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How SARS-CoV-2 penetrates the airway barrier of mucus and periciliary mucins to infect nasal epithelium remains unclear. Using primary nasal epithelial organoid cultures, we found that the virus attaches to motile cilia via the ACE2 receptor. SARS-CoV-2 traverses the mucus layer, using motile cilia as tracks to access the cell body. Depleting cilia blocks infection for SARS-CoV-2 and other respiratory viruses. SARS-CoV-2 progeny attach to airway microvilli 24 h post-infection and trigger formation of apically extended and highly branched microvilli that organize viral egress from the microvilli back into the mucus layer, supporting a model of virus dispersion throughout airway tissue via mucociliary transport. Phosphoproteomics and kinase inhibition reveal that microvillar remodeling is regulated by p21-activated kinases (PAK). Importantly, Omicron variants bind with higher affinity to motile cilia and show accelerated viral entry. Our work suggests that motile cilia, microvilli, and mucociliary-dependent mucus flow are critical for efficient virus replication in nasal epithelia., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

The coronavirus SARS-CoV-2 causes the severe disease COVID-19. SARS-CoV-2 infection is initiated by interaction of the viral spike protein and host receptor angiotensin-converting enzyme 2 (ACE2). We report an improved bright and reversible fluorogenic reporter, named SURF (split UnaG-based reversible and fluorogenic protein-protein interaction reporter), that we apply to monitor real-time interactions between spike and ACE2 in living cells. SURF has a large dynamic range with a dark-to-bright fluorescence signal that requires no exogenous cofactors. Utilizing this reporter, we carried out a high-throughput screening of small-molecule libraries. We identified three natural compounds that block replication of SARS-CoV-2 in both Vero cells and human primary nasal and bronchial epithelial cells. Cell biological and biochemical experiments validated all three compounds and showed that they block the early stages of viral infection. Two of the inhibitors, bruceine A and gamabufotalin, were also found to block replication of the Delta and Omicron variants of SARS-CoV-2. Both bruceine A and gamabufotalin exhibited potent antiviral activity in K18-hACE2 and wild-type C57BL6/J mice, as evidenced by reduced viral titres in the lung and brain, and protection from alveolar and peribronchial inflammation in the lung, thereby limiting disease progression. We propose that our fluorescent assay can be applied to identify antiviral compounds with potential as therapeutic treatment for COVID-19 and other respiratory diseases., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Objectives/hypothesis: To determine the effect of povidone-iodine (PVP-I) nasal sprays on nasopharyngeal (NP) viral load as assessed by cycle threshold (Ct) on quantitative polymerase chain reaction (qPCR) of SARS-CoV-2 in outpatients., Study Design: Three arm, triple blinded, randomized, placebo-controlled clinical trial., Methods: Participants were randomized within 5 days of testing positive for COVID-19 to receive nasal sprays containing placebo (0.9% saline), 0.5% PVP-I, or 2.0% PVP-I. NP swabs for qPCR analysis were taken at baseline, 1-hour post-PVP-I spray (two sprays/nostril), and 3 days post-PVP-I spray (20 sprays/nostril). Symptom and adverse event questionnaires were completed at baseline, day 3, and day 5. University of Pennsylvania Smell Identification Tests (UPSIT) were completed at baseline and day 30., Results: Mean Ct values increased over time in all groups, indicating declining viral loads, with no statistically significant difference noted in the rate of change between placebo and PVP-I groups. The 2.0% PVP-I group showed statistically significant improvement in all symptom categories; however, it also reported a high rate of nasal burning. Olfaction via UPSIT showed improvement by at least one category in all groups. There were no hospitalizations or mortalities within 30 days of study enrollment., Conclusions: Saline and low concentration PVP-I nasal sprays are well tolerated. Similar reductions in SARS-CoV-2 NP viral load were seen over time in all groups. All treatment groups showed improvement in olfaction over 30 days. These data suggest that dilute versions of PVP-I nasal spray are safe for topical use in the nasal cavity, but that PVP-I does not demonstrate virucidal activity in COVID-19 positive outpatients., Level of Evidence: 2 Laryngoscope, 132:2089-2095, 2022., (© 2021 The American Laryngological, Rhinological and Otological Society, Inc.)

Emerging evidence points toward an intricate relationship between the pandemic of coronavirus disease 2019 (COVID-19) and diabetes. While preexisting diabetes is associated with severe COVID-19, it is unclear whether COVID-19 severity is a cause or consequence of diabetes. To mechanistically link COVID-19 to diabetes, we tested whether insulin-producing pancreatic β cells can be infected by SARS-CoV-2 and cause β cell depletion. We found that the SARS-CoV-2 receptor, ACE2, and related entry factors (TMPRSS2, NRP1, and TRFC) are expressed in β cells, with selectively high expression of NRP1. We discovered that SARS-CoV-2 infects human pancreatic β cells in patients who succumbed to COVID-19 and selectively infects human islet β cells in vitro. We demonstrated that SARS-CoV-2 infection attenuates pancreatic insulin levels and secretion and induces β cell apoptosis, each rescued by NRP1 inhibition. Phosphoproteomic pathway analysis of infected islets indicates apoptotic β cell signaling, similar to that observed in type 1 diabetes (T1D). In summary, our study shows SARS-CoV-2 can directly induce β cell killing., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Understanding viral tropism is an essential step toward reducing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, decreasing mortality from coronavirus disease 2019 (COVID-19) and limiting opportunities for mutant strains to arise. Currently, little is known about the extent to which distinct tissue sites in the human head and neck region and proximal respiratory tract selectively permit SARS-CoV-2 infection and replication. In this translational study, we discover key variabilities in expression of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2), essential SARS-CoV-2 entry factors, among the mucosal tissues of the human proximal airways. We show that SARS-CoV-2 infection is present in all examined head and neck tissues, with a notable tropism for the nasal cavity and tracheal mucosa. Finally, we uncover an association between smoking and higher SARS-CoV-2 viral infection in the human proximal airway, which may explain the increased susceptibility of smokers to developing severe COVID-19. This is at least partially explained by differences in interferon (IFN)-β1 levels between smokers and non-smokers.

The omicron BA.1 bivalent booster is used globally. Previous open-label studies of the omicron BA.1 (Moderna mRNA-1273.214) booster showed superior neutralising antibody responses against omicron BA.1 and other variants compared with the original mRNA-1273 booster. We aimed to compare the safety and immunogenicity of omicron BA.1 monovalent and bivalent boosters with the original mRNA-1273 vaccine in a large, randomised controlled trial. In this large, randomised, observer-blind, active-controlled, phase 3 trial in the UK (28 hospital and vaccination clinic sites), individuals aged 16 years or older who had previously received two injections of any authorised or approved COVID-19 vaccine, with or without an mRNA vaccine booster (third dose), were randomly allocated (1:1) using interactive response technology to receive 50 μg omicron BA.1 monovalent or bivalent vaccines or 50 μg mRNA-1273 administered as boosters via deltoid intramuscular injection. The primary outcomes were safety and immunogenicity at day 29, including prespecified non-inferiority and superiority of booster immune responses, based on the neutralising antibody geometric mean concentration (GMC) ratios of the monovalent and bivalent boosters compared with mRNA-1273. Safety was assessed in all participants who received first or second boosters, and primary immunogenicity outcomes were assessed in all participants who received the planned booster dose, had pre-booster and day 29 antibody data, had no major protocol deviations, and who were SARS-CoV-2-negative. The study is registered with EudraCT (2022-000063-51) and ClinicalTrials.gov (NCT05249829) and is ongoing. Between Feb 16 and March 24, 2022, 724 participants were randomly allocated to receive omicron BA.1 monovalent (n=366) or mRNA-1273 (n=357), and between April 2 and June 17, 2022, 2824 participants were randomly allocated to receive omicron BA.1 bivalent (n=1418) or mRNA-1273 (n=1395) vaccines as second boosters. Median durations (months) between the most recent COVID-19 vaccine and study boosters were similar for omicron BA.1 monovalent (4·0 months [IQR 3·6–4·7]) and mRNA-1273 (4·1 [3·5–4·7]), and for the omicron BA.1 bivalent (5·5 [4·8–6·2]) and mRNA-1273 (5·4 [4·8–6·2]) boosters. The omicron BA.1 monovalent and bivalent boosters elicited superior neutralising GMCs against the omicron BA.1 variant compared with mRNA-1273, with GMC ratios of 1·68 (99% CI 1·45−1·95) and 1·53 (1·41−1·67) at day 29 post-booster doses in participants without previous SARS-CoV-2 infection. Both boosters induced non-inferior ancestral SARS-CoV-2 (Asp614Gly) immune responses with GMCs that were similar for the bivalent (2987·2 [95% CI 2814·9–3169·9]) versus mRNA-1273 (2911·3 [2750·9–3081·0]) and lower for the monovalent (2699·7 [2431·3–2997·7] vs 3020·6 [2776·5–3286·2]) boosters, with respective GMC ratios of 1·05 (99% CI 0·96–1·15) and 0·82 (95% CI 0·74–0·91). Results were comparable regardless of previous SARS-CoV-2 infection status. Incidences of solicited adverse reactions with the omicron BA.1 monovalent (335 [91·3%] of 367 participants) and omicron BA.1 bivalent (1285 [90·4%] of 1421 participants) boosters were similar to those observed previously for mRNA-1273, with no new safety concerns identified and no occurrences of fatal adverse events. Omicron-containing booster vaccines generated superior immunogenicity against omicron BA.1 and comparable immunogenicity against the original strain with no new safety concerns. It remains important to continuously monitor the immune responses and real-world vaccine effectiveness as divergent SARS-CoV-2 variants emerge. Moderna. [ABSTRACT FROM AUTHOR]

Observational studies have identified the potential prognostic value for severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) viral load and anti‐SARS‐CoV‐2 antibodies in coronavirus disease 2019 (COVID‐19). However, viral load in nasopharyngeal (NP) swabs produced inconsistent results in prognostic analyses, and the prognostic value of viral load or antibodies has not been confirmed in large clinical trials. COVACTA and REMDACTA were double‐blind, randomized, controlled trials with a combined enrollment of 1078 patients hospitalized with COVID‐19 treated with tocilizumab or placebo in COVACTA or tocilizumab plus remdesivir or placebo plus remdesivir in REMDACTA. We assessed the potential prognostic value of NP and serum SARS‐CoV‐2 viral load and serum anti‐SARS‐CoV‐2 antibodies at baseline as biomarkers for clinical outcomes in patients enrolled in these trials. In adjusted Cox proportional hazard models, serum viral load was a more reliable predictor of clinical outcomes than NP viral load; high serum viral load was associated with higher risk for death and mechanical ventilation/death and lower likelihood of hospital discharge (high vs. negative viral load hazard ratios [95% confidence interval {CI}] were 2.87 [1.57–5.25], 3.86 [2.23–6.68], and 0.23 [0.14–0.36], respectively, in COVACTA and 8.11 [2.95–22.26], 10.29 [4.5–23.55], and 0.21 [0.15–0.29], respectively, in REMDACTA) and high serum viral load correlated with levels of inflammatory cytokines and lung damage biomarkers. High anti‐SARS‐CoV‐2 spike protein antibody (ACOV2S) levels were associated with higher likelihood of hospital discharge (high vs. below the limit of quantification hazard ratios [95% CI] were 2.55 [1.59–4.08] for COVACTA and 1.54 [1.13–2.09] for REMDACTA). These results support the role of baseline SARS‐CoV‐2 serum viral load and ACOV2S antibody titers in predicting clinical outcomes for patients hospitalized with COVID‐19. [ABSTRACT FROM AUTHOR]

The coronavirus SARS-CoV-2 is the causative agent of the ongoing severe acute respiratory disease pandemic COVID-19. Tissue and cellular tropism is one key to understanding the pathogenesis of SARS-CoV-2. We investigate the expression and subcellular localization of the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2), within the upper (nasal) and lower (pulmonary) respiratory tracts of human donors using a diverse panel of banked tissues. Here, we report our discovery that the ACE2 receptor protein robustly localizes within the motile cilia of airway epithelial cells, which likely represents the initial or early subcellular site of SARS-CoV-2 viral entry during host respiratory transmission. We further determine whether ciliary ACE2 expression in the upper airway is influenced by patient demographics, clinical characteristics, comorbidities, or medication use, and show the first mechanistic evidence that the use of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARBs) does not increase susceptibility to SARS-CoV-2 infection through enhancing the expression of ciliary ACE2 receptor. These findings are crucial to our understanding of the transmission of SARS-CoV-2 for prevention and control of this virulent pathogen. Understanding how SARS-CoV-2 gains initial entry into the human body is a key step towards the development of prophylaxes and therapeutics for COVID-19. Here, the authors show that ACE2, the receptor for SARS-CoV-2, is abundantly expressed in the motile cilia of the human nasal and respiratory tract and is not affected by the use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. [ABSTRACT FROM AUTHOR]