key: cord-0938887-1fuf8eti
authors: HANNA, Nazeeh; LIN, Xinhua; THOMAS, Kristen; VINTZILEOS, Anthony; CHAVEZ, Martin; PALAIA, Thomas; RAGOLIA, Louis; VERMA, Sourabh; KHULLAR, Poonam; HANNA, Iman
title: Underestimation of SARS-CoV-2 infection in placental samples
date: 2021-07-21
journal: Am J Obstet Gynecol
DOI: 10.1016/j.ajog.2021.07.010
sha: 69ba03a6c899602b6d0322afeb568ccc4bdf2b86
doc_id: 938887
cord_uid: 1fuf8eti

nan

contributing medical history or pregnancy complications. The patient was tested positive for 132 SARS-CoV-2 by PCR and was admitted for severe pneumonia. She progressed rapidly to hypoxic 133 respiratory failure requiring intensive care admission and intubation. However, her condition 134 continued to deteriorate, and repeat cesarean delivery was performed to deliver the baby at 29 135 weeks gestation. The placenta was collected for histopathologic examination. The baby was 136 SARS-CoV-2 negative by RT-PCR of nasopharyngeal swabs done at days 1, 2, and 5. The baby's 137 weight was appropriate for gestational age and had prematurity-related complications but an 138 otherwise uncomplicated course, including normal head ultrasounds and no retinopathy of 139 prematurity. The baby was discharged home at 36 weeks post gestational age. COVID-19 IgG 140 antibody testing was done at six weeks of life and was negative. Developmental testing at six 141 months of age was within normal limits. The same procedures were followed as described above for the detection of SARS-CoV-2 RNA 193 in placenta FFPE samples. Sequence-specific oligonucleotide primers were used. The relative 194 level of RNA was expressed as -dCt using CYC1 as an internal control. The IHC results also confirm that the viral infection is not consistent throughout each placental 239 slide and that virus localization is more concentrated in some areas relative to others. According 240 to our data, the site of infection did not correlate with differential ACE2 or TEMPRESS placental In conclusion, this report suggests that the SARS-CoV-2 placental infection is patchy within the 251 same placenta and using RT-PCR testing from a single placental biopsy may lead to 252 underestimation of the incidence of SARS-CoV-2 placental infection. SARS-CoV-2 detection 253 using RT-PCR might depend on the maternal viral load and if the site of the placental biopsy is 254 coincidentally infected. Furthermore, our results may suggest that IHC is a more sensitive test in 255 detecting SARS-CoV-2 placental infection compared to RT-PCR. We suggest that RT-PCR 256 testing should be done using multiple placental sections before declaring that the placental RT-257 PCR is negative for SARS-CoV-2 infection. 258 SARS-CoV-2 gene N1 and N2 were assayed by two-step RT-PCR. For Case #1 (preterm placenta at 29 weeks), only 3 out of 10 biopsies (labeled A-K) were positive for the SARS-CoV-2 genes N1 and N2 RT-PCR. For Case #2 (intrauterine fetal death, IUFD), the RT-PCR was positive in all 6 placental biopsies (labeled A-F). Two lung tissue autopsy samples from COVID patients were used as positive control. The relative viral load in Case #2 was four orders of magnitude higher than Case #1 and similar to the control lung samples.

J o u r n a l P r e -p r o o f The gene expression of SARS-CoV-2 receptors ACE2 and TMPRESS2 were evaluated in placental sections from Case #1. The gene expressions in all sections were comparable with no correlation with the SARS-CoV-2 PCR positive sections (sections D, H, and I).

SARS-CoV-2 cell entry depends on ACE2 and TMPRSS2 and is blocked by a clinically 267 proven protease inhibitor

Is pregnancy an immunological contributor to severe or 269 controlled COVID-19 disease?

A structured review of placental 273 morphology and histopathological lesions associated with SARS-CoV-2 infection

SARS-CoV-2 can infect the placenta and is 277 not associated with specific placental histopathology: a series of 19 placentas from 278

COVID-19-positive mothers