The latest Paper of the Month from Parasitology is ‘X-ray micro-computed tomography (μCT): an emerging opportunity in parasite imaging‘ by James D. B. O’Sullivan, Julia Behnsen, Tobias Starborg et al.

For any research on parasites, microscopy is often a core part of the experimental toolkit. Indeed, capturing microscopic morphology has been an indispensable part of unpicking the classifications, life cycles and pathologies of the diverse range of parasites we know today. Many commonly-used imaging techniques rely on histological sectioning of the target tissues to produce cross-sectional images of the region of interest. However, a limitation of this approach is that the presence, orientation and location of parasites within tissue often remain unknown until the tissue is sectioned, potentially leading to loss of valuable information. Additionally, the spatial positioning of parasite relative to host may be complex and not lend itself well to visualisation in two dimensions – see, for example, whipworms (Trichuridae), which thread themselves tortuously within the colonic lining of their host. In our paper, we propose that X-ray micro-computed tomography (μCT), a 3D microscopy modality which can non-destructively image within tissue deeper than confocal and multiphoton, bypasses the above issues and could provide insights into previously unanswerable questions addressing parasite biology, host interactions and gross pathology.
Authors from the School of Biological Sciences first encountered μCT whilst trying to generate a 3D print of Schistosoma mansoni adults. Following some mixed results with electron microscopy, a new approach was tried – using μCT in collaboration with the School of Materials. Although the technique had more commonly been employed for imaging metals and polymers, we were impressed with the resulting image of the Schistosome (pictured). Curious to see what the technique could achieve, we began imaging a wider range of tissues, and were driven to investigate the tomographic literature further to optimise our approach for imaging the parasites. From these efforts, it became clear that μCT had a huge amount of potential to provide new information about the lifestyles and pathologies of parasites themselves.
In the paper, we describe different kinds of scanners, designed for either in vivo or ex vivo imaging, and provide some background on the best practice for ex vivo sample preparation. We also discuss the existing range of parasite-focussed tomographic studies, as well as the types of analyses which can be performed. Our hope is that we can alert a broader range of researchers to the potential of tomographic imaging for studying parasite life cycles and pathology. The ability to non-destructively look inside tissues opens up new avenues of investigation into unknown questions surrounding the invasion and migration of developing parasites throughout the host body, their accumulation within tissues as well as the distribution of the pathology which they cause.

3D volume rendering of male (blue) and female (green) trematodes (Schistosoma mansoni)

Read the full article ‘X-ray micro-computed tomography (μCT): an emerging opportunity in parasite imaging‘ in full for free until 3rd March 2018.


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