20.500.12556/RUL-136194 Just seeing is not enough for believing immunolabelling as indisputable proof of SARS-CoV-2 virions in infected tissue Background: There is increasing evidence that identification of SARS-CoV-2 virions by transmission electron microscopy could be misleading due to the similar morphology of virions and ubiquitous cell structures. This study thus aimed to establish methods for indisputable proof of the presence of SARS-CoV-2 virions in the observed tissue. Methods: We developed a variant of the correlative microscopy approach for SARS-CoV-2 protein identification using immunohistochemical labelling of SARS-CoV-2 proteins on light and electron microscopy levels. We also performed immunogold labelling of SARS-CoV-2 virions. Results: Immunohistochemistry (IHC) of SARS-CoV-2 nucleocapsid proteins and subsequent correlative microscopy undoubtedly proved the presence of SARS-CoV-2 virions in the analysed human nasopharyngeal tissue. The presence of SARS-CoV-2 virions was also confirmed by immunogold labelling for the first time. Conclusions: Immunoelectron microscopy is the most reliable method for distinguishing intracellular viral particles from normal cell structures of similar morphology and size as virions. Furthermore, we developed a variant of correlative microscopy that allows pathologists to check the results of IHC performed first on routinely used paraffin-embedded samples, followed by semithin, and finally by ultrathin sections. Both methodological approaches indisputably proved the presence of SARS-CoV-2 virions in cells. SARS-CoV-2 immunolabelling microscopy light microscopy electron microscopy correlative microscopy SARS-CoV-2 imunooznačevanje mikroskopija true false true Angleški jezik Slovenski jezik Članek v reviji 2022-04-19 09:58:25 2022-04-19 09:58:30 2022-09-15 04:13:31 0000-00-00 00:00:00 2021 0 0 9 str. iss. 9, art. 1816 Vol. 13 2021 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 616.9 1999-4915 10.3390/v13091816 76924931 viruses-13-01816.pdf viruses-13-01816.pdf 1 4F1B96D21B482E3FAF6CCC785218A7FF 7403d293cbd236dcbc84c10c2b430392c4eb40971d8f8fc0e04197b2af4a0151 ac1cfbc7-bfb6-11ec-8aca-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=155710 https://www.mdpi.com/1999-4915/13/9/1816 1 708dc290-bfb6-11ec-8aca-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=155709 Medicinska fakulteta 0 0 0