LOEWE-DRUID
The research group "Electron Microscopy of Pathogens" is funded by the support programme of the federal state of Hessen for the development of scientific and economic excellence LOEWE within the LOEWE centre DRUID. Besides research, the group provides support in microscopy. Our research projects also establish advanced microscopy techniques, made available to the users of the microscopy platform.
Our research focuses on the replication of intracellular pathogens, in particular viruses. Since viruses rely on cells to replicate, understanding the replication cycle can help to understand how to combat them (Krijnse Locker, 2022). We focus on large DNA viruses, specifically the poxvirus vaccinia virus (VACV). VACV was used as live vaccine against human smallpox (variola virus), leading to its eradication in the 1970s. Recombinant VACV are used as vectors against other pathogens and in cancer therapy.
One focus is to understand how poxviruses acquire their envelope (Sodeik and Krijnse Locker, 2002). Because membrane preservation poses a particular challenge in electron microscopy (EM), we apply complementary and quantitative EM methods (Chlanda and Krijnse Locker, 2017). Using a combination of cryo- and 3D-EM, we showed that a small protein of VACV is essential for the proper organisation of the viral scaffold protein, and thus for viral membrane assembly (Tonnemacher et al., 2022). Similar EM methods were also applied to characterise membrane rearrangements induced by other viruses. Examples include HIV (Welsch et al., 2007), dengue virus (Welsch et al., 2009), hepatitis C virus (HCV; Romero-Brey et al., 2012) and SARS coronavirus-2 (SARS-CoV-2).
Figure 1. Electron microscopy images of different pathogens. Upper left, thin section of a cell infected with poxvirus; upper right, thin section of Salmonella, lower left, slice of the cryo-tomogram of SARS CoV2- inset negative staining EM of SARS CoV2, lower right thin section of HIV-infected cell. Bars- 500nm, except for SARS CoV2- 50nm
Source: Paul-Ehrlich-Institut
Another research focus is VACV entry and disassembly early in infection. Since these rare and dynamic events (Quemin et al., 2018), correlative light and electron microscopy (CLEM) is required. By light microscopy (LM) the rare events observed are registered and transferred to EM by correlation for high resolution imaging (Sartori-Rupp et al., 2019). Such a CLEM workflow was used to study HIV disassembly and entry at the nuclear pore (Blanco-Rodriguez et al., 2020).
Figure 2. Schematic representation of CLEM. Cells are grown on specialised electron microscopy grids and infected with fluorescent viruses. Cells are plunge frozen and positions of interest registered by cryo-light microscopy the so-called cryoCLEM. The positions of interest are then transferred to the cryoEM for high resolution imaging.
Source: Illustration by Weber et al. (2019, https://www.mdpi.com/2073-4409/8/1/57); CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/); Cropped from original
Our group also provides scientific and technical support in microscopy. The platform is equipped with modern light- and electron microscopes, advanced equipment for EM sample preparation, including a workflow for cryo-EM.
Figure 3. Examples of equipment of the microscopy platform.
Source: left: Paul-Ehrlich-Institut; right: Sascha Mannel
Professor Dr Jacomine Krijnse Locker
LOEWE Professorship for Neglected Infectious Diseases/Imaging Techniques
Publications
Phone: +49 6103 77 2011
Email: Jacomina.KrijnseLocker@pei.de
Updated: 27.06.2023
