SARS-CoV-2 infection is associated with anti-desmoglein 2 autoantibody detection.

Post-acute cardiac sequelae, following SARS-CoV-2 infection, are well recognised as complications of COVID-19. We have previously shown the persistence of autoantibodies against antigens in skin, muscle, and heart in individuals following severe COVID-19; the most common staining on skin tissue displayed an inter-cellular cement pattern consistent with antibodies against desmosomal proteins. Desmosomes play a critical role in maintaining the structural integrity of tissues. For this reason, we analysed desmosomal protein levels and the presence of anti-desmoglein (DSG) 1, 2 and 3 antibodies in acute and convalescent sera from patients with COVID 19 of differing clinical severity. We find increased levels of DSG2 protein in sera from acute COVID patients. Furthermore, we find that DSG2 autoantibody levels are increased significantly in convalescent sera following severe COVID-19 but not in hospitalised patients recovering from influenza infection or healthy controls. Levels of autoantibody in sera from patients with severe COVID-19 were comparable to levels in patients with non-COVID-19-associated cardiac disease, potentially identifying DSG2 autoantibodies as a novel biomarker for cardiac damage. To determine if there was any association between severe COVID-19 and DSG2, we stained post-mortem cardiac tissue from patients who died from COVID-19 infection. This revealed disruption of the intercalated disc between cardiomyocytes that was consistent with separation of the DSG2 protein homodimer. Our results reveal the potential for DSG2 protein and autoimmunity to DSG2 to contribute to unexpected pathologies associated with COVID-19 infection.

Cross reactivity of spike glycoprotein induced antibody against delta and omicron variants before and after third SARS-CoV-2 vaccine dose

Variants of SARS-CoV-2 may evade natural and vaccine induced immunity and monoclonal antibody immunotherapeutics. There is an urgent need to know how well antibodies, induced by healthy and Clinically Extremely Vulnerable (CEV) patients, will bind and thus help reduce transmission and severity of infection from variants of concern (VOC). This study determines the cross-reactive binding of serum antibodies obtained prior to and 28 days after a third vaccination in three cohorts; a health care worker cohort who received three doses of Pfizer-BioNtech (PPP), a cohort of CEV patients received two doses of the AstraZeneca-ChAdOx1-nCoV-19 (AAP) vaccine, followed by a third PFZ vaccine and a haemodialysis cohort that had a mixture of two AZ or PFZ vaccines followed by a PFZ booster. Six months post second vaccine there was evidence of antibody waning with 58.9% of individuals in the HD cohort seropositive against Wuhan, 34.4% Delta and 62.2% Omicron strains. For the AAP cohort, equivalent figures were 62.5%, 45.8% and 91.7% and the PPP cohort 92.2%, 90% and 91.1%. Post third dose vaccination there were universal increases in seropositivity and median optical density. For the HD cohort, 98.8% were seropositive to the Wuhan strain, 97.6% against Delta and 100% against Omicron strains. For the PPP and AAP cohorts, 100% were seropositive against all 3 strains. Lastly, we examined the WHO NIBSC 20/136 standard and there was no loss of antibody binding to either VOC. Similarly, a dilution series of Sotrovimab (GSK) found this therapeutic monoclonal antibody bound similarly to all VOC. HighlightsO_LIIgG anti-SARS-CoV-2 Omicron spike glycoprotein antibody levels were high in 100% of health care workers (HCW), a general practice population considered clinically extremely vulnerable (CEV) and haemodialysis patients (HD) 4 weeks after a third SARS-CoV-2 vaccine dose (Pfizer-BioNtech-PFZ). C_LIO_LIFor both Delta and Omicron variant spike glycoproteins these antibody levels were highest in the CEV cohort who had previously received two doses of AstraZeneca ChAdOx1 nCoV-19 vaccine (AAP), lower in HCW who had previously received two doses of PFZ (PPP) and lowest in HD who had a mix of vaccines for the first and second dose C_LIO_LIPrior to this third vaccine dose and 6 months post second vaccine dose there was evidence of significant waning of antibodies against VOC. C_LI

In vitro, classical complement activation differs by disease severity and between SARS-CoV-2 antigens

Antibodies specific for the spike glycoprotein (S) and nucleocapsid (N) SARS-CoV-2 proteins are typically present during severe COVID-19, and induced to S after vaccination. The binding of viral antigens by antibody can initiate the classical complement pathway. Since complement could play pathological or protective roles at distinct times during SARS-CoV-2 infection we determined levels of antibody-dependent complement activation along the complement cascade. Here, we used an ELISA assay to assess complement protein binding (C1q) and the deposition of C4b, C3b, and C5b to S and N antigens in the presence of anti-SARS-CoV-2 antibodies from different test groups: non-infected, single and double vaccinees, non-hospitalised convalescent (NHC) COVID-19 patients and convalescent hospitalised (ITU-CONV) COVID-19 patients. C1q binding correlates strongly with antibody responses, especially IgG1 levels. However, detection of downstream complement components, C4b, C3b and C5b shows some variability associated with the antigen and subjects studied. In the ITU-CONV, detection of C3b-C5b to S was observed consistently, but this was not the case in the NHC group. This is in contrast to responses to N, where median levels of complement deposition did not differ between the NHC and ITU-CONV groups. Moreover, for S but not N, downstream complement components were only detected in sera with higher IgG1 levels. Therefore, the classical pathway is activated by antibodies to multiple SARS-CoV-2 antigens, but the downstream effects of this activation may differ depending on the specific antigen targeted and the disease status of the subject. O_LISpike- and nucleocapsid-specific antibodies activate complement in vitro C_LIO_LIC1q binding correlates with IgG1 antibody levels C_LIO_LIGeneration of C4b, C3b and C5b relates to the antigen targeted and the patient group tested C_LI

Stimulation of vascular organoids with SARS-CoV-2 antigens increases endothelial permeability and regulates vasculopathy

ObjectiveThrombotic complications and vasculopathy have been extensively associated with severe COVID-19 infection, however the mechanisms by which endotheliitis is induced remain poorly understood. Here we investigate vascular permeability in the context of SARS-CoV-2-mediated endotheliitis in patient samples and a vascular organoid model. Methods and ResultsWe report the presence of the Spike glycoprotein in pericytes associated with pericyte activation and increased endothelial permeability in post-mortem COVID-19 lung autopsies. A pronounced decrease in the expression of the adhesion molecule VE-cadherin is observed in patients with thrombotic complications. Interestingly, fibrin-rich thrombi did not contain platelets, did not colocalize with tissue factor and have heterogenous levels of Von Willebrand factor, suggesting a biomarker-guided therapy might be required to target thrombosis in severe patients. Using a 3D vascular organoid model, we observe that ACE2 is primarily expressed in pericytes adjacent to vascular networks, consistent with patient data, indicating a preferential uptake of the S glycoprotein by these cells. Exposure of vascular organoids to SARS-CoV-2 or its antigens, recombinant trimeric Spike glycoprotein and Nucleocapsid protein, reduced endothelial cell and pericyte viability as well as CD144 expression with no additive effect upon endothelial activation via IL-1{beta}. ConclusionsOur data suggest that pericyte uptake of SARS-CoV-2 or Spike glycoprotein contributes to vasculopathy by altering endothelial permeability increasing the risk of thrombotic complications.

Validation of a combined ELISA to detect IgG, IgA and IgM antibody responses to SARS-CoV-2 in mild or moderate non-hospitalised patients

BackgroundFrequently SARS-CoV-2 results in mild or moderate disease with potentially lower concentrations of antibodies compared to those that are hospitalised. Here, we validated an ELISA using SARS-CoV-2 trimeric spike glycoprotein, with targeted detection of IgG, IgA and IgM (IgGAM) using serum and dried blood spots (DBS) from adults with mild or moderate disease. MethodsTargeting the SARS-CoV-2 trimeric spike, a combined anti-IgG, IgA and IgM serology ELISA assay was developed using 62 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, [≥]14 days post symptom onset and 624 COVID-19 negative samples. The assay was validated using 73 PCR-confirmed non-hospitalised COVID-19 and 359 COVID-19 negative serum samples with an additional 81 DBSs, and further validated in 226 PCR-confirmed non-hospitalised COVID-19 and 426 COVID-19 negative clinical samples. ResultsA sensitivity and specificity of 98.6% (95% CI, 92.6-100.0), 98.3% (95% CI, 96.4-99.4), respectively, was observed following validation of the SARS-CoV-2 ELISA. No cross-reactivities with endemic coronaviruses or other human viruses were observed, and no change in results were recorded for interfering substances. The assay was stable at temperature extremes and components were stable for 15 days once opened. A matrix comparison showed DBS to correlate with serum results. Clinical validation of the assay reported a sensitivity of 94.7% (95% CI, 90.9-97.2%) and a specificity of 98.4% (95% CI, 96.6-99.3%). ConclusionsThe human anti-IgGAM SARS-CoV-2 ELISA provides accurate and sensitive detection of SARS-CoV-2 antibodies in non-hospitalised adults with mild or moderate disease. The use of dried blood spots makes the assay accessible to the wider community. Supplementary MaterialNo

Serological responses to SARS-CoV-2 following non-hospitalised infection: clinical and ethnodemographic features associated with the magnitude of the antibody response

ObjectiveTo determine clinical and ethnodemographic correlates of serological responses against the SARS-CoV-2 spike glycoprotein following mild-to-moderate COVID-19. DesignA retrospective cohort study of healthcare workers who had self-isolated due to COVID-19. SettingUniversity Hospitals Birmingham NHS Foundation Trust, UK (UHBFT). Participants956 health care workers were recruited by open invitation via UHBFT trust email and social media. InterventionParticipants volunteered a venous blood sample that was tested for the presence of anti-SARS-CoV-2 spike glycoprotein antibodies. Results were interpreted in the context of the symptoms of their original illness and ethnodemographic variables. ResultsUsing an assay that simultaneously measures the combined IgG, IgA and IgM response against the spike glycoprotein (IgGAM), the overall seroprevalence within this cohort was 46.2% (n=442/956). The seroprevalence of immunoglobulin isotypes was 36.3%, 18.7% and 8.1% for IgG, IgA and IgM respectively. IgGAM identified serological responses in 40.6% (n=52/128) of symptomatic individuals who reported a negative SARS-CoV-2 PCR test. Increasing age, non-white ethnicity and obesity were independently associated with greater IgG antibody response against the spike glycoprotein. Self-reported fever and fatigue were associated with greater IgG and IgA responses against the spike glycoprotein. The combination of fever and/or cough and/or anosmia had a positive predictive value of 92.3% for seropositivity. Conclusions and relevanceAssays employing combined antibody detection demonstrate enhanced seroepidemiological sensitivity and can detect prior viral exposure even when PCR swabs have been negative. We demonstrate an association between known ethnodemographic risk factors associated with mortality from COVID-19 and the magnitude of serological responses in mild-to-moderate disease. The combination of cough, and/or fever and/or anosmia identifies the majority of individuals who should self-isolate for COVID-19.

Sensitive detection of SARS-CoV-2-specific-antibodies in dried blood spot samples

ImportancePopulation-wide serological testing is an essential component in understanding the COVID-19 pandemic. The logistical challenges of undertaking widespread serological testing could be eased through use of a reliable dried blood spot (DBS) sampling method. ObjectiveTo validate the use of dried blood spot sampling for the detection of SARS-CoV-2-specific antibodies. Design, setting and participantsEighty-seven matched DBS and serum samples were obtained from eighty individuals, including thirty-one who were previously PCR-positive for SARS-CoV-2. DBS eluates and sera were used in an ELISA to detect antibodies to the viral spike protein. ResultsSpecific anti-SARS-Cov-2 spike glycoprotein antibodies were detectable in both serum and DBS eluate and there was a significant correlation between the antibody levels detected in matched samples (r = 0.96, p<0.0001). Using serum as the gold standard in the assay, matched DBS samples achieved a Cohens kappa coefficient of 0.975 (near-perfect agreement), a sensitivity of 98.1% and specificity of 100%, for detecting anti-spike glycoprotein antibodies. Conclusions and relevanceEluates from DBS samples are a reliable and reproducible source of antibodies to be used for the detection of SARS-CoV-2-specific antibodies. The use of DBS sampling could complement the use of venepuncture in the immunosurveillance of COVID-19 in both low and high income settings.

Detection of antibodies to the SARS-CoV-2 spike glycoprotein in both serum and saliva enhances detection of infection

BackgroundDetecting antibody responses during and after SARS-CoV-2 infection is essential in determining the seroepidemiology of the virus and the potential role of antibody in disease. Scalable, sensitive and specific serological assays are essential to this process. The detection of antibody in hospitalized patients with severe disease has proven straightforward; detecting responses in subjects with mild disease and asymptomatic infections has proven less reliable. We hypothesized that the suboptimal sensitivity of antibody assays and the compartmentalization of the antibody response may contribute to this effect. MethodsWe systemically developed an ELISA assay, optimising different antigens and amplification steps, in serum and saliva from symptomatic and asymptomatic SARS-CoV-2-infected subjects. ResultsUsing trimeric spike glycoprotein, rather than nucleocapsid enabled detection of responses in individuals with low antibody responses. IgG1 and IgG3 predominate to both antigens, but more anti-spike IgG1 than IgG3 was detectable. All antigens were effective for detecting responses in hospitalized patients. Anti-spike, but not nucleocapsid, IgG, IgA and IgM antibody responses were readily detectable in saliva from non-hospitalized symptomatic and asymptomatic individuals. Antibody responses in saliva and serum were largely independent of each other and symptom reporting. ConclusionsDetecting antibody responses in both saliva and serum is optimal for determining virus exposure and understanding immune responses after SARS-CoV-2 infection. FundingThis work was funded by the University of Birmingham, the National Institute for Health Research (UK), the NIH National Institute for Allergy and Infectious Diseases, the Bill and Melinda Gates Foundation and the University of Southampton.

Serology confirms SARS-CoV-2 infection in PCR-negative children presenting with Paediatric Inflammatory Multi-System Syndrome

BackgroundDuring the COVID-19 outbreak, reports have surfaced of children who present with features of a multisystem inflammatory syndrome with overlapping features of Kawasaki disease and toxic shock syndrome - Paediatric Inflammatory Multisystem Syndrome-temporally associated with SARS-CoV-2 pandemic (PIMS-TS). Initial reports find that many of the children are PCR-negative for SARS-CoV-2, so it is difficult to confirm whether this syndrome is a late complication of viral infection in an age group largely spared the worst consequences of this infection, or if this syndrome reflects enhanced surveillance. MethodsChildren hospitalised for symptoms consistent with PIMS-TS between 28 April and 8 May 2020, and who were PCR-negative for SARS-CoV-2, were tested for antibodies to viral spike glycoprotein using an ELISA test. ResultsEight patients (age range 7-14 years, 63% male) fulfilled case-definition for PIMS-TS during the study period. Six of the eight patients required admission to intensive care. All patients exhibited significant IgG and IgA responses to viral spike glycoprotein. Further assessment showed that the IgG isotypes detected in children with PIMS-TS were of the IgGl and lgG3 subclasses, a distribution similar to that observed in samples from hospitalised adult COVID-19 patients. In contrast, lgG2 and lgG4 were not detected in children or adults. IgM was not detected in children, which contrasts with adult hospitalised adult COVID-19 patients of whom all had positive IgM responses. ConclusionsStrong IgG antibody responses can be detected in PCR-negative children with PIMS-TS. The low detection rate of IgM in these patients is consistent with infection having occurred weeks previously and that the syndrome onset occurs well after the control of SARS-CoV-2 viral load. This implies that the disease is largely immune-mediated. Lastly, this indicates that serology can be an appropriate diagnostic tool in select patient groups.

SARS-CoV-2 seroconversion in health care workers

BackgroundThe correlates of protection against SARS-CoV-2 and their longevity remain unclear. Studies in severely ill individuals have identified robust cellular and humoral immune responses against the virus. Asymptomatic infection with SARS-CoV-2 has also been described, but it is unknown whether this is sufficient to produce antibody responses. MethodsWe performed a cross-sectional study recruiting 554 health care workers from University Hospitals Birmingham NHS Foundation Trust who were at work and asymptomatic. Participants were tested for current infection with SARS-CoV-2 by nasopharyngeal swab for real-time polymerase chain reaction and for seroconversion by the measurement of anti-SARS-CoV-2 spike glycoprotein antibodies by enzyme linked immunosorbent assay. Results were interpreted in the context of previous, self-reported symptoms of illness consistent with COVID-19. ResultsThe point prevalence of infection with SARS-CoV-2, determined by the detection of SARS-CoV-2 RNA on nasopharnygeal swab was 2.39% (n=13/544). Serum was available on 516 participants. The overall rate of seroconversion in the cohort was 24.4% (n=126/516). Individuals who had previously experienced a symptomatic illness consistent with COVID-19 had significantly greater seroconversion rates than those who had remained asymptomatic (37.5% vs 17.1%, {chi}2 =21.1034, p<0.0001). In the week preceding peak COVID-19-related mortality at UHBFT, seroconversion rates amongst those who were suffering from symptomatic illnesses peaked at 77.8%. Prior symptomatic illness generated quantitatively higher antibody responses than asymptomatic seroconversion. Seroconversion rates were highest amongst those working in housekeeping (34.5%), acute medicine (33.3%) and general internal medicine (30.3%) with lower rates observed in participants working in intensive care (14.8%) and emergency medicine (13.3%). ConclusionsIn a large cross-sectional seroprevalence study of health-care workers, we demonstrate that asymptomatic seroconversion occurs, however prior symptomatic illness is associated with quantitatively higher antibody responses. The identification that the potential for seroconversion in health-care workers can associate differentially with certain hospital departments may inform future infection control and occupational health practices. Research in contextO_ST_ABSEvidence before the studyC_ST_ABSTo date, no study has examined the cross-sectional seroprevalence of anti-SARS-CoV-2 antibodies in health care workers during the COVID-19 pandemic. Existing evidence suggests that the levels of SARS-CoV-2 antibodies developing following infection may vary with disease severity in keeping with previous coronavirus pandemics. Added value of this studyWe demonstrate that seroconversion can occur in health care workers who have suffered no previous symptoms of SARS-Cov-2 infection. However, prior symptomatic infection tends to drive quantitatively superior antibody responses against the virus. We observed differential seroconversion rates in individuals working within different hospital departments. Using intensive care as a reference, the relative risk for seroconversion was greatest for those working in housekeeping, acute and general internal medicine. Implications of all the available evidenceInsight into the current seroprevalence of SARS-CoV-2 antibodies within a high-risk cohort of health-care workers is of direct relevance as a reference point for future community serological surveys. We provide further evidence of asymptomatic infection and seroconversion, strengthening the argument for regular, routine screening of health-care workers. Finally, we provide evidence that individuals working in particular roles within the NHS are at greater risk of seroconversion with significant implications for their occupational health.