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Rodrigues JF, Lourenço RF, Maeda DLNF, de Jesus Cintra M, Nakao N, Mathias-Santos C, Luiz WB, de Souza Ferreira LC. Strain-specific transcriptional and posttranscriptional regulation of heat-labile toxin expression by enterotoxigenic Escherichia coli. Braz J Microbiol 2020; 51:455-465. [PMID: 32016818 PMCID: PMC7203263 DOI: 10.1007/s42770-020-00231-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 01/18/2020] [Indexed: 11/30/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) represents one of the most important etiological agents of diarrhea in developing countries and characteristically produces at least one of two enterotoxins: heat-labile toxin (LT) and heat-stable toxin (ST). It has been previously shown that the production and release of LT by human-derived ETEC strains are variable. Although the natural genetic polymorphisms of regulatory sequences of LT-encoding (eltAB) genes may explain the variable production of LT, the knowledge of the transcriptional and posttranscriptional aspects affecting LT expression among ETEC strains is not clear. To further understand the factors affecting LT expression, we evaluated the impact of the natural polymorphism in noncoding regulatory sequences of eltAB among clinically derived ETEC strains. Sequence analyses of seven clinically derived strains and the reference strain H10407 revealed polymorphic sites at both the promoter and upstream regions of the eltAB operon. Operon fusion assays with GFP revealed that specific nucleotide changes in the Pribnow box reduce eltAB transcription. Nonetheless, the total amounts of LT produced by the tested ETEC strains did not strictly correspond to the detected LT-specific mRNA levels. Indeed, the stability of LT varied according to the tested strain, indicating the presence of posttranscriptional mechanisms affecting LT expression. Taken together, our results indicate that the production of LT is a strain-specific process and involves transcriptional and posttranscriptional mechanisms that regulate the final amount of toxin produced and released by specific strains.
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Affiliation(s)
- Juliana Falcão Rodrigues
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil. .,Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
| | - Rogério Ferreira Lourenço
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil.,Institute of Biology, The State University of Campinas, São Paulo, Brazil
| | - Denicar Lina Nascimento Fabris Maeda
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil.,Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
| | - Mariana de Jesus Cintra
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil
| | - Naomi Nakao
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil
| | - Camila Mathias-Santos
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil.,Technical-Scientific Police Superintendency, São Paulo State, Criminalistic Institute, São Paulo, Brazil
| | - Wilson Barros Luiz
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil.,Department of Biological Sciences, State University of Santa Cruz, Ilhéus, Bahia, Brazil
| | - Luís Carlos de Souza Ferreira
- Vaccine Development Laboratory, Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1374, Cidade Universitária, São Paulo, SP, 05508-900, Brazil.
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Rezaie E, Nekoie H, Miri A, Oulad G, Ahmadi A, Saadati M, Bozorgmehr M, Ebrahimi M, Salimian J. Different frequencies of memory B-cells induced by tetanus, botulinum, and heat-labile toxin binding domains. Microb Pathog 2018; 127:225-232. [PMID: 30528250 DOI: 10.1016/j.micpath.2018.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 10/18/2018] [Accepted: 12/03/2018] [Indexed: 12/18/2022]
Abstract
Along with robust immunogenicity, an ideal vaccine candidate should be able to produce a long lasting protection. In this regard, the frequency of memory B-cells is possibly an important factor in memory B-cell persistency and duration of immunological memory. On this basis, binding domains of tetanus toxin (HcT), botulinum type A1 toxin (HcA), and heat-labile toxin (LTB) were selected as antigen models that induced long-term, midterm and short-term immune memory, respectively. In the present study, the frequency of total memory B-cells after immunization with HcT, HcA and LTB antigens after 90 and 180 days, and also after one booster, in 190 days, was evaluated. The results showed a significant correlation between frequency of total memory B-cells and duration of humoral immunity. Compared to other antigens, the HcT antibody titers and HcT total memory B-cell populations were greater and persistent even after 6 months. At 6 months after the final immunization, all HcT- and HcA-immunized mice survived against tetanus and botulinum toxins, and also LT toxin binding to GM1 ganglioside was blocked in LTB-immunized mice. We conclude the frequency of memory B-cells and their duration are likely a key factor for vaccine memory duration.
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Affiliation(s)
- Ehsan Rezaie
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Science, Tehran, Iran
| | - Hekmat Nekoie
- Biology Research Center, IH University, Tehran, Iran
| | - Ali Miri
- Human Genetic Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Gholamreza Oulad
- Applied Biotechnology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Ali Ahmadi
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Science, Tehran, Iran
| | | | - Mahmood Bozorgmehr
- Department of Immunology, Avicenna Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Marzieh Ebrahimi
- Department of Stem Cells and Developmental Biology, Royan Institute for Stem Cell Biology and Technology, Tehran, Iran.
| | - Jafar Salimian
- Chemical Injuries Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran.
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Henrique C, Caetano BA, Mitsunari T, Dos Santos LF, Piazza RMF, Rocha LB. Large-scale evaluation of a rapid diagnostic test for diarrhea caused by enterotoxigenic Escherichia coli targeting the heat-labile toxin. J Microbiol Methods 2017; 144:125-127. [PMID: 29175533 DOI: 10.1016/j.mimet.2017.11.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/22/2017] [Accepted: 11/22/2017] [Indexed: 10/18/2022]
Abstract
We standardized an immunochromatographic test (IC) for heat-labile toxin I (LT-I) detection using LT-I antibodies and a specific platform containing the apparatus for application, assembly and cutting. IC detected as little as 62.5ng/mL of purified LT-I toxin and presented 91% sensitivity, 99.5% specificity and 96.0% accuracy, thereby proving to be an excellent point-of-care test for the diagnosis of enterotoxigenic E. coli infection in low-income countries.
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Affiliation(s)
- Camila Henrique
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil
| | - Bruna A Caetano
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil
| | - Thais Mitsunari
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil
| | | | - Roxane M F Piazza
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil.
| | - Letícia B Rocha
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil
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Zhu C, Setty P, Boedeker EC. Development of live attenuated bacterial vaccines targeting Escherichia coli heat-labile and heat-stable enterotoxins. Vet Microbiol 2017; 202:72-78. [PMID: 28527491 DOI: 10.1016/j.vetmic.2017.04.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/04/2017] [Accepted: 04/12/2017] [Indexed: 10/19/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC), defined by the production of heat labile (LT) and/or heat stable (ST) toxins, are major causes of diarrhea in animals, children in developing countries and to travelers. No broadly protective ETEC vaccine is available, largely because of the difficulty in inducing immunity to the small ST molecule. To take advantage of the demonstration (Liu et al., 2011; Zhang et al., 2013, 2010) that genetically produced fusions of mutant ST with LT subunits can induce effective immunity against both toxins, we engineered a live attenuated vaccine vector strain of E. coli (ZCR533), expressing the immunogenic LT-ST fusions. To present the LT-ST fusions to the mucosal immune system, we used restriction-free cloning to incorporate them into the passenger domain of the autotransporter protein (EspP) expressed on a medium copy number plasmid. This versatile system permits expression of incorporated antigens in either surface-bound or secreted forms by the ZCR533 vector, for delivery to the mucosal inductive sites. Incorporation of the fusions into EspP plasmids was confirmed by PCR and DNA sequencing. Protein expression was confirmed by Western blot of whole cell lysates and culture supernatents using polyclonal antisera to LT. Expression of the surface-targeted fusion on the surface of ZCR533 was confirmed by immuno-fluorescent staining. These studies show that antigenic LT-ST fusions can be surface-expressed or secreted, by our attenuated E. coli ZCR533 vaccine vector via the EspP autotransporter. These constructs could serve as broadly protective vaccine candidates to protect against both LT- and ST-producing ETEC.
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Affiliation(s)
- Chengru Zhu
- School of Medicine, University of New Mexico, MSC10 5550, Albuquerque, NM 87131, USA
| | - Prashanth Setty
- New Mexico Veterans Administration Health Care System, 1501 San Pedro SE, Albuquerque, NM 87108, USA; School of Medicine, University of New Mexico, MSC10 5550, Albuquerque, NM 87131, USA
| | - Edgar C Boedeker
- New Mexico Veterans Administration Health Care System, 1501 San Pedro SE, Albuquerque, NM 87108, USA; School of Medicine, University of New Mexico, MSC10 5550, Albuquerque, NM 87131, USA.
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