Association of SARS-COV-2 viral RNAemia, IL- 6 gene polymorphism, serum IL-6 and peripheral blood lymphocytes and monocytes with disease severity in COVID-19 patients

Coronavirus disease 2019 (COVID-19) is a fatal pandemic viral disease caused by the severe acute respiratory syndrome corona virus type-2 (SARS-CoV-2). The aim of this study is to observe the associations of IL-6, SARS-COV-2 viral load (RNAemia), IL- 6 gene polymorphism and lymphocytes and monocytes in peripheral blood with disease severity in COVID-19 patients. This study was carried out from March 2021 to January 2022. RT-PCR positive 84 COVID-19 patients and 28 healthy subjects were enrolled. Blood was collected to detect SARS-COV-2 viral RNA (RNAemia) by rRT-PCR, serum IL-6 level by chemiluminescence method, SNPs of IL-6 by SSP-PCR, immunophenotyping of lymphocytes and monocyte by flow cytometry. Serum IL-6 level (pg/ml) was considerably high among critical patients (102.02 +/- 149.7) compared to severe (67.20 +/- 129.5) and moderate patients (47.04 +/- 106.5) and healthy controls (3.5 +/- 1.8). Serum SARS-CoV-2 nucleic acid positive cases detected mostly in critical patients (39.28%) and was correlated with extremely high IL-6 level and high mortality (R =.912, P < 0.001). Correlation between IL-6 and monocyte was statistically significant with disease severity (severe group, p < 0.001, and 0.867*** and critical group p < 0.001 and 0.887***). In healthy controls, moderate, severe and critically ill COVID-19 patients, IL-6 174G/C (rs 1800795) GG genotype was 82.14%, 89.20%, 67.85% and 53.57% respectively. CC and GC genotype had strong association with severity of COVID-19 when compared with GG genotype. Significant statistical difference found in genotypes between critical and moderate groups (p < 0.001, OR-10.316, CI-3.22-23.86), where CC genotype was associated with COVID-19 severity and mortality. The absolute count of T cell, B cell, NK cell, CD4+ T cells and CD8+ T cells were significantly decreased in critical group compared to healthy, moderate and severe group (P < 0.001). Exhaustion marker CD94/NKG2A was increased on NK cells and CD8+ cytotoxic T cell among critical and severe group. Absolute count of monocyte was significantly increased in critical group (P < 0.001). Serum IL-6, IL-6 174 G/C gene and SARS-CoV-2 RNAaemia can be used in clinical practice for risk assessment;T cell subsets and monocyte as biomarkers for monitoring COVID-19 severity. Monoclonal antibody targeting IL-6 receptor and NKG2A for therapeutics may prevent disease progression and decrease morbidity and mortality.Copyright © 2023 Elsevier Inc.

SIGLEC-9 RESTRAINS ANTIBODY-DEPENDENT NK CELL CYTOTOXICITY AGAINST SARS-CoV-2

Background: SARS CoV 2 infection alters the immunological profiles of natural killer (NK) cells. However, whether NK anti-viral functions (direct cytotoxicity and/or antibody-dependent cell cytotoxicity (ADCC)) are impaired during severe COVID-19 and what host factors modulate these functions remain unclear. Method(s): Using functional assays, we examined the ability of NK cells from SARS-CoV-2 negative controls (n=12), mild COVID-19 patients (n=26), and hospitalized COVID-19 patients (n=41) to elicit direct cytotoxicity and ADCC [NK degranulation by flow] against cells expressing SARS-CoV-2 antigens. SARS-CoV- 2 N antigen plasma load was measured using an ultra-sensitive Simoa assay. We also phenotypically characterized the baseline expression of NK activating (CD16 and NKG2C), maturation (CD57), and inhibitory (NKG2A and the glyco-immune negative checkpoint Siglec-9) by flow cytometry. Finally, an anti-Siglec-9 blocking antibody was used to examine the impact of Siglec-9 expression on anti-SARS-CoV-2-specific ADCC [degranulation and target cell lysis]. Result(s): NK cells from hospitalized COVID-19 patients degranulate less against SARS-CoV-2-antigen-expressing cells (in direct cytolytic and ADCC assays) than did cells from mild COVID-19 patients or negative controls (Fig. 1A). The lower NK degranulation was associated with higher plasma levels of SARS-CoV-2 N-antigen (P<=0.02). Phenotypic and functional analyses showed that NK cells expressing Siglec-9 elicited higher ADCC than Siglec-9- NK cells (P<0.05;Fig. 1B). Consistently, Siglec-9+ NK cells expressed an activated and mature phenotype with higher expression of CD16, CD57, and NKG2C, and lower expression of NKG2A, than Siglec-9- NK cells (P<=0.03). These data are consistent with the concept that the NK cell subpopulation expressing Siglec-9 is highly activated and cytotoxic. However, the Siglec-9 molecule itself is an inhibitory receptor that restrains NK cytotoxicity during cancer and other infections. Indeed, blocking Siglec-9 significantly enhanced the ADCC-mediated NK degranulation and lysis of SARS-CoV-2-antigen-positive target cells (P<=0.05;Fig. 1C). Conclusion(s): These data support a model (Fig. 1D) in which the Siglec-9+ CD56dim NK subpopulation is cytotoxic even while being restrained by the inhibitory effects of Siglec-9. However, alleviating the Siglec-9-mediated restriction on NK cytotoxicity can further improve NK immune surveillance and presents an opportunity to develop novel immunotherapeutic tools against SARS-CoV-2 infected cells. (Figure Presented).

Clinical Validation of a Novel T-cell Receptor Sequencing Assay for Identification of Recent or Prior SARS-CoV-2 Infection.

BACKGROUND: While diagnostic, therapeutic, and vaccine development in the COVID-19 pandemic has proceeded at unprecedented speed, critical gaps in our understanding of the immune response to SARS-CoV-2 remain unaddressed by current diagnostic strategies. METHODS: A statistical classifier for identifying prior SARS-CoV-2 infection was trained using >4000 SARS-CoV-2-associated TCRß sequences identified by comparing 784 cases and 2447 controls from 5 independent cohorts. The T-Detect™ COVID assay applies this classifier to TCR repertoires sequenced from blood samples to yield a binary assessment of past infection. Assay performance was assessed in 2 retrospective (n = 346; n = 69) and 1 prospective cohort (n = 87) to determine positive percent agreement (PPA) and negative percent agreement (NPA). PPA was compared to 2 commercial serology assays, and pathogen cross-reactivity was evaluated. RESULTS: T-Detect COVID demonstrated high PPA in individuals with prior RT-PCR-confirmed SARS-CoV-2 infection (97.1% 15 + days from diagnosis; 94.5% 15 + days from symptom onset), high NPA (∼100%) in presumed or confirmed SARS-CoV-2 negative cases, equivalent or higher PPA than 2 commercial serology tests, and no evidence of pathogen cross-reactivity. CONCLUSION: T-Detect COVID is a novel T-cell immunosequencing assay demonstrating high clinical performance for identification of recent or prior SARS-CoV-2 infection from blood samples, with implications for clinical management, risk stratification, surveillance, and understanding protective immunity and long-term sequelae.

The emerging Omicron variant spike mutation: the relative receptor-binding domain affinity and molecular dynamics

This study aims to fill a knowledge gap in our understanding of Omicron variant receptor-binding domain (RBD) interactions with host cell receptor, angiotensin-converting enzyme 2 (ACE2). Protein-protein docking, scoring, and filtration were all performed using the HDOCK server. A coarse-grained prediction of the changes in binding free energy caused by point mutations in Omicron RBD was requested from the Binding Affinity Changes upon Mutation (BeAtMuSiC) tools. GROMACS was utilized to perform molecular dynamics simulations (MD). Within the 15 mutations in Omicron RBD, several mutations have been linked to increased receptor affinity, immunological evasion, and inadequate antibody response. Wild-type (wt) SARS-CoV-2 and its Omicron variant have 92.27% identity. Nonetheless, Omicron RBD mutations resulted in a slight increase in the route mean square deviations (RMSD) of the Omicron structural model during protein-protein docking, as evidenced by RMSDs of 0.47 and 0.85 A for the wt SARS-CoV-2 and Omicron RBD-ACE2 complexes, respectively. About five-point mutations had essentially an influence on binding free energy, namely G6D, S38L, N107K, E151A, and N158Y. The rest of the mutations were expected to reduce the binding affinity of Omicron RBD and ACE2. The MD simulation supports the hypothesis that Omicron RBD is more stably bound to ACE2 than wt SARS-CoV-2 RBD. Lower RMSD and greater radius of gyration (Rg) imply appropriate Omicron structure 3D folding and stability. However, the increased solvent accessible surface area (SASA) with a greater Omicron shape may have a different interaction with receptor binding and regulate virus entrance. Omicron RBD's mutations help it maintain its structural stability, compactness, ACE2 binding, and immune evasion.Copyright © 2022 AEPress, s.r.o.. All rights reserved.

COVID-19 Invades Several Important Organs other than the Lungs: Organs Crosstalk

In December 2019, a new severe acute respiratory coronavirus (SARS-COV-2) had caused outbreaks of pneumonia in Wuhan city, China. It was known as coronavirus infected dis-ease-2019 (COVID-19). COVID-19 patients typically have a fever and respiratory syndrome, where the lung is the main target organ affected by this virus. The objective of this review is to monitor and evaluate injuries caused by the SARS-COV-2 virus on multiple organs other than the lung as the gastrointestinal tract, liver, kidney, heart, ovary, ocular, olfactory, gonad, skin, central nervous system, and sense organs. As SARS-COV-2 virus enters host cells via cell receptor an-giotensin circulating enzyme-2 (ACE2), so it is important to identify the main target cells attacked by SARS-COV-2 virus by comparing the ACE2 expression and viral upload in different organs. In conclusion, the definite role of body organs is explored in the manifestation of COVID-19 infection and crosstalk between other organs are useful tools to find any correlation between disease severity and organs dysfunction, exact prognosis, disease prevention measures, clinical care, and treatment strategies.Copyright © 2021 Bentham Science Publishers.

Viral enteritis in cattle: To well known viruses and beyond

Livestock products supply about 13 percent of energy and 28 percent of protein in diets consumed worldwide. Diarrhea is a leading cause of sickness and death of beef and dairy calves in their first month of life and also affecting adult cattle, resulting in large economic losses and a negative impact on animal welfare. Despite the usual multifactorial origin, viruses are generally involved, being among the most important causes of diarrhea. There are several viruses that have been confirmed as etiological agents (i.e., rotavirus and coronavirus), and some viruses that are not yet confirmed as etiological agents. This review summarizes the viruses that have been detected in the enteric tract of cattle and tries to deepen and gather knowledge about them.Copyright © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

The Significance of Angiotensin-Converting Enzyme-2 (ACE2) in SARS-Cov-2 Infection and COVID-19

The new coronavirus was first reported in 2019 (China) and officially announced by the World Health Organization as a pandemic in March 2020. Severe acute respiratory syndrome coro-navirus 2 (SARS-CoV-2) is the causative agent of the pneumonia-associated illnesses and shares structural homology with the related Severe acute respiratory syndrome coronavirus-1 (SARS-CoV--1). One of the mechanisms for SARS-Cov-1 and-2 infection is mediated by the angiotensin-con-verting enzyme-2 (ACE2) cell receptor, enabling the virus to enter the host cells. ACE2 is an iso-form of the angiotensin-converting enzyme 1 (ACE). The actions of ACE2 counterbalance the clas-sic renin-angiotensin system (RAS) axis through the production of Ang 1-7, which promotes car-diovascular, renal, and lung-protective effects. The ACE2 is not the only route for SARS-CoV-2 to enter the host cells. However, due to its roles in the RAS and its participation in the SARS-CoV-2 virulence, ACE2 has gained attention regarding viral mechanisms of pathogenesis, effects of drugs that interfere with the RAS, and as a potential target for therapeutic strategies for the damages caused by SARS-CoV-2 infection. Among other tissues, ACE2 gene expression seems to be in-creased in the lungs upon SARS-CoV-2 infection;however, amid other variables, expression and/or activity of ACE2 is shown as a disease, sex, and age-dependent. The present review covers critical aspects for a comprehensive understanding of ACE2 and its current involvement in SARS-CoV-2 infection and the development of COVID-19.Copyright © 2021 Bentham Science Publishers.

Impact and Inescapable Effects of Coronavirus: History to Modern Pandemic Episode

Coronavirus disease 2019 (COVID-19) is an acute respiratory tract infection causing a pandemic that emerged in 2019 initially in China involving 13.8% cases with severe, and 6.1% with critical course and later throughout the globe. Vaccines or antiviral medications are yet to be used to prevent or treat infections of Human Coronavirus (HCoV). The much-discovered HCoV found in 2003, SARS-COVID-19, which caused respiratory syndrome, has special pathogenesis as it causes respiratory tract infection. The coronavirus spike protein's association with its host cell receptor complement is crucial in deciding the virus infectivity, tissue tropism and species variety. SARS, COVID-19, infects human cells by binding to angiotensin-converting enzyme 2 (ACE2) receptor and uses the TMPRSS2 cell protease to activate it. Lungs are most affected by COVID-19 as host cells are accessed by the virus through ACE2, which is most abundant in alveolar cells of the lungs. Special attention and efforts should be given in reducing transmission in vulnerable populations, including infants, health care providers and the elderly. COVID 19, is the main causative agent of potentially lethal disease and is of significant concern for global public health and in pandemics which was highlighted in this review.Copyright © 2021 Bentham Science Publishers.

Case report: SARS-CoV-2 specific T-cells are associated with myocarditis after COVID-19 vaccination with mRNA-1273.

Vaccination of SARS-CoV-2 with BNT162b2 or mRNA-1273 both have a low incidence of induction of myocarditis. Here we report on utilizing adaptive immune receptor repertoire sequencing (AIRR-Seq) as a way to assess the specificity of tissue infiltrating immune cells.

Case report: Immunological characteristics of de novo ulcerative colitis in a child post COVID-19.

The pathological mechanisms of de novo inflammatory bowel disease (IBD) following SARS-CoV-2 infection are unknown. However, cases of coexisting IBD and multisystem inflammatory syndrome in children (MIS-C), which occurs 2-6 weeks after SARS-CoV-2 infection, have been reported, suggesting a shared underlying dysfunction of immune responses. Herein, we conducted the immunological analyses of a Japanese patient with de novo ulcerative colitis following SARS-CoV-2 infection based on the pathological hypothesis of MIS-C. Her serum level of lipopolysaccharide-binding protein, a microbial translocation marker, was elevated with T cell activation and skewed T cell receptor repertoire. The dynamics of activated CD8+ T cells, including T cells expressing the gut-homing marker α4ß7, and serum anti-SARS-CoV-2 spike IgG antibody titer reflected her clinical symptoms. These findings suggest that SARS-CoV-2 infection may trigger the de novo occurrence of ulcerative colitis by impairing intestinal barrier function, T cell activation with a skewed T cell receptor repertoire, and increasing levels of anti-SARS-CoV-2 spike IgG antibodies. Further research is needed to clarify the association between the functional role of the SARS-CoV-2 spike protein as a superantigen and ulcerative colitis.

Resolving SARS-CoV-2 CD4+ T cell specificity via reverse epitope discovery.

The current strategy to detect immunodominant T cell responses focuses on the antigen, employing large peptide pools to screen for functional cell activation. However, these approaches are labor and sample intensive and scale poorly with increasing size of the pathogen peptidome. T cell receptors (TCRs) recognizing the same epitope frequently have highly similar sequences, and thus, the presence of large sequence similarity clusters in the TCR repertoire likely identify the most public and immunodominant responses. Here, we perform a meta-analysis of large, publicly available single-cell and bulk TCR datasets from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected individuals to identify public CD4+ responses. We report more than 1,200 αßTCRs forming six prominent similarity clusters and validate histocompatibility leukocyte antigen (HLA) restriction and epitope specificity predictions for five clusters using transgenic T cell lines. Collectively, these data provide information on immunodominant CD4+ T cell responses to SARS-CoV-2 and demonstrate the utility of the reverse epitope discovery approach.

Structural insights into protection against a SARS-CoV-2 spike variant by T cell receptor diversity.

T cells play a crucial role in combatting SARS-CoV-2 and forming long-term memory responses to this coronavirus. The emergence of SARS-CoV-2 variants that can evade T cell immunity has raised concerns about vaccine efficacy and the risk of reinfection. Some SARS-CoV-2 T cell epitopes elicit clonally restricted CD8+ T cell responses characterized by T cell receptors (TCRs) that lack structural diversity. Mutations in such epitopes can lead to loss of recognition by most T cells specific for that epitope, facilitating viral escape. Here, we studied an HLA-A2-restricted spike protein epitope (RLQ) that elicits CD8+ T cell responses in COVID-19 convalescent patients characterized by highly diverse TCRs. We previously reported the structure of an RLQ-specific TCR (RLQ3) with greatly reduced recognition of the most common natural variant of the RLQ epitope (T1006I). Opposite to RLQ3, TCR RLQ7 recognizes T1006I with even higher functional avidity than the WT epitope. To explain the ability of RLQ7, but not RLQ3, to tolerate the T1006I mutation, we determined structures of RLQ7 bound to RLQ-HLA-A2 and T1006I-HLA-A2. These complexes show that there are multiple structural solutions to recognizing RLQ and thereby generating a clonally diverse T cell response to this epitope that assures protection against viral escape and T cell clonal loss.

No association of malignant B-cell non-Hodgkin lymphomas with ipsilateral SARS-CoV-2 vaccination.

PURPOSE: SARS-CoV-2 vaccines cause acute ipsilateral lymph node swelling in an important proportion of vaccines. Thus far, no malignant lymphadenopathies have been reported in temporal context to vaccination in the ipsilateral draining lymph node areas. EXPERIMENTAL DESIGN: Prompted by two cases with unilateral axillary lymphomas that occurred ipsilaterally to prior SARS-CoV-2 vaccination, we systematically retrieved all B-cell non-Hodgkin lymphomas at two German University Medical Centers diagnosed before and after introduction of SARS-CoV-2 vaccines in Germany. Available lymphoma tissue (n=19) was subjected to next-generation immunosequencing of the IGH locus. Malignant clonotypes were mined in the CoVabDab database and published data sets from 342 uninfected individuals, 55 individuals 28 days after anti-SARS-CoV-2 vaccination and 139 individuals with acute COVID-19 together encompassing over 1 million CDR3 sequences in total. RESULTS: Of 313 newly diagnosed cases in the two centers and observation periods, 27 unilateral manifestations in the defined deltoid draining regions were identified. The majority thereof were diffuse large B-cell lymphomas (18 of 27 cases). Eleven unilateral cases were diagnosed in the era of SARS-CoV-2 vaccination and 16 in the control period before introduction of such vaccines. Of the 11 unilateral lymphomas that occurred during the vaccination period, ten had received a SARS-CoV-2 vaccine prior to lymphoma diagnosis. These cases were further evaluated. While left-sided were more frequent than right-sided lymphomas (19 vs 8 cases), no statistically significant association of vaccination site and laterality of the lymphoma manifestation was found. The unilateral lymphomas showed a normal range of B-cell receptors typically found in these lymphoma subtypes with no evidence for anti-SARS-CoV-2 sequences in the malignant clonotype. CONCLUSIONS: Together, we found no evidence that the current SARS-CoV-2 vaccines could serve as a trigger for lymphomagenesis in the draining lymph node areas of the deltoid region used for vaccination.

T Cell Receptor Sequences Amplified during Severe COVID-19 and Multisystem Inflammatory Syndrome in Children Mimic SARS-CoV-2, Its Bacterial Co-Infections and Host Autoantigens.

Published hypervariable region V-beta T cell receptor (TCR) sequences were collected from people with severe COVID-19 characterized by having various autoimmune complications, including blood coagulopathies and cardiac autoimmunity, as well as from patients diagnosed with the Kawasaki disease (KD)-like multisystem inflammatory syndrome in children (MIS-C). These were compared with comparable published v-beta TCR sequences from people diagnosed with KD and from healthy individuals. Since TCR V-beta sequences are supposed to be complementary to antigens that induce clonal expansion, it was surprising that only a quarter of the TCR sequences derived from severe COVID-19 and MIS-C patients mimicked SARS-CoV-2 proteins. Thirty percent of the KD-derived TCR mimicked coronaviruses other than SARS-CoV-2. In contrast, only three percent of the TCR sequences from healthy individuals and those diagnosed with autoimmune myocarditis displayed similarities to any coronavirus. In each disease, significant increases were found in the amount of TCRs from healthy individuals mimicking specific bacterial co-infections (especially Enterococcus faecium, Staphylococcal and Streptococcal antigens) and host autoantigens targeted by autoimmune diseases (especially myosin, collagen, phospholipid-associated proteins, and blood coagulation proteins). Theoretical explanations for these surprising observations and implications to unravel the causes of autoimmune diseases are explored.

CoV2-TCR: A web server for screening TCR CDR3 from TCR immune repertoire of COVID-19 patients and their recognized SARS-CoV-2 epitopes.

Although multiple vaccines have been developed and widely administered, several severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have been reported to evade immune responses and spread diffusely. Here, 108 RNA-seq files from coronavirus disease 2019 (COVID-19) patients and healthy donors (HD) were downloaded to extract their TCR immune repertoire by MiXCR. Those extracted TCR repertoire were compared and it was found that disease progression was related negatively with diversity and positively with clonality. Specifically, greater proportions of high-abundance clonotypes were observed in active and severe COVID-19 samples, probably resulting from strong stimulation of SARS-CoV-2 epitopes and a continued immune response in host. To investigate the specific recognition between TCR CDR3 and SARS-CoV-2 epitopes, we constructed an accurate classifier CoV2-TCR with an AUC of 0.967 in an independent dataset, which outperformed several similar tools. Based on this model, we observed a huge range in the number of those TCR CDR3 recognizing those different peptides, including 28 MHC-I epitopes from SARS-CoV-2 and 22 immunogenic peptides from SARS-CoV-2 variants. Interestingly, their proportions of high-abundance, low-abundance and rare clonotypes were close for each peptide. To expand the potential application of this model, we established the webserver, CoV2-TCR, in which users can obtain those recognizing CDR3 sequences from the TCR repertoire of COVID-19 patients based on the 9-mer peptides containing mutation site(s) on the four main proteins of SARS-CoV-2 variants. Overall, this study provides preliminary screening for candidate antigen epitopes and the TCR CDR3 that recognizes them, and should be helpful for vaccine design on SARS-CoV-2 variants.

pyTCR: A comprehensive and scalable solution for TCR-Seq data analysis to facilitate reproducibility and rigor of immunogenomics research.

T cell receptor (TCR) studies have grown substantially with the advancement in the sequencing techniques of T cell receptor repertoire sequencing (TCR-Seq). The analysis of the TCR-Seq data requires computational skills to run the computational analysis of TCR repertoire tools. However biomedical researchers with limited computational backgrounds face numerous obstacles to properly and efficiently utilizing bioinformatics tools for analyzing TCR-Seq data. Here we report pyTCR, a computational notebook-based solution for comprehensive and scalable TCR-Seq data analysis. Computational notebooks, which combine code, calculations, and visualization, are able to provide users with a high level of flexibility and transparency for the analysis. Additionally, computational notebooks are demonstrated to be user-friendly and suitable for researchers with limited computational skills. Our tool has a rich set of functionalities including various TCR metrics, statistical analysis, and customizable visualizations. The application of pyTCR on large and diverse TCR-Seq datasets will enable the effective analysis of large-scale TCR-Seq data with flexibility, and eventually facilitate new discoveries.

Tracking the clonal dynamics of SARS-CoV-2-specific T cells in children and adults with mild/asymptomatic COVID-19.

Children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop less severe coronavirus disease 2019 (COVID-19) than adults. The mechanisms for the age-specific differences and the implications for infection-induced immunity are beginning to be uncovered. We show by longitudinal multimodal analysis that SARS-CoV-2 leaves a small footprint in the circulating T cell compartment in children with mild/asymptomatic COVID-19 compared to adult household contacts with the same disease severity who had more evidence of systemic T cell interferon activation, cytotoxicity and exhaustion. Children harbored diverse polyclonal SARS-CoV-2-specific naïve T cells whereas adults harbored clonally expanded SARS-CoV-2-specific memory T cells. A novel population of naïve interferon-activated T cells is expanded in acute COVID-19 and is recruited into the memory compartment during convalescence in adults but not children. This was associated with the development of robust CD4+ memory T cell responses in adults but not children. These data suggest that rapid clearance of SARS-CoV-2 in children may compromise their cellular immunity and ability to resist reinfection.

IgTreeZ, A Toolkit for Immunoglobulin Gene Lineage Tree-Based Analysis, Reveals CDR3s Are Crucial for Selection Analysis.

Somatic hypermutation (SHM) is an important diversification mechanism that plays a part in the creation of immune memory. Immunoglobulin (Ig) variable region gene lineage trees were used over the last four decades to model SHM and the selection mechanisms operating on B cell clones. We hereby present IgTreeZ (Immunoglobulin Tree analyZer), a python-based tool that analyses many aspects of Ig gene lineage trees and their repertoires. Using simulations, we show that IgTreeZ can be reliably used for mutation and selection analyses. We used IgTreeZ on empirical data, found evidence for different mutation patterns in different B cell subpopulations, and gained insights into antigen-driven selection in corona virus disease 19 (COVID-19) patients. Most importantly, we show that including the CDR3 regions in selection analyses - which is only possible if these analyses are lineage tree-based - is crucial for obtaining correct results. Overall, we present a comprehensive lineage tree analysis tool that can reveal new biological insights into B cell repertoire dynamics.

Machine-Learning-Assisted Analysis of TCR Profiling Data Unveils Cross-Reactivity between SARS-CoV-2 and a Wide Spectrum of Pathogens and Other Diseases.

During the last two years, the emergence of SARS-CoV-2 has led to millions of deaths worldwide, with a devastating socio-economic impact on a global scale. The scientific community's focus has recently shifted towards the association of the T cell immunological repertoire with COVID-19 progression and severity, by utilising T cell receptor sequencing (TCR-Seq) assays. The Multiplexed Identification of T cell Receptor Antigen (MIRA) dataset, which is a subset of the immunoACCESS study, provides thousands of TCRs that can specifically recognise SARS-CoV-2 epitopes. Our study proposes a novel Machine Learning (ML)-assisted approach for analysing TCR-Seq data from the antigens' point of view, with the ability to unveil key antigens that can accurately distinguish between MIRA COVID-19-convalescent and healthy individuals based on differences in the triggered immune response. Some SARS-CoV-2 antigens were found to exhibit equal levels of recognition by MIRA TCRs in both convalescent and healthy cohorts, leading to the assumption of putative cross-reactivity between SARS-CoV-2 and other infectious agents. This hypothesis was tested by combining MIRA with other public TCR profiling repositories that host assays and sequencing data concerning a plethora of pathogens. Our study provides evidence regarding putative cross-reactivity between SARS-CoV-2 and a wide spectrum of pathogens and diseases, with M. tuberculosis and Influenza virus exhibiting the highest levels of cross-reactivity. These results can potentially shift the emphasis of immunological studies towards an increased application of TCR profiling assays that have the potential to uncover key mechanisms of cell-mediated immune response against pathogens and diseases.

Haploidentical CD3+ TCR αß/CD19+ depleted HSCT for MHC Class II deficiency and persistent SARS-CoV-2 pneumonitis.

Background & Objectives: SARS-CoV-2 infection leads to coronavirus disease 2019 (COVID-19), which can range from a mild illness to a severe phenotype characterised by acute respiratory distress, needing mechanical ventilation. Children with combined immunodeficiencies might be unable to mount a sufficient cellular and humoral immune response against Covid-19 and have persistent disease. The authors describe a child with combined immunodeficiency, with favorable post-HSCT course following a haploidentical haematopoietic stem cell transplant in the presence of persistent SARS-CoV-2 infection. Methods & results: A 13-month-old girl with MHC class II deficiency developed persistent pre-HSCT SARS-CoV-2 infection. Faced with a significant challenge of balancing the risk of progressive infection due to incompetent immune system with the danger of inflammatory pneumonitis peri-immune reconstitution post-HSCT, she underwent a maternal (with a recent history of Covid-19 infection) haploidentical haematopoietic stem cell transplant. The patient received Regdanvimab® (post stem cell infusion) and Remdesivir (pre and post stem cell infusion). We noted a gradual increase in the Ct (cycle threshold) values, implying reduction in viral RNA with concomitant expansion in the CD3 lymphocyte subset and clinical/radiological improvement. Conclusions: Combination of adoptive transfer of maternal CD45RO+ memory add-back T-lymphocytes after haploidentical HSCT, use of Regdanvimab® (SARS-CoV-2 neutralising monoclonal antibody) and Remdesivir may have led to the successful outcome in our patient with severe immunodeficiency, undergoing HSCT. Our case highlights the role of novel antiviral strategies (monoclonal antibodies and CD45RO+ memory T-lymphocytes) in contributing to viral clearance in a challenging clinical scenario.