ABSTRACT
The ongoing coronavirus disease 2019 (COVID-19) pandemic calls for a method to rapidly and conveniently evaluate neutralizing antibody (NAb) activity in patients. Here, an up-conversion phosphor technology-based point-of-care testing (UPT-POCT) and a microneutralization assay were employed to detect total antibodies against the receptor-binding domain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein and NAb activity in COVID-19 patients' sera, respectively, in order to determine if UPT-POCT could be used as a surrogate method for rapid evaluation of serum NAb activity in COVID-19 patients. In total, 519 serum samples from 213 recovered and 99 polymerase chain reaction re-positive (RP) COVID-19 patients were used in this report. We found that UPT-POCT reporting values correlated highly with NAb titers from 1:4 to 1:1024, with a correlation coefficient r = 0.9654 (P < 0.001), as well as protection rate against RP (r = 0.9886, P < 0.0001). As a significant point for reducing re-positive rate, UPT-POCT values of 4.380, corresponding to NAb titer of 1:64, may be appropriate as an indicator for evaluating high efficiency of protection. This study demonstrates that the quantitative lateral flow based UPT-POCT, could be used to rapidly evaluate NAb titer, which is of importance for assessing vaccine immunization efficacy, herd immunity, and screening patient plasma for high NAbs.
Subject(s)
COVID-19 , Coronavirus InfectionsABSTRACT
Abstract The recently emerged pathogenic SARS-coronavirus 2 (SARS-CoV-2) has spread rapidly, leading to a global pandemic. In this study, we show that SARS-CoV-2 infection was associated with clinically significant lower level of HDL cholesterol (HDL-C), which can be used as indicators of disease severity and poor prognosis. Importantly, we found the spike protein of SARS-CoV-2 (SARS-2-S) bound to HDL. Antagonists of HDL receptor-Scavenger receptor class B type I (SR-B1), strongly inhibited SARS-CoV-2 infection. Notably, the lipids transfer function of SR-B1 was indispensable for this inhibition, offering explanations for the reduced serum HDL level observed in COVID-19 patients. Basing on findings here, we speculate that SR-B1-mediated pulmonary HDL-vitamin E uptake could participate in mediating SARS-CoV-2 infection of lung cells, and the unique expression profile of SR-B1 may also affect SARS-CoV-2 cell and tissue tropism. These findings might help to provide further insights into viral transmission, pathological characteristics and reveal therapeutic targets.
Subject(s)
COVID-19 , Coronavirus InfectionsABSTRACT
Background: The colloidal gold immunochromatography assay (GICA) is a rapid diagnostic tool for novel coronavirus disease 2019 (COVID-19) infections. However, with significant numbers of false negatives, improvements to GICA are needed. Methods: Six recombinant HCoV-19 nucleocapsid and spike proteins were prepared and evaluated. The optimal proteins were employed to develop a sandwich-format GICA strip to detect total antibodies (IgM and IgG) against HCoV-19. GICA performance was assessed with comparison of viral RNA detection. Results: Recombinant HCoV-19 proteins were obtained, including three prokaryotically expressed rN, rN1, rN2 nucleocapsid proteins, and three eukaryotically expressed rS1, rS-RBD, rS-RBD-mFc spike proteins. The recombinant proteins with the highest ELISA titers (rS1 and rS-RBD-mFc) against coronavirus-specific IgM and IgG were chosen for GICA development. The GICA has a sensitivity and specificity of 86.89% (106/122) and 99.39% (656/660), respectively. Furthermore, 65.63% (21/32) of the clinically confirmed but RT-PCR negative samples were GICA positive. Conclusions: The eukaryotically-expressed spike proteins (rS1and rS-RBD-mFc) are more suitable than the prokaryotically expressed nucleocapsid proteins for HCoV-19 serological diagnosis. The GICA sandwich used to detect total antibodies is a powerful complement to the current standard RNA-based tests.