Endemic Human Coronaviruses Research Articles

Comparison of seven commercial SARS-CoV-2 rapid point-of-care antigen tests: a single-centre laboratory evaluation study

SummaryBackgroundAntigen point-of-care tests (AgPOCTs) can accelerate SARS-CoV-2 testing. As some AgPOCTs have become available, interest is growing in their utility and performance. Here we aimed to compare the analytical sensitivity and specificity of seven commercially available AgPOCT devices.MethodsIn a single-centre, laboratory evaluation study, we compared AgPOCT products from seven suppliers: the Abbott Panbio COVID-19 Ag Rapid Test, the RapiGEN BIOCREDIT COVID-19 Ag, the Healgen Coronavirus Ag Rapid Test Cassette (Swab), the Coris BioConcept COVID-19 Ag Respi-Strip, the R-Biopharm RIDA QUICK SARS-CoV-2 Antigen, the nal von minden NADAL COVID-19 Ag Test, and the Roche-SD Biosensor SARS-CoV Rapid Antigen Test. Tests were evaluated on recombinant SARS-CoV-2 nucleoprotein, cultured endemic and emerging coronaviruses, stored respiratory samples with known SARS-CoV-2 viral loads, stored samples from patients with respiratory pathogens other than SARS-CoV-2, and self-sampled swabs from healthy volunteers. We estimated analytical sensitivity in terms of approximate viral concentrations (quantified by real-time RT-PCR) that yielded positive AgPOCT results, and specificity in terms of propensity to generate false-positive results.FindingsIn 138 clinical samples with quantified SARS-CoV-2 viral load, the 95% limit of detection (concentration at which 95% of test results were positive) in six of seven AgPOCT products ranged between 2·07 × 106 and 2·86 × 107 copies per swab, with an outlier (RapiGEN) at 1·57 × 1010 copies per swab. The assays showed no cross-reactivity towards cell culture or tissue culture supernatants containing any of the four endemic human coronaviruses (HCoV‑229E, HCoV‑NL63, HCoV‑OC43, or HCoV‑HKU1) or MERS-CoV, with the exception of the Healgen assay in one repeat test on HCoV-HKU1 supernatant. SARS-CoV was cross-detected by all assays. Cumulative specificities among stored clinical samples with non-SARS-CoV-2 infections (n=100) and self-samples from healthy volunteers (n=35; cumulative sample n=135) ranged between 98·5% (95% CI 94·2–99·7) and 100·0% (97·2–100·0) in five products, with two outliers at 94·8% (89·2–97·7; R-Biopharm) and 88·9% (82·1–93·4; Healgen). False-positive results did not appear to be associated with any specific respiratory pathogen.InterpretationThe sensitivity range of most AgPOCTs overlaps with SARS-CoV-2 viral loads typically observed in the first week of symptoms, which marks the infectious period in most patients. The AgPOCTs with limit of detections that approximate virus concentrations at which patients are infectious might enable shortcuts in decision making in various areas of health care and public health.FundingEU's Horizon 2020 research and innovation programme, German Ministry of Research, German Federal Ministry for Economic Affairs and Energy, German Ministry of Health, and Bill & Melinda Gates Foundation.

Antibody responses to endemic coronaviruses modulate COVID-19 convalescent plasma functionality.

SARS-CoV-2 (CoV2) antibody therapies, including COVID-19 convalescent plasma (CCP), monoclonal antibodies, and hyperimmune globulin, are among the leading treatments for individuals with early COVID-19 infection. The functionality of convalescent plasma varies greatly, but the association of antibody epitope specificities with plasma functionality remains uncharacterized. We assessed antibody functionality and reactivities to peptides across the CoV2 and the 4 endemic human coronavirus (HCoV) genomes in 126 CCP donations. We found strong correlation between plasma functionality and polyclonal antibody targeting of CoV2 spike protein peptides. Antibody reactivity to many HCoV spike peptides also displayed strong correlation with plasma functionality, including pan-coronavirus cross-reactive epitopes located in a conserved region of the fusion peptide. After accounting for antibody cross-reactivity, we identified an association between greater alphacoronavirus NL63 antibody responses and development of highly neutralizing antibodies against CoV2. We also found that plasma preferentially reactive to the CoV2 spike receptor binding domain (RBD), versus the betacoronavirus HKU1 RBD, had higher neutralizing titer. Finally, we developed a 2-peptide serosignature that identifies plasma donations with high anti-spike titer, but that suffer from low neutralizing activity. These results suggest that analysis of coronavirus antibody fine specificities may be useful for selecting desired therapeutics and understanding the complex immune responses elicited by CoV2 infection.

A conserved immunogenic and vulnerable site on the coronavirus spike protein delineated by cross-reactive monoclonal antibodies

The coronavirus spike glycoprotein, located on the virion surface, is the key mediator of cell entry and the focus for development of protective antibodies and vaccines. Structural studies show exposed sites on the spike trimer that might be targeted by antibodies with cross-species specificity. Here we isolated two human monoclonal antibodies from immunized humanized mice that display a remarkable cross-reactivity against distinct spike proteins of betacoronaviruses including SARS-CoV, SARS-CoV-2, MERS-CoV and the endemic human coronavirus HCoV-OC43. Both cross-reactive antibodies target the stem helix in the spike S2 fusion subunit which, in the prefusion conformation of trimeric spike, forms a surface exposed membrane-proximal helical bundle. Both antibodies block MERS-CoV infection in cells and provide protection to mice from lethal MERS-CoV challenge in prophylactic and/or therapeutic models. Our work highlights an immunogenic and vulnerable site on the betacoronavirus spike protein enabling elicitation of antibodies with unusual binding breadth.

Infection patterns of endemic human coronaviruses in rural households in coastal Kenya

Background: The natural history and transmission patterns of endemic human coronaviruses are of increased interest following the emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Methods: In rural Kenya 483 individuals from 47 households were followed for six months (2009-10) with nasopharyngeal swabs collected twice weekly regardless of symptoms. A total of 16,918 swabs were tested for human coronavirus (hCoV) OC43, NL63 and 229E and other respiratory viruses using polymerase chain reaction. Results: From 346 (71.6%) household members, 629 hCoV infection episodes were defined, with 36.3% being symptomatic: varying by hCoV type and decreasing with age. Symptomatic episodes (aHR=0.6 (95% CI:0.5-0.8) or those with elevated peak viral load (medium aHR=0.4 (0.3-0.6); high aHR=0.31 (0.2-0.4)) had longer viral shedding compared to their respective counterparts. Homologous reinfections were observed in 99 (19.9%) of 497 first infections. School-age children (55%) were the most common index cases with those having medium (aOR=5.3 (2.3 – 12.0)) or high (8.1 (2.9 - 22.5)) peak viral load most often generating secondary cases. Conclusion: Household coronavirus infection was common, frequently asymptomatic and mostly introduced by school-age children. Secondary transmission was influenced by viral load of index cases. Homologous-type reinfection was common. These data may be insightful for SARS-CoV-2.

Exploring beyond clinical routine SARS-CoV-2 serology using MultiCoV-Ab to evaluate endemic coronavirus cross-reactivity

The humoral immune response to SARS-CoV-2 is a benchmark for immunity and detailed analysis is required to understand the manifestation and progression of COVID-19, monitor seroconversion within the general population, and support vaccine development. The majority of currently available commercial serological assays only quantify the SARS-CoV-2 antibody response against individual antigens, limiting our understanding of the immune response. To overcome this, we have developed a multiplex immunoassay (MultiCoV-Ab) including spike and nucleocapsid proteins of SARS-CoV-2 and the endemic human coronaviruses. Compared to three broadly used commercial in vitro diagnostic tests, our MultiCoV-Ab achieves a higher sensitivity and specificity when analyzing a well-characterized sample set of SARS-CoV-2 infected and uninfected individuals. We find a high response against endemic coronaviruses in our sample set, but no consistent cross-reactive IgG response patterns against SARS-CoV-2. Here we show a robust, high-content-enabled, antigen-saving multiplex assay suited to both monitoring vaccination studies and facilitating epidemiologic screenings for humoral immunity towards pandemic and endemic coronaviruses.

Infection patterns of endemic human coronaviruses in rural households in coastal Kenya.

Background: The natural history and transmission patterns of endemic human coronaviruses are of increased interest following the emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Methods: In rural Kenya 483 individuals from 47 households were followed for six months (2009-10) with nasopharyngeal swabs collected twice weekly regardless of symptoms. A total of 16,918 swabs were tested for human coronavirus (hCoV) OC43, NL63 and 229E and other respiratory viruses using polymerase chain reaction. Results: From 346 (71.6%) household members, 629 hCoV infection episodes were defined, with 36.3% being symptomatic: varying by hCoV type and decreasing with age. Symptomatic episodes (aHR=0.6 (95% CI:0.5-0.8) or those with elevated peak viral load (medium aHR=0.4 (0.3-0.6); high aHR=0.31 (0.2-0.4)) had longer viral shedding compared to their respective counterparts. Homologous reinfections were observed in 99 (19.9%) of 497 first infections. School-age children (55%) were the most common index cases with those having medium (aOR=5.3 (2.3 - 12.0)) or high (8.1 (2.9 - 22.5)) peak viral load most often generating secondary cases. Conclusion: Household coronavirus infection was common, frequently asymptomatic and mostly introduced by school-age children. Secondary transmission was influenced by viral load of index cases. Homologous-type reinfection was common. These data may be insightful for SARS-CoV-2.

Circulating CD4 T Cells Elicited by Endemic Coronaviruses Display Vast Disparities in Abundance and Functional Potential Linked to Antigen Specificity and Age.

Repeated infections with endemic human coronaviruses are thought to reflect lack of long-lasting protective immunity. Here, we evaluate circulating human CD4 T cells collected prior to 2020 for reactivity towards hCoV spike proteins, probing for the ability to produce IFN-γ, IL-2 or granzyme B. We find robust reactivity to spike-derived epitopes, comparable to influenza, but highly variable abundance and functional potential across subjects, depending on age and viral antigen specificity. To explore the potential of these memory cells to be recruited in SARS-CoV-2 infection, we examined the same subjects for cross-reactive recognition of epitopes from SARS-CoV-2 nucleocapsid, membrane/envelope, and spike. The functional potential of these cross-reactive CD4 T cells was highly variable, with nucleocapsid-specific CD4 T cells, but not spike-reactive cells showing exceptionally high levels of granzyme production upon stimulation. These results are considered in light of recruitment of hCoV-reactive cells into responses of humans to SARS-CoV infections or vaccinations.

Distinct antibody repertoires against endemic human coronaviruses in children and adults.

Four endemic human coronaviruses (HCoVs) are commonly associated with acute respiratory infection in humans. B cell responses to these “common cold” viruses remain incompletely understood. Here we report a comprehensive analysis of CoV-specific antibody repertoires in 231 children and 1168 adults using phage immunoprecipitation sequencing. Seroprevalence of antibodies against endemic HCoVs ranged between approximately 4% and 27% depending on the species and cohort. We identified at least 136 novel linear B cell epitopes. Antibody repertoires against endemic HCoVs were qualitatively different between children and adults in that anti-HCoV IgG specificities more frequently found among children targeted functionally important and structurally conserved regions of the spike, nucleocapsid, and matrix proteins. Moreover, antibody specificities targeting the highly conserved fusion peptide region and S2′ cleavage site of the spike protein were broadly cross-reactive with peptides of epidemic human and nonhuman coronaviruses. In contrast, an acidic tandem repeat in the N-terminal region of the Nsp3 subdomain of the HCoV-HKU1 polyprotein was the predominant target of antibody responses in adult donors. Our findings shed light on the dominant species-specific and pan-CoV target sites of human antibody responses to coronavirus infection, thereby providing important insights for the development of prophylactic or therapeutic monoclonal antibodies and vaccine design.

Circulation of human coronaviruses OC43 and 229E in Córdoba, Argentina.

This is the first study of respiratory infections in Córdoba, Argentina, caused by endemic human coronavirus (HCoV)-OC43 and HCOV-229E, which circulated during 2011-2012 at a 3% rate, either as single or multiple infections. They were detected mainly in children, but HCoV-229E was also found in adults. HCoV-229E was detected in five out of 631 samples (0.8%), and HCoV-OC43 was found in 14 out of 631 (2.2%) samples. Clinical manifestations ranged from fever to respiratory distress, and a significant association of HCoV-229E with asthma was observed. Further studies and surveillance are needed to provide better clinical insights, early diagnosis, and medical care of patients, as well as to contribute to epidemiology modeling and prevention.

Drivers of Infectious Disease Seasonality: Potential Implications for COVID-19.

Not 1 year has passed since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19). Since its emergence, great uncertainty has surrounded the potential for COVID-19 to establish as a seasonally recurrent disease. Many infectious diseases, including endemic human coronaviruses, vary across the year. They show a wide range of seasonal waveforms, timing (phase), and amplitudes, which differ depending on the geographical region. Drivers of such patterns are predominantly studied from an epidemiological perspective with a focus on weather and behavior, but complementary insights emerge from physiological studies of seasonality in animals, including humans. Thus, we take a multidisciplinary approach to integrate knowledge from usually distinct fields. First, we review epidemiological evidence of environmental and behavioral drivers of infectious disease seasonality. Subsequently, we take a chronobiological perspective and discuss within-host changes that may affect susceptibility, morbidity, and mortality from infectious diseases. Based on photoperiodic, circannual, and comparative human data, we not only identify promising future avenues but also highlight the need for further studies in animal models. Our preliminary assessment is that host immune seasonality warrants evaluation alongside weather and human behavior as factors that may contribute to COVID-19 seasonality, and that the relative importance of these drivers requires further investigation. A major challenge to predicting seasonality of infectious diseases are rapid, human-induced changes in the hitherto predictable seasonality of our planet, whose influence we review in a final outlook section. We conclude that a proactive multidisciplinary approach is warranted to predict, mitigate, and prevent seasonal infectious diseases in our complex, changing human-earth system.

The evolutionary dynamics of endemic human coronaviruses.

Community protective immunity can affect RNA virus evolution by selecting for new antigenic variants on the scale of years, exemplified by the need of annual evaluation of influenza vaccines. The extent to which this process termed antigenic drift affects coronaviruses remains unknown. Alike the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), seasonal human coronaviruses (HCoV) likely emerged from animal reservoirs as new human pathogens in the past. We therefore analyzed the long-term evolutionary dynamics of the ubiquitous HCoV-229E and HCoV-OC43 in comparison with human influenza A virus (IAV) subtype H3N2. We focus on viral glycoprotein genes that mediate viral entry into cells and are major targets of host neutralizing antibody responses. Maximum likelihood and Bayesian phylogenies of publicly available gene datasets representing about three decades of HCoV and IAV evolution showed that all viruses had similar ladder-like tree shapes compatible with antigenic drift, supported by different tree shape statistics. Evolutionary rates inferred in a Bayesian framework were 6.5 × 10−4 (95% highest posterior density (HPD), 5.4–7.5 × 10−4) substitutions per site per year (s/s/y) for HCoV-229E spike (S) genes and 5.7 × 10−4 (95% HPD, 5–6.5 × 10−4) s/s/y for HCoV-OC43 S genes, which were about fourfold lower than the 2.5 × 10−3 (95% HPD, 2.3–2.7 × 10−3) s/s/y rate for IAV hemagglutinin (HA) genes. Coronavirus S genes accumulated about threefold less (P < 0.001) non-synonymous mutations (dN) over time than IAV HA genes. In both IAV and HCoV, the average rate of dN within the receptor binding domains (RBD) was about fivefold higher (P < 0.0001) than in other glycoprotein gene regions. Similarly, most sites showing evidence for positive selection occurred within the RBD (HCoV-229E, 6/14 sites, P < 0.05; HCoV-OC43, 23/38 sites, P < 0.01; IAV, 13/15 sites, P = 0.08). In sum, the evolutionary dynamics of HCoV and IAV showed several similarities, yet amino acid changes potentially representing antigenic drift occurred on a lower scale in endemic HCoV compared to IAV. It seems likely that pandemic SARS-CoV-2 evolution will bear similarities with IAV evolution including accumulation of adaptive changes in the RBD, requiring vaccines to be updated regularly, whereas higher SARS-CoV-2 evolutionary stability resembling endemic HCoV can be expected in the post-pandemic stage.

Clinical and radiological findings of adult hospitalized patients with community-acquired pneumonia from SARS-CoV-2 and endemic human coronaviruses.

Endemic human coronaviruses (HCoVs) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are members of the family Coronaviridae. Comparing the findings of the infections caused by these viruses would help reveal the novel characteristics of SARS-CoV-2 and provide insight into the unique pathogenesis of SARS-CoV-2 infection. This study aimed to compare the clinical and radiological characteristics of SARS-CoV-2 and endemic HCoVs infection in adult hospitalized patients with community-acquired pneumonia (CAP). This study was performed at a university-affiliated tertiary hospital in the Republic of Korea, between January 1, 2015, and July 31, 2020. A total of 109 consecutive patients who were over 18 years of age with confirmed SARS-CoV-2 and endemic HCoVs were enrolled. Finally, 19 patients with SARS-CoV-2 CAP were compared to 40 patients with endemic HCoV CAP. Flu-like symptoms such as cough, sore throat, headache, myalgia, and prolonged fever were more common in SARS-CoV-2 CAP, whereas clinical findings suggestive of bacterial pneumonia such as dyspnea, leukocytosis with left shift, and increased C-reactive protein were more common in endemic HCoV CAP. Bilateral peripherally distributed ground-glass opacities (GGOs) were typical radiologic findings in SARS-CoV-2 CAP, whereas mixed patterns of GGOs, consolidations, micronodules, and pleural effusion were observed in endemic HCoV CAP. Coinfection was not observed in patients with SARS-CoV-2 CAP, but was observed in more than half of the patients with endemic HCoV CAP. There were distinctive differences in the clinical and radiologic findings between SARS-CoV-2 and endemic HCoV CAP. Further investigations are required to elucidate the mechanism underlying this difference. Follow-up observations are needed to determine if the presentation of SARS-CoV-2 CAP changes with repeated infection.

Potential impact of individual exposure histories to endemic human coronaviruses on age-dependent severity of COVID-19

BackgroundCross-reactivity to SARS-CoV-2 from exposure to endemic human coronaviruses (eHCoV) is gaining increasing attention as a possible driver of both protection against infection and COVID-19 severity. Here we explore the potential role of cross-reactivity induced by eHCoVs on age-specific COVID-19 severity in a mathematical model of eHCoV and SARS-CoV-2 transmission.MethodsWe use an individual-based model, calibrated to prior knowledge of eHCoV dynamics, to fully track individual histories of exposure to eHCoVs. We also model the emergent dynamics of SARS-CoV-2 and the risk of hospitalisation upon infection.ResultsWe hypothesise that primary exposure with any eHCoV confers temporary cross-protection against severe SARS-CoV-2 infection, while life-long re-exposure to the same eHCoV diminishes cross-protection, and increases the potential for disease severity. We show numerically that our proposed mechanism can explain age patterns of COVID-19 hospitalisation in EU/EEA countries and the UK. We further show that some of the observed variation in health care capacity and testing efforts is compatible with country-specific differences in hospitalisation rates under this model.ConclusionsThis study provides a “proof of possibility” for certain biological and epidemiological mechanisms that could potentially drive COVID-19-related variation across age groups. Our findings call for further research on the role of cross-reactivity to eHCoVs and highlight data interpretation challenges arising from health care capacity and SARS-CoV-2 testing.

Recent endemic coronavirus infection is associated with less-severe COVID-19.

Four different endemic coronaviruses (eCoVs) are etiologic agents for the seasonal common cold, and these eCoVs share extensive sequence homology with human SARS coronavirus 2 (SARS-CoV-2). Here, we show that individuals with, as compared with those without, a recent documented infection with eCoV were tested at greater frequency for respiratory infections but had a similar rate of SARS-CoV-2 acquisition. Importantly, the patients with a previously detected eCoV had less-severe coronavirus disease 2019 (COVID-19) illness. Our observations suggest that preexisting immune responses against endemic human coronaviruses can mitigate disease manifestations from SARS-CoV-2 infection.

1H, 15N and 13C resonance assignments of the N-terminal domain of the nucleocapsid protein from the endemic human coronavirus HKU1.

Coronaviruses have become of great medical and scientific interest because of the Covid-19 pandemic. The hCoV-HKU1 is an endemic betacoronavirus that causes mild respiratory symptoms, although the infection can progress to severe lung disease and death. During viral replication, a discontinuous transcription of the genome takes place, producing the subgenomic messenger RNAs. The nucleocapsid protein (N) plays a pivotal role in the regulation of this process, acting as an RNA chaperone and participating in the nucleocapsid assembly. The isolated N-terminal domain of protein N (N-NTD) specifically binds to the transcriptional regulatory sequences and control the melting of the double-stranded RNA. Here, we report the resonance assignments of the N-NTD of HKU1-CoV.

Epitope-resolved profiling of the SARS-CoV-2 antibody response identifies cross-reactivity with endemic human coronaviruses

SummaryThe SARS-CoV-2 proteome shares regions of conservation with endemic human coronaviruses (CoVs), but it remains unknown to what extent these may be cross-recognized by the antibody response. Here, we study cross-reactivity using a highly multiplexed peptide assay (PepSeq) to generate an epitope-resolved view of IgG reactivity across all human CoVs in both COVID-19 convalescent and negative donors. PepSeq resolves epitopes across the SARS-CoV-2 Spike and Nucleocapsid proteins that are commonly targeted in convalescent donors, including several sites also recognized in some uninfected controls. By comparing patterns of homologous reactivity between CoVs and using targeted antibody-depletion experiments, we demonstrate that SARS-CoV-2 elicits antibodies that cross-recognize pandemic and endemic CoV antigens at two Spike S2 subunit epitopes. We further show that these cross-reactive antibodies preferentially bind endemic homologs. Our findings highlight sites at which the SARS-CoV-2 response appears to be shaped by previous CoV exposures and which have the potential to raise broadly neutralizing responses.

Adaptive immunity to human coronaviruses is widespread but low in magnitude.

ObjectivesEndemic human coronaviruses (hCoVs) circulate worldwide but cause minimal mortality. Although seroconversion to hCoV is near ubiquitous during childhood, little is known about hCoV‐specific T‐cell memory in adults.MethodsWe quantified CD4 T‐cell and antibody responses to hCoV spike antigens in 42 SARS‐CoV‐2‐uninfected individuals. Antigen‐specific memory T cells and circulating T follicular helper (cTFH) cells were identified using an activation‐induced marker assay and characterised for memory phenotype and chemokine receptor expression.ResultsT‐cell responses were widespread within conventional memory and cTFH compartments but did not correlate with IgG titres. SARS‐CoV‐2 cross‐reactive T cells were observed in 48% of participants and correlated with HKU1 memory. hCoV‐specific T cells exhibited a CCR6+ central memory phenotype in the blood, but were enriched for frequency and CXCR3 expression in human lung‐draining lymph nodes.ConclusionOverall, hCoV‐specific humoral and cellular memory are independently maintained, with a shared phenotype existing among coronavirus‐specific CD4 T cells. This understanding of endemic coronavirus immunity provides insight into the homeostatic maintenance of immune responses that are likely to be critical components of protection against SARS‐CoV‐2.

Identification of Broad Anti-Coronavirus Chemical Agents for Repurposing Against SARS-CoV-2 and Variants of Concern

Endemic human coronaviruses (hCoVs) 229E and OC43 cause respiratory disease with recurrent infections, while severe acute respiratory syndrome (SARS)-CoV-2 spreads across the world with impact on health and societies. Here, we report an image-based multicycle infection procedure with α-coronavirus hCoV 229E-eGFP in an arrayed chemical library screen of 5440 clinical and preclinical compounds. Toxicity counterselection and challenge with the β-coronaviruses OC43 and SARS-CoV-2 in tissue culture and human airway epithelial explant cultures (HAEEC) identified four FDA-approved compounds with oral availability. Methylene blue (MB, used for the treatment of methemoglobinemia), Mycophenolic acid (MPA, used in organ transplantion) and the anti-fungal agent Posaconazole (POS) had the broadest anti-CoV spectrum. They inhibited the shedding of SARS CoV 2 and variants-of-concern (alpha, beta, gamma) from HAEEC in either pre- or post exposure regimens at clinically relevant dosage. Co-treatment of cultured cells with MB and the FDA-approved SARS-CoV-2 RNA-polymerase inhibitor Remdesivir reduced the effective anti-viral dosage of MB by 2-fold, and Remdesivir by 4 to 10-fold, indicated by BLISS independence syner-gy modelling. Neither MB, MPA or POS affected the cell delivery of SARS-CoV-2 or OC43 (+)sense RNA, but blocked subsequent viral RNA accumulation in cells. Unlike Remdesivir, MB, MPA or POS did not reduce the release of viral RNA in post exposure regimen, thus indicating infection inhibition at a post-replicating step as well. In summary, the data emphasize the power of unbiased, full cycle compound screens to identify and repurpose broadly acting drugs against coronaviruses.Funding Information: We acknowledge financial support from the Swiss National Science foundation (SNSF) to UFG and GT (31CA30_196177 / 1), the NCCR Chemical Biology supported by the SNSF for purchasing the BSF-EPFL repurposing collection, and a special Coronavirus Research grant from the University of Zurich to UFG. Declaration of Interests: UFG has been a consultant and stock owner in 3V-Biosciences (now Sagimet Biosciences), and a consultant to F. Hoffmann-La Roche Ltd. The authors filed a patent application on the use of MPA for the treatment of COVID-19 (EP20213904, European Patent Office, University of Zurich).Ethical Approval: Nasal polyp epithelial cells and bronchial epithelial cells were purchased from Epithelix SARL (Geneva, Switzerland). Mucilair™ cells were reconstituted from patients undergoing surgical nasal polypectomy or bronchial biopsies, respectively. All samples from Epithelix SARL were obtained with informed consent, according to the declaration of Helsinki on biomedical research (Hong Kong amendment, 1989), and received approval from local ethics committee (commission cantonale d’éthique de la recherche CCER de Genève).Coronavirus storage and procedures have been registered and validated by the Swiss Federal Office for the Environment (Bundesamt für Umwelt, BAFU) and the Swiss Federal Office of Public Health (Bundesamt für Gesundheit, BAG); Ecogen A203032-00, registered the 01-Sep-2020 for a duration of 5-years for the University of Zurich (Department of Molecular Life Sciences).

Endothelial Dysfunction as a Primary Consequence of SARS-CoV-2 Infection.

A number of different viral species are known to have effects on the endothelium. These include dengue, Ebola, Marburg, Lassa fever, yellow fever and influenza viruses, cytomegalovirus and coronaviruses. There are currently seven human endemic coronaviruses, all of which cause respiratory diseases and bind to receptors found within the endothelium. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the coronavirus disease 2019 (COVID-19) is highly infectious. Like its predecessor, SARS-CoV, it binds to angiotensin-converting enzyme-2 (ACE-2), which is expressed in many cell types, particularly in the lung, including endothelial cells. The initiation of a cytokine storm by the virus along with infection of endothelial cells leads to apoptosis and structural and functional changes that attenuate vascular integrity in many organs including the lungs, heart, liver and kidney. Endothelial damage also enhances the coagulation pathway leading to thrombus formation in major vessels and capillaries. Infection with SARS-CoV-2 has an adverse outcome for individuals with particular comorbid diseases, e.g. hypertension, obesity, type 2 diabetes and cardiovascular disease. It is possible that this is due to the presence of pre-existing endothelial dysfunction and systemic inflammation in subjects with these diseases. Therapies for COVID-19 that target the endothelium, the inflammatory response and the coagulation pathway are currently under trial.

SARS-CoV-2 mRNA Vaccine Induces Robust Specific and Cross-Reactive IgG and Unequal Strain-Specific Neutralizing Antibodies in Naïve and Previously Infected Recipients

With the advance of SARS-CoV-2 vaccines, the outlook for overcoming the global COVID-19 pandemic has improved. However, understanding of immunity and protection offered by the SARS-CoV-2 vaccines against circulating variants of concern (VOC) is rapidly evolving. We investigated the mRNA vaccine-induced antibody responses against the referent WIV04 (Wuhan) strain, circulating variants, and human endemic coronaviruses in 168 naïve and previously infected people at three-time points. Samples were collected prior to vaccination, after the first and after the second doses of one of the two available mRNA-based vaccines. After full vaccination, both naïve and previously infected participants developed comparable robust SARS-CoV-2 specific spike IgG levels, modest IgM and IgA binding antibodies, and varying degrees of HCoV cross-reactive antibodies. However, the strength and frequency of neutralizing antibodies produced in naïve people were significantly lower than in the previously infected group. We also found that 1/3rd of previously infected people had undetectable neutralizing antibodies after the first vaccine dose; 40% of this group developed neutralizing antibodies after the second dose. In all subjects neutralizing antibodies produced against the B.1.351 and P.1 variants were weaker than those produced against the reference and B.1.1.7 strains. Our findings provide support for future booster vaccinations modified to be active against the circulating variants.Funding Information: This study was supported by grants from the National Cancer Institute (U54CA260543 to A.M.de, R.S.B, and L.P.) and National Institutes of Health, Allergy and Infectious Diseases (U01AI151788 to A.M.de and L.P).Competing Interest: None to declare. Ethics Approval Statement: The study was approved by the George Washington University IRB#: NCR202406. All ED HCP personnel who chose to participate in this study provided written informed consent.