Diagnosis of Taenia solium infections based on “mail order” RNA-sequencing of single tapeworm egg isolates from stool samples

Combined community health programs aiming at health education, preventive anti-parasitic chemotherapy, and vaccination of pigs have proven their potential to regionally reduce and even eliminate Taenia solium infections that are associated with a high risk of neurological disease through ingestion of T. solium eggs. Yet it remains challenging to target T. solium endemic regions precisely or to make exact diagnoses in individual patients. One major reason is that the widely available stool microscopy may identify Taenia ssp. eggs in stool samples as such, but fails to distinguish between invasive (T. solium) and less invasive Taenia (T. saginata, T. asiatica, and T. hydatigena) species. The identification of Taenia ssp. eggs in routine stool samples often prompts a time-consuming and frequently unsuccessful epidemiologic workup in remote villages far away from a diagnostic laboratory. Here we present “mail order” single egg RNA-sequencing, a new method allowing the identification of the exact Taenia ssp. based on a few eggs found in routine diagnostic stool samples. We provide first T. solium transcriptome data, which show extremely high mitochondrial DNA (mtDNA) transcript counts that can be used for subspecies classification. “Mail order” RNA-sequencing can be administered by health personnel equipped with basic laboratory tools such as a microscope, a Bunsen burner, and access to an international post office for shipment of samples to a next generation sequencing facility. Our suggested workflow combines traditional stool microscopy, RNA-extraction from single Taenia eggs with mitochondrial RNA-sequencing, followed by bioinformatic processing with a basic laptop computer. The workflow could help to better target preventive healthcare measures and improve diagnostic specificity in individual patients based on incidental findings of Taenia ssp. eggs in diagnostic laboratories with limited resources.

Diagnosis of Taenia solium infections based on “mail order” RNA-sequencing of single tapeworm egg isolates from stool samples v1

Here we present a detailed protocol for the identification of Taenia solium based on the few Taenia spp. eggs found in diagnostic stool samples. Our approach is based on "mail order" RNA sequencing of single eggs and can be performed in laboratories equipped with basic tools such as a microscope, a Bunsen burner, and access to an international post office for shipping samples to a next-generation sequencing facility. This protocol describes sample collection and transport, isolation of individual Taenia spp. eggs, reliable disruption of individual Taenia eggs, and important considerations for shipping samples to a next-generation sequencing facility. We provide images and videos to help prepare the tools needed for the protocol. Additional information on our rationale for designing the critical steps can help implement the protocol in new environments.

Identification of Taenia solium based on single tapeworm eggs in diagnostic stool samples using RNA sequencing v1

Here we present a detailed protocol for the identification of Taenia solium based on the few Taenia spp. eggs found in diagnostic stool samples. Our approach is based on "mail order" RNA sequencing of single eggs and can be performed in laboratories equipped with basic tools such as a microscope, a Bunsen burner, and access to an international post office for shipping samples to a next-generation sequencing facility. This protocol describes sample collection and transport, isolation of individual Taenia spp. eggs, reliable disruption of individual Taenia eggs, and important considerations for shipping samples to a next-generation sequencing facility. We provide images and videos to help prepare the tools needed for the protocol. Additional information on our rationale for designing the critical steps can help implement the protocol in new environments.

A day in the life of a bioinformatician

Dr James Campbell studied applied biology at the University of the West of England and went on to receive a PhD for a study of the utilization of glycoprotein substrates by grampositive pathogenic bacteria. James then joined a proteomics research company focusing on biomarker discovery and the development of quantitative mass spectrometry methods, before moving to The Institute of Cancer Research, London. Since then, James has worked with the next generation sequencing facility and helped set up the bioinformatic analysis pipelines for the Tumour Profiling Unit. He currently leads the Bioinformatics Facility of the ICR's Cancer Research UK Centre, supporting research groups across the institute. Lorenza Giannella (Training Manager, Biochemical Society) spoke to him about his work.

Introducing ribosomal tandem repeat barcoding for fungi

Sequence analysis of the various ribosomal genetic markers is the dominant molecular method for identification and description of fungi. However, there is little agreement on what ribosomal markers should be used, and research groups utilize different markers depending on what fungal groups are targeted. New environmental fungal lineages known only from DNA data reveal significant gaps in the coverage of the fungal kingdom both in terms of taxonomy and marker coverage in the reference sequence databases. In order to integrate references covering all of the ribosomal markers, we present three sets of general primers that allow the amplification of the complete ribosomal operon from the ribosomal tandem repeats. The primers cover all ribosomal markers (ETS, SSU, ITS1, 5.8S, ITS2, LSU, and IGS) from the 5’ end of the ribosomal operon all the way to the 3’ end. We coupled these primers successfully with third generation sequencing (PacBio and Nanopore sequencing) to showcase our approach on authentic fungal herbarium specimens. In particular, we were able to generate high-quality reference data with Nanopore sequencing in a high-throughput manner, showing that the generation of reference data can be achieved on a regular desktop computer without the need for a large-scale sequencing facility. The quality of the Nanopore generated sequences was 99.85 %, which is comparable with the 99.78 % accuracy described for Sanger sequencing. With this work, we hope to stimulate the generation of a new comprehensive standard of ribosomal reference data with the ultimate aim to close the huge gaps in our reference datasets.