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Jiang X, Bai J, Zhang H, Yuan J, Lu G, Wang Y, Jiang L, Liu B, Huang D, Feng L. Development of an O-polysaccharide based recombinant glycoconjugate vaccine in engineered E. coli against ExPEC O1. Carbohydr Polym 2022; 277:118796. [PMID: 34893224 DOI: 10.1016/j.carbpol.2021.118796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 11/19/2022]
Abstract
Extraintestinal pathogenic Escherichia coli O1 is a frequently identified serotype that causes serious infections and is often refractory to antimicrobial therapy. Glycoconjugate vaccine represents a promising measure to reduce ExPEC infections. Herein, we designed an O1-specific glyco-optimized chassis strain for manufacture of O-polysaccharide (OPS) antigen and OPS-based bioconjugate. Specifically, OPS and OPS-based glycoprotein were synthesized in glyco-optimized chassis strain, when compared to the unmeasurable level of the parent strain. The optimal expression of oligosaccharyltransferase and carrier protein further improved the titer. MS analysis elucidated the correct structure of resulting bioconjugate at routine and unreported glycosylation sequons of carrier protein, with a higher glycosylation efficiency. Finally, purified bioconjugate stimulated mouse to generate specific IgG antibodies and protected them against virulent ExPEC O1 challenge. The plug-and-play glyco-optimized platform is suitable for bioconjugate synthesis, thus providing a potential platform for future medical applications.
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Affiliation(s)
- Xiaolong Jiang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Jing Bai
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Huijing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Jian Yuan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Gege Lu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Yuhui Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Lingyan Jiang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Bin Liu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China
| | - Di Huang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China.
| | - Lu Feng
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, Tianjin, PR China; TEDA Institute of Biological Sciences and Biotechnology, Tianjin Key Laboratory of Microbial Functional Genomics, Nankai University, Tianjin, PR China.
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Reginald K, Wong YR, Shah SMR, Teh KF, Freddy Jalin EJ, Khan NA. Investigating immune responses of the house cricket, Acheta domesticus to pathogenic Eschericia coli K1. Microbes Infect 2021; 23:104876. [PMID: 34332091 DOI: 10.1016/j.micinf.2021.104876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND Insects models are excellent models of the innate immune system, as they are free from the influences of the vertebrate adaptive immunity. Crickets are hemimetabolous insects belonging to the order Orthopteran order that have not been as extensively characterized as other holometabolous insects, and may provide new insights to the insect immune responses. In this study, we aim to characterize the innate immune responses of the common house cricket, Acheta domesticus in response to a human pathogenic bacterium E. coli K1. METHODS Crickets were injected with sterile buffer, live E. coli K1 or heat-killed E. coli K1. Physiological effects such as mortality and weight change of the crickets were determined 24-, 48 and 72-hours post injection while immunological effects such as hemocyte counts, bacteremia, phenoloxidase and lysozyme activity of the crickets were measured at 2- and 24-hours post-injection. RESULTS The injection of E. coli K1 in crickets resulted in >85% mortality 3-days post injection, accompanied by significant weight loss. E. coli K1 injection caused a significant increase in both phenoloxidase and lysozyme activities in cricket hemolymphs 24-hours post injection. Live E. coli K1 injected crickets resulted in a significant reduction in circulating hemocytes 24-hours post injection which was not observed in other treatment groups. This was consistent with the resolution of bacteremia observed 24-hours post infection in live E. coli K1 injected crickets. CONCLUSION Our study provides new insights on the innate immune response to pathogenic E. coli K1 in a cricket model.
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Affiliation(s)
- Kavita Reginald
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Bandar Sunway, Selangor, Malaysia.
| | - Yi Ru Wong
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Bandar Sunway, Selangor, Malaysia
| | - Smyrna Moti Rawanan Shah
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Bandar Sunway, Selangor, Malaysia
| | - Keng Foo Teh
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Bandar Sunway, Selangor, Malaysia
| | - Eunice Jalin Freddy Jalin
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Bandar Sunway, Selangor, Malaysia
| | - Naveed Ahmed Khan
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Bandar Sunway, Selangor, Malaysia; Clinical Sciences Department, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
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Siddiqui R, Muhammad JS, Khan NA. Locust as an in Vivo Model. ACS Chem Neurosci 2021; 12:1469-1471. [PMID: 33877824 DOI: 10.1021/acschemneuro.1c00190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The combination of newly available genome sequence information on locusts together with high throughput genomics capabilities, novel approaches for genetic traceability, and their large size for easier handling makes locusts a valuable in vivo tool to study brain formation, functional adaptations, and neuropathogenesis during embryonic development in various environmental niches.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- College of Arts and Sciences, American University of Sharjah, Sharjah 26666, United Arab Emirates
| | | | - Naveed Ahmed Khan
- College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
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4
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Siddiqui R, Khan NA. Locusts: A Model to Investigate Human Disease and Sickness Behavior. ACS Pharmacol Transl Sci 2020; 3:1423-1424. [PMID: 33344911 DOI: 10.1021/acsptsci.0c00151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Indexed: 11/29/2022]
Abstract
Traditionally, vertebrate models have been utilized and are viewed as more pertinent; however, we propose the application of an invertebrate model such as locusts to study human disease and sickness behavior at an early phase of research. This model has numerous benefits, namely, expense, swiftness, procedural convenience, and ethical acceptance. For example, the injection of immunogen-induced anorexia behavior in rats and locusts in vivo are analogous. Moreover, the presence of a brain barrier in locusts reveals remarkable similarities in molecular methods utilized by E. coli K1 to traverse the central nervous system of rats and locusts, consequently providing a worthwhile model to investigate pathogenesis. The presence of cytokines in these insects and presence of a brain barrier (which is physiologically relevant to human blood-brain barrier) makes it a relevant model in determining disease mechanisms and invasion of the brain by central nervous system pathogens.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- Department of Biology, Chemistry and Environmental Sciences, College of Arts and Sciences, American University of Sharjah, PO Box 26666, University City, Sharjah, United Arab Emirates
| | - Naveed Ahmed Khan
- Department of Biology, Chemistry and Environmental Sciences, College of Arts and Sciences, American University of Sharjah, PO Box 26666, University City, Sharjah, United Arab Emirates
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5
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Siddiqui R, Khan NA. An Innovative in Vivo Model for Bioassay-Guided Testing of Potential Antimicrobials. ACS Pharmacol Transl Sci 2020; 3:788-789. [PMID: 32832878 DOI: 10.1021/acsptsci.0c00091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Indexed: 11/29/2022]
Abstract
The use of in vivo models is critical in determining clinical relevance of potential chemotherapeutic molecules. Albeit mammals are of physiological relevance, the use of nonmammalian animals to investigate therapeutic efficacy of potential molecules at an initial stage of clinical research can complement in vitro studies. Here we suggest the use of a simple and inexpensive in vivo locust model in exploring the efficacy of novel chemotherapeutic molecules and/or large chemical libraries using high-throughput experimentation without legislative restrictions.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- Department of Biology, Chemistry and Environmental Sciences, College of Arts and Sciences, American University of Sharjah, University City, Sharjah, United Arab Emirates
| | - Naveed Ahmed Khan
- Department of Biology, Chemistry and Environmental Sciences, College of Arts and Sciences, American University of Sharjah, University City, Sharjah, United Arab Emirates
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6
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Alkurashi MM, May ST, Kong K, Bacardit J, Haig D, Elsheikha HM. Susceptibility to experimental infection of the invertebrate locusts (Schistocerca gregaria) with the apicomplexan parasite Neospora caninum. PeerJ 2014; 2:e674. [PMID: 25493211 PMCID: PMC4260130 DOI: 10.7717/peerj.674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 11/01/2014] [Indexed: 11/20/2022] Open
Abstract
Neuropathogenesis is a feature of Neospora caninum infection. In order to explore this in the absence of acquired host immunity to the parasite, we have tested infection in locusts (Schistocerca gregaria). We show for the first time that locusts are permissive to intra-hemocoel infection with N. caninum tachyzoites. This was characterized by alteration in body weight, fecal output, hemoparasitemia, and sickness-related behavior. Infected locusts exhibited progressive signs of sickness leading to mortality. Also, N. caninum showed neuropathogenic affinity, induced histological changes in the brain and was able to replicate in the brain of infected locusts. Fatty acid (FA) profiling analysis of the brains by gas chromatography and multi-variate prediction models discriminated with high accuracy (98%) between the FA profiles of the infected and control locusts. DNA microarray gene expression profiling distinguished infected from control S. gregaria brain tissues on the basis of distinct differentially-expressed genes. These data indicate that locusts are permissible to infection with N. caninum and that the parasite retains its tropism for neural tissues in the invertebrate host. Locusts may facilitate preclinical testing of interventional strategies to inhibit the growth of N. caninum tachyzoites. Further studies on how N. caninum brings about changes in locust brain tissue are now warranted.
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Affiliation(s)
- Mamdowh M Alkurashi
- School of Veterinary Medicine and Science, University of Nottingham , Sutton Bonington Campus, Leicestershire , UK ; Animal Production Department, College of Food and Agricultural Sciences, King Saud University , Riyadh , Saudi Arabia
| | - Sean T May
- Nottingham Arabidopsis Stock Centre, Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham , Leicestershire , UK
| | - Kenny Kong
- School of Physics and Astronomy, University of Nottingham , UK
| | - Jaume Bacardit
- The Interdisciplinary Computing and Complex BioSystems (ICOS) Research Group, School of Computing Science, Newcastle University , Newcastle-upon-Tyne , UK
| | - David Haig
- School of Veterinary Medicine and Science, University of Nottingham , Sutton Bonington Campus, Leicestershire , UK
| | - Hany M Elsheikha
- School of Veterinary Medicine and Science, University of Nottingham , Sutton Bonington Campus, Leicestershire , UK
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7
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Krishnan S, Shanmuganathan MV, Behenna D, Stoltz BM, Prasadarao NV. Angiotensin II receptor type 1--a novel target for preventing neonatal meningitis in mice by Escherichia coli K1. J Infect Dis 2013; 209:409-19. [PMID: 24041786 DOI: 10.1093/infdis/jit499] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The increasing incidence of Escherichia coli K1 meningitis due to escalating antibiotic resistance warrants alternate treatment options to prevent this deadly disease. We screened a library of small molecules from the National Institutes of Health clinical collection and identified telmisartan, an angiotensin II receptor type 1 (AT1R) blocker, as a potent inhibitor of E. coli invasion into human brain microvascular endothelial cells (HBMECs). Immunoprecipitation studies revealed that AT1R associates with endothelial cell gp96, the receptor in HBMECs for E. coli outer membrane protein A. HBMECs pretreated with telmisartan or transfected with AT1R small interfering RNA were resistant to E. coli invasion because of downregulation of protein kinase C-α phosphorylation. Administration of a soluble derivative of telmisartan to newborn mice before infection with E. coli prevented the onset of meningitis and suppressed neutrophil infiltration and glial cell migration in the brain. Therefore, telmisartan has potential as an alternate treatment option for preventing E. coli meningitis.
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Landraud L, Jauréguy F, Frapy E, Guigon G, Gouriou S, Carbonnelle E, Clermont O, Denamur E, Picard B, Lemichez E, Brisse S, Nassif X. Severity of Escherichia coli bacteraemia is independent of the intrinsic virulence of the strains assessed in a mouse model. Clin Microbiol Infect 2013; 19:85-90. [DOI: 10.1111/j.1469-0691.2011.03750.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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9
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Siddiqui R, Osman K, Khan NA. A novel in vivo model to study bacterial pathogenesis and screen potential therapeutic targets. J Med Microbiol 2012; 61:1036-1038. [PMID: 22466033 DOI: 10.1099/jmm.0.040865-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Affiliation(s)
- Ruqaiyyah Siddiqui
- Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan
| | - Khadijo Osman
- School of Biological and Chemical Sciences, Birkbeck, University of London, UK
| | - Naveed Ahmed Khan
- Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan
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10
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Siddiqui R, Edwards-Smallbone J, Flynn R, Khan NA. Next generation of non-mammalian blood-brain barrier models to study parasitic infections of the central nervous system. Virulence 2012; 3:159-63. [PMID: 21921682 PMCID: PMC3396694 DOI: 10.4161/viru.17631] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Transmigration of neuropathogens across the blood-brain barrier is a key step in the development of central nervous system infections, making it a prime target for drug development. The ability of neuropathogens to traverse the blood-brain barrier continues to inspire researchers to understand the specific strategies and molecular mechanisms that allow them to enter the brain. The availability of models of the blood-brain barrier that closely mimic the situation in vivo offers unprecedented opportunities for the development of novel therapeutics.
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Affiliation(s)
- Ruqaiyyah Siddiqui
- Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan
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11
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Siddiqui R, Beattie R, Khan NA. The role of the twin-arginine translocation pathway in Escherichia coli K1 pathogenicity in the African migratory locust, Locusta migratoria. ACTA ACUST UNITED AC 2011; 64:162-8. [DOI: 10.1111/j.1574-695x.2011.00870.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 09/05/2011] [Accepted: 09/06/2011] [Indexed: 11/28/2022]
Affiliation(s)
- Ruqaiyyah Siddiqui
- Department of Biological and Biomedical Sciences; Aga Khan University; Karachi; Pakistan
| | - Rachael Beattie
- School of Biological and Chemical Sciences; Birkbeck, University of London; London; UK
| | - Naveed A. Khan
- Department of Biological and Biomedical Sciences; Aga Khan University; Karachi; Pakistan
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12
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Heng SSJ, Chan OYW, Keng BMH, Ling MHT. Glucan Biosynthesis Protein G Is a Suitable Reference Gene in Escherichia coli K-12. ISRN MICROBIOLOGY 2011; 2011:469053. [PMID: 23724305 PMCID: PMC3658596 DOI: 10.5402/2011/469053] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 10/13/2011] [Indexed: 11/24/2022]
Abstract
The expressions of reference genes used in gene expression studies are assumed to be stable under most circumstances. However, a number of studies had demonstrated that such genes were found to vary under experimental conditions. In addition, genes that are stably expressed in an organ may not be stably expressed in other organs or other organisms, suggesting the need to identify reference genes for each organ and organism. This study aims at identifying stably expressed genes in Escherichia coli. Microarray datasets from E. coli substrain MG1655 and 1 dataset from W3110 were analysed. Coefficient of variance (COV) of was calculated and 10% of the lowest COV from 4631 genes common in the 3 MG1655 sets were analysed using NormFinder. Glucan biosynthesis protein G (mdoG), which is involved in cell wall synthesis, displayed the lowest weighted COV and weighted NormFinder Stability Index for the MG1655 datasets, while also showing to be the most stable in the dataset for substrain W3110, suggesting that mdoG is a suitable reference gene for E. coli K-12. Gene ontology over-representation analysis on the 39 genes suggested an over-representation of cell division, carbohydrate metabolism, and protein synthesis which supports the short generation time of E. coli.
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Affiliation(s)
- Sean S J Heng
- Raffles Institution, One Raffles Institution Lane, Singapore 575954
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13
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Hauber S, Parkes H, Siddiqui R, Khan NA. The use of high-resolution ¹H nuclear magnetic resonance (NMR) spectroscopy in the clinical diagnosis of Acanthamoeba. Parasitol Res 2011; 109:1661-9. [PMID: 21556684 DOI: 10.1007/s00436-011-2439-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Accepted: 04/27/2011] [Indexed: 10/18/2022]
Abstract
Acanthamoeba are opportunistic protozoan pathogens that can produce sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba spp. followed by aggressive treatment regimen. In this study, we tested the use of high-resolution (1)H NMR spectroscopy in the clinical diagnosis of Acanthamoeba. Using NMR spectroscopy combined with Pattern Recognition Analysis (PRA), we analysed variations in the biochemical 'fingerprint' of invasive and non-invasive Acanthamoeba, its closely related genus, Balamuthia mandrillaris, neuropathogenic Escherichia coli K1 strain E44, a laboratory strain of E. coli K-12, HB101, mammalian cells including human brain microvascular endothelial cells and monkey kidney cells. The findings revealed significant variations in the metabolites of amoebae, mammalian cells and bacteria. Interestingly, (1)H NMR spectra provided distinct biochemical profiles of clinical and non-clinical Acanthamoeba isolates highlighting the potential of (1)H NMR spectroscopy combined with PRA for the development of a novel diagnostic test that could rapidly identify pathogenic Acanthamoeba isolates with high sensitivity and specificity.
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Affiliation(s)
- Sandra Hauber
- School of Biological and Chemical Sciences, Birkbeck College, University of London, London, UK
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Dissemination and systemic colonization of uropathogenic Escherichia coli in a murine model of bacteremia. mBio 2010; 1. [PMID: 21116344 PMCID: PMC2993011 DOI: 10.1128/mbio.00262-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 10/27/2010] [Indexed: 01/19/2023] Open
Abstract
Infection with uropathogenic Escherichia coli (UPEC), the causative agent of most uncomplicated urinary tract infections, proceeds in an ascending manner and, if left untreated, may result in bacteremia and urosepsis. To examine the fate of UPEC after its entry into the bloodstream, we developed a murine model of sublethal bacteremia. CBA/J mice were inoculated intravenously with 1 × 106 CFU of pyelonephritis strain E. coli CFT073 carrying a bioluminescent reporter. Biophotonic imaging, used to monitor the infection over 48 h, demonstrated that the bacteria disseminated systemically and appeared to localize at discrete sites. UPEC was recovered from the spleen, liver, kidneys, lungs, heart, brain, and intestines as early as 20 min postinoculation, peaking at 24 h postinoculation. A nonpathogenic E. coli K-12 strain, however, disseminated at significantly lower levels (P < 0.01) and was cleared from the liver and cecum by 24 h postinoculation. Isogenic mutants lacking type 1 fimbriae, P fimbriae, capsule, TonB, the heme receptors Hma and ChuA, or particularly the sialic acid catabolism enzyme NanA were significantly outcompeted by wild-type CFT073 during bacteremia (P < 0.05), while flagellin and hemolysin mutants were not. E. coli is the primary cause of urinary tract infections. In severe cases of kidney infection, bacteria can enter the bloodstream and cause systemic disease. While the ability of E. coli to cause urinary tract infection has been extensively studied, the fate of these bacteria once they enter the bloodstream is largely unknown. Here we used an imaging technique to develop a mouse model of E. coli bloodstream infection and identify bacterial genes that are important for the bacteria to spread to and infect various organs. Understanding how urinary tract pathogens like E. coli cause disease after they enter the bloodstream may aid in the development of protective and therapeutic treatments.
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Non-vertebrate models to study parasite invasion of the central nervous system. Trends Parasitol 2010; 27:5-10. [PMID: 20832363 DOI: 10.1016/j.pt.2010.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/06/2010] [Accepted: 08/10/2010] [Indexed: 11/20/2022]
Abstract
Infections of the central nervous system due to neuroparasites have contributed significantly to morbidity and mortality. In part, this is because of our incomplete understanding of parasite traversal of the blood-brain barrier, a key step in the development of central nervous system infections, and the lack of available drugs that can cross the blood-brain barrier to gain entry into the brain to kill parasites. The novel in vitro, ex vivo, and in vivo models of the blood-brain barrier can offer strategies to elucidate the physical barriers, cellular mechanisms and molecular elements participating from both sides of parasite-host interactions leading to neuropathogenesis. Improving our knowledge of these core processes might elevate the efficiency of therapy of diseases caused by them.
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Goldsworthy G. Locusts as model organisms in which to study immunogen-induced anorectic behaviour. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:991-997. [PMID: 20416315 DOI: 10.1016/j.jinsphys.2010.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 04/13/2010] [Accepted: 04/14/2010] [Indexed: 05/29/2023]
Abstract
When injected into adult or nymphal Locusta that have been deprived of food for 2h, immunogens such as laminarin and bacterial LPS can induce an almost immediate dose-dependent state of anorexia for at least 1h. Such anorexia is a component of a medley of physiological and behavioural changes called collectively 'sickness behaviour' that occurs in a wide range of animals in response to infection or immune challenge. Sub-optimal amounts of injected laminarin allow some locusts to feed, but with a longer latency than in controls, although the length of the first meal is unaffected. The feeding behaviour of fifth instar nymphs is more sensitive to laminarin than that of adults, but both stages respond to amounts of immunogen that are lower than those required to activate the phenoloxidase cascade. Injection of adipokinetic hormone (AKH) before the period of food deprivation prevents the anorexigenic action of the laminarin in adults but not in nymphs. It is argued that the effect of the AKH may be indirect, through its lipid-mobilising action. The insecticide pymetrozine increases the latency to feed but also reduces the length of the first meal, and its anorexigenic activity is not affected by injection of AKH. The present data support the concept that laminarin-induced anorexia involves a central lack of motivation to eat, rather than a 'stop eating' signal. Others have shown that the mechanism of action of pymetrozine involves the serotonergic system and can be blocked by mianserin, so it is intriguing that in the present study injection of mianserin prior to that of laminarin modulates the anorexigenic effect of the immunogen. This suggests that biogenic amines are involved in the control of appetitive behaviour in locusts, as they are in vertebrates. The possible usefulness of the locust model in studying sickness-induced anorexia is discussed briefly.
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Affiliation(s)
- Graham Goldsworthy
- Biology Department, School of Biological and Chemical Sciences, Birkbeck College, University of London, Malet Street, London W1CE 7HX, UK.
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Acanthamoeba produces disseminated infection in locusts and traverses the locust blood-brain barrier to invade the central nervous system. BMC Microbiol 2010; 10:186. [PMID: 20615207 PMCID: PMC2908093 DOI: 10.1186/1471-2180-10-186] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 07/08/2010] [Indexed: 11/22/2022] Open
Abstract
Background Many aspects of Acanthamoeba granulomatous encephalitis remain poorly understood, including host susceptibility and chronic colonization which represent important features of the spectrum of host-pathogen interactions. Previous studies have suggested locusts as a tractable model in which to study Acanthamoeba pathogenesis. Here we determined the mode of parasite invasion of the central nervous system (CNS). Results Using Acanthamoeba isolates belonging to the T1 and T4 genotypes, the findings revealed that amoebae induced sickness behaviour in locusts, as evidenced by reduced faecal output and weight loss and, eventually, leading to 100% mortality. Significant degenerative changes of various tissues were observed by histological sectioning. Both isolates produced disseminated infection, with viable amoebae being recovered from various tissues. Histological examination of the CNS showed that Acanthamoeba invaded the locust CNS, and this is associated with disruption of the perineurium cell/glial cell complex, which constitutes the locust blood-brain barrier. Conclusions This is the first study to demonstrate that Acanthamoeba invades locust brain by modulating the integrity of the insect's blood-brain barrier, a finding that is consistent with the human infection. These observations support the idea that locusts provide a tractable model to study Acanthamoeba encephalitis in vivo. In this way the locust model may generate potentially useful leads that can be tested subsequently in mammalian systems, thus replacing the use of vertebrates at an early stage, and reducing the numbers of mammals required overall.
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Osman K, Khan NA. A novel in vivo model to screen antimicrobial compounds. Int J Antimicrob Agents 2010; 36:288-9. [PMID: 20430591 DOI: 10.1016/j.ijantimicag.2010.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 03/19/2010] [Indexed: 11/29/2022]
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Landraud L, Brisse S. Enterobacteriaceae. Infect Dis (Lond) 2010. [DOI: 10.1016/b978-0-323-04579-7.00169-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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Mortazavi PN, Goldsworthy G, Kirk R, Khan NA. Novel model for the in vivo study of central nervous system infection due to Acanthamoeba spp. (T4 genotype). J Med Microbiol 2009; 58:503-508. [DOI: 10.1099/jmm.0.005462-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study it was shown for what is believed to be the first time that the African migratory locust can be used as a model for the study of Acanthamoeba pathogenesis. Mature adult locusts were injected intra-abdominally with 10 μl suspension of 106
Acanthamoeba (a clinical isolate of the T4 genotype) in culture medium, or with the same volume of sterile culture medium. Locusts injected with Acanthamoeba showed significant weight loss and reduced production of faeces compared with control locusts. Furthermore, injection of amoebae killed all of the locusts within 17 days at room temperature, although the speed of kill was temperature and dose dependent. When samples of faecal pellets and various tissues of infected locusts were cultured on non-nutrient agar plates containing bacterial lawns, live amoebae were recovered from haemolymph, flight muscle and fat body samples, but not from faeces. When brains dissected from locusts were incubated with an anti-amoebic drug (100 μM chlorhexidine) to kill extracellular amoebae, and then washed, homogenized and cultured on bacteria-seeded non-nutrient agar plates, only lysates from amoebae-infected locusts were positive for Acanthamoeba. This strongly suggests that amoebae invade the locust brain and, indeed, trophozoites of Acanthamoeba could be identified within the brain in histological sections of brains from infected locusts, but not from uninfected locusts. These findings support the view that locusts can be used as a model for the study of Acanthamoeba pathogenesis in vivo.
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Affiliation(s)
| | - Graham Goldsworthy
- School of Biological and Chemical Sciences, Birkbeck, University of London, London, UK
| | - Ruth Kirk
- School of Life Sciences, Kingston University, Kingston upon Thames, Surrey, UK
| | - Naveed Ahmed Khan
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, England, UK
- School of Biological and Chemical Sciences, Birkbeck, University of London, London, UK
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Identification of the putative protein phosphatase gene PTC1 as a virulence-related gene using a silkworm model of Candida albicans infection. EUKARYOTIC CELL 2008; 7:1640-8. [PMID: 18708562 DOI: 10.1128/ec.00129-08] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Protein phosphatases are critical for the regulation of many cellular processes. Null mutants of 21 putative protein phosphatases of Candida albicans were constructed by consecutive allele replacement using the URA3 and ARG4 marker genes. A simple silkworm model of C. albicans infection was used to screen the panel of mutants. Four null mutant (cmp1Delta, yvh1Delta, sit4Delta, and ptc1Delta) strains showed attenuated virulence in the silkworm model relative to that of control and parental strains. Three of the mutants, the cmp1Delta, yvh1Delta, and sit4Delta mutants, had previously been identified as affecting virulence in a conventional mouse model, indicating the validity of the silkworm model screen. Disruption of the putative protein phosphatase gene PTC1 of C. albicans, which has 52% identity to the Saccharomyces cerevisiae type 2C protein phosphatase PTC1, significantly reduced virulence in the silkworm model. The mutant was also avirulent in a mouse model of disseminated candidiasis. Reintroducing either of the C. albicans PTC1 alleles into the disruptant strain, using a cassette containing either allele under the control of a constitutive ACT1 promoter, restored virulence in both infection models. Characterization of ptc1Delta revealed other phenotypic traits, including reduced hyphal growth in vitro and in vivo, and reduced extracellular proteolytic activity. We conclude that PTC1 may contribute to pathogenicity in C. albicans.
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