Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy
Abstract Background SARS-CoV-2 replicates efficiently in the upper airways of humans and produces high loads of virus RNA and, at least in the initial phase after infection, many infectious virus particles. Studying virus ultrastructure, such as particle integrity or presence of spike proteins, and...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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BMC
2023-02-01
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| Series: | Virology Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s12985-023-01981-9 |
| _version_ | 1811166079143116800 |
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| author | Michael Laue Tobias Hoffmann Janine Michel Andreas Nitsche |
| author_facet | Michael Laue Tobias Hoffmann Janine Michel Andreas Nitsche |
| author_sort | Michael Laue |
| collection | DOAJ |
| description | Abstract Background SARS-CoV-2 replicates efficiently in the upper airways of humans and produces high loads of virus RNA and, at least in the initial phase after infection, many infectious virus particles. Studying virus ultrastructure, such as particle integrity or presence of spike proteins, and effects on their host cells in patient samples is important to understand the pathogenicity of SARS-CoV-2. Methods Suspensions from swab samples with a high load of virus RNA (Ct < 20) were sedimented by desktop ultracentrifugation and prepared for thin section electron microscopy using a novel method which is described in detail. Embedding was performed in Epon or in LR White resin using standard or rapid protocols. Thin sections were examined using transmission electron microscopy. Results Virus particles could be regularly detected in the extracellular space, embedded in a background of heterogenous material (e.g. vesicles and needle-like crystals), and within ciliated cells. Morphology (i.e. shape, size, spike density) of virus particles in the swab samples was very similar to particle morphology in cell culture. However, in some of the samples the virus particles hardly revealed spikes. Infected ciliated cells occasionally showed replication organelles, such as double-membrane vesicles. The most common cells in all samples were keratinocytes from the mucosa and bacteria. Conclusions The new method allows the ultrastructural visualization and analysis of coronavirus particles and of infected host cells from easy to collect naso/oropharyngeal patient swab samples. |
| first_indexed | 2024-04-10T15:46:42Z |
| format | Article |
| id | doaj.art-b139968f510b41d6ac845cfe673228f9 |
| institution | Directory Open Access Journal |
| issn | 1743-422X |
| language | English |
| last_indexed | 2024-04-10T15:46:42Z |
| publishDate | 2023-02-01 |
| publisher | BMC |
| record_format | Article |
| series | Virology Journal |
| spelling | doaj.art-b139968f510b41d6ac845cfe673228f92023-02-12T12:04:34ZengBMCVirology Journal1743-422X2023-02-012011910.1186/s12985-023-01981-9Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopyMichael Laue0Tobias Hoffmann1Janine Michel2Andreas Nitsche3Advanced Light and Electron Microscopy, Center for Biological Threats and Special Pathogens (ZBS 4), Robert Koch InstituteAdvanced Light and Electron Microscopy, Center for Biological Threats and Special Pathogens (ZBS 4), Robert Koch InstituteHighly Pathogenic Viruses, Center for Biological Threats and Special Pathogens (ZBS 1), Robert Koch InstituteHighly Pathogenic Viruses, Center for Biological Threats and Special Pathogens (ZBS 1), Robert Koch InstituteAbstract Background SARS-CoV-2 replicates efficiently in the upper airways of humans and produces high loads of virus RNA and, at least in the initial phase after infection, many infectious virus particles. Studying virus ultrastructure, such as particle integrity or presence of spike proteins, and effects on their host cells in patient samples is important to understand the pathogenicity of SARS-CoV-2. Methods Suspensions from swab samples with a high load of virus RNA (Ct < 20) were sedimented by desktop ultracentrifugation and prepared for thin section electron microscopy using a novel method which is described in detail. Embedding was performed in Epon or in LR White resin using standard or rapid protocols. Thin sections were examined using transmission electron microscopy. Results Virus particles could be regularly detected in the extracellular space, embedded in a background of heterogenous material (e.g. vesicles and needle-like crystals), and within ciliated cells. Morphology (i.e. shape, size, spike density) of virus particles in the swab samples was very similar to particle morphology in cell culture. However, in some of the samples the virus particles hardly revealed spikes. Infected ciliated cells occasionally showed replication organelles, such as double-membrane vesicles. The most common cells in all samples were keratinocytes from the mucosa and bacteria. Conclusions The new method allows the ultrastructural visualization and analysis of coronavirus particles and of infected host cells from easy to collect naso/oropharyngeal patient swab samples.https://doi.org/10.1186/s12985-023-01981-9SARS-CoV-2Swab sampleThin section electron microscopyUltrastructureVirus particle |
| spellingShingle | Michael Laue Tobias Hoffmann Janine Michel Andreas Nitsche Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy Virology Journal SARS-CoV-2 Swab sample Thin section electron microscopy Ultrastructure Virus particle |
| title | Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy |
| title_full | Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy |
| title_fullStr | Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy |
| title_full_unstemmed | Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy |
| title_short | Visualization of SARS-CoV-2 particles in naso/oropharyngeal swabs by thin section electron microscopy |
| title_sort | visualization of sars cov 2 particles in naso oropharyngeal swabs by thin section electron microscopy |
| topic | SARS-CoV-2 Swab sample Thin section electron microscopy Ultrastructure Virus particle |
| url | https://doi.org/10.1186/s12985-023-01981-9 |
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