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Awuah-Mensah G, McDonald J, Steketee PC, Autheman D, Whipple S, D'Archivio S, Brandt C, Clare S, Harcourt K, Wright GJ, Morrison LJ, Gadelha C, Wickstead B. Reliable, scalable functional genetics in bloodstream-form Trypanosoma congolense in vitro and in vivo. PLoS Pathog 2021; 17:e1009224. [PMID: 33481935 PMCID: PMC7870057 DOI: 10.1371/journal.ppat.1009224] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/08/2021] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
Animal African trypanosomiasis (AAT) is a severe, wasting disease of domestic livestock and diverse wildlife species. The disease in cattle kills millions of animals each year and inflicts a major economic cost on agriculture in sub-Saharan Africa. Cattle AAT is caused predominantly by the protozoan parasites Trypanosoma congolense and T. vivax, but laboratory research on the pathogenic stages of these organisms is severely inhibited by difficulties in making even minor genetic modifications. As a result, many of the important basic questions about the biology of these parasites cannot be addressed. Here we demonstrate that an in vitro culture of the T. congolense genomic reference strain can be modified directly in the bloodstream form reliably and at high efficiency. We describe a parental single marker line that expresses T. congolense-optimized T7 RNA polymerase and Tet repressor and show that minichromosome loci can be used as sites for stable, regulatable transgene expression with low background in non-induced cells. Using these tools, we describe organism-specific constructs for inducible RNA-interference (RNAi) and demonstrate knockdown of multiple essential and non-essential genes. We also show that a minichromosomal site can be exploited to create a stable bloodstream-form line that robustly provides >40,000 independent stable clones per transfection-enabling the production of high-complexity libraries of genome-scale. Finally, we show that modified forms of T. congolense are still infectious, create stable high-bioluminescence lines that can be used in models of AAT, and follow the course of infections in mice by in vivo imaging. These experiments establish a base set of tools to change T. congolense from a technically challenging organism to a routine model for functional genetics and allow us to begin to address some of the fundamental questions about the biology of this important parasite.
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Affiliation(s)
| | - Jennifer McDonald
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Pieter C. Steketee
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Delphine Autheman
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Sarah Whipple
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Simon D'Archivio
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Cordelia Brandt
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Simon Clare
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Katherine Harcourt
- Pathogen Support Team, Wellcome Sanger Institute, Cambridge, United Kingdom
| | - Gavin J. Wright
- Cell Surface Signalling Laboratory, Wellcome Sanger Institute, Cambridge, United Kingdom
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, York, United Kingdom
| | - Liam J. Morrison
- The Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Catarina Gadelha
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Bill Wickstead
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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