, P28 [GRA2], P29 [GRA7], P30 [SAG1], P35, P41 [GRA4], P54 [ROP2], P66 [ROP1], and P68) in immunoglobulin G (IgG) and IgM recombinant enzyme-linked immunosorbent assays (Rec-ELISAs). Following an initial evaluation, six recombinant antigens (P29, P30, P35, P54, P66, and P68) were tested in the IgG and IgM Rec-ELISAs with four groups of samples which span the toxoplasmosis disease spectrum (negative, chronic infection, acute infection, and recent seroconversion). Our results suggest that the combination of P29, P30, and P35 in an IgG Rec-ELISA and the combination of P29, P35, and P66 in an IgM Rec-ELISA can replace the tachyzoite antigen in IgG and IgM serologic tests, respectively. The relative sensitivity, specificity, and agreement for the IgG P29-P30-P35 Rec-ELISA were 98.4, 95.7, and 97.2%, respectively. The resolved sensitivity, specificity, and agreement for the IgM P29-P35-P66 Rec-ELISA were 93.1, 95.0, and 94. 5%, respectively. Relative to the tachyzoite-based immunocapture IgM assay, the IgM P29-P35-P66 Rec-ELISA detects fewer samples that contain IgG antibodies with elevated avidity from individuals with an acute toxoplasmosis.
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Affiliation(s)
- D Aubert
- Laboratoire de Parasitologie, EA2070, IFR 53 CHU Maison Blanche, 51092 REIMS Cédex, France
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20
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Silva NM, Gazzinelli RT, Silva DA, Ferro EA, Kasper LH, Mineo JR. Expression of Toxoplasma gondii-specific heat shock protein 70 during In vivo conversion of bradyzoites to tachyzoites. Infect Immun 1998; 66:3959-63. [PMID: 9673286 PMCID: PMC108462 DOI: 10.1128/iai.66.8.3959-3963.1998] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Stage conversion between bradyzoites and tachyzoites was investigated in C57BL/6 mice chronically infected with the ME-49 strain of Toxoplasma gondii. In order to promote bradyzoite-tachyzoite conversion, mice were treated in vivo with neutralizing doses of anti-gamma interferon (IFN-gamma) or anti-tumor necrosis factor alpha (TNF-alpha) antibodies. Expression of parasite-specific antigens SAG-1, SAG-2, and heat shock protein 70 (Hsp-70) was visualized in the central nervous system by immunocytochemistry and measured by photometric assay. The immunosuppressive effect of anti-IFN-gamma or anti-TNF-alpha treatment was immediate, leading to parasite stage conversion as indicated by the increased expression of tachyzoite-specific antigens (SAG-1 and SAG-2) and by rapid parasite replication. We also observed expression of high levels of Hsp-70 during a short period of conversion of bradyzoites to tachyzoites. Our data suggest that Hsp-70 may have an important role in the process of bradyzoite-tachyzoite conversion during the reactivation of chronic toxoplasmosis.
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Affiliation(s)
- N M Silva
- Laboratory of Immunology, Department of Pathology, Universidade Federal de Uberlandia, Uberlandia 38400-902, Minas Gerais, Brazil
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Abstract
The past 10 years of research aimed at developing subunit vaccines against a number of apicomplexans, including Eimeria, Plasmodium and Toxoplasma, have, if anything, revealed the complex nature of parasite-host interactions. The Knowledge gained from this research has shown why developing a subunit vaccine based on a single recombinant antigen from one developmental stage of the parasite was an overly optimistic approach. Many apicomplexan parasites have acquired unique strategies to evade host immunity. The variable expression of genes encoding erythrocyte membrane protein 1 of Plasmodium falciparum [1] (Berendt et al. Parasitology 1994;108:S19-S28) exemplifies one such strategy. The particular mechanism for evading immune destruction depends on a number of interrelated factors, not least of which is the parasite life-cycle and the availability of susceptible hosts. The goal of any vaccine, be it an attenuated organism or a recombinant antigen, is to break the cycle of infection. The development of a recombinant vaccine against apicomplexan parasites will depend on identifying those antigens and intracellular processes that are vital to the parasite survival and those which exist merely as a way of evading immunity. The information that follows is a review of both molecular biology/biochemistry of eimerian parasites and factors that influence host immune responses to coccidia.
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Affiliation(s)
- M C Jenkins
- Immunology and Disease Resistance Laboratory, USDA, BARC-EAST, Beltsville, MD 20705, USA
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Coombs GH, Denton H, Brown SM, Thong KW. Biochemistry of the coccidia. ADVANCES IN PARASITOLOGY 1997; 39:141-226. [PMID: 9241816 DOI: 10.1016/s0065-308x(08)60046-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- G H Coombs
- Institute of Biomedical and Life Sciences, University of Glasgow, UK
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Ng HC, Singh M, Jeyaseelan K. Nucleotide sequence of ToxPK1 gene from Toxoplasma gondii. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 1997; 7:179-91. [PMID: 9254011 DOI: 10.3109/10425179709034033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report here for the first time a complete nucleotide sequence (6.8 kb) of a protein kinase gene (ToxPK1) from the obligate intracellular protozoan parasite of man, Toxoplasma gondii. This gene comprising putatively of 9 exons and 8 introns forms the Toxoplasma gene with the largest number and size of introns reported so far. The predicted protein with 508 amino acids contains the 15 invariant residues as well as the characteristic motifs specific to protein serine/threonine kinases. Homology-based computational comparisons suggested that TOXPK1 belongs to or closely resembles the SNF1 subfamily of protein-serine/threonine kinases. Based on the functions of SNF1 homologs in other organisms and our RT-PCR results, it is likely that TOXPK1 may be transiently expressed to up-regulate glycogen biosynthesis during the development of tachyzoites into bradyzoites.
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Affiliation(s)
- H C Ng
- Department of Biochemistry, National University of Singapore
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24
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Inoue N, Omata Y, Yonemasu K, Claveria FG, Igarashi I, Saito A, Suzuki N. Collagen cross-reactive antigen of Sarcocystis cruzi. Vet Parasitol 1996; 63:17-23. [PMID: 8792577 DOI: 10.1016/0304-4017(95)00844-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Collagen cross-reactive antigenic substance(s) in Sarcocystis cruzi cysts were examined with immunologic techniques using anti-bovine collagen type-specific, but non-species-specific, antibodies. By immunoperoxidase test, anti-bovine collagen type-specific, but non-species-specific, antibodies. By immunoperoxidase test, anti-bovine type IV collagen antibody showed higher reactivity to the cysts than other antibodies tested. Cyst wall rupture was induced by collagenase treatment and digestion was inhibited with EDTA supplementation. With immunoblotting analysis, one band of the cyst extract, which exhibited specific reactivity to anti-bovine type IV collagen antibody, was detected. The band had a molecular weight of approximately 66 kDa. These results suggest that sarcocysts of S. cruzi may be comprised of bovine collagen type IV cross-reactive antigenic substances.
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Affiliation(s)
- N Inoue
- Department of Veterinary Physiology, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan
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25
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Letillois MF, Laigle V, Santoro F, Micoud M, Chumpitazi BF. Toxoplasma gondii surface antigen-1 in sera of HIV-infected patients as an indicator of reactivated toxoplasmosis. Eur J Clin Microbiol Infect Dis 1995; 14:899-903. [PMID: 8605904 DOI: 10.1007/bf01691497] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The major surface antigen from the proliferative form of Toxoplasma gondii (P-30 of SAG-1) was chosen as a target for exploration of Toxoplasma gondii reactivation in sera from immunocompromised patients. Samples were obtained from 37 HIV-infected subjects with lymphocyte levels of CD4+ < 200/mm3. The prevalence of IgG antibodies to Toxoplasma gondii was 64.9%. Ten patients had clinical symptoms of reactivated toxoplasmosis; eight of these had Toxoplasma encephalitis. The SAG-1 epitopes were found as circulating antigen in five cases with an immunocapture enzyme immunoassay (EIA). The EIA was improved with an IgG1 monoclonal antibody to SAG-1 and a streptavidinbiotin amplification. The sensitivity, specificity and positive predictive value were 30, 92 and 60%, respectively. The SAG-1 levels were compared with different biological parameters such as HIV p24 antigen, beta 2 microglobulin, CD4+ cell count and IgG antibodies to Toxoplasma gondii. The levels of SAG-1 in these patients were significantly higher than those in the 75 healthy control persons with or without a chronic Toxoplasma gondii infection. Therefore, SAG-1 may be involved as a marker of reactivated toxoplasmosis in HIV-infected patients.
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Affiliation(s)
- M F Letillois
- Service de Parasitologie, Hôpital Albert Michallon, Grenoble, France
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26
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Analysis of in vivo immune responses during Toxoplasma gondii infection using the technique of lymphatic cannulation. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0169-4758(95)80210-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Wastling JM, Harkins D, Maley S, Innes E, Panton W, Thomson K, Buxton D. Kinetics of the local and systemic antibody response to primary and secondary infection with S48 Toxoplasma gondii in sheep. J Comp Pathol 1995; 112:53-62. [PMID: 7722008 DOI: 10.1016/s0021-9975(05)80089-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Vaccination of sheep with live tachyzoites of Toxoplasma gondii, strain S48, affords protection against subsequent challenge with the parasite, but the mechanisms of immunity have not been fully determined. To understand better the nature of the antibody response the kinetics of both local and systemic antibody production were monitored in vaccinated sheep by means of an enzyme-linked immunosorbent assay and Western blotting. Local specific IgG production was analysed in efferent lymph obtained from the cannulated pre-femoral lymph node draining the site of infection. Antibody in efferent lymph plasma and peripheral blood serum from animals vaccinated with S48 tachyzoites was monitored and compared with IgG production in vaccinated sheep given a secondary tachyzoite challenge. Secondary challenge resulted in a clear immunological memory response, antibody being detected in the lymph 3 to 4 days after infection as compared with 7 to 8 days after a primary infection. IgG production was dominated by antibody recognizing a protein with an apparent molecular weight of 30 kDa, but other antigens (32, 24 and 11 kDa) were also readily detected.
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28
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Wastling JM, Harkins D, Buxton D. Western blot analysis of the IgG response of sheep vaccinated with S48 Toxoplasma gondii (Toxovax). Res Vet Sci 1994; 57:384-6. [PMID: 7871261 DOI: 10.1016/0034-5288(94)90135-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The IgG antibody responses of sheep vaccinated by the subcutaneous injection of live tachyzoites of 'incomplete' strain S48 toxoplasma (Toxovax) were analysed by Western blotting. Antibodies corresponding to a range of tachyzoite antigens (13 to 48 kD) were detected, but the response was dominated by antibody recognising a 30 to 32 kD band. Unvaccinated ewes challenged orally with oocysts of the 'complete' M3 toxoplasma strain had a more complex IgG response that recognised antigens in six dominant bands of similar intensity as those in sheep vaccinated with S48 tachyzoites and then challenged with M3 oocysts. No differences were detected between the antigenic structures of the S48 tachyzoites and RH strain tachyzoites when the antigens were probed with immune ovine sera. Many of the anitgens of the S48 tachyzoites that were recognised had molecular weights similar to those of antigens that have been identified in other strains of toxoplasma.
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Joiner KA, Beckers CJ, Bermudes D, Ossorio PN, Schwab JC, Dubremetz JF. Structure and function of the parasitophorous vacuole membrane surrounding Toxoplasma gondii. Ann N Y Acad Sci 1994; 730:1-6. [PMID: 8080165 DOI: 10.1111/j.1749-6632.1994.tb44233.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- K A Joiner
- Yale University School of Medicine, New Haven, Connecticut 06510-8056
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Parasite-Host-Cell Interactions of Eimeria papillata Sporozoites with Cultured Cells A Freeze-Fracture Study. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/s0003-9365(11)80334-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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32
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Affiliation(s)
- K A Joiner
- Section of Infectious Diseases, Yale University School of Medicine, New Haven, Connecticut
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33
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Guay JM, Huot A, Gagnon S, Tremblay A, Levesque RC. Physical and genetic mapping of cloned ribosomal DNA from Toxoplasma gondii: primary and secondary structure of the 5S gene. Gene X 1992; 114:165-71. [PMID: 1601300 DOI: 10.1016/0378-1119(92)90570-f] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The ribosomal DNA (rDNA encoding rRNA) of the obligately intracellular protozoan parasite, Toxoplasma gondii, was identified, cloned, physically mapped, its copy number determined, and the 5S gene sequenced. Using total RNA as a probe, a collection of recombinant lambda phages containing copies of rDNA were isolated from a lambda 2001 tachyzoite genomic library. Northern gel hybridization confirmed specific homology of the 7.5-kb rDNA unit, subcloned into pTZ18R, to T. gondii rRNA. The mapped rDNA found in pTOX1 contained small ribosomal subunit (SS; 18S)- and large ribosomal subunit (LS; 26S)-encoding genes localized using intragenic heterologous probes from the conserved sequences of the SS (18S) and LS (28S) Xenopus laevis genes. the physical mapping data, together with partial digestion experiments and Southern gel hybridization, confirmed a 7.5-kb rDNA unit arranged in a simple head-to-tail fashion that is tandemly repeated. We estimated the rDNA repeat copy number in T. gondii to be 110 copies per haploid tachyzoite genome. Parts of the SS gene and the complete 5S gene were sequenced. The 5S gene was found to be within the rDNA locus, a rare occurrence found only in some fungi and protozoa. Secondary-structure analysis revealed an organization remarkably similar to the 5S RNA of eukaryotes.
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Affiliation(s)
- J M Guay
- Département de Microbiologie, Faculté de Médecine, Université Laval, Ste-Foy, Québec, Canada
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Youn JH, Nam HW, Kim DJ, Park YM, Kim WK, Kim WS, Choi WY. Cell cycle-dependent entry of Toxoplasma gondii into synchronized HL-60 cells. KISAENGCH'UNGHAK CHAPCHI. THE KOREAN JOURNAL OF PARASITOLOGY 1991; 29:121-8. [PMID: 1954195 DOI: 10.3347/kjp.1991.29.2.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The degree of attraction of Toxoplasma gondii to vertebrate cells varies with cell type and cell phase. Human promyelocytic leukemia cells, HL-60, were synchronized by double thymidine block method and co-cultured with Toxoplasma for 1 hr at each cell stage to investigate the cell cycle specific susceptibility of parasites to host cells. For 30 hr the average number of Toxoplasma that invaded was a little changed except at 3 hr from G1/S phase boundary which concurred with the peak point of DNA synthesis. At 3 hr which is a relatively short interval compared to whole S phase, modification of cells by parasitic invasion was most remarkable. The number of Toxoplasma that penetrated was increased to more than six times. The shape of the cells became sludgy and almost indiscernible by strong accessibility of parasites only for an hour of mid-S phase. The same fluctuation was also observed at the second peak of S phase but weakly. This suggests that there be surface molecules concerning with the attachment of Toxoplasma to the host cells, which is expressed at special point of S phase. Further studies on the specific protein or similar molecules related could be carried out using synchronized HL-60 cells.
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Affiliation(s)
- J H Youn
- Catholic Institute of Parasitic Diseases, Catholic University Medical College, Seoul, Korea
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