ABSTRACT
Purpose: The immunogenicity of SARS-CoV-2 vaccines is poor in kidney transplant recipients (KTRs). The factors related to poor immunogenicity to vaccination in KTRs are not well defined. Methods An observational study was conducted in KTRs and healthy individuals who had received two doses of SARS-CoV-2 inactivated vaccine. IgG antibodies against the receptor-binding domain found in the S1 subunit of the spike protein, and against nucleocapsid protein were measured using enzyme-linked immunosorbent assay. Receptor-binding domain (RBD)-angiotensin-converting enzyme 2 interaction-blocking antibodies were measured using commercial kits. T cell responses against the spike and nucleocapsid proteins were detected using enzyme-linked immunosorbent spot assay. Results No severe adverse effects were observed in KTRs after first or second dose of SARS-CoV-2 inactivated vaccine. IgG antibodies against the receptor- binding domain, and nucleocapsid protein were not effectively induced in a majority of KTRs after second dose of inactivated vaccine. Specific T cell immunity response was detectable in 32%-40% KTRs after second doses of inactivated vaccine. KTRs who developed specific T cell immunity were more likely to be female, and have lower levels of total bilirubin, unconjugated bilirubin, and blood tacrolimus concentration. Multivariate logistic regression analysis found that blood unconjugated bilirubin was significantly negatively associated with SARS-CoV-2 specific T cell immunity response in k KTRs. Conclusions Specific T cell immunity response could be induced in 32%-40% KTRs after two doses of inactivated vaccine. Blood unconjugated bilirubin was negatively associated with specific cellular immunity response in KTRs following vaccination.
ABSTRACT
Population antibody response is believed to be important in selection of new variant viruses. We identified that SARS-CoV-2 infections elicit a population immune response mediated by a lineage of VH1-69 germline antibodies. The representative antibody R1-32 targets a novel semi-cryptic epitope defining a new class of RBD targeting antibodies. Binding to this non-ACE2 competing epitope leading to spike destruction impairing virus entry. Based on epitope location, neutralization mechanism and analysis of antibody binding to spike variants we propose that recurrent substitutions at 452 and 490 are associated with immune evasion of this population antibody response. These substitutions, including L452R found in the Delta variant, disrupt interaction mediated by the VH1-69 specific hydrophobic HCDR2 to impair antibody-antigen association allowing variants to escape. Lacking 452/490 substitutions, the Omicron variant is sensitive to this class of antibodies. Our results provide new insights into SARS-CoV-2 variant genesis and immune evasion.
Subject(s)
COVID-19ABSTRACT
COVID-19, caused by SARS-CoV-2, is an acute self-resolving disease in most of the patients, but some patients can develop a severe illness or even death. To characterize the host responses and identify potential biomarkers during disease progression, we performed a longitudinal transcriptome analysis for peripheral blood mononuclear cells (PBMCs) collected from 4 COVID-19 patients at 4 different time points from symptom onset to recovery. We found that PBMCs at different COVID-19 disease stages exhibited unique transcriptome characteristics. SARS-CoV-2 infection dysregulated innate immunity especially type I interferon response as well as the disturbed release of inflammatory cytokines and lipid mediators, and an aberrant increase of low-density neutrophils may cause tissue damage. Activation of cell death, exhaustion and migratory pathways may lead to the reduction of lymphocytes and dysfunction of adaptive immunity. COVID-19 induced hypoxia may exacerbate disorders in blood coagulation. Based on our analysis, we proposed a set of potential biomarkers for monitoring disease progression and predicting the risk of severity.