SARS-CoV-2 neutralizing antibodies : longevity, breadth, and evasion by emerging viral variants

The Severe Acute Respiratory Syndrome Coronavirus 2 (SAU ARS-CoV-2) antibody neutralization response and its evasion by emerging viral variants and variant of concern (VOC) are unknown, but critical to understand reinfection risk and breakthrough infection following vaccination. Antibody immunoreactivity against SARS-CoV-2 antigens and Spike variants, inhibition of Spike-driven virus–cell fusion, and infectious SARS-CoV-2 neutralization were characterized in 807 serial samples from 233 reverse transcription polymerase chain reaction (RT-PCR)–confirmed Coronavirus Disease 2019 (COVID-19) individuals with detailed demographics and followed up to 7 months. A broad and sustained polyantigenic immunoreactivity against SARS-CoV-2 Spike, Membrane, and Nucleocapsid proteins, along with high viral neutralization, was associated with COVID-19 severity. A subgroup of “high responders” maintained high neutralizing responses over time, representing ideal convalescent plasma donors. Antibodies generated against SARS-CoV-2 during the first COVID-19 wave had reduced immunoreactivity and neutralization potency to emerging Spike variants and VOC. Accurate monitoring of SARS-CoV-2 antibody responses would be essential for selection of optimal responders and vaccine monitoring and design

The Autoimmune T cell Response Against the Dopamine-2 Receptor in Movement and Psychiatric Disorders

Autoimmunity and immune dysregulation are associated with a subset of movement and psychiatric disorders. This paradigm is largely supported by the discovery of autoantibodies against neuronal antigens, like the dopamine-2 receptor (D2R). T cells are a prominent cell subset in the immune system, however, their role in these diseases is unknown. Herein, we identified and characterised D2R-specific T cells in movement and psychiatric disorders in children and adults. In children with suspected autoimmune or neurodevelopmental movement and psychiatric disorders (n=24), activated D2R-specific T cells were detected in 8/24 (33%) patients when their peripheral blood was stimulated with a library of D2R peptides and assessed for CD25+CD134+CD4+ T cells via flow cytometry. The D2R-specific T cells recognised three immunodominant regions: aa121-131, aa171-181, and aa396-416. These regions were predicted with computational methods to bind with high affinity to the HLA of D2R-specific T cell positive patients and were associated with elevated levels of pro-inflammatory cytokines that characterise Th1 and Th17 cells, as quantified by a cytometric bead array and an enzyme-linked immunosorbent assay. The eight D2R-specific T cell-positive patients were seronegative for D2R antibodies, as evaluated with the flow cytometry live cell-based assay. These findings on autoreactive T cells in children formed the basis for investigating D2R-specific T cells in adults with isolated dystonia, a movement disorder that is often idiopathic and has been associated with impaired dopamine signalling. In adults with dystonia (n=20), activated D2R-specific T cells were detected in 6/20 (30%) patients via flow cytometry after stimulation with seven immunogenic regions of D2R. A subset of the D2R-specific T cell-positive patients had activated CD39+ Treg cells (2/6) and 1/6 D2R-specific T cell-positive patient concomitantly harboured activated CXCR5+ Tfh cells and D2R antibodies. In summary, this thesis offers new insights into autoreactive T cells against D2R in the movement and psychiatric disorders. Our observations encourage studies to further understand explore T cell dysregulation to better identify novel subsets of movement and psychiatric disorders and have clinical implications in improving diagnosis and treatment

Additional file 1: Figure S1. of Dopamine-2 receptor extracellular N-terminus regulates receptor surface availability and is the target of human pathogenic antibodies from children with movement and psychiatric disorders

a, b Anti-D2R antibody-positive movement and psychiatric disorder (MPD) protein G-purified IgG from patient does not induce a downregulation of surface D2R on live cells compared to IgG purified from control (CTL) after 30 min at room temperature or 37 °C. c Anti-D2R antibody-positive MPD protein G-purified IgG-incubated on live cells have a similar expression of cytoplasmic GFP compared to IgG purified from control (CTL) after 30 min at room temperature or 37 °C. Representative images are shown (scale bar = 25μm). 15-18 different cells for each control and patient out of two independent experiments are shown. Figure S2. Compared to WT D2R-immunoabsorbed MPD sera, NTermD1RχD2R-immunoabsorbed MPD sera had a higher binding to WT D2R-transfected HEK293 cells. Representative data out of two independent experiments is shown. Figure S3. Live L Δ2-22 D2R-transfected HEK293 cells were not immunolabeled, by the commercial antibody (Sigma; clone 1B11). Representative data out of three independent experiments is shown. Figure S4. a Alignment of extracellular N-terminal 37 amino acids of N5Q/N17Q/N23Q and WT D2R. b Confocal images of live and fixed/permeabilized N5Q/N17Q/N23Q-transfected HEK293 cells after immunolabeling with anti-HA antibody. Mutations of all three N-glycosylation sites led to low surface expression and intracellular sequestration of the mutant (scale bar = 50 μm). Figure S5. Amino acids 1-37 of D2R extracellular N-terminus aligned in 12 different animal species to highlight conserved sequences in mammals (yellow). Amino acid sequences derived from Uniprot database and Uniprot code for the different species. Figure S6. Sequence homology between human D2R (20-29) and an unknown protein of the fungus Penicillium roqueforti FM164 (55-64) was identified using the protein–protein Basic Local Alignment Search Tool from National Center for Biotechnology Information. Bolded residues represent identical residues between the two sequences. Underlined residues represent immunodominant amino acids in D2R N-terminus. (PDF 53400 kb

Long-term persistence of neutralizing memory B cells in SARS-CoV-2

Considerable concerns relating to the duration of protective immunity against SARS-CoV-2 have been raised, with evidence of antibody titres declining rapidly after infection and reports of reinfection. Here we monitored antibody responses against SARS-CoV-2 receptor binding domain (RBD) for up to six months after infection. While antibody titres were maintained, half of the cohort's neutralising responses had returned to background. However, encouragingly in a selected subset of 13 participants, 12 had detectable RBD-specific memory B cells and these generally increased out to 6 months. Furthermore, we were able to generate monoclonal antibodies with SARS-CoV-2 neutralising capacity from these memory B cells. Overall our study suggests that the loss of neutralising antibodies in plasma may be countered by the maintenance of neutralising capacity in the memory B cell repertoire

Characterization of the human myelin oligodendrocyte glycoprotein antibody response in demyelination

Over recent years, human autoantibodies targeting myelin oligodendrocyte glycoprotein (MOG Ab) have been associated with monophasic and relapsing central nervous system demyelination involving the optic nerves, spinal cord, and brain. While the clinical relevance of MOG Ab detection is becoming increasingly clear as therapeutic and prognostic differences from multiple sclerosis are acknowledged, an in-depth characterization of human MOG Ab is required to answer key challenges in patient diagnosis, treatment, and prognosis. Herein, we investigated the epitope, binding sensitivity, and affinity of MOG Ab in a cohort of 139 and 148 MOG antibody-seropositive children and adults (n = 287 patients at baseline, 130 longitudinal samples, and 22 cerebrospinal fluid samples). MOG extracellular domain was also immobilized to determine the affinity of MOG Ab. MOG Ab response was of immunoglobulin G1 isotype, and was of peripheral rather than intrathecal origin. High affinity MOG Ab were detected in 15% paediatric and 18% adult sera. More than 75% of paediatric and adult MOG Ab targeted a dominant extracellular antigenic region around Proline42. MOG Ab titers fluctuated over the progression of disease, but affinity and reactivity to Proline42 remained stable. Adults with a relapsing course intrinsically presented with a reduced immunoreactivity to Proline42 and had a more diverse MOG Ab response, a feature that may be harnessed for predicting relapse. Higher titers of MOG Ab were observed in more severe phenotypes and during active disease, supporting the pathogenic role of MOG Ab. Loss of MOG Ab seropositivity was observed upon conformational changes to MOG, and this greatly impacted the sensitivity of the detection of relapsing disorders, largely considered as more severe. Careful consideration of the binding characteristics of autoantigens should be taken into account when detecting disease-relevant autoantibodies