Conjunctival epithelial cells resist productive SARS-CoV-2 infection.

Conjunctival epithelial cells, which express viral-entry receptors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine type 2 (TMPRSS2), constitute the largest exposed epithelium of the ocular surface tissue and may represent a relevant viral-entry route. To address this question, we generated an organotypic air-liquid-interface model of conjunctival epithelium, composed of basal, suprabasal, and superficial epithelial cells, and fibroblasts, which could be maintained successfully up to day 75 of differentiation. Using single-cell RNA sequencing (RNA-seq), with complementary imaging and virological assays, we observed that while all conjunctival cell types were permissive to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome expression, a productive infection did not ensue. The early innate immune response to SARS-CoV-2 infection in conjunctival cells was characterised by a robust autocrine and paracrine NF-κB activity, without activation of antiviral interferon signalling. Collectively, these data enrich our understanding of SARS-CoV-2 infection at the human ocular surface, with potential implications for the design of preventive strategies and conjunctival transplantation.

SARS-COV2 placentitis and pregnancy outcome: A multicentre experience during the Alpha and early Delta waves of coronavirus pandemic in England.

Background: Pregnant women with SARS-CoV-2 infection experience higher rates of stillbirth and preterm birth. A unique pattern of chronic histiocytic intervillositis (CHI) and/or massive perivillous fibrin deposition (MPFD) has emerged, coined as SARS-CoV-2 placentitis. Methods: The aim of this study was to describe a cohort of placentas diagnosed with SARS-CoV-2 placentitis during October 2020-March 2021. Cases with a histological diagnosis of SARS-CoV-2 placentitis and confirmatory immunohistochemistry were reported. Maternal demographic data, pregnancy outcomes and placental findings were collected. Findings: 59 mothers delivered 61 infants with SARS-CoV-2 placentitis. The gestational age ranged from 19 to 41 weeks with most cases (78.6%) being third trimester. 30 infants (49.1%) were stillborn or late miscarriages. Obese mothers had higher rates of pregnancy loss when compared with those with a BMI <30 [67% (10/15) versus 41% (14/34)]. 47/59 (79.7%) mothers had a positive SARS-CoV-2 PCR test either at the time of labour or in the months before, of which 12 (25.5%) were reported to be asymptomatic. Ten reported only CHI, two cases showed MPFD only and in 48 placentas both CHI and MPFD was described. Interpretation: SARS-CoV2 placentitis is a distinct entity associated with increased risk of pregnancy loss, particularly in the third trimester. Women can be completely asymptomatic and still experience severe placentitis. Unlike 'classical' MPFD, placentas with SARS-CoV-2 are generally normal in size with adequate fetoplacental weight ratios. Further work should establish the significance of the timing of maternal SARS-CoV-2 infection and placentitis, the significance of SARS-CoV2 variants, and rates of vertical transmission associated with this pattern of placental inflammation. Funding: There was not funding associated with this study.