Monoclonal antibody pairs against SARS-CoV-2 for rapid antigen test development

Abstract

Background The focus on laboratory-based diagnosis of coronavirus disease 2019 (COVID-19) warrants alternative public health tools such as rapid antigen tests. While there are a number of commercially available antigen tests to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), all cross-react with the genetically similar SARS-CoV-1 or require an instrument for results interpretation. Methodology/Principal findings We developed and validated rapid antigen tests that use pairs of murine-derived monoclonal antibodies (mAbs), along with gold nanoparticles, to detect SARS-CoV-2 with or without cross-reaction to SARS-CoV-1 and other coronaviruses. In this development, we demonstrate a robust antibody screening methodology for the selection of mAb pairs that can recognize SARS-CoV-2 spike (S) and nucleocapsid (N) proteins. Linear epitope mapping of the mAbs helped elucidate SARS-CoV-2 S and N interactions in lateral flow chromatography. A candidate rapid antigen test for SARS-CoV-2 N was validated using nasal swab specimens that were confirmed positive or negative by quantitative reverse-transcription polymerase chain reaction (RT-PCR). Test results were image-captured using a mobile phone and normalized signal pixel intensities were calculated; signal intensities were inversely correlated to RT-PCR cycle threshold (Ct) value. Conclusion/Significance Overall, our results suggest that the rapid antigen test is optimized to detect SARS-CoV-2 N during the acute phase of COVID-19. The rapid antigen tests developed in this study are alternative tools for wide scale public health surveillance of COVID-19.

Features of antibody responses after SARS-COV-2 infection in healthcare workers in the first wave of COVID-19 pandemic in Mexico City

“…This method has been used elsewhere. 16 Using this method, we found a seroprevalence of 66% (73/111) in the HCWs. However, this value was well above seroprevalence levels previously reported.…”

“…This method has been previously used in antigen rapid test development. 16 With regard to COVID-19 symptomatology, asymptomatic infection was defined as having a body temperature <37.5 C and no clinical symptoms at the time of virus detection by PCR. Mild infection was defined as having at least one sign or symptom (i.e., sputum, rhinorrhoea, cough, headache, sore throat, chest discomfort/dyspnea, myalgia, and/or febrile/chilling sensation) in association with positive PCR.…”

Monoclonal Antibodies Specific for SARS-CoV-2 Spike Protein Suitable for Multiple Applications for Current Variants of Concern

“…Since the outbreak of SARS-CoV-2 and the ensuing pandemic, a sizable number of mAbs have been generated for various applications [ 5 , 48 , 50 , 51 , 52 , 53 , 54 ]. Perhaps the standout mAb described herein is the RBD-binding, SCV2-1E8, which showed excellent performance in IHC and recognized multiple variants of concern.…”

“…The global SARS-CoV-2 pandemic has spawned a considerable demand for new monoclonal antibodies (mAbs) for a range of diagnostic and research applications. These include immunohistochemistry (IHC) [ 1 , 2 ], immunofluorescence assays [ 3 , 4 ], lateral flow rapid antigen tests [ 5 ], ELISA [ 6 , 7 ], and Western blotting [ 8 , 9 ]. In addition, several mAbs have also been developed by a range of companies [ 10 ] for use in the treatment of COVID-19 patients [ 11 ] and for prophylactic prevention of COVID-19 [ 12 , 13 ], although many commercially developed mAbs are no longer effective against new strains of concern [ 14 ].…”

SARS-CoV-2 Variant Surveillance in Genomic Medicine Era

“…During the infection with SARS-CoV-2 in the nasopharynx and oropharynx of infected people, high concentrations of S and N protein were detected and because of that, they became ideal candidates for diagnostic targets for the detection of viral protein by antigen-antibody (Ag-Ab) reaction. Thus, monoclonal antibodies against viral N and S proteins react with the viral proteins N and/or S present in patients' specimens and this interaction can be easily visualized [21][22][23]. The major limitations of this technique are that it could generate false negative results for patients with low viral loads, and has lower sensitivity for cycle of quantification >30.…”