The pathogen imaging facility at the University of Edinburgh

The pathogen imaging facility at the University of Edinburgh

From left to right: Balazs Szoor, Stephanie Monk, Adam Mott, Eleanor Barnwell, Paula MacGregor, Keith Matthews, Sarah Kabani. Lab members not shown are Melanie Buhlmann, Pegine Walrad, Katelyn Fenn, Irene Ruberto, Sam Dean and Deborah Hall.

This month’s featured research group is The Pathogen Imaging Facility at the Institute of Immunology and Infection at the University of Edinburgh. This is a recently established research facility aimed at addressing basic questions in parasite cell biology and the interactions of pathogens with host cells. Researchers throughout the Institute and within Edinburgh’s Centre for Infectious Disease pursue very diverse questions in all aspects of infection biology and immunology and the facility is accessible and used by a wide range of researchers. A key aspect of the facility is that it can operate under appropriate containment levels for live pathogen work providing an essential capability for tracking, for example, the invasion pathway or kinetics of transgenic pathogens expressing fluorescently tagged proteins or trafficking through colour-coded host cell compartments.

The facility is jointly managed by Dr Toni Aebischer and Dr Keith Matthews. Toni and Keith both study kinetoplastid protozoan parasites. These parasites are transmitted between mammalian hosts via biting flies. African trypanosome parasites are responsible for epidemics of sleeping sickness in sub-Saharan Africa. This disease is always fatal unless treated and is the second biggest killer behind HIV in parts of Africa. Also in this genus of parasite re the Leishmania parasites which can cause deadly skin sores and effects 12 million people across 88 countries.

Keith studied at Glasgow University for his PhD, followed by post doctoral positions at Yale and Manchester Universities. He moved to the University of Edinburgh in 2004 where he is now Professor of Parasite Biology. The work in Keith Matthews’ lab on the developmental biology of trypanosomes was recently recognised by his award by the British Society for Parasitology of the C.A. Wright Memorial medal.

Toni studied Biology at the University of Fribourg, Switzerland. He obtained his PhD in Experimental Immunology at the ETH in Zuerich before moving to Australia to work on Leishmaniasis. In 2006, he moved to Edinburgh University from Berlin, on the basis of a Marie Curie Award.

Keith’s lab is examining the signalling and molecular control of the differentiation events that accompany the transition from the trypanosome’s transmissible bloodstream form (the so called ‘stumpy form’) to the stage of the parasite that colonies the mid-gut of the parasite’s tsetse fly vector. This is a particularly attractive system for studying developmental cell biology in an evolutionarily ancient eukaryotic pathogen because differentiation between these life cycle stages occurs highly synchronously in the population and is characterised by a number of easily assayable molecular, morphological and metabolic events. In addition, trypanosomes are very easily genetically modified in culture, allowing the expression of labelled marker proteins to track differentiation or associated signalling events.

Gene silencing by inducible RNAi in vitro and in vivo is also routine in these parasites allowing gene function to be directly examined in the context of the well-characterised differentiation programme. This tractable framework has proved invaluable in dissecting the control of differentiation at all levels, including understanding the unusual mechanisms of gene expression control in trypanosomes (where genes are almost exclusively controlled at the post-transcriptional level) and in tracking the signalling events responsible for the reception of the initial signal to differentiate and its downstream transduction. Most importantly the Pathogen Imaging Facility enables integration of these molecular and cellular studies at the level of the individual parasite, allowing dynamic or transient regulatory developmental events to be followed in live parasites or understood at the sub cellular level.

Keith uses Volocity software to examine the location and interactions of regulators and signalling molecules in the trypansome cell as they undergo development.

Keith says “My lab is quite new to confocal microscopy but we are already impressed by the ease of use and capabilities of the Volocity software”

From left to right: Daniel Paape, Athina Paterou,Toni Aebischer, Martin Barrios-Llerena, Juliane Schroeder

The ambition of Toni's lab is to decipher the modes of intracellular parasitism through a comprehensive analysis of habitats occupied by a model parasite, Leishmania spp.. They have developed a novel coloured approach to investigate such habitats (Paape et al.. 2008. Molecular and Cellular Proteomics online May 12, 2008 as Manuscript M700343-MCP200) and created a unique series of transgenic mice with a fluorescently tagged endocytic pathway via ES cell technology and complementary colour coded parasites. This live colour system is used to dissect establishment and composition of pathogen-infested compartments in primary host cells. On a confocal platform of a new Pathogen Imaging Facility established by the Aebischer and Matthews Labs with the help of a BBSRC REI grant parasites and parasite host cell interactions are studied by still and live imaging. Improvision’s Volocity visualisation, quantitation and tracking software is used to analyze images and gain critical insight.

Toni says "I find the quantitation/tracking functions of Volocity easy to use and of great benefit when trying to recognize and enumerate pathogen-inhabited compartments in infected host cell."

Keith and Toni’s research has the potential to affect millions of lives across the globe. Through furthering the understanding of these parasites the team hopes to help prevent trypanosome parasite related diseases. If you would like to read more about Keith and Toni’s research please visit the web pages for Keith Matthews and Toni Aebischer

Two trypanosomes undergoing differentiation from their bloodstream to tsetse midgut form. The procyclin coat, expressed on insect forms, is shown in green. Parasite DNA (nucleus and kinetoplast(s)) are stained in blue. The kinetoplast is the parasite's specialized mitochondrial genome. The left hand cell has initiated differentiation, the right hand cell has not.