Plant-derived single domain COVID-19 antibodies.

Data show a decrease in the risk of hospitalization and death from COVID-19. To date, global vaccinations for SARS-CoV-2 protections are underway, but additional treatments are urgently needed to prevent and cure infection among naïve and even vaccinated people. Neutralizing monoclonal antibodies are very promising for prophylaxis and therapy of SARS-CoV-2 infections. However, traditional large-scale methods of producing such antibodies are slow, extremely expensive and possess a high risk of contamination with viruses, prions, oncogenic DNA and other pollutants. The present study is aimed at developing an approach of producing monoclonal antibodies (mAbs) against SARS-CoV-2 spike (S) protein in plant systems which offers unique advantages, such as the lack of human and animal pathogens or bacterial toxins, relatively low-cost manufacturing, and ease of production scale-up. We selected a single N-terminal domain functional camelid-derived heavy (H)-chain antibody fragments (VHH, AKA nanobodies) targeted to receptor binding domain of SARS-CoV-2 spike protein and developed methods of their rapid production using transgenic plants and plant cell suspensions. Isolated and purified plant-derived VHH antibodies were compared with mAbs produced in traditional mammalian and bacterial expression systems. It was found that plant generated VHH using the proposed methods of transformation and purification possess the ability to bind to SARS-CoV-2 spike protein comparable to that of monoclonal antibodies derived from bacterial and mammalian cell cultures. The results of the present studies confirm the visibility of producing monoclonal single-chain antibodies with a high ability to bind the targeted COVID-19 spike protein in plant systems within a relatively shorter time span and at a lower cost when compared with traditional methods. Moreover, similar plant biotechnology approaches can be used for producing monoclonal neutralizing antibodies against other types of viruses.

IgG3 Antibody Response to COVID-19 Vaccination in a Patient With a Large Heavy Chain Deletion.

Vaccinations for pathogenic organisms have been utilized for decades in both the protection and diagnosis of immunodeficiency patients. Some of these immunodeficient patients may not create an adequate response to vaccination, although some who have significant aberrancies in their immune system may surprisingly create antibodies to immunizations. We present a patient with a large Ig heavy chain deletion (severe deficiency of serum IgG1, IgG2, IgG4, and IgA1) that showed a considerable response (presumably through IgG3) after the Pfizer BioNTech COVID-19 vaccination. This finding in this unique immunodeficient patient warrants further research into alternate antibody response pathways against COVID-19.

Avidity engineering of human heavy-chain-only antibodies mitigates neutralization resistance of SARS-CoV-2 variants.

Emerging SARS-CoV-2 variants have accrued mutations within the spike protein rendering most therapeutic monoclonal antibodies against COVID-19 ineffective. Hence there is an unmet need for broad-spectrum mAb treatments for COVID-19 that are more resistant to antigenically drifted SARS-CoV-2 variants. Here we describe the design of a biparatopic heavy-chain-only antibody consisting of six antigen binding sites recognizing two distinct epitopes in the spike protein NTD and RBD. The hexavalent antibody showed potent neutralizing activity against SARS-CoV-2 and variants of concern, including the Omicron sub-lineages BA.1, BA.2, BA.4 and BA.5, whereas the parental components had lost Omicron neutralization potency. We demonstrate that the tethered design mitigates the substantial decrease in spike trimer affinity seen for escape mutations for the hexamer components. The hexavalent antibody protected against SARS-CoV-2 infection in a hamster model. This work provides a framework for designing therapeutic antibodies to overcome antibody neutralization escape of emerging SARS-CoV-2 variants.

Evolutive emergence and divergence of an Ig regulatory node: An environmental sensor getting cues from the aryl hydrocarbon receptor?

One gene, the immunoglobulin heavy chain (IgH) gene, is responsible for the expression of all the different antibody isotypes. Transcriptional regulation of the IgH gene is complex and involves several regulatory elements including a large element at the 3' end of the IgH gene locus (3'RR). Animal models have demonstrated an essential role of the 3'RR in the ability of B cells to express high affinity antibodies and to express different antibody classes. Additionally, environmental chemicals such as aryl hydrocarbon receptor (AhR) ligands modulate mouse 3'RR activity that mirrors the effects of these chemicals on antibody production and immunocompetence in mouse models. Although first discovered as a mediator of the toxicity induced by the high affinity ligand 2,3,7,8-tetracholordibenzo-p-dioxin (dioxin), understanding of the AhR has expanded to a physiological role in preserving homeostasis and maintaining immunocompetence. We posit that the AhR also plays a role in human antibody production and that the 3'RR is not only an IgH regulatory node but also an environmental sensor receiving signals through intrinsic and extrinsic pathways, including the AhR. This review will 1) highlight the emerging role of the AhR as a key transducer between environmental signals and altered immune function; 2) examine the current state of knowledge regarding IgH gene regulation and the role of the AhR in modulation of Ig production; 3) describe the evolution of the IgH gene that resulted in species and population differences; and 4) explore the evidence supporting the environmental sensing capacity of the 3'RR and the AhR as a transducer of these cues. This review will also underscore the need for studies focused on human models due to the premise that understanding genetic differences in the human population and the signaling pathways that converge at the 3'RR will provide valuable insight into individual sensitivities to environmental factors and antibody-mediated disease conditions, including emerging infections such as SARS-CoV-2.

Imprinted repertoire restriction in immunodeficiency

Background: Impaired generation of antibody responses define 'predominantly antibody immuno-deficiencies' (PAD) with reduced IgG and impaired vaccination responses. However, the antibody repertoire defects underpinning PAD are unknown. Here, we examine the antibody repertoire using mass spectrometry-based proteomics (MS-proteomics) in PAD and healthy controls (HC). Method(s): Following SARS-CoV-2 vaccination, anti -S1 ELISA, and live-virus neutralisation assays were assessed. Purified anti-S1 IgG and IgM was sequenced by MS-Proteomics to define immunoglobulin heavy chain variable region subfamily (IGHVsf) usage and somatic hypermutation (SHM). Result(s): 12 vaccine responsive PAD subjects were included, matched to 11 HC. Neutralisation and anti-S1 titres were reduced in PAD. Strikingly, all PAD subjects demonstrated restricted IgG IGHVsf utilisation, [median 3, (range 2-4), vs 6 (5-11) in HC, p<0.001], irrespective neutralisation or total antibody response. IgG SHM and IgM repertoire did not differ but IgG IGHV 3-7 utilisation was less frequent in PAD. Conclusion(s): MS proteomics uncovers stereotyped anti-S1 IgG IGHVsf restriction in PAD subjects following vaccination. Our results suggest that a relatively pauci-clonal antibody repertoire can produce a functional immune response, otherwise masked by traditional serology measures. Further studies to uncover the determinants of antibody repertoire breadth and elaborate on this novel approach to assessing serological responses are required. Copyright © 2022

Preparation of the Monoclonal Antibody against the African Swine Fever Virus p54 Protein and Identification of the Antigenic Epitope.

The aim of this paper was to prepare specific monoclonal antibody (mAb) against African swine fever virus (ASFV) p54 protein. The p54 protein was expressed in Escherichia coli expression system and used as the antigen in mAb production. The spleen cells from the immunized BALB/c mice were fused with myeloma cells SP2/0. To screen the positive hybridoma cells, the purified p54 protein was used as envelope antigen for indirect ELISA. After four times' subcloning, the supernatant of hybridoma cells were used to identify mAb subtype, ascites were prepared via in vivo induction method in mice and then the mAb was purified. The titer of the mAb was detected by indirect ELISA, and the specificity of the mAb was identified by cross reactivity assay, IFA and Western blot. According to the predicted secondary structure of p54 protein, using the stepwise truncation method identified the epitope region of mAbs, and labeled the region in tertiary structure of p54 protein. Results were as follows: six hybridoma cells secreting p54 monoclonal antibody were successfully screened and named 28G12-1, 31G7-1, 31G7-2, 35F10-1, 35F10-2, 38D3-1, respectively. The heavy chains of 28G12-1, 31G7-1, and 31G7-2 were IgG2a type, the heavy chains of 35F10-1, 35F10-2, 38D3-1 were IgG1 type, light chains were all kappa chains. The lowest titer of mAb was 1:25 600, and having no cross reaction with PRRSV, PRV, PEDV, PPV, SADS-CoV, PCV2, the specificity was strong. All six monoclonal antibodies could recognize the 127-146 aa on carboxyl end. In this study, ASFV p54 protein and p54 monoclonal antibody were successfully obtained, and the epitopes of six mAbs were identified, these experimental data laid a foundation for the functional research of p54 protein and the study of ASFV epitope vaccine. Copyright © 2023 Editorial Board, Institute of Animal Science of the Chinese Academy of Agricultural Sciences. All rights reserved.

Defining background shared antibody sequences between unrelated healthy individuals (public clonotypes) to support future studies on specific infectious disease related conditions

Background. Public clonotypes, antibodies against specific antigens in unrelated individuals that have genetic similarities, have been shown in a variety of infections, including SARS-CoV-2 and HIV. Likely, there are shared antibody responses between individuals for many infections. To explore antibody responses that would coincide with specific infectious diseases that may set off chronic illnesses, such as Multiple Sclerosis or Alzheimer's disease, defining the background shared clonotypes is needed to differentiate disease from normal background public clonotype responses. Methods. Heavy chain variable sequences were retrieved from public biorepositories (Bioproject PRJNA486667) composed of 43 healthy persons, and two groups of HIV infected persons;114 with broadly neutralizing antibodies and 91 without broadly neutralizing antibodies. We utilized the Immcantation package of software run on our SUNY Buffalo computational cluster. After PRESTo annotation, duplicate sequences were collapsed and sequences of only single counts were removed. Clonal groups were determined using ChangeO requiring IGHV, IGHJ, and CDR3 amino acid sequence to be perfectly matched. Figures and statistics were generated with immcantation, excel, and graphpad prism 8. Results. 244850 heavy chain sequences from 43 healthy controls were compared for exact matches to predicted germline variable segment and CDR3 amino acid sequence and identified 0.23% as public clonotypes. Comparison to 205 HIV + individuals (a total of 1.4 million comparative sequences) showed that 2.35% of heavy chain sequences were seen in more than one individual. Generally, public clonotypes had shorter CDR3s (peak of 9 amino acids). VH 3-9, 3-30 and 4-34 were the most commonly used variable segments in public clonotypes. Common exact match CDR3 sequences using a variety of variable sequences, including an 11 amino acid CDR3 sequence motif, were also discovered. Conclusion. This early work has identified several public clonotypes that are shared among subjects who are HIV positive and otherwise healthy people. Defining the sequences commonly seen between individuals can assist in specifying antibody responses specific to disease states from larger sequence databases.

A TOUCH OF THE HEART AND THE TOOLS FOR DIAGNOSIS

SESSION TITLE: Infections In and Around the Heart Case Posters SESSION TYPE: Case Report Posters PRESENTED ON: 10/17/2022 12:15 pm - 01:15 pm INTRODUCTION: Myocarditis is inflammation of the heart muscle, and its onset is usually followed by an inciting event such as a viral infection. Here, we report a case of myocarditis in an adolescent male with no significant medical history who presented with chest pain after his second dose of the covid vaccine. CASE PRESENTATION: An 18-year old male presented with no significant past medical/surgical history presented with chest pain. His only triggering event was receiving the second dose of his covid vaccine. A physical examination, chest x-ray, electrocardiogram, and echocardiogram revealed no significant findings. His laboratory findings were positive for myocardial damage with elevated troponin. All other laboratories for autoimmune and inflammation were negative. He was transferred to another facility for cardiac MRI, which subsequently had findings consistent with myocarditis. He remained asymptomatic, and laboratories were normalized. He was discharged and, on follow-up, remained asymptomatic. DISCUSSION: Covid vaccine-induced myocarditis has become a prominent issue. As of March 2022, there are 2323 preliminary reports of myocarditis/pericarditis following either mRNA vaccine, with most cases being young male adolescents. Prior vaccination, such as the smallpox vaccine, has a well-documented history of causing myocarditis, initially thought to be a rare occurrence, it had a prevalence as high as 10% when reviewed. A similar pattern may be observed with the covid vaccine;thus, this complication can be significantly underestimated, and physicians must be vigilant. Thus, cardiac MRI should be pursued if clinically suspected. It has been shown to provide reliable clinical information even in the early phases of inflammation as well as the extent of the inflammatory process, and it avoids invasive procedures1 It can also be used prognostically to monitor disease status. Myocarditis may be immune-related. Key observations include increased systemic reactogenicity and immunogenicity in younger study participants in Pfizer-biotech clinical trials. However, another report showed no difference in spike antibody between patients with myocarditis and those without myocarditis post-covid mRNA vaccine, arguing against a hyperimmune response2. Another plausible mechanism is molecular mimicry between the spike protein and self-antigens, showing cross-reactivity between human peptides in the body, including alpha-myosin3, which may explain why only mRNA covid vaccine causes this complication. Currently, there is no causal relationship, but numerous hypotheses are being examined. CONCLUSIONS: Myocarditis must be recognized as a complication of the covid vaccine and a possible differential of chest pain,specifically in young men in the current pandemic.Early referral of cardiac MRI, if unavailable at centers, is essential for diagnosis and prognostication,given the unknown sequela of this disease. Reference #1: M. Giulia Gagliardi and Bruno Polletta Paolo Di Renzi, Gagliardi, M. G., M. Giulia Gagliardi Department of Cardiology and Cardiac Surgery, Polletta, B., Bruno Polletta Department of Cardiology and Cardiac Surgery, Renzi, P. D., & Paolo Di Renzi Department of Radiology Fatebenefratelli-Isola Tiberina Hospital. (1999, January 26). MRI for the diagnosis and follow-up of Myocarditis. Circulation. Retrieved April 13, 2022, from https://www.ahajournals.org/doi/full/10.1161/circ.99.3.457/a Reference #2: Muthukumar, A., Alagarraju Muthukumar Department of Pathology (A.M., Narasimhan, M., Madhusudhanan Narasimhan Department of Pathology (A.M., Li, Q.-Z., Quan-Zhen Li Department of Immunology (Q.-Z.L.), Mahimainathan, L., Lenin Mahimainathan Department of Pathology (A.M., Hitto, I., Imran Hitto https://orcid.org/0000-0002-9928-4175 Department of Pathology (A.M., Fuda, F., Franklin Fuda Department of Pathology (A.M., Batra, K., Kiran Batra Department of Radiology (K.B.), Jiang, X., Xuan Jiang Department of Internal Medicine (Q.-Z.L., Zhu, C., Chengsong Zhu Department of Internal Medicine (Q.-Z.L., Schoggins, J., … Al., E. (2021, June 16). In-depth evaluation of a case of presumed myocarditis after the second dose of COVID-19 mrna vaccine. Circulation. Retrieved March 31, 2022, from https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.056038 Reference #3: Vojdani, A., & Kharrazian, D. (2020, August). Potential antigenic cross-reactivity between SARS-COV-2 and human tissue with a possible link to an increase in autoimmune diseases. Clinical immunology (Orlando, Fla.). Retrieved March 31, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7246018/ DISCLOSURES: No relevant relationships by Aaron Douen No relevant relationships by Sudhanva Hegde No relevant relationships by Marc Sukhoo-Pertab

A megadiverse naïve library derived from numerous camelids for efficient and rapid development of VHH antibodies.

The field of antibody development is under pressure to meet rising demands for speed, cost-effectiveness, efficacy, reliability, and large-scale production. It is costly and time-consuming to immunize animals and build a single-domain antibody (sdAb) library for each target. Using the variable domain (VHH) of heavy-chain only antibodies (HcAbs) derived from blood samples of 75 non-immunized camelid animals (51 alpacas, 13 llamas, 11 Bactrian camels), and spleens from two Bactrian camels, a naïve sdAb library with extensive megadiversity and reusability was constructed. The library was evaluated using next-generation DNA sequencing (NGS) and was found to contain hundreds of billions of unique clones. To confirm the availability of target-specific VHHs, a naive library was screened for a variety of targets. At least two VHH candidates were extracted for each target using a 20-day selection pipeline. Some binders had ultrahigh potencies, with binding affinities in the nanomolar range. This naïve library, in particular, offers the possibility of acquiring unique antibodies targeting antigens of interest with low feasible dissociation constant (kD) without the time, effort, and price associated in producing antibodies in animals via antigen injection. Overall, the study shows that the megadiverse naïve library provides a rapid, adaptable, and easy platform for antibody creation, emphasizing its therapeutic and diagnostic implications.

Single domain antibodies derived from ancient animals as broadly neutralizing agents for SARS-CoV-2 and other coronaviruses.

With severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as an emergent human virus since December 2019, the world population is susceptible to coronavirus disease 2019 (COVID-19). SARS-CoV-2 has higher transmissibility than the previous coronaviruses, associated by the ribonucleic acid (RNA) virus nature with high mutation rate, caused SARS-CoV-2 variants to arise while circulating worldwide. Neutralizing antibodies are identified as immediate and direct-acting therapeutic against COVID-19. Single-domain antibodies (sdAbs), as small biomolecules with non-complex structure and intrinsic stability, can acquire antigen-binding capabilities comparable to conventional antibodies, which serve as an attractive neutralizing solution. SARS-CoV-2 spike protein attaches to human angiotensin-converting enzyme 2 (ACE2) receptor on lung epithelial cells to initiate viral infection, serves as potential therapeutic target. sdAbs have shown broad neutralization towards SARS-CoV-2 with various mutations, effectively stop and prevent infection while efficiently block mutational escape. In addition, sdAbs can be developed into multivalent antibodies or inhaled biotherapeutics against COVID-19.

Effects of Prior Infection with SARS-CoV-2 on B Cell Receptor Repertoire Response during Vaccination.

Understanding the B cell response to SARS-CoV-2 vaccines is a high priority. High-throughput sequencing of the B cell receptor (BCR) repertoire allows for dynamic characterization of B cell response. Here, we sequenced the BCR repertoire of individuals vaccinated by the Pfizer SARS-CoV-2 mRNA vaccine. We compared BCR repertoires of individuals with previous COVID-19 infection (seropositive) to individuals without previous infection (seronegative). We discovered that vaccine-induced expanded IgG clonotypes had shorter heavy-chain complementarity determining region 3 (HCDR3), and for seropositive individuals, these expanded clonotypes had higher somatic hypermutation (SHM) than seronegative individuals. We uncovered shared clonotypes present in multiple individuals, including 28 clonotypes present across all individuals. These 28 shared clonotypes had higher SHM and shorter HCDR3 lengths compared to the rest of the BCR repertoire. Shared clonotypes were present across both serotypes, indicating convergent evolution due to SARS-CoV-2 vaccination independent of prior viral exposure.

The development of a novel SARS-CoV-2 virus neutralizing immunotoxin

For decades, scientific efforts were focused on the improvement of the effectiveness of the therapeutic antibodies, mainly in order reduce the dosage and thus lower the side-effects and costs. P4A1, a potent SARS-CoV-2 virus neutralizing antibody was already engineered to contain Fc fragment mutations, that dramatically increased the blood circulation time. In this work, we aimed to further enhance this neutralizing antibody efficacy by creating a next-generation virus neutralizing agent based on the P4A1 and conjugated with a highly processive Bacillus amyloliquefaciens RNase (barnase). Barnase itself is known to act as a mild toxin that drives the cells to apoptosis, and we propose that its RNase activity may enhance the protective effect through the hydrolysis of viral RNA in infected cells, and thereby additionally preventing pathogen replication. The main challenge in the assembly of such molecule is the intrinsic barnase toxicity in mammalian cells, what precludes the possibility to express it as a fusion protein. Further, we had shown that barnase, being a small (12.5 kDa) protein, contains very few surface reactive moieties that are available for conventional chemical crosslinking strategies. Therefore, the antibody-barnase fusion protein was obtained by enzymatic conjugation via the sortase A enzyme. The reaction conditions for bacterially expressed barnase and HEK293 derived P4A1 modified to contain heavy chain C-terminal sortase motif were thoroughly optimized and the reaction yield approached 80%. The immunotoxin RBD binding EC50 was not found to differ from the unconjugated P4A1 antibody and barnase activity was found to be 33% of the one for unmodified enzyme. Thus, we obtained the promising immunotoxin with a good yield, which had retained its RNase activity for the further in vitro virus neutralization studies.

COVID-19 infection and myocarditis after surgical left ventricle reconstruction in patient with hypertrophic cardiomyopathy

It has now been shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing a new COVID-19 infection, can penetrate the myocardium and have both direct damaging and toxic effects. The main cardiac manifestations of this disease are fulminant myocarditis, atrial and ventricular arrhythmias, and heart failure. Cardiac arrhythmias are common complication not only in adult patients, but also in children. In this paper, we present a clinical case of the young female patient who successfully underwent operation because of a submitral (diffuse-generalized) form of HCM, with a long event-free postoperative course, and with the rapid cardiac dysfunction, syncopes and cardiac arrhythmias after COVID-19 infection. Syncopes were caused by self-terminating short runs of ventricular tachycardia that did not trigger ICD shock. After the medical treatment of myocarditis, she has a clinical improvement and further favorable postoperative period.

An Autoimmune Epilepsy Case Series: Atypical Presentations with Atypical Autoimmune Antibodies

Objective: We present three patients with insidious onset of high-frequency atypical seizures, in association with atypical autoantibodies, with significant improvement with immunotherapy. Background: Autoimmune epilepsy (AE) is a relatively newly discovered epilepsy etiology. Although, It was described to present as New-Onset Refractory Status Epilepticus (NORSE). Our understanding of the clinical presentations and autoantibodies linked to AE is still sparse. Design/Methods: Case Series Case 1: A 44-year-old man presented with more than 10 years of recurrent episodes of mild confusion. Patient presented to our ER during one of these episodes where EEG revealed right temporal lobe status epilepticus. He had suboptimal response to multiple Antiepileptic Drugs (AEDs). MRI brain showed T2/FLAIR hyperintensities in the right frontal, parietal, and temporal lobes consistent with postictal effect. CSF was positive Neuronal Intermediate Filament (NIF) heavy chain antibodies Treatment with plasmapheresis (PLEX) and intravenous immunoglobulin (IVIG) with a good response. Case 2: A 73-year-old woman presented with daily episodes of mild confusion and falls over few months. EEG was consistent with frontal lobe seizures. MRI brain and CSF were unremarkable. She was treated with multiple AEDs, without adequate control. Serum paraneoplastic panel was positive for voltage-gated potassium channel antibodies. Seizures were controlled with PLEX. Case 3: A 22-year-old woman presented with daily episodes of behavioral arrest and confusion few weeks after COVID-19 vaccination. EEG showed bitemporal seizures, refractory to AEDs, requiring pentobarbital induced coma. CSF and MRI brain were unremarkable. Thyroid peroxidase and anti-thyrotropin antibodies were highly elevated. Treatment with IVIG and PLEX for AE, with a prolonged recovery. Conclusions: Seizures associated with AE appear to be trivial;however, it can have an aggressive course. Among antibodies have been reported in AE, NIF antibodies has not been reported. AE should be considered in patients with High-frequency of atypical seizures. Early initiation of immunotherapy is the key for disease control.

Landscape of B Cell Receptor Repertoires in COVID-19 Patients Revealed Through CDR3 Sequencing of Immunoglobulin Heavy and Light Chains.

The outbreak and persistence of coronavirus disease 2019 (COVID-19) threaten human health. B cells play a vital role in fighting the infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite many studies on the immune responses in COVID-19 patients, it is still unclear how B cell receptor (BCR) constituents, including immunoglobulin heavy (IGHs) and light chains (IGLs), respond to SARS-CoV-2 in patients with varying symptoms. In this study, we conducted complementarity-determining region 3 (CDR3) sequencing of BCR IGHs and IGLs from the peripheral blood of COVID-19 patients and healthy donors. The results showed significantly reduced clonal diversity, more expanded clones, and longer CDR3 lengths of IGH and IGL in COVID-19 patients than those in healthy individuals. The IGLs had a much higher percentage of VJ skew usage (47.83% IGLV and 42.86% IGLJ were significantly regulated) than the IGHs (12.09% IGHV and 0% IGHJ) between the healthy individuals and patients, which indicated the importance of BCR light chains. Furthermore, we found a largely expanded IGLV3-25 gene cluster mostly pairing with IGLJ1 and ILGJ2 in COVID-19 patients and a newly identified upregulated IGLJ1 gene and IGLJ2+IGLV13-21 recombination, both of which are potential sources of SARS-CoV-2-targeting antibodies. Our findings on specific immune B-cell signatures associated with COVID-19 have clinical implications for vaccine and biomarker development for disease diagnosis.

TGF-β SIGNALING PATHWAY SHAPES ADAPTIVE IMMUNITY in EARLY SARS-CoV-2 INFECTION

Background: SARS-CoV-2 induces cytokine response dysregulation and immune dysfunction. What remains unclear is how cytokine signaling shapes immune responses during early SARS-CoV-2 infection when adaptive immunity is developing. Our goal is to identify immune pathways that shape the early development of adaptive immune responses in COVID-19 patients. We performed paired single-cell transcriptomic and epigenomic profiling at two time-points of early SARS-CoV-2 infection to determine immune signatures of acute infection and epigenetic drivers that underpin immune response dynamics. Methods: PBMC samples were collected from four moderate to severe COVID-19 patients at two early time-points (n = 3 for Week 1 and n = 3 for Week 2 after symptom onset, including 2 participants having paired blood sampling at both time points) and from two healthy controls (n = 2). Using paired scRNA-Seq and scATAC-Seq, we captured transcriptomic and epigenomic profiles in the same single cells to identify chromatin accessibility changes as a potential mechanism for the surge and decline of immune responses elicited during acute SARS-CoV-2 infection. Using bioinformatic approaches, we identified heterogeneous immune cell populations, modeled cell differentiation trajectories, determined dysregulated immune pathways through gene set enrichment analysis, and connected chromatin co-accessible landscapes. Results: We captured transcriptomic and epigenomic profiles of 43,726 single cells and identified paired transcriptional and epigenetic landscapes in six major immune cell types: CD4+ T cells, CD8+ T cells, B cells, dendritic cells, monocytes, and NK cells. We found that early SARS-CoV-2 infection induced a surge in IL-2, IL-6, IFN-α, IFN-γ, TNF-α, and NF-κB responses at Week 1 that declined at Week 2 in adaptive immune cells (CD4+ T, CD8+ T, and B cells). In contrast, TGF-β responses surged early at Week 1 and continued to increase at Week 2 in these cells. In B cells and plasmablasts, we found early surges of IGHA1 (encoding IgA heavy chain) and SOX4 (an essential transcription factor for B cell development) expressions that correlated with expression of SMAD-dependent TGF-β signaling pathway. Further, we found a notable increase in chromatin accessibility at the SMAD binding regulatory element 150 kb upstream of SOX4 in B cells of infected patients. Conclusion: Our data suggest a significant increase in TGF-β activity that instructs dynamic B cell-associated protective immunity during early SARS-CoV-2 infection.

Hybridoma technology: is it still useful?

The isolation of single monoclonal antibodies (mAbs) against a given antigen was only possible with the introduction of the hybridoma technology, which is based on the fusion of specific B lymphocytes with myeloma cells. Since then, several mAbs were described for therapeutic, diagnostic, and research purposes. Despite being an old technique with low complexity, hybridoma-based strategies have limitations that include the low efficiency on B lymphocyte-myeloma cell fusion step, and the need to use experimental animals. In face of that, several methods have been developed to improve mAb generation, ranging from changes in hybridoma technique to the advent of completely new technologies, such as the antibody phage display and the single B cell antibody ones. In this review, we discuss the hybridoma technology along with emerging mAb isolation approaches, taking into account their advantages and limitations. Finally, we explore the usefulness of the hybridoma technology nowadays.

The selective bruton tyrosine kinase (BTK) inhibitor TG-1701 as monotherapy and in combination with ublituximab and umbralisib (U2) in patients with B-cell malignancies

Introduction: TG-1701 is an irreversible, selective, novel Bruton's tyrosine kinase inhibitor (BTKi) administered once daily (QD). BTK inhibitors, as well as the U2 combination (anti-CD20 mAb ublituximab + the PI3Kδ-CK1ϵ inhibitor umbralisib), are highly efficacious in chronic lymphocytic leukemia (CLL), each of which have been previously demonstrated to be superior over standard chemoimmunotherapy. Treatment with a more selective BTK inhibitor could result in improved efficacy and safety outcomes compared with ibrutinib (ALPINE study, EHA 2021), and we hypothesized that dual blockade of the B-cell receptor (BCR) pathway through combination of TG-1701 with U2 may confer greater depth of response compared to either regimen alone. Methods: Patients with CLL and non-Hodgkin lymphoma (NHL) were enrolled in an ongoing Phase 1 study. After characterizing the safety profile of TG-1701 monotherapy, a parallel dose escalation arm of TG-1701+U2 was implemented. Select dose levels of TG-1701 monotherapy and TG-1701+U2 were also expanded. All patients were treated until disease progression, unacceptable toxicity, or investigator/patient decision to withdraw. Safety was evaluated in all treated patients, and efficacy was evaluated in all treated patients who had at least 1 post-baseline assessment. TG-1701 monotherapy data were previously presented;herein we present data from the TG-1701+U2 dose escalation/expansion and the TG-1701 monotherapy CLL expansion cohorts Results: As of July 2021, 142 patients were treated with TG-1701, 36 of whom were enrolled in the TG-1701+U2 arm. The median # of prior therapies across all treated patients was 1 (range, 0-10) and all patients were BTKi-naïve. Among the 36 patients treated with U2+1701, 19 were evaluable for efficacy and safety (17 too early to evaluate). The median age was 69 years (range 47-81), and 56% were male. TG-1701+U2 was well tolerated at 4 different dose levels without dose-limiting toxicities. The most common (>30%) all-causality, all grade treatment-emergent adverse events (TEAEs) were diarrhea (53%) contusion (42%), nausea (37%), hypertension, ALT/AST increase, and fatigue (all 32% each) with TG-1701+U2. Grade 3/4 AEs >15% were limited to ALT/AST increase (21%). Dose reduction occurred in 1 patient due to an AE, and 4 patients discontinued at least 1 study drug due to an AE: 2 discontinued umbralisib, 1 discontinued umbralisib and TG-1701, and 1 discontinued all 3 agents. At the data cut-off, overall response rate (ORR) was 84% (4 CR and 12 PR) among 19 evaluable patients, with remaining patients awaiting post-baseline assessment. In the monotherapy CLL-specific cohorts (200 mg QD, n=20;and 300 mg QD, n=20), 40 pts were evaluable for safety, and 39 for efficacy (1 pt withdrew due to COVID prior to first response assessment). The median age was 71 (range 49-86), and 43% were male. The most common TEAEs were increased ALT/AST (all grades: 18%;grade ≥3: 3%), followed by diarrhea (all grades: 15%;grade ≥3: none), and neutropenia (all grades: 13%;grades ≥3: 13%). There were no cases of atrial fibrillation, major bleeding, or ventricular tachyarrhythmia in the CLL cohorts at a median follow-up of 12.8 months (range 2.5 - 20.8). TEAEs leading to TG-1701 dose reduction occurred in 1 (3%) patient. No patients in the 200 mg or 300 mg CLL cohorts have discontinued due to AEs. In patients with anemia and thrombocytopenia at baseline, sustained improvement in hematologic variables was observed. The ORR among 39 patients was 97% (all PR/PR-L). Lymphocytosis resolved to normal value or <50% of baseline in 69% (24 of 35 of patients with lymphocytosis). Consistent response rates were observed across all subgroups, including the following high-risk genomic features: del17p/TP53 mutations, unmutated immunoglobulin heavy-chain variable-region (IGHV), and complex karyotype (defined as 3 ≤cytogenetic abnormalities). The median duration of response has not been reached in either cohort. Best change in tumor burden from baseline in patients with CLL is presented in Figure 1. C nclusions: TG-1701 exhibits an encouraging safety and efficacy profile as monotherapy in patients with CLL and additionally shows promising activity and a manageable tolerability profile in combination with U2. Future registration trials are being planned in CLL with TG-1701. Recruitment to this study (NCT03671590) continues. (Figure Presented).

TG-1701, a selective bruton tyrosine kinase (BTK) inhibitor, as monotherapy and in combination with ublituximab and umbralisib (U2) in patients with chronic lymphocytic leukemia

Introduction: TG-1701 is a selective, covalent BTK inhibitor administered once daily (QD). Both the 'U2' combination (anti-CD20 mAb ublituximab+the PI3Kd-CK1e inhibitor umbralisib) and BTK inhibitors are highly efficacious in treatment- naïve (TN) and relapsed/refractory (R/R) CLL, each having previously demonstrated superiority over standard chemoimmunotherapy. Here, we report results for patients treated with TG-1701 alone or in combination with U2 from an ongoing Phase 1 study, with a focus on patients with CLL. Methods: Patients with R/R CLL and B-cell non-Hodgkin lymphoma were enrolled in an ongoing Phase 1 study initially evaluating dose escalation (DE) of oral TG-1701 QD continuously administered in 28-day cycles (100, 200, 300, and 400 mg). After characterizing the safety profile of TG-1701 monotherapy, we implemented a parallel DE arm of TG-1701+U2. Select dose levels of TG-1701 monotherapy were also expanded. All patients were treated until disease progression, unacceptable toxicity, or investigator/patient decision to withdraw. Safety was evaluated in all treated patients, and efficacy was evaluated in all treated patients with CLL who had at least 1 post-baseline assessment. Results: As of 30 April 2021, 125 patients were treated with TG-1701, 49 of whom had CLL. Enrollment was: 25 patients in the monotherapy DE arm (6 with CLL), 61 in the 200-mg disease-specific cohorts (20 CLL [5 TN], 21 mantle cell lymphoma [MCL, 4 TN], 20 Waldenström's macroglobulinemia [WM, 8 TN]), 20 in the 300-mg CLL cohort (4 TN), and 19 in the 1701+U2 DE arm (3 with CLL). Patients with MCL or WM in the 200-mg disease-specific cohorts were excluded from this analysis. The median # of prior therapies among CLL patients was 1 (range, 0-5) and all patients were BTKi-naïve. TG-1701 was well-tolerated and the maximum tolerated dose for monotherapy was not reached up to 400mg (near 100% saturation of the BTK at all dose levels studied). In the DE arms, the most common all-causality treatment-emergent adverse events (TEAE) were constipation (32%), increased ALT (28%), bruising (28%), and upper respiratory tract infection (28% of patients) with TG-1701 monotherapy;diarrhea (53%) and bruising (42%) with TG-1701+U2. Grade 3/4 AEs were limited. In the CLL-specific cohorts, the most common TEAE was increased ALT/AST (all grades, 17.5%;grade 3, 2.5%;grade ≥4, none), followed by diarrhea (all grades, 12.5%;grade ≥3, none), and COVID-19 (all grades, 12.5%;grade 3-4, none;grade 5, 7.5%). There were no cases of atrial fibrillation, major bleeding, or ventricular tachyarrhythmia in the CLL cohorts at a median follow-up of 10.5 months. TEAEs leading to TG-1701 dose reduction occurred in 7.5% of patients. TEAEs leading to treatment discontinuation occurred in 7.5% of patients (all COVID-19). At the data cut-off, 48 patients with CLL were evaluable for response, including nine in DE. ORR was 95.6% for TG-1701 monotherapy (all PR/PR-L) and 100% for TG-1701+U2 (all PR). The median duration of response has not been reached in either cohort. The best change from baseline in tumor burden in patients with CLL is presented in Figure 1, and treatment exposure and response duration data are presented in Figure 2 below. In patients with anemia and thrombocytopenia at baseline, sustained improvement in hematologic variables was observed in the 200- and 300-mg cohorts. Lymphocytosis was observed in 70% of the monotherapy patients, with a resolution to normal or <50% of baseline in 57.1%. Consistent response rates were observed across all subgroups, including age and high-risk genomic features, such as del17p/TP53, unmutated immunoglobulin heavy-chain variable-region (IGHV), and complex karyotype (defined as three or more cytogenetic abnormalities). Time to event data will be reported at the time of presentation. Conclusions: TG-1701 exhibits an encouraging safety and efficacy profile in patients with CLL, with promising activity and a manageable tolerability profile as monotherapy and in combination with U2 (Figure 1). Future registration trials ar being planned in CLL with TG-1701. Recruitment to this study (NCT03671590) continues.