Prehospital Telestroke vs Paramedic Scores to Accurately Identify Stroke Reperfusion Candidates: A Cluster Randomized Controlled Trial.

BACKGROUND AND OBJECTIVE: Stroke reperfusion therapy is time critical. Improving prehospital diagnostic accuracy including the likelihood of large vessel occlusion can aid with efficient and appropriate diversion decisions to optimize onset-to-treatment time. In this study, we investigated whether prehospital telestroke improves diagnostic accuracy when compared with paramedic assessments and assessed feasibility. METHODS: We conducted a pragmatic, community-based, cluster randomized controlled trial comparing the diagnostic accuracy of telestroke assessments inside the ambulance with a modified Los Angeles Motor Scale (PASTA score). The primary outcome was the accuracy of predicting reperfusion candidates; secondary outcomes were accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of either approach to identify IV thrombolysis (IVT) and endovascular thrombectomy (EVT) candidates and true stroke patients by study group. The accuracy of telestroke and PASTA assessments was compared against in-person assessment in the emergency department and with the final diagnosis/intervention for the patient. We also monitored for technical challenges. RESULTS: We recruited 76 patients (35 telestroke and 41 PASTA) between August 2019 and September 2020. The mean age was 72.2 (±14.6) years. Telestroke was 100% (95% CI 90%-100%) and PASTA 70.7% (54.5%-83.9%) accurate in predicting reperfusion candidates compared with preimaging emergency department neurologist assessment (p < 0.001). When compared with actual reperfusion therapy administered, the predictive accuracy was 80% (63.1%-91.6%) and 60.1% (44.5%-75.8%) for telestroke and PASTA, respectively (p < 0.001). In predicting the administration of IVT, telestroke was 80% (63.1-91.6) and PASTA was 56.1% (39.8-71.5) accurate (p < 0.001). In predicting intervention with EVT, telestroke was 88.6% (73.3-96.8) and PASTA 56.1% (39.8-71.5) accurate (p = 0.005). The service model proved technically feasible and was acceptable to neurologists. DISCUSSION: Prehospital telestroke assessment is feasible, accurate, and superior to the PASTA score in predicting acute reperfusion therapies, presenting an effective option to guide prehospital diversion decisions. TRIAL REGISTRATION: The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12619001678189).anzctr.org.au/Trial/Registration/TrialReview.aspx?id=378655&isReview=true. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that intra-ambulance telestroke evaluation has a greater diagnostic accuracy compared with the PASTA score performed by paramedics in distinguishing hyperacute stroke patients who are candidates for reperfusion therapy.

Synthetic repertoires derived from convalescent COVID-19 patients enable discovery of SARS-CoV-2 neutralizing antibodies and a novel quaternary binding modality

The ongoing evolution of SARS-CoV-2 into more easily transmissible and infectious variants has sparked concern over the continued effectiveness of existing therapeutic antibodies and vaccines. Hence, together with increased genomic surveillance, methods to rapidly develop and assess effective interventions are critically needed. Here we report the discovery of SARS-CoV-2 neutralizing antibodies isolated from COVID-19 patients using a high-throughput platform. Antibodies were identified from unpaired donor B-cell and serum repertoires using yeast surface display, proteomics, and public light chain screening. Cryo-EM and functional characterization of the antibodies identified N3-1, an antibody that binds avidly (Kd,app = 68 pM) to the receptor binding domain (RBD) of the spike protein and robustly neutralizes the virus in vitro. This antibody likely binds all three RBDs of the trimeric spike protein with a single IgG. Importantly, N3-1 equivalently binds spike proteins from emerging SARS-CoV-2 variants of concern, neutralizes UK variant B.1.1.7, and binds SARS-CoV spike with nanomolar affinity. Taken together, the strategies described herein will prove broadly applicable in interrogating adaptive immunity and developing rapid response biological countermeasures to emerging pathogens.

Prevalent, protective, and convergent IgG recognition of SARS-CoV-2 non-RBD spike epitopes in COVID-19 convalescent plasma

Although humoral immunity is essential for control of SARS-CoV-2, the molecular composition, binding epitopes and effector functions of the immunoglobulin G (IgG) antibodies that circulate in blood plasma following infection are unknown. Proteomic deconvolution of the circulating IgG repertoire (Ig-Seq1) to the spike ectodomain (S-ECD2) in four convalescent study subjects revealed that the plasma response is oligoclonal and directed predominantly (>80%) to S-ECD epitopes that lie outside the receptor binding domain (RBD). When comparing antibodies directed to either the RBD, the N-terminal domain (NTD) or the S2 subunit (S2) in one subject, just four IgG lineages (1 anti-S2, 2 anti-NTD and 1 anti-RBD) accounted for 93.5% of the repertoire. Although the anti-RBD and one of the anti-NTD antibodies were equally potently neutralizing in vitro, we nonetheless found that the anti-NTD antibody was sufficient for protection to lethal viral challenge, either alone or in combination as a cocktail where it dominated the effect of the other plasma antibodies. We identified in vivo protective plasma anti-NTD antibodies in 3/4 subjects analyzed and discovered a shared class of antibodies targeting the NTD that utilize unmutated or near-germline IGHV1-24, the most electronegative IGHV gene in the human genome. Structural analysis revealed that binding to NTD is dominated by interactions with the heavy chain, accounting for 89% of the entire interfacial area, with germline residues uniquely encoded by IGHV1-24 contributing 20% (149 [A]2). Together with recent reports of germline IGHV1-24 antibodies isolated by B-cell cloning3,4 our data reveal a class of shared IgG antibodies that are readily observed in convalescent plasma and underscore the role of NTD-directed antibodies in protection against SARS-CoV-2 infection.

Relationship between Anti-Spike Protein Antibody Titers and SARS-CoV-2 In Vitro Virus Neutralization in Convalescent Plasma

Newly emerged pathogens such as SARS-CoV-2 highlight the urgent need for assays that detect levels of neutralizing antibodies that may be protective. We studied the relationship between anti-spike ectodomain (ECD) and anti-receptor binding domain (RBD) IgG titers, and SARS-CoV-2 virus neutralization (VN) titers generated by two different in vitro assays using convalescent plasma samples obtained from 68 COVID-19 patients, including 13 who donated plasma multiple times. Only 23% (16/68) of donors had been hospitalized. We also studied 16 samples from subjects found to have anti-spike protein IgG during surveillance screening of asymptomatic individuals. We report a strong positive correlation between both plasma anti-RBD and anti-ECD IgG titers, and in vitro VN titer. Anti-RBD plasma IgG correlated slightly better than anti-ECD IgG titer with VN titer. The probability of a VN titer [≥]160 was 80% or greater with anti-RBD or anti-ECD titers of [≥]1:1350. Thirty-seven percent (25/68) of convalescent plasma donors lacked VN titers [≥]160, the FDA-recommended level for convalescent plasma used for COVID-19 treatment. Dyspnea, hospitalization, and disease severity were significantly associated with higher VN titer. Frequent donation of convalescent plasma did not significantly decrease either VN or IgG titers. Analysis of 2,814 asymptomatic adults found 27 individuals with anti-RBD or anti-ECD IgG titers of [≥]1:1350, and evidence of VN [≥]1:160. Taken together, we conclude that anti-RBD or anti-ECD IgG titers can serve as a surrogate for VN titers to identify suitable plasma donors. Plasma anti-RBD or anti-ECD titer of [≥]1:1350 may provide critical information about protection against COVID-19 disease.