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Liu Z, Vucetich S, DeToy K, Duran Saucedo G, Verastegui M, Carballo-Jimenez P, Mercado-Saavedra BN, Tinajeros F, Malaga-Machaca ES, Marcus R, Gilman RH, Bowman NM, McCall LI. Small molecule biomarkers predictive of Chagas disease progression. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.13.24307310. [PMID: 38798659 PMCID: PMC11118624 DOI: 10.1101/2024.05.13.24307310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Chagas disease (CD) is a neglected tropical disease caused by the parasitic protozoan Trypanosoma cruzi. However, only 20% to 30% of infected individuals will progress to severe symptomatic cardiac manifestations. Current treatments are benznidazole and nifurtimox, which are poorly tolerated regimens. Developing a biomarker to determine the likelihood of patient progression would be helpful for doctors to optimize patient treatment strategies. Such a biomarker would also benefit drug discovery efforts and clinical trials. In this study, we combined untargeted and targeted metabolomics to compare serum samples from T. cruzi-infected individuals who progressed to severe cardiac disease, versus infected individuals who remained at the same disease stage (non-progressors). We identified four unannotated biomarker candidates, which were validated in an independent cohort using both untargeted and targeted analysis techniques. Overall, our findings demonstrate that serum small molecules can predict CD progression, offering potential for clinical monitoring.
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Activity of the sesquiterpene lactone goyazensolide against Trypanosoma cruzi in vitro and in vivo. Parasitology 2019; 147:108-119. [PMID: 31455451 DOI: 10.1017/s0031182019001276] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND The current drugs for Chagas disease treatment present several limitations. METHODS The sesquiterpene lactone goyazensolide (GZL) was evaluated regarding to cytotoxicity and trypanocidal activity against amastigotes, selectivity index (SI) in vitro, acute toxicity and anti-Trypanosoma cruzi activity in vivo. RESULTS The in vitro cytotoxicity in H9c2 cells was observed at doses >250 ng mL-1 of GZL and the SI were of 52.82 and 4.85 (24 h) and of 915.00 and 41.00 (48 h) for GZL and BZ, respectively. Nephrotoxicity and hepatotoxicity were not verified. Treatment with GZL of mice infected with CL strain led to a significant decrease of parasitaemia and total survival at doses of 1 and 3 mg kg-1 day-1 by oral and IV, respectively. This last group cured 12.5% of the animals (negativation of HC, PCR, qPCR and ELISA). Animals infected with Y strain showed significant decrease of parasitaemia and higher negativation in all parasitological tests in comparison to BZ and control groups, but were ELISA reactive, as well as the BZ group, but mice treated with 5.0 mg kg-1 day-1 by oral were negative in parasitological tests and survived. CONCLUSION GZL was more active against T. cruzi than benznidazole in vitro and presented important therapeutic activity in vivo in both T. cruzi strains.
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Oliveira MTD, Branquinho RT, Alessio GD, Mello CGC, Nogueira-de-Paiva NC, Carneiro CM, Toledo MJDO, Reis AB, Martins-Filho OAM, Lana MD. TcI, TcII and TcVI Trypanosoma cruzi samples from Chagas disease patients with distinct clinical forms and critical analysis of in vitro and in vivo behavior, response to treatment and infection evolution in murine model. Acta Trop 2017; 167:108-120. [PMID: 27908747 DOI: 10.1016/j.actatropica.2016.11.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 11/11/2016] [Accepted: 11/24/2016] [Indexed: 01/10/2023]
Abstract
The clonal evolution of Trypanosoma cruzi sustains scientifically the hypothesis of association between parasite's genetic, biological behavior and possibly the clinical aspects of Chagas disease in patients from whom they were isolated. This study intended to characterize a range of biological properties of TcI, TcII and TcVI T. cruzi samples in order to verify the existence of these associations. Several biological features were evaluated, including in vitro epimastigote-growth, "Vero"cells infectivity and growth, along with in vivo studies of parasitemia, polymorphism of trypomastigotes, cardiac inflammation, fibrosis and response to treatment by nifurtimox during the acute and chronic murine infection. The global results showed that the in vitro essays (acellular and cellular cultures) TcII parasites showed higher values for all parameters (growth and infectivity) than TcVI, followed by TcI. In vivo TcII parasites were more virulent and originated from patients with severe disease. Two TcII isolates from patients with severe pathology were virulent in mice, while the isolate from a patient with the indeterminate form of the disease caused mild infection. The only TcVI sample, which displayed low values in all parameters evaluated, was also originated of an indeterminate case of Chagas disease. Response to nifurtimox was not associated to parasite genetic and biology, as well as to clinical aspects of human disease. Although few number of T. cruzi samples have been analyzed, a discreet correlation between parasite genetics, biological behavior in vitro and in vivo (murine model) and the clinical form of human disease from whom the samples were isolated was verified.
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Affiliation(s)
- Maykon Tavares de Oliveira
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | - Renata Tupinambá Branquinho
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas (CIPHARMA), Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | - Gláucia Diniz Alessio
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | - Carlos Geraldo Campos Mello
- Programa de Pós-Graduação em Ciências Farmacêuticas (CIPHARMA), Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | - Nívia Carolina Nogueira-de-Paiva
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | - Cláudia Martins Carneiro
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas (CIPHARMA), Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Departamento de Análises Clínicas, Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | - Max Jean de Ornelas Toledo
- Departamento de Ciências Básicas da Saúde-Parasitologia, Universidade Estadual de Maringá, CEP: 87020-900, Maringá, Paraná, PR, Brazil
| | - Alexandre Barbosa Reis
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas (CIPHARMA), Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Departamento de Análises Clínicas, Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil
| | | | - Marta de Lana
- Núcleo de Pesquisas em Ciências Biológicas (NUPEB), Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas (CIPHARMA), Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil; Departamento de Análises Clínicas, Escola de Farmácia, Campus Universitário Morro do Cruzeiro, Universidade Federal de Ouro Preto, CEP: 35400-000 Ouro Preto, MG, Brazil.
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Molecular Approaches for Diagnosis of Chagas' Disease and Genotyping of Trypanosoma cruzi. Mol Microbiol 2016. [DOI: 10.1128/9781555819071.ch36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Revisiting the Posttherapeutic Cure Criterion in Chagas Disease: Time for New Methods, More Questions, Doubts, and Polemics or Time to Change Old Concepts? BIOMED RESEARCH INTERNATIONAL 2015; 2015:652985. [PMID: 26583124 PMCID: PMC4637035 DOI: 10.1155/2015/652985] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 08/10/2015] [Indexed: 01/17/2023]
Abstract
One of the most relevant issues beyond the effectiveness of etiological treatment of Chagas disease is the lack of consensual/feasible tools to identify and certify the definitive parasitological cure. Several methods of distinct natures (parasitological, serological, and molecular) have been continuously proposed and novel perspectives are currently under investigation. Although the simultaneous use of distinct tests may offer better contributions and advances, it also leads to controversies of interpretation, with lack of mutual consent of cure criterion amongst researchers and physicians. In fact, when distinct host compartments (blood/tissues) are evaluated and explored, novel questions may arise due to the nature and sensitivity limit of each test. This short analytical review intends to present a chronological and critical overview and discuss the state-of-the-art distinct devices available for posttherapeutic cure assessment in Chagas disease, their contributions, meanings, and interpretation, aiming to point out the major gaps and propose novel insight for future perspectives of posttherapeutic management of Chagas disease patients.
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Teixeira-Carvalho A, Campos FMF, Geiger SM, Rocha RDR, de Araújo FF, Vitelli-Avelar DM, Andrade MC, Araújo MSS, Lemos EM, de Freitas Carneiro Proietti AB, Sabino EC, Caldas RG, Freitas CRC, Campi-Azevedo AC, Elói-Santos SM, Martins-Filho OA. FC-TRIPLEX Chagas/Leish IgG1: a multiplexed flow cytometry method for differential serological diagnosis of chagas disease and leishmaniasis. PLoS One 2015; 10:e0122938. [PMID: 25875961 PMCID: PMC4398351 DOI: 10.1371/journal.pone.0122938] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 02/03/2015] [Indexed: 11/18/2022] Open
Abstract
Differential serological diagnosis of Chagas disease and leishmaniasis is difficult owing to cross-reactivity resulting from the fact that the parasites that cause these pathologies share antigenic epitopes. Even with optimized serological assays that use parasite-specific recombinant antigens, inconclusive test results continue to be a problem. Therefore, new serological tests with high sensitivity and specificity are needed. In the present work, we developed and evaluated the performance of a new flow cytometric serological method, referred to as FC-TRIPLEX Chagas/Leish IgG1, for the all-in-one classification of inconclusive tests. The method uses antigens for the detection of visceral leishmaniasis, localized cutaneous leishmaniasis, and Chagas disease and is based on an inverted detuned algorithm for analysis of anti-Trypanosomatidae IgG1 reactivity. First, parasites were label with fluorescein isothiocyanate or Alexa Fluor 647 at various concentrations. Then serum samples were serially diluted, the dilutions were incubated with suspensions of mixed labeled parasites, and flow cytometric measurements were performed to determine percentages of positive fluorescent parasites. Using the new method, we obtained correct results for 76 of 80 analyzed serum samples (95% overall performance), underscoring the outstanding performance of the method. Moreover, we found that the fluorescently labeled parasite suspensions were stable during storage at room temperature, 4 °C, and -20 °C for 1 year. In addition, two different lots of parasite suspensions showed equivalent antigen recognition; that is, the two lots showed equivalent categorical segregation of anti-Trypanosomatidae IgG1 reactivity at selected serum dilutions. In conclusion, we have developed a sensitive and selective method for differential diagnosis of Chagas disease, visceral leishmaniasis, and localized cutaneous leishmaniasis.
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Affiliation(s)
- Andréa Teixeira-Carvalho
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Fernanda Magalhães Freire Campos
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Stefan Michael Geiger
- Laboratório de Helmintoses Intestinais, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Roberta Dias Rodrigues Rocha
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Fernanda Fortes de Araújo
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Danielle Marquete Vitelli-Avelar
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Mariléia Chaves Andrade
- Departamento de Fisiopatologia, Centro de Ciências Biológicas e da Saúde, Universidade Estadual de Montes Claros, Montes Claros, Brasil
| | - Márcio Sobreira Silva Araújo
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Elenice Moreira Lemos
- Núcleo de Doenças Infecciosas, Centro Biomédico, Universidade Federal do Espírito Santo, Vitória, Brasil
| | | | - Ester Cerdeira Sabino
- Departamento de Doenças Infecciosas, Instituto de Medicina Tropical, Universidade de São Paulo—USP, São Paulo, Brasil
| | - Rafaella Gaiotti Caldas
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Carolina Renata Camargos Freitas
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Ana Carolina Campi-Azevedo
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
| | - Silvana Maria Elói-Santos
- Departamento de Pós-Graduação em Patologia Geral, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
- Departamento de Propedêutica Complementar, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brasil
| | - Olindo Assis Martins-Filho
- Laboratório de Biomarcadores de Diagnóstico e Monitoração, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brasil
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Alessio GD, Côrtes DF, Machado de Assis GF, Júnior PAS, Ferro EAV, Antonelli LRDV, Teixeira-Carvalho A, Martins-Filho OA, de Lana M. Innovations in diagnosis and post-therapeutic monitoring of Chagas disease: Simultaneous flow cytometric detection of IgG1 antibodies anti-live amastigote, anti-live trypomastigote, and anti-fixed epimastigote forms of Trypanosoma cruzi. J Immunol Methods 2014; 413:32-44. [DOI: 10.1016/j.jim.2014.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/23/2014] [Accepted: 07/15/2014] [Indexed: 12/14/2022]
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Nagarkatti R, de Araujo FF, Gupta C, Debrabant A. Aptamer based, non-PCR, non-serological detection of Chagas disease biomarkers in Trypanosoma cruzi infected mice. PLoS Negl Trop Dis 2014; 8:e2650. [PMID: 24454974 PMCID: PMC3894185 DOI: 10.1371/journal.pntd.0002650] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 12/03/2013] [Indexed: 12/18/2022] Open
Abstract
Chagas disease affects about 5 million people across the world. The etiological agent, the intracellular parasite Trypanosoma cruzi (T. cruzi), can be diagnosed using microscopy, serology or PCR based assays. However, each of these methods has their limitations regarding sensitivity and specificity, and thus to complement these existing diagnostic methods, alternate assays need to be developed. It is well documented that several parasite proteins called T. cruzi Excreted Secreted Antigens (TESA), are released into the blood of an infected host. These circulating parasite antigens could thus be used as highly specific biomarkers of T. cruzi infection. In this study, we have demonstrated that, using a SELEx based approach, parasite specific ligands called aptamers, can be used to detect TESA in the plasma of T. cruzi infected mice. An Enzyme Linked Aptamer (ELA) assay, similar to ELISA, was developed using biotinylated aptamers to demonstrate that these RNA ligands could interact with parasite targets. Aptamer L44 (Apt-L44) showed significant and specific binding to TESA as well as T. cruzi trypomastigote extract and not to host proteins or proteins of Leishmania donovani, a related trypanosomatid parasite. Our result also demonstrated that the target of Apt-L44 is conserved in three different strains of T. cruzi. In mice infected with T. cruzi, Apt-L44 demonstrated a significantly higher level of binding compared to non-infected mice suggesting that it could detect a biomarker of T. cruzi infection. Additionally, Apt-L44 could detect these circulating biomarkers in both the acute phase, from 7 to 28 days post infection, and in the chronic phase, from 55 to 230 days post infection. Our results show that Apt-L44 could thus be used in a qualitative ELA assay to detect biomarkers of Chagas disease. Chagas disease, caused by the parasite Trypanosoma cruzi, is a major health concern for people living in Latin America. There are no vaccines to prevent this disease and only two drugs are prescribed for treatment. Current methods to diagnose patients are not always successful and thus new methods need to be developed. One approach to develop an alternate method is to detect proteins and metabolites that are secreted by parasites into the blood of infected individuals. We have utilized a selection based method to isolate ligands that bind to these secreted proteins. These ligands, called aptamers, have been used to develop an assay that can detect the circulating parasite targets in the plasma or serum of an infected host. In an animal model of Chagas disease, our assay can detect parasite biomarkers as early as seven days after infection and as late as 230 days post infection. As the laboratory instruments and procedures are similar to performing an ELISA, the aptamer assay reported here could be easily performed at diagnostic facilities. Further improvement in this assay can lead to a new quantitative diagnostic test for Chagas disease. A similar selection based approach could also be used to develop ligands for the detection of biomarkers in other diseases.
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Affiliation(s)
- Rana Nagarkatti
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, U. S. Food and Drug Administration, Bethesda, Maryland, United States of America
| | - Fernanda Fortes de Araujo
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, U. S. Food and Drug Administration, Bethesda, Maryland, United States of America
| | - Charu Gupta
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, U. S. Food and Drug Administration, Bethesda, Maryland, United States of America
| | - Alain Debrabant
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Center for Biologics Evaluation and Research, U. S. Food and Drug Administration, Bethesda, Maryland, United States of America
- * E-mail:
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González-Tomé MI, Rivera M, Camaño I, Norman F, Flores-Chávez M, Rodríguez-Gómez L, Fumadó V, García-López Hortelano M, López-Vélez R, González-Granado LI, García-Burguillo A, Santos MDM, Ávila O. Recomendaciones para el diagnóstico, seguimiento y tratamiento de la embarazada y del niño con enfermedad de Chagas. Enferm Infecc Microbiol Clin 2013; 31:535-42. [DOI: 10.1016/j.eimc.2012.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 09/13/2012] [Accepted: 09/19/2012] [Indexed: 10/27/2022]
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Ajua A, Engleitner T, Esen M, Theisen M, Issifou S, Mordmüller B. A flow cytometry-based workflow for detection and quantification of anti-plasmodial antibodies in vaccinated and naturally exposed individuals. Malar J 2012; 11:367. [PMID: 23130649 PMCID: PMC3545855 DOI: 10.1186/1475-2875-11-367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 10/30/2012] [Indexed: 11/14/2022] Open
Abstract
Background Antibodies play a central role in naturally acquired immunity against Plasmodium falciparum. Current assays to detect anti-plasmodial antibodies against native antigens within their cellular context are prone to bias and cannot be automated, although they provide important information about natural exposure and vaccine immunogenicity. A novel, cytometry-based workflow for quantitative detection of anti-plasmodial antibodies in human serum is presented. Methods Fixed red blood cells (RBCs), infected with late stages of P. falciparum were utilized to detect malaria-specific antibodies by flow cytometry with subsequent automated data analysis. Available methods for data-driven analysis of cytometry data were assessed and a new overlap subtraction algorithm (OSA) based on open source software was developed. The complete workflow was evaluated using sera from two GMZ2 malaria vaccine trials in semi-immune adults and pre-school children residing in a malaria endemic area. Results Fixation, permeabilization, and staining of infected RBCs were adapted for best operation in flow cytometry. As asexual blood-stage vaccine candidates are designed to induce antibody patterns similar to those in semi-immune adults, serial dilutions of sera from heavily exposed individuals were compared to naïve controls to determine optimal antibody dilutions. To eliminate investigator effects introduced by manual gating, a non-biased algorithm (OSA) for data-driven gating was developed. OSA-derived results correlated well with those obtained by manual gating (r between 0.79 and 0.99) and outperformed other model-driven gating methods. Bland-Altman plots confirmed the agreement of manual gating and OSA-derived results. A 1.33-fold increase (p=0.003) in the number of positive cells after vaccination in a subgroup of pre-school children vaccinated with 100 μg GMZ2 was present and in vaccinated adults from the same region we measured a baseline-corrected 1.23-fold, vaccine-induced increase in mean fluorescence intensity of positive cells (p=0.03). Conclusions The current workflow advances detection and quantification of anti-plasmodial antibodies through improvement of a bias-prone, low-throughput to an unbiased, semi-automated, scalable method. In conclusion, this work presents a novel method for immunofluorescence assays in malaria research.
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Affiliation(s)
- Anthony Ajua
- Institute of Tropical Medicine, University of Tübingen, Wilhelmstraße 27, Tübingen D-72074, Germany
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