New imaging technology sheds light on pathogens during degradation

Degradation by phagocytes is a key mechanism by which the immune system attacks and destroys pathogens. Unfortunately, many parasites are somehow able to circumvent this important line of defense, causing disease and sometimes even death in their host. Detailed insight in the interactions between immune cells and pathogens is much needed, but also complicated. One of the reasons is that is difficult to (genetically or chemically) alter intracellular pathogens in such a way that they can be visualized using imaging approaches. And when such approaches do succeed, it is only when infection has been established, leaving the degradation steps literally in the dark. On the other hand, successful phagocytic degradation leaves no traces behind, such as reporter proteins and epitopes that could be used to track all the steps in the phagolysosomal pathway.

ICI PhD student Daphne van Elsland (Leiden University) and colleagues have combined two established techniques that enable visualization of bacteria being degraded by immune cells. For labelling, they employ bioorthogonal non-canonical amino acid tagging (BONCAT) to incorporate bioorthogonal groups in the bacteria. To allow visualization of the BONCAT-labelled bacteria inside phagocytes, they developed a CLEM (correlative light-electron microscopy)-imaging based approach.

Daphne M. van Elsland, Erik Bos, Wouter de Boer, Hermen S. Overkleeft, Abraham J. Koster, Sander I. van Kasteren
Detection of bioorthogonal groups by correlative light and electron microscopy allows imaging of degraded bacteria in phagocytes
Chemical Science, 2016, Advanced online publication 23 October 2015, doi:10.1039/C5SC02905H

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