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Papaiakovou M, Fraija-Fernández N, James K, Briscoe AG, Hall A, Jenkins TP, Dunn J, Levecke B, Mekonnen Z, Cools P, Doyle SR, Cantacessi C, Littlewood DTJ. Evaluation of genome skimming to detect and characterise human and livestock helminths. Int J Parasitol 2023; 53:69-79. [PMID: 36641060 DOI: 10.1016/j.ijpara.2022.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/08/2022] [Accepted: 12/08/2022] [Indexed: 01/13/2023]
Abstract
The identification of gastrointestinal helminth infections of humans and livestock almost exclusively relies on the detection of eggs or larvae in faeces, followed by manual counting and morphological characterisation to differentiate species using microscopy-based techniques. However, molecular approaches based on the detection and quantification of parasite DNA are becoming more prevalent, increasing the sensitivity, specificity and throughput of diagnostic assays. High-throughput sequencing, from single PCR targets through to the analysis of whole genomes, offers significant promise towards providing information-rich data that may add value beyond traditional and conventional molecular approaches; however, thus far, its utility has not been fully explored to detect helminths in faecal samples. In this study, low-depth whole genome sequencing, i.e. genome skimming, has been applied to detect and characterise helminth diversity in a set of helminth-infected human and livestock faecal material. The strengths and limitations of this approach are evaluated using three methods to characterise and differentiate metagenomic sequencing data based on (i) mapping to whole mitochondrial genomes, (ii) whole genome assemblies, and (iii) a comprehensive internal transcribed spacer 2 (ITS2) database, together with validation using quantitative PCR (qPCR). Our analyses suggest that genome skimming can successfully identify most single and multi-species infections reported by qPCR and can provide sufficient coverage within some samples to resolve consensus mitochondrial genomes, thus facilitating phylogenetic analyses of selected genera, e.g. Ascaris spp. Key to this approach is both the availability and integrity of helminth reference genomes, some of which are currently contaminated with bacterial and host sequences. The success of genome skimming of faecal DNA is dependent on the availability of vouchered sequences of helminths spanning both taxonomic and geographic diversity, together with methods to detect or amplify minute quantities of parasite nucleic acids in mixed samples.
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Affiliation(s)
- Marina Papaiakovou
- Natural History Museum, Cromwell Road, London, UK; Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Natalia Fraija-Fernández
- Natural History Museum, Cromwell Road, London, UK; Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain
| | - Katherine James
- Natural History Museum, Cromwell Road, London, UK; Interdisciplinary Computing and Complex BioSystems, School of Computing, Newcastle University, Newcastle upon Tyne, UK
| | - Andrew G Briscoe
- Natural History Museum, Cromwell Road, London, UK; NatureMetrics, Surrey Research Park, Guildford, UK
| | - Andie Hall
- Natural History Museum, Cromwell Road, London, UK
| | - Timothy P Jenkins
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK; Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Julia Dunn
- Department of Infectious Disease Epidemiology, Imperial College, London W2 1PG, UK
| | - Bruno Levecke
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | - Zeleke Mekonnen
- Jimma University Institute of Health (JUIH), Jimma, Ethiopia
| | - Piet Cools
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | | | - Cinzia Cantacessi
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
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2
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Advantages and Limitations of Microscopy and Molecular Detections for Diagnosis of Soil-transmitted Helminths: An Overview. Helminthologia 2022; 59:321-340. [PMID: 36875683 PMCID: PMC9979072 DOI: 10.2478/helm-2022-0034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 10/31/2022] [Indexed: 02/05/2023] Open
Abstract
World Health Organization (WHO) reported that over 1.5 billion people are infected by soil-transmitted helminths (STH) worldwide in sub-Saharan Africa, the United States of America, China, and East Asia. Heavy infections and polyparasitism are associated with higher morbidity rates, and the patients are exposed to increased vulnerability to other diseases. Therefore, accurate diagnosis followed by mass treatment for morbidity control is necessary.STH diagnosis commonly involves the microscopic observation of the presence of the STH eggs and larvae in the faecal samples. Furthermore, molecular approaches are increasingly utilised in monitoring and surveillance as they show higher sensitivity. Their capability to differentiate hookworm species is an advantage over the Kato-Katz technique. This review discusses the advantages and limitations of microscopy and various molecular tools used for STH detection.
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3
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Pilotte N, Thomas T, Zulch MF, Sirois AR, Minetti C, Reimer LJ, Williams SA, Saunders LJ. Targeting a highly repetitive genomic sequence for sensitive and specific molecular detection of the filarial parasite Mansonella perstans from human blood and mosquitoes. PLoS Negl Trop Dis 2022; 16:e0010615. [PMID: 36580452 PMCID: PMC9833530 DOI: 10.1371/journal.pntd.0010615] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 01/11/2023] [Accepted: 12/15/2022] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Mansonella perstans is among the most neglected of the neglected tropical diseases and is believed to cause more human infections than any other filarial pathogen in Africa. Based largely upon assumptions of limited infection-associated morbidity, this pathogen remains understudied, and many basic questions pertaining to its pathogenicity, distribution, prevalence, and vector-host relationships remain unanswered. However, in recent years, mounting evidence of the potential for increased Mansonella infection-associated disease has sparked a renewal in research interest. This, in turn, has produced a need for improved diagnostics, capable of providing more accurate pictures of infection prevalence, pathogen distribution, and vector-host interactions. METHODOLOGY/PRINCIPAL FINDINGS Utilizing a previously described pipeline for the discovery of optimal molecular diagnostic targets, we identified a repetitive DNA sequence, and developed a corresponding assay, which allows for the sensitive and species-specific identification of M. perstans in human blood samples. Testing also demonstrated the ability to utilize this assay for the detection of M. perstans in field-collected mosquito samples. When testing both sample types, our repeat-targeting index assay outperformed a ribosomal sequence-targeting reference assay, facilitating the identification of additional M. perstans-positive samples falsely characterized as "negative" using the less sensitive detection method. CONCLUSIONS/SIGNIFICANCE Through the development of an assay based upon the systematic identification of an optimal DNA target sequence, our novel diagnostic assay will provide programmatic efforts with a sensitive and specific testing platform that is capable of accurately mapping M. perstans infection and determining prevalence. Furthermore, with the added ability to identify the presence of M. perstans in mosquito samples, this assay will help to define our knowledge of the relationships that exist between this pathogen and the various geographically relevant mosquito species, which have been surmised to represent potential secondary vectors under certain conditions. Detection of M. perstans in mosquitoes will also demonstrate proof-of-concept for the mosquito-based monitoring of filarial pathogens not vectored primarily by mosquitoes, an approach expanding opportunities for integrated surveillance.
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Affiliation(s)
- Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Department of Biological Sciences, Quinnipiac University, Hamden, Connecticut, United States of America
| | - Tamara Thomas
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Michael F. Zulch
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Allison R. Sirois
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Corrado Minetti
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lisa J. Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Lori J. Saunders
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
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4
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Halili S, Grant JR, Pilotte N, Gordon CA, Williams SA. Development of a novel real-time polymerase chain reaction assay for the sensitive detection of Schistosoma japonicum in human stool. PLoS Negl Trop Dis 2021; 15:e0009877. [PMID: 34695134 PMCID: PMC8568117 DOI: 10.1371/journal.pntd.0009877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 11/04/2021] [Accepted: 10/06/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Elimination and control of Schistosoma japonicum, the most virulent of the schistosomiasis-causing blood flukes, requires the development of sensitive and specific diagnostic tools capable of providing an accurate measurement of the infection prevalence in endemic areas. Typically, detection of S. japonicum has occurred using the Kato-Katz technique, but this methodology, which requires skilled microscopists, has been shown to radically underestimate levels of infection. With the ever-improving capabilities of next-generation sequencing and bioinformatic analysis tools, identification of satellite sequences and other highly repetitive genomic elements for use as real-time PCR diagnostic targets is becoming increasingly common. Assays developed using these targets have the ability to improve the sensitivity and specificity of results for epidemiological studies that can in turn be used to inform mass drug administration and programmatic decision making. METHODOLOGY/PRINCIPAL FINDINGS Utilizing Tandem Repeat Analyzer (TAREAN) and RepeatExplorer2, a cluster-based analysis of the S. japonicum genome was performed and a tandemly arranged genomic repeat, which we named SjTR1 (Schistosoma japonicum Tandem Repeat 1), was selected as the target for a real-time PCR diagnostic assay. Based on these analyses, a primer/probe set was designed and the assay was optimized. The resulting real-time PCR test was shown to reliably detect as little as 200 ag of S. japonicum genomic DNA and as little as 1 egg per gram of human stool. Based on these results, the index assay reported in this manuscript is more sensitive than previously published real-time PCR assays for the detection of S. japonicum. CONCLUSIONS/SIGNIFICANCE The extremely sensitive and specific diagnostic assay described in this manuscript will facilitate the accurate detection of S. japonicum, particularly in regions with low levels of endemicity. This assay will be useful in providing data to inform programmatic decision makers, aiding disease control and elimination efforts.
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Affiliation(s)
- Sara Halili
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Program in Biochemistry, Smith College, Northampton, Massachusetts, United States of America
| | - Jessica R. Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Department of Biological Sciences, Quinnipiac University, Hamden, Connecticut, United States of America
| | - Catherine A. Gordon
- QIMR Berghofer Institute of Medical Research, Molecular Parasitology Laboratory, Brisbane, Australia
| | - Steven A. Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
- Program in Biochemistry, Smith College, Northampton, Massachusetts, United States of America
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
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5
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Khurana S, Singh S, Mewara A. Diagnostic Techniques for Soil-Transmitted Helminths - Recent Advances. Res Rep Trop Med 2021; 12:181-196. [PMID: 34377048 PMCID: PMC8349539 DOI: 10.2147/rrtm.s278140] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 07/01/2021] [Indexed: 12/26/2022] Open
Abstract
Soil-transmitted helminth (STH) infections (hookworms, Trichuris, Ascaris) and Strongyloides spp. are associated with a substantial global burden and high morbidity. Sensitive and specific methods for diagnosis of these infections are essential for mapping the burden in communities, accurate assessment of infection levels, to guide interventions and monitoring the success of STH control programs. Despite considerable progress to control STH over several decades, we are still far from identifying a fully adequate diagnostic test. Conventional microscopy-based methods such as direct Kato–Katz smear or mounts after stool centrifugation/flotation-based concentration techniques have been the mainstay of diagnosis, especially in resource-poor countries where these infections abound. However, recently, these are being adapted to closed, easy to perform, digital formats, thereby improving the sensitivity as well as applicability in a remote, resource-limited setting. The use of image analysis systems to identify and quantify helminth eggs, with potential adaptation to smartphones, is also promising. Antibody detection tests have a limited role mostly in the case of Strongyloides hyperinfection. Coproantigen detection tests have been developed and used in veterinary practice for detection of STH, but these have not been evaluated for use in humans. More sensitive molecular diagnostics, including assays developed with new bioinformatic tools and techniques such as polymerase chain reaction (PCR), quantitative PCR (qPCR) and loop-mediated amplification assay, can help in the clear and precise assessment of STH burden during elimination phase and are of immense value for diagnosis in areas with low endemicity and in travelers to endemic regions. Moreover, the molecular techniques will help detect new species that may emerge. Sample preservation and efficient DNA extraction are critical and significantly affect the efficiency of molecular diagnostic tests. In addition to the diagnosis of clinical or asymptomatic infection in humans, detection of STH eggs in environmental samples is imperative to boost STH control efforts. Overall the diagnostic performance, cost-effectiveness, ease of performance, rapidity and in-field applicability of any test should be considered when choosing from the various diagnostic assays in areas with different endemicity, in addition to striving towards the development of novel technologies and optimization of existing methods.
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Affiliation(s)
- Sumeeta Khurana
- Department of Medical Parasitology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Shreya Singh
- Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Abhishek Mewara
- Department of Medical Parasitology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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6
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Papaiakovou M, Littlewood DTJ, Gasser RB, Anderson RM. How qPCR complements the WHO roadmap (2021-2030) for soil-transmitted helminths. Trends Parasitol 2021; 37:698-708. [PMID: 33931342 DOI: 10.1016/j.pt.2021.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/02/2021] [Accepted: 04/08/2021] [Indexed: 12/19/2022]
Abstract
Complementing the launch of the World Health Organization (WHO) roadmap (2021-2030) we explore key elements needing attention before recruitment of qPCR as the main diagnostics tool to confirm reduction or elimination of soil-transmitted helminth (STH) transmission in both control and elimination programmes. Given the performance limitations of conventional methods, a proposed harmonised qPCR will provide a diagnostic tool, with the sensitivity and specificity required to monitor low-intensity infections, following mass drug administration (MDA). Technical and logistical challenges associated with introducing qPCR as a stand-alone tool are highlighted, and a decision-making scheme on how qPCR can support surveillance, resistance detection, and elimination is presented. An accurate point-of-care (POC) diagnostic test needs to be developed to support STH control in the field, and STH biorepositories need to be established and maintained to ensure that reference materials are available for research and validation.
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Affiliation(s)
- Marina Papaiakovou
- Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research (LCNTDR), Imperial College London, London, UK.
| | - D Timothy J Littlewood
- Science Directorate, Natural History Museum, London, UK; London Centre for Neglected Tropical Disease Research (LCNTDR), Imperial College London, London, UK
| | - Robin B Gasser
- Department of Veterinary Biosciences, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Roy M Anderson
- Department of Infectious Disease Epidemiology, St Mary's Campus, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research (LCNTDR), Imperial College London, London, UK
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7
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Abstract
![]()
Helminths
represent a diverse category of parasitic organisms that
can thrive within a host for years, if not decades, in the absence
of treatment. As such, they must establish mechanisms to subsist off
their hosts, evade the immune system, and develop a niche among the
other cohabiting microbial communities. The complex interplay of biologically
small molecules (collectively known as the metabolome) derived from,
utilized by, or in response to the presence of helminths within a
host is an emerging field of study. In this Perspective, we briefly
summarize the current existing literature, categorize key host–pathogen–microbiome
interfaces that could be studied in the context of the metabolome,
and provide background on mass spectrometry-based metabolomic methodology.
Overall, we hope to provide a comprehensive guide for utilizing metabolomics
in the context of helminthic disease.
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Affiliation(s)
- Jeffrey D. Whitman
- Department of Laboratory Medicine, University of California, San Francisco, San Francisco, California 94110, United States
| | - Judy A. Sakanari
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158, United States
| | - Makedonka Mitreva
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63130, United States
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8
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Yu Z, Zhao Z, Chen L, Li J, Ju X. Development of a Droplet Digital PCR for Detection of Trichuriasis in Sheep. J Parasitol 2021; 106:603-610. [PMID: 32997756 DOI: 10.1645/20-16] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Trichuriasis is a serious threat to the economic development of animal husbandry. This research aimed to establish a droplet digital PCR (ddPCR) method to detect Trichuris spp. for the early diagnosis and prevention of trichuriasis in sheep. The real-time quantitative PCR (qPCR) and ddPCR methods were used for the detection of nematodes by targeted amplification of the ITS gene. Each means was evaluated to optimize the limit of detection and reproducibility. For a recombinant plasmid, the qPCR results showed that the detection limit was 31.7 copies per reaction. In contrast to qPCR, ddPCR was able to detect concentrations below 3.17 copies per reaction. Both assays exhibited good reproducibility. However, the ddPCR method was more stable for low-copy-number detection. This new assay was specific for Trichuris spp. and did not cross-react with other relevant gastrointestinal nematodes. A total of 98 clinical samples were tested with both assays. The results showed that the positive rate of ddPCR (80.6%) was higher than that of qPCR (72.4%). This method could be used as an efficient molecular biology tool to test for Trichuris spp. and could be a new valuable tool for the clinical diagnosis and prevention of trichuriasis.
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Affiliation(s)
- Zhichao Yu
- Department of Veterinary Medicine, College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, Guangdong, China.,Technology Center, Hohhot Customs District, Hohhot, 010020, Inner Mongolia, China
| | - Zhiguo Zhao
- Technology Center, Hohhot Customs District, Hohhot, 010020, Inner Mongolia, China
| | - Linjun Chen
- Technology Center, Hohhot Customs District, Hohhot, 010020, Inner Mongolia, China
| | - Junyan Li
- Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, Hohhot, 010031, China
| | - Xianghong Ju
- Department of Veterinary Medicine, College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, 524088, Guangdong, China
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9
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Global analysis of repetitive DNA from unassembled sequence reads using RepeatExplorer2. Nat Protoc 2020; 15:3745-3776. [PMID: 33097925 DOI: 10.1038/s41596-020-0400-y] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 08/21/2020] [Indexed: 11/08/2022]
Abstract
RepeatExplorer2 is a novel version of a computational pipeline that uses graph-based clustering of next-generation sequencing reads for characterization of repetitive DNA in eukaryotes. The clustering algorithm facilitates repeat identification in any genome by using relatively small quantities of short sequence reads, and additional tools within the pipeline perform automatic annotation and quantification of the identified repeats. The pipeline is integrated into the Galaxy platform, which provides a user-friendly web interface for script execution and documentation of the results. Compared to the original version of the pipeline, RepeatExplorer2 provides automated annotation of transposable elements, identification of tandem repeats and enhanced visualization of analysis results. Here, we present an overview of the RepeatExplorer2 workflow and provide procedures for its application to (i) de novo repeat identification in a single species, (ii) comparative repeat analysis in a set of species, (iii) development of satellite DNA probes for cytogenetic experiments and (iv) identification of centromeric repeats based on ChIP-seq data. Each procedure takes approximately 2 d to complete. RepeatExplorer2 is available at https://repeatexplorer-elixir.cerit-sc.cz .
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10
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Williams KM, Fessler MK, Bloomfield RA, Sandke WD, Malekshahi CR, Keroack CD, Duignan PJ, Torquato SD, Williams SA. A novel quantitative real-time PCR diagnostic assay for fecal and nasal swab detection of an otariid lungworm, Parafilaroides decorus. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2020; 12:85-92. [PMID: 32489853 PMCID: PMC7256429 DOI: 10.1016/j.ijppaw.2020.04.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/30/2020] [Accepted: 04/30/2020] [Indexed: 01/08/2023]
Abstract
Parafilaroides decorus, also known as sea lion lungworm, is a metastrongyloid nematode that infects otariid hosts, such as the charismatic California sea lion, Zalophus californianus. P. decorus causes bronchointerstitial pneumonia, respiratory distress, reduced ability to swim, dive and hunt and as a result, increased mortality particularly in young animals. Respiratory disease is a leading cause of stranding and admission to rehabilitation centers on the Pacific coast. Low-coverage genomic sequencing of four P. decorus individuals analyzed through Galaxy's RepeatExplorer identified a novel repeat DNA family we employed to design a sensitive quantitative PCR (qPCR) assay for diagnosing infections from fecal or sputum samples. The assay detects as little as 10 fg of P. decorus DNA and a linear regression model developed using a standard curve can be used to estimate the concentration of P. decorus DNA in a sample, ± 0.015 ng. This knowledge can be leveraged to estimate the level of parasite burden, which can be used to design improved treatments for animals in rehabilitation. Improved treatment of infections will aid in more animals being successfully released back into the wild. Developed qPCR assay for P. decorus. Sensitive to 10 fg. Applicable for feces or sputum.
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Affiliation(s)
- Kalani M Williams
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - M K Fessler
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - R A Bloomfield
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - William D Sandke
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - Clara R Malekshahi
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - Caroline D Keroack
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | | | - Samantha D Torquato
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA
| | - Steven A Williams
- Smith College, Department of Biological Sciences, Northampton, MA, 01063, USA.,University of Massachusetts, Molecular and Cellular Biology Program, Amherst, MA, 01003, USA
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11
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Zulch MF, Pilotte N, Grant JR, Minetti C, Reimer LJ, Williams SA. Selection and exploitation of prevalent, tandemly repeated genomic targets for improved real-time PCR-based detection of Wuchereria bancrofti and Plasmodium falciparum in mosquitoes. PLoS One 2020; 15:e0232325. [PMID: 32357154 PMCID: PMC7194414 DOI: 10.1371/journal.pone.0232325] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/12/2020] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Optimization of polymerase chain reaction (PCR)-based diagnostics requires the careful selection of molecular targets that are both highly repetitive and pathogen-specific. Advances in both next-generation sequencing (NGS) technologies and bioinformatics-based analysis tools are facilitating this selection process, informing target choices and reducing labor. Once developed, such assays provide disease control and elimination programs with an additional set of tools capable of evaluating and monitoring intervention successes. The importance of such tools is heightened as intervention efforts approach their endpoints, as accurate and complete information is an essential component of the informed decision-making process. As global efforts for the control and elimination of both lymphatic filariasis and malaria continue to make significant gains, the benefits of diagnostics with improved analytical and clinical/field-based sensitivities and specificities will become increasingly apparent. METHODOLOGY/PRINCIPAL FINDINGS Coupling Illumina-based NGS with informatics approaches, we have successfully identified the tandemly repeated elements in both the Wuchereria bancrofti and Plasmodium falciparum genomes of putatively greatest copy number. Utilizing these sequences as quantitative real-time PCR (qPCR)-based targets, we have developed assays capable of exploiting the most abundant tandem repeats for both organisms. For the detection of P. falciparum, analysis and development resulted in an assay with improved analytical and field-based sensitivity vs. an established ribosomal sequence-targeting assay. Surprisingly, analysis of the W. bancrofti genome predicted a ribosomal sequence to be the genome's most abundant tandem repeat. While resulting cycle quantification values comparing a qPCR assay targeting this ribosomal sequence and a commonly targeted repetitive DNA sequence from the literature supported our finding that this ribosomal sequence was the most prevalent tandemly repeated target in the W. bancrofti genome, the resulting assay did not significantly improve detection sensitivity in conjunction with field sample testing. CONCLUSIONS/SIGNIFICANCE Examination of pathogen genomes facilitates the development of PCR-based diagnostics targeting the most abundant and specific genomic elements. While in some instances currently available tools may deliver equal or superior performance, systematic analysis of potential targets provides confidence that the selected assays represent the most advantageous options available and that informed assay selection is occurring in the context of a particular study's objectives.
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Affiliation(s)
- Michael F Zulch
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America.,Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Jessica R Grant
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America
| | - Corrado Minetti
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Lisa J Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Steven A Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, United States of America.,Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, United States of America
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12
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Hasegawa M, Pilotte N, Kikuchi M, Means AR, Papaiakovou M, Gonzalez AM, Maasch JRMA, Ikuno H, Sunahara T, Ásbjörnsdóttir KH, Walson JL, Williams SA, Hamano S. What does soil-transmitted helminth elimination look like? Results from a targeted molecular detection survey in Japan. Parasit Vectors 2020; 13:6. [PMID: 31915050 PMCID: PMC6950881 DOI: 10.1186/s13071-019-3875-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 12/30/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Japan is one of the few countries believed to have eliminated soil-transmitted helminths (STHs). In 1949, the national prevalence of Ascaris lumbricoides was 62.9%, which decreased to 0.6% in 1973 due to improvements in infrastructure, socioeconomic status, and the implementation of national STH control measures. The Parasitosis Prevention Law ended in 1994 and population-level screening ceased in Japan; therefore, current transmission status of STH in Japan is not well characterized. Sporadic cases of STH infections continue to be reported, raising the possibility of a larger-scale recrudescence of STH infections. Given that traditional microscopic detection methods are not sensitive to low-intensity STH infections, we conducted targeted prevalence surveys using sensitive PCR-based assays to evaluate the current STH-transmission status and to describe epidemiological characteristics of areas of Japan believed to have achieved historical elimination of STHs. METHODS Stool samples were collected from 682 preschool- and school-aged children from six localities of Japan with previously high prevalence of STH. Caregivers of participants completed a questionnaire to ascertain access to water, sanitation and hygiene (WASH), and potential exposures to environmental contamination. For fecal testing, multi-parallel real-time PCR assays were used to detect infections of Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale and Trichuris trichiura. RESULTS Among the 682 children, no positive samples were identified, and participants reported high standards of WASH. CONCLUSIONS To our knowledge, this is the first STH-surveillance study in Japan to use sensitive molecular techniques for STH detection. The results suggest that recrudescence of STH infections has not occurred, and that declines in prevalence have been sustained in the sampled areas. These findings suggest that reductions in prevalence below the elimination thresholds, suggestive of transmission interruption, are possible. Additionally, this study provides circumstantial evidence that multi-parallel real-time PCR methods are applicable for evaluating elimination status in areas where STH prevalence is extremely low.
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Affiliation(s)
- Mitsuko Hasegawa
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.,Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA.,Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, USA
| | - Mihoko Kikuchi
- Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.,Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Arianna R Means
- Department of Global Health, University of Washington, Seattle, Washington, USA.,Department of Life Sciences, Natural History Museum, London, UK
| | - Marina Papaiakovou
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA.,Department of Life Sciences, Natural History Museum, London, UK
| | - Andrew M Gonzalez
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA
| | | | - Hiroshi Ikuno
- Department of Bacteriology, BML, Inc, Saitama, Japan
| | - Toshihiko Sunahara
- The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.,Department of Vector Ecology and Environment, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | | | - Judd L Walson
- Department of Global Health, University of Washington, Seattle, Washington, USA.,Department of Life Sciences, Natural History Museum, London, UK.,Departments of Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, Washington, USA
| | - Steven A Williams
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, USA.,Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts, USA
| | - Shinjiro Hamano
- Department of Parasitology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan. .,Doctoral Leadership Program, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan. .,The Joint Usage/Research Center on Tropical Disease, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.
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