SARS-CoV-2 infection induces robust mucosal antibody responses in the upper respiratory tract

Despite multiple research efforts to characterize coronavirus disease 2019 (COVID-19) in humans, there is no clear data on the specific role of mucosal immunity on COVID-19 disease. Here, we longitudinally profile the antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and seasonal HCoV-OC43 S proteins in serum and nasopharyngeal swabs from COVID-19 patients. Results showed that specific antibody responses against SARS-CoV-2 and HCoV-OC43 S proteins can be detected in the upper respiratory tract. We found that COVID-19 patients mounted a robust mucosal antibody response against SARS-CoV-2 S with specific secretory immunoglobulin A (sIgA), IgA, IgG, and IgM antibody subtypes detected in the nasal swabs. Additionally, COVID-19 patients showed IgG, IgA, and sIgA responses against HCoV-OC43 S in the local mucosa, whereas no specific IgM was detected. Interestingly, mucosal antibody titers against SARS-CoV-2 peaked at day 7, whereas HCoV-OC43 titers peaked earlier at day 3 post -recruitment, suggesting an immune memory recall to conserved epitopes of beta-HCoVs in the upper respiratory tract

Transmission and evolutionary dynamics of human coronavirus OC43 strains in coastal Kenya investigated by partial spike sequence analysis, 2015-2016

Human coronavirus OC43 (HCoV-OC43) is a major contributor to seasonal outbreaks of acute respiratory illness (ARI). The origins of locally circulating HCoV-OC43 strains and characteristics of their genetic diversity are unknown for most settings despite significance to effective HCoV control strategies. Between December 2015 and June 2016, we undertook ARI surveillance in coastal Kenya in nine outpatients and one inpatient health facility (HF). Ninety-two patient samples tested HCoV-OC43 positive and forty (43.5%) were successfully sequenced in spike (S) gene region (2,864 long, ∼70%). Phylogenetic analysis confirmed co-circulation of two distinct HCoV-OC43 clades that closely clustered with genotype G (n = 34, 85%) and genotype H (n = 6, 15%) reference strains. Local viruses within the same clade displayed low genetic diversity yielding identical sequences in multiple HF. Furthermore, the newly sequenced Kenyan viruses showed close phylogenetic relationship to other contemporaneous sampled strains (2015–16) including those originating from distant places (e.g. USA and China). Using a genetic similarity threshold of 99.1 per cent at nucleotide level, the HCoV-OC43 strains sampled globally between 1967 and 2019 fell into nine sequence clusters. Notably, some of these clusters appeared to have become extinct, or occurred only sporadically in a few geographical areas while others persisted globally for multiple years. In conclusion, we found that HCoV-OC43 strains spread rapidly both locally and across the globe with limited genetic evolution in the spike gene. Full-genome sequences that are spatio-temporally representative are required to advance understanding of the transmission pathways of this important human respiratory pathogen

Humani koronavirusi u kontekstu ‘Jednog zdravlja’

Seven human coronaviruses have been identified so far: four seasonal coronaviruses (HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1) and three novel coronaviruses (SARS-CoV, MERS-CoV, SARS-CoV-2). While seasonal coronaviruses cause only mild symptoms, novel coronaviruses cause severe and potentially fatal infections. All known coronaviruses originated in animals. Bats are considered as an origin for the majority of coronaviruses capable of infecting humans; however, rodents are proposed as natural hosts for HCoV-OC43 and HCoV-HKU1. Different animal species could serve as intermediate hosts including alpacas (HCoV-229E), livestock (HCoV-OC43), civet cats (SARS-CoV), camels (MERS-CoV), and pangolins (SARS-CoV-2). In Croatia, SARS-CoV-2 was detected in humans, pet animals, wildlife, and the environment. The COVID-19 pandemic has highlighted the role of the ‘One Health’ approach in the surveillance of zoonotic diseases.Do sada je otkriveno sedam humanih koronavirusa: četiri sezonska koronavirusa (HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1) i tri nova koronavirusa (SARS-CoV, MERS-CoV, SARS-CoV-2). Dok sezonski koronavirusi uzrokuju tek blage infekcije, novi koronavirusi su uzročnici teških i potencijalno smrtonosnih infekcija. Svi poznati koronavirusi su podrijetlom od životinja. Šišmiši se smatraju izvorom većine koronavirusa koji uzrokuju infekcije u ljudi, međutim prirodnim rezervoarima HCoV-OC43 i HCoV-HKU1 se smatraju glodavci. Različite životinjske vrste predstavljaju prijelazne domaćine uključujući alpake (HCoV-229E), stoku (HCoV-OC43), cibetke (SARS-CoV), deve (MERS-CoV) te ljuskaše (SARS-CoV-2). Na području Hrvatske SARS-CoV-2 je dokazan u ljudi, kućnih ljubimaca, divljih životinja te okolišu. Pandemija COVID-19 naglašava ulogu pristupa ‘Jedno zdravlje’ u nadzoru zoonoza

Antigenic cross-reactivity between severe acute respiratory syndrome-associated coronavirus and human coronaviruses 229E and OC43

Cross-reactivity between antibodies to different human coronaviruses (HCoVs) has not been systematically studied. By use of Western blot analysis, indirect immunofluorescence assay (IFA), and enzyme-linked immunosorbent assay (ELISA), antigenic cross-reactivity between severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) and 2 HCoVs (229E and OC43) was demonstrated in immunized animals and human serum. In 5 of 11 and 10 of 11 patients with SARS, paired serum samples showed a ≥4-fold increase in antibody titers against HCoV-229E and HCoV-OC43, respectively, by IFA. Overall, serum samples from convalescent patients who had SARS had a 1-way cross-reactivity with the 2 known HCoVs. Antigens of SARS-CoV and HCoV-OC43 were more cross-reactive than were those of SARS-CoV and HCoV-229E. © 2005 by the Infectious Diseases Society of America. All rights reserved.published_or_final_versio

Disinfectant Efficacy Against SARS-CoV-2 Surrogates, Bovine Coronavirus and Human Coronavirus OC43, on Hard and Soft Non-porous Surfaces

The novel human coronavirus (HCoV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged from Wuhan, China in the latter part of 2019. The rapid spread of SARS-CoV-2 amid the most recent COVID-19 pandemic forced countless foodservice establishments (FSEs) across the United States to close, taking a tremendous toll on the foodservice industry. Although primarily transmitted person-to-person, previous studies indicate that the duration of SARS-CoV-2 survival on different environmental surfaces provides adequate time for secondary transmission to occur. To prevent the further spread of SARS-CoV-2, effective disinfection of surfaces in FSEs is necessary. While disinfectants approved for use against SARS-CoV-2 are found on the Environmental Protection Agency’s (EPA’s) List N, there is limited data available regarding the efficacy of these products against two SARS-CoV-2 surrogates, bovine coronavirus (BCoV) and human coronavirus OC43 (HCoV OC43) on surfaces other than glass and stainless steel. Therefore, our aims for this study were to (I) optimize a neutralization method for chlorine- and quaternary ammonium compound (QAC)-based disinfectants during efficacy testing, (II) determine the efficacy of two separate batches of three ready-to-use (RTU) spray disinfectants of different active ingredients (chlorine, hydrogen peroxide, and QAC + alcohol) against SARS-CoV-2 surrogates, BCoV and HCoV OC43, in suspension and (III) on surfaces commonly found in the ‘front-of-the-house’ in FSEs (polyethylene terephthalate [PET] plastic and vinyl upholstery fabric). Cytotoxicity to the host cell line during efficacy testing was successfully eliminated via infection media paired with centrifugation in PierceTM detergent removal columns for the QAC-based disinfectant, and a 5% fetal bovine serum (FBS) + 1% sodium thiosulfate (Na2S2O3) solution for the chorine-based disinfectant. In suspension testing, all three RTU disinfectants tested achieved a \u3e3.0 log10 reduction of BCoV and HCoV OC43 within 2 min. On PET carriers, all three RTU disinfectants reduced BCoV by \u3e3.0 log10 TCID50/mL, whereas Oxivir Tb was the only disinfectant efficacious against BCoV on vinyl carriers. None of the three RTU disinfectants tested achieved a \u3e3.0 log10 reduction of HCoV OC43 on PET or vinyl. However, after a 2 min contact time, all three disinfectants reduced the infectivity of BCoV and HCoV OC43 below the limit of detection (LOD) on both PET and vinyl surfaces. Those cases with \u3c3.0 log10 reduction of virus titer were due to the decreased dynamic range on the carrier prior to disinfection. Further analysis of carrier test results revealed that the mean reduction in titer of BCoV and HCoV OC43 after drying was greater on vinyl carriers. In addition, greater amounts of reduction of BCoV and HCoV OC43 were observed on both PET and vinyl carriers as the relative humidity (RH) level increased. At low RH (20-29%) conditions, the reduction in the titer of HCoV OC43 was significantly greater than that of BCoV on both PET and vinyl carriers. Our data showed that both SARS-CoV-2 surrogates are very sensitive to the tested disinfectants, and further analysis of the quantitative carrier test data indicates that additional factors (i.e., surface type, RH, and surrogate) must be carefully considered when performing disinfectant efficacy testing on carriers. Collectively, these data highlight the importance of verifying disinfectant suspension test data by performing disinfectant carrier tests which expose the virus and disinfectant to conditions (i.e., surface type, relative humidity, surrogate) similar to those encountered during ‘real-world’ application

Novel antiviral activity of PAD inhibitors against human beta-coronaviruses HCoV-OC43 and SARS-CoV-2

The current SARS-CoV-2 pandemic, along with the likelihood that new coronavirus strains will appear in the nearby future, highlights the urgent need to develop new effective antiviral agents. In this scenario, emerging host-targeting antivirals (HTAs), which act on host-cell factors essential for viral replication, are a promising class of antiviral compounds. Here we show that a new class of HTAs targeting peptidylarginine deiminases (PADs), a family of calcium-dependent enzymes catalyzing protein citrullination, is endowed with a potent inhibitory activity against human beta-coronaviruses (HCoVs). Specifically, we show that infection of human fetal lung fibroblasts with HCoV-OC43 leads to enhanced protein citrullination through transcriptional activation of PAD4, and that inhibition of PAD4-mediated citrullination with either of the two pan-PAD inhibitors Cl-A and BB-Cl or the PAD4-specific inhibitor GSK199 curbs HCoV-OC43 replication. Furthermore, we show that either Cl-A or BB-Cl treatment of African green monkey kidney Vero-E6 cells, a widely used cell system to study beta-CoV replication, potently suppresses HCoV-OC43 and SARS-CoV-2 replication. Overall, our results demonstrate the potential efficacy of PAD inhibitors, in suppressing HCoV infection, which may provide the rationale for the repurposing of this class of inhibitors for the treatment of COVID-19 patients

Structural basis for the identification of the N-terminal domain of coronavirus nucleocapsid protein as an antiviral target

Coronaviruses (CoVs) cause numerous diseases, including Middle East respiratory syndrome and severe acute respiratory syndrome, generating significant health-related and economic consequences. CoVs encode the nucleocapsid (N) protein, a major structural protein that plays multiple roles in the virus replication cycle and forms a ribonucleoprotein complex with the viral RNA through the N protein's N-terminal domain (N-NTD). Using human CoV-OC43 (HCoV-OC43) as a model for CoV, we present the 3D structure of HCoV-OC43 N-NTD complexed with ribonucleoside 5'-monophosphates to identify a distinct ribonucleotide-binding pocket. By targeting this pocket, we identified and developed a new coronavirus N protein inhibitor, N-(6-oxo-5,6-dihydrophenanthridin-2-yl)(N,N-dimethylamino)acetamide hydrochloride (PJ34), using virtual screening; this inhibitor reduced the N protein's RNA-binding affinity and hindered viral replication. We also determined the crystal structure of the N-NTD-PJ34 complex. On the basis of these findings, we propose guidelines for developing new N protein-based antiviral agents that target CoVs

Favourable antibody responses to human coronaviruses in children and adolescents with autoimmune rheumatic diseases

Background: Differences in humoral immunity to coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), between children and adults remain unexplained and the impact of underlying immune dysfunction or suppression unknown. Here, we sought to examine the antibody immune competence of children and adolescents with prevalent inflammatory rheumatic diseases, juvenile idiopathic arthritis (JIA), juvenile dermatomyositis (JDM) and juvenile systemic lupus erythematosus (JSLE), against the seasonal human coronavirus (HCoV)-OC43 that frequently infects this age group. // Methods: Sera were collected from JIA (n=118), JDM (n=49) and JSLE (n=30) patients, and from healthy control (n=54) children and adolescents, prior to the coronavirus disease-19 (COVID-19) pandemic. We employed sensitive flow cytometry-based assays to determine titres of antibodies that reacted with the spike and nucleoprotein of HCoV-OC43 and cross-reacted with the spike and nucleoprotein of SARS-CoV-2, and compared with respective titres in sera from patients with multisystem inflammatory syndrome in children and adolescents (MIS-C). // Findings: Despite immune dysfunction and immunosuppressive treatment, JIA, JDM and JSLE patients maintained comparable or stronger humoral responses than healthier peers, dominated by IgG antibodies to HCoV-OC43 spike, and harboured IgG antibodies that cross-reacted with SARS-CoV-2 spike. In contrast, responses to HCoV-OC43 and SARS-CoV-2 nucleoproteins exhibited delayed age-dependent class-switching and were not elevated in JIA, JDM and JSLE patients, arguing against increased exposure. // Conclusions: Consequently, autoimmune rheumatic diseases and their treatment were associated with a favourable ratio of spike to nucleoprotein antibodies

Canine Respiratory Coronavirus, Bovine Coronavirus, and Human Coronavirus OC43: Receptors and Attachment Factors

Despite high similarity of canine respiratory coronavirus (CRCoV), bovine coronavirus, (BCoV) and human coronavirus OC43 (HCoV-OC43), these viruses differ in species specificity. For years it was believed that they share receptor specificity, utilizing sialic acids for cell surface attachment, internalization, and entry. Interestingly, careful literature analysis shows that viruses indeed bind to the cell surface via sialic acids, but there is no solid data that these moieties mediate virus entry. In our study, using a number of techniques, we showed that all three viruses are indeed able to bind to sialic acids to a different extent, but these molecules render the cells permissive only for the clinical strain of HCoV-OC43, while for others they serve only as attachment receptors. CRCoV and BCoV appear to employ human leukocyte antigen class I (HLA-1) as the entry receptor. Furthermore, we identified heparan sulfate as an alternative attachment factor, but this may be related to the cell culture adaptation, as in ex vivo conditions, it does not seem to play a significant role. Summarizing, we delineated early events during CRCoV, BCoV, and HCoV-OC43 entry and systematically studied the attachment and entry receptor utilized by these viruses