ABSTRACT
There is a pressing need to characterise the nature, extent and duration of immune response to SARS-CoV-2 in cancer patients, to inform risk-reduction strategies and preserve cancer outcomes. CAPTURE is a prospective, longitudinal cohort study of cancer patients and healthcare workers (HCWs) integrating immune profiles and clinical annotation. We evaluated 529 blood samples and 1051 oronasopharyngeal swabs from 144 cancer patients and 73 HCWs and correlated with >200 clinical variables. In patients with solid cancers and HCWs, S1-reactive and neutralising antibodies to SARS-CoV-2 were detectable five months post-infection. In these participants, SARS-CoV-2-specific T-cell responses were detected. CD4+ T-cell response correlated with S1 antibody levels. Patients with haematological malignancies had impaired but partially compensated immune responses, depending on malignancy and therapy. Overall, cancer stage, disease status, and therapies did not correlate with immune responses. These findings have implications for understanding individual risks and potential effectiveness of SARS-CoV-2 vaccination in this population.
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Introduction: Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe disease that affects a small proportion of children exposed to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Differences in SARS-CoV-2 antibody responses and immune gene expression between SARS-CoV-2-infected children who develop MIS-C and those who do not may provide insight into the mechanism of MIS-C. Objectives: To determine the difference in SARS-CoV2 antibody responses and immune gene expression in children with MIS-C and healthy children with evidence of previous SARS-CoV2 infection. Methods: Healthy children presenting for elective surgery and those with MIS-C were recruited between 22 June 2020 and 5 November 2020 from a single paediatric hospital during the first wave of SARSCoV- 2 in the region. Clinical data, whole blood RNA and serum were collected. Titres of SARS-CoV-2 spike-specific antibody (SAb) and their capacity to perform neutralization, antibody-dependent cellular phagocytosis (ADCP) and antibody dependant cellular cytotoxicity (ADCC) were measured. Whole blood RNA gene expression was measured using multiplex Fluidigm quantitative Polymerase Chain Reaction (qPCR) with a panel of 84 immune genes. Principal component analysis was performed to assess for differences in gene expression. A linear regression model was developed with a forward stepwise model selection method to assess which genes associated with Creactive protein (CRP) in MIS-C after controlling for the neutrophil to lymphocyte ratio (NLR). Results: Twenty-three children with MIS-C and 25 healthy children were recruited. Nine healthy children had detectable SARS-CoV-2 serum antibodies (healthy exposed). No children had preceding clinical disease related to SARS-CoV-2 infection. Comparing children with MIS-C and healthy exposed children showed no difference in SAb binding responses (p=0.372) or ADCC (p=0.992). Increased neutralisation titre (p=0.084) and ADCP (p=0.086) in children with MIS-C was observed although was non-significant. Antibody function or titre did not change over time or with treatment in MIS-C. There was a clear distinction in immune gene expression between healthy children and those with MIS-C. Immune gene expression in MIS-C resolved to become indistinct from healthy children with time. Whole blood immune gene expression associated with an abundance of neutrophils in MIS-C. In a model that accounted for 66% of the variance in CRP (adjusted R2 = 0.66) the expression of IL27 accounted for 64% of the model effect (B=35;p<0.001) followed by NLR (15%, B=6.6, p=0.002) and the expression of MCP2 (11%, B=-14.59, p=0.008). Conclusion: Comparing children infected with SARS-COV-2 from the same time period and region with or without MIS-C provides unique mechanistic insight into the disease. A trend towards higher SAb titres and ADCP implies a distinct humoral immune response to SARSCOV- 2 in children with MIS-C, although further studies are required to validate this observation. The resolution of the abnormal immune gene expression in MIS-C implies a monophasic immune perturbation. The association of IL27 and MCP2 with CRP suggests that these may be important targets in future studies for possible pathogenicity and as potential biomarkers in MIS-C.
ABSTRACT
The ongoing pandemic of SARS-CoV-2 calls for rapid and cost-effective methods to accurately identify infected individuals. The vast majority of patient samples is assessed for viral RNA presence by RT-qPCR. Our biomedical research institute, in collaboration between partner hospitals and an accredited clinical diagnostic laboratory, established a diagnostic testing pipeline that has reported on more than 252,000 RT-qPCR results since its commencement at the beginning of April 2020. However, due to ongoing demand and competition for critical resources, alternative testing strategies were sought. In this work, we present a clinically-validated procedure for high-throughput SARSCoV-2 detection by RT-LAMP in 25 minutes that is robust, reliable, repeatable, sensitive, specific, and inexpensive © 2021. Buck MD et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
ABSTRACT
Background: Patients with cancer are at increased risk of severe outcomes from COVID-19. Understanding the impact of SARS-CoV-2 infection and vaccination induced-immunity is an area of unmet need. Methods: CAPTURE (NCT03226886) is a prospective longitudinal cohort study of COVID-19 vaccine or SARS-CoV-2 infection-induced immunity. SARS-CoV-2 infections were confirmed by RT-PCR and ELISA. Neutralising antibody titres (NAbT) against wild-type (WT) SARS-CoV-2 and variants of concern (VOC;Alpha, Beta, Delta) and SARS-CoV-2 specific T-cells (SsT-cells) were quantified. Results: 118 patients (89% solid malignancy, [SM]) were SARS-CoV-2-positive (median follow-up: 154 days). 85% patients were symptomatic;2 died of COVID-19. 82% had S1-reactive antibodies, of whom 89% had neutralising antibodies (NAbs);NAbT were lower against all VOCs. While S1-reactive antibody levels declined over time, NAbT remained stable up to 329 days. Most patients had detectable SsT-cells (76% CD4+, 52% CD8+). Haematological malignancy (HM) patients had impaired immune responses that were disease and treatment-specific (anti-CD20), but with evidence suggestive of compensation from T-cells. 585 patients were evaluated following 2 doses of BNT162b2 or AZD1222 vaccines, administered 12 weeks apart. Seroconversion rates after 2 doses were 85% and 54% in patients with SM and HM, respectively. A lower proportion of patients had detectable NAbs against SARS-CoV-2 VOC (Alpha 62%, Beta 54%, Delta 49%) vs WT (84%), with corresponding significantly lower NAbT. Patients with HM were more likely to have an undetectable NAb and had lower NAbT vs solid malignancies to both WT and VOCs. Seroconversion showed poor concordance with NAbTs against VOCs. Prior SARS-CoV-2 infection boosted NAbT including against VOCs. Anti-CD20 treatment was associated with severely diminished NAbTs. Vaccine-induced T-cell responses were detected in 80% of patients, with no differences between vaccines or cancer types. Conclusions: Patients with HM had blunted humoural responses to infection and vaccination, particularly against VOCs, but preserved cellular responses might contribute to protection. Our results lend support to prioritisation of all cancer patients for further booster vaccination. Clinical trial identification: NCT03226886. Legal entity responsible for the study: The Royal Marsden NHS Foundation Trust. Funding: The Royal Marsden Charity;The National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) at the Royal Marsden Hospital and Institute for Cancer Research (ICR). Disclosure: All authors have declared no conflicts of interest.
ABSTRACT
Background: Understanding antibody immunity to SARS-CoV-2 and how the virus evades it is of critical importance in the fight against COVID-19. Our best hope of ending the pandemic is antibody-inducing vaccination, yet the precise targets and indeed protective capacity of antibodies remain incompletely defined. The coronaviral spike is the dominant viral antigen and the target of neutralizing antibodies. We discovered neutralizing epitopes located on the distal face of the SARS-CoV-2 spike N-terminal domain (NTD). Remarkably, instead of glycosylation, the virus uses a surface-exposed loop to restrict the access to this patch, and the gate is controlled through recruitment and dissociation of a metabolite. Methods: Using cryo-electron microscopy and X-ray crystallography we mapped a tetrapyrrole binding site to a deep cleft on the spike N-terminal domain (NTD, Fig. 1) and characterized structural features of a neutralizing epitope controlled by metabolite dissociation. Results: We show that SARS-CoV-2 spike binds biliverdin and bilirubin, the tetrapyrrole products of haem metabolism, with nanomolar affinity in a pH-sensitive manner. At physiological concentrations, biliverdin significantly dampened the reactivity of SARS-CoV-2 spike with immune sera and inhibited a subset of neutralizing antibodies. Access to the tetrapyrrole-sensitive epitope is gated by a flexible loop on the distal face of the NTD. Accompanied by profound conformational changes in the NTD, antibody binding requires relocation of the gating loop, which folds into the cleft vacated by the metabolite. Conclusion: It is well-established that viruses employ extensive glycosylation of their envelopes to shield antibody epitopes. Compared to glycosylation, epitope masking via metabolite recruitment has the advantage of reversibility. For instance, pH-dependence of the spike-tetrapyrrole interaction potentially allows dissociation within the late endosomal compartment. In summary, our results indicate that the virus co-opts the haem metabolite for the evasion of humoral immunity via allosteric shielding of a sensitive epitope and demonstrate the remarkable structural plasticity of the NTD.