ABSTRACT
The need for high-affinity, SARS-CoV-2-specific monoclonal antibodies (mAbs) is critical in the face of the global COVID-19 pandemic, as such reagents can have important diagnostic, research, and therapeutic applications. Of greatest interest is the ~300 amino acid receptor binding domain (RBD) within the S1 subunit of the spike protein because of its key interaction with the human angiotensin converting enzyme 2 (hACE2) receptor present on many cell types, especially lung epithelial cells. We report here the development and functional characterization of 29 nanomolar-affinity mouse SARS-CoV-2 mAbs created by an accelerated immunization and hybridoma screening process. Differing functions, including binding of diverse protein epitopes, viral neutralization, impact on RBD-hACE2 binding, and immunohistochemical staining of infected lung tissue, were correlated with variable gene usage and sequence.
ABSTRACT
SARS-CoV-2 emerged in late 2019 and has since spread around the world, causing a pandemic of the respiratory disease COVID-19. Detecting antibodies against the virus is an essential tool for tracking infections and developing vaccines. Such tests, primarily utilizing the enzyme-linked immunosorbent assay (ELISA) principle, can be either qualitative (reporting positive/negative results) or quantitative (reporting a value representing the quantity of specific antibodies). Quantitation is vital for determining stability or decline of antibody titers in convalescence, efficacy of different vaccination regimens, and detection of asymptomatic infections. Quantitation typically requires two-step ELISA testing, in which samples are first screened in a qualitative assay and positive samples are subsequently analyzed as a dilution series. To overcome the throughput limitations of this approach, we developed a simpler and faster system that is highly automatable and achieves quantitation in a single-dilution screening format with sensitivity and specificity comparable to those of ELISA.
ABSTRACT
OBJECTIVE: To develop a method of evaluating trauma center mortality that addresses the limitations of currently available methodology-Standardized Mortality Ratios (SMRs) based on the Trauma and Injury Severity Score. SUMMARY OF BACKGROUND DATA: TRISS SMRs have important limitations including inadequate risk adjustment, comparison to an inappropriate standard, lack of consideration for inter- and intrahospital variation, and incomparability across hospitals. METHODS: The methodology was developed using data from a provincial trauma registry with mandatory participation of all trauma centers, uniform inclusion criteria, and standardized data collection methods. Institutional performance was described with estimates of risk-adjusted mortality derived from a hierarchical logistic regression model. Risk adjustment was performed with a risk score generated by the Trauma Risk Adjustment Model (TRAM), as well as a term for incoming transfers and an interaction between transfer and the risk score. Outliers were identified by comparing each hospital to all remaining hospitals. RESULTS: The study population comprised 88,235 patients including 4731 deaths (5.4%) from 59 trauma centers. Crude mortality varied between 1.3% and 14.3%. TRAM-adjusted mortality estimates varied between 3.7% (95% CI: 3.2%-4.3%) and 6.9% (5.8%-8.2%). Three trauma centers had significantly higher adjusted mortality and one center had statistically significant lower mortality when compared with all other centers. CONCLUSIONS: The proposed method of trauma center profiling offers comprehensive adjustment for patient-level risk factors and consideration of transfer status, is based on comparisons to an internal standard, accounts for inter- and intrahospital variation, and replaces SMRs with estimates of regression-adjusted mortality that are comparable across hospitals. TRAM-adjusted mortality estimates can be used to describe institutional outcome performance and to identify institutional outliers. Such information is the key to identifying ways to improve the quality of modern trauma care.
