Using EM data to understand COVID-19 pathophysiology
Authors: Marisa Dolhnikoff, Amaro N Duarte-Neto, Paulo H N Saldiva, Elia G Caldini
Journal: The Lancet (2021)

The pathophysiology of multisystem inflammatory syndrome in children is not completely understood, but it is a field in COVID-19 under extensive investigation. Evidence of the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on extrapulmonary tissues is essential for understanding the disease's course and treatment. We read with concern Carsten Dittmayer and colleagues' Correspondence,1Dittmayer C Meinhardt J Radbruch H et al.Why misinterpretation of electron micrographs in SARS-CoV-2-infected tissue goes viral.Lancet. 2020; 396: e64-e65Summary Full Text Full Text PDF PubMed Scopus (84) Google Scholar in which they which questioned the evidence of a viral particle shown in our recent Case Report2Dolhnikoff M Ferreira Ferranti J de Almeida Monteiro RA et al.SARS-CoV-2 in cardiac tissue of a child with COVID-19-related multisystem inflammatory syndrome.Lancet Child Adolesc Health. 2020; 4: 790-794Summary Full Text Full Text PDF PubMed Scopus (184) Google Scholar of a child with COVID-19-related multisystem inflammatory syndrome. The ultrastructural evidence of SARS-CoV-2 in cardiac tissue was undisputed (a cardiomyocyte was shown in figure 3A, an endothelial cell was shown in figure 3C, and a neutrophil in figure 3D).2Dolhnikoff M Ferreira Ferranti J de Almeida Monteiro RA et al.SARS-CoV-2 in cardiac tissue of a child with COVID-19-related multisystem inflammatory syndrome.Lancet Child Adolesc Health. 2020; 4: 790-794Summary Full Text Full Text PDF PubMed Scopus (184) Google Scholar This finding was further corroborated by the detection of SARS-CoV-2 RNA by RT-PCR, and by immunohistochemistry. We share Dittmayer and colleagues'1Dittmayer C Meinhardt J Radbruch H et al.Why misinterpretation of electron micrographs in SARS-CoV-2-infected tissue goes viral.Lancet. 2020; 396: e64-e65Summary Full Text Full Text PDF PubMed Scopus (84) Google Scholar opinion that electron microscopy (EM) is the gold standard to prove the presence of an infectious unit and requires specialised staff. For this reason, the EM in our report was done by a professor with more than 30 years of experience in ultrastructural analysis.3Mauad T Hajjar LA Callegari GD et al.Lung pathology in fatal novel human influenza A (H1N1) infection.Am J Respir Crit Care Med. 2010; 181: 72-79Crossref PubMed Scopus (452) Google Scholar, 4Ono SK Bassit L Van Vaisberg V et al.Acute acalculous cholecystitis during zika virus infection in an immunocompromised patient.Hepatology. 2018; 67: 2051-2054Crossref PubMed Scopus (5) Google Scholar Figure 3B in our case report2Dolhnikoff M Ferreira Ferranti J de Almeida Monteiro RA et al.SARS-CoV-2 in cardiac tissue of a child with COVID-19-related multisystem inflammatory syndrome.Lancet Child Adolesc Health. 2020; 4: 790-794Summary Full Text Full Text PDF PubMed Scopus (184) Google Scholar does show a rough endoplasmic reticulum, as suggested by Dittmayer and colleagues, but it also shows a particular aspect of viral particle assembly (a section through a spherical cluster of viral nucleocapsids apposed on the membrane of the rough endoplasmic reticulum), which is probably a viral translation centre.5Goldsmith CS Tatti KM Ksiazek TG et al.Ultrastructural characterization of SARS coronavirus.Emerg Infect Dis. 2004; 10: 320-326Crossref PubMed Scopus (311) Google Scholar The presence of SARS-CoV-2 particles within membrane compartments, as shown by Dittmayer and colleagues,1Dittmayer C Meinhardt J Radbruch H et al.Why misinterpretation of electron micrographs in SARS-CoV-2-infected tissue goes viral.Lancet. 2020; 396: e64-e65Summary Full Text Full Text PDF PubMed Scopus (84) Google Scholar is typical of preserved non-necrotic cells in which there is viral replication. In our Case Report, cells were undergoing necrotic degeneration (corroborated by C4d staining on figure 2D),2Dolhnikoff M Ferreira Ferranti J de Almeida Monteiro RA et al.SARS-CoV-2 in cardiac tissue of a child with COVID-19-related multisystem inflammatory syndrome.Lancet Child Adolesc Health. 2020; 4: 790-794Summary Full Text Full Text PDF PubMed Scopus (184) Google Scholar which led to cardiac failure and death. In this situation, viral particles might not appear in clusters within membranes but free in the cytosol, intermingled with organelle membranes undergoing fragmentation—much harder to recognise. Although the criticism of one of the figures in our report does not affect the main message—that SARS-CoV-2 infection of cardiac tissue was probably a major contributor to the child's myocarditis and heart failure2Dolhnikoff M Ferreira Ferranti J de Almeida Monteiro RA et al.SARS-CoV-2 in cardiac tissue of a child with COVID-19-related multisystem inflammatory syndrome.Lancet Child Adolesc Health. 2020; 4: 790-794Summary Full Text Full Text PDF PubMed Scopus (184) Google Scholar—in our opinion, criticism of peer-reviewed published data should be more careful and preferentially addressed directly to the authors to avoid the spread of misleading information, clouding the scientific literature. We declare no competing interests. Why misinterpretation of electron micrographs in SARS-CoV-2-infected tissue goes viralWith interest we follow the publications that show the presence of putative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by electron microscopy (EM) in patient tissues and the debate about these results, which should have sufficiently raised attention to their correct interpretation.1,2 Full-Text PDF Using EM data to understand COVID-19 pathophysiology – Authors' replyWe fully agree with Marisa Dolhnikoff and colleagues that we should aim to understand COVID-19 pathophysiology. However, their arguments directed at our Correspondence,1 which should support their Case Report2 on ultrastructural identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patient tissue, are not convincing. As in other fields of ultrastructural research, identification of subcellular structures is made on the basis of ultrastructural features, which are characteristic for each structure. Full-Text PDF