Ultrastructural evidence for vertical transmission of SARS-C
Get authentic, real-time news that helps you fight COVID-19 better.
Install PlexusMD App for doctors. It's free.
Since the initial Lancet correspondence by Goldsmith et al., 2020, there have been numerous published electron micrographs of putative SARS-CoV-2 virions in biopsy and autopsy tissues. A recent review of these images indicated that previous ultrastructural reports of virions in placental tissue, were mis-identifications.

Placental histology of mothers and neonates both testing positive for SARS-CoV-2, is typified by chronic histiocytic intervillositis and trophoblast necrosis, with RNA in situ hybridization/immuno-histochemical findings localising viral RNA/viral antigens to the syncytiotrophoblast. This histopathology is considered a risk factor for vertical transmission of SARS-CoV-2, which, as yet, is infrequently documented.

Ten days prior to a caesarean section performed at 30 weeks due to decreased fetal movements, a mother tested positive for SARS-CoV-2 by routine PCR. The neonate tested positive for the virus by rectal swab, two days after delivery. Histology of the formalin-fixed placental tissue showed high grade lymphohistiocytic villitis with extensive histiocytic (CD68- positive) intervillositis with massive perivillous fibrin deposition (+/-60% of the placental parenchyma), low grade fetal vascular malperfusion, and diffuse villous oedema.

RNA was extracted from a section of formalin-fixed placental tissue using the Promega Maxwell® 16 System. The extract tested positive for SARS-CoV-2 using the Applied Biosystems TaqPath COVID-19 CE-IVD RT-PCR assay. The Ct values obtained for each gene were N=28.65, S=29.25 and Orf1=27.45. Transmission electron microscopy of the formalin-fixed tissue revealed the presence of Coronavirus particles in membranous vacuoles within the syncytiotrophoblast, thus providing ultrastructural evidence of vertical transmission.

Source: https://www.ijidonline.com/article/S1201-9712(21)00653-6/fulltext?rss=yes#relatedArticles