Abstract
BackgroundThe novel coronavirus SARS-CoV-2 is the etiological agent of COVID-19. This virus has become one of the most dangerous in recent times with a very high rate of transmission. At present, several publications show the typical crown-shape of the novel coronavirus grown in cell cultures. However, an integral ultramicroscopy study done directly from clinical specimens has not been published. Methods Nasopharyngeal swabs were collected from two Cuban individuals, one asymptomatic and RT-PCR negative (negative control) and the other from a COVID-19 symptomatic and RT-PCR positive for SARS CoV-2. Samples were treated with an aldehyde solution and processed by Scanning Electron Microscopy, Confocal Microscopy and, Atomic Force Microscopy. Improvement and segmentation of coronavirus images were performed by mathematic algorithms. Results The images of the negative control sample showed the characteristic healthy microvilli morphology at the apical region of the nasal epithelial cells. As expected, they do not display virus-like structures. The images of the positive sample showed characteristic coronavirus-like particles and evident destruction of microvilli. In some regions, virions gemmating through the cell membrane were observed. Microvilli destruction could explain the anosmia reported by some patients. Virus-particles emerging from the cell-surface with a variable size ranging from 80 to 400 nm were observed by scanning electron microscopy (SEM). A confocal study showed viral antigen recognition in the apical cells zone. Conclusions The integral microscopy study showed that SARS-CoV-2 has a similar image to SARS-CoV. The application of several high-resolution microscopy techniques to clinical samples can help to answer important questions its replicative cycle and immunopathogenic mechanism of this novel coronavirus, relevant for the development of new treatments against this disease.
SARS-CoV-2: High-Resolution Microscopy Study in Human Nasopharyngeal Samples.