Rigid monoclonal antibodies improve detection of SARS-CoV-2 nucleocapsid protein

Abstract

Monoclonal antibodies (mAbs) are the basis of treatments and diagnostics for pathogens and other biological phenomena. We conducted a structural characterization of mAbs against the N-terminal domain of nucleocapsid protein (NPNTD) from SARS-CoV-2 using small angle X-ray scattering (SAXS). Our solution-based results distinguished the mAbs’ flexibility and how this flexibility impacts the assembly of multiple mAbs on an antigen. By pairing two mAbs that bind different epitopes on the NPNTD, we show that flexible mAbs form a closed sandwich-like complex. With rigid mAbs, a juxtaposition of the Fabs is prevented, enforcing a linear arrangement of the mAb pair, which facilitates further mAb polymerization. In a modified sandwich ELISA, we show the rigid mAb-pairings with linear polymerization led to increased NPNTD detection sensitivity. These enhancements can expedite the development of more sensitive and selective antigen-detecting point-of-care lateral flow devices (LFA), key for early diagnosis and epidemiological studies of SARS-CoV-2 and other pathogens.

One-pot high-yield synthesis of Pd nanocubes for Pd-Ir nanocube-based immunoassay of nucleocapsid protein from SARS-CoV-2

“…Immunoassay of NP and PSA by Pd-Ir nanocubes NP is the most abundant structural protein of SARS-CoV-2 involved in the incorporation, package, replication, and transcription of viral RNA, and are encoded within a relatively conserved and stable gene, which make NP an ideal candidate for the development of antigen-based immunoassays for the diagnosis of COVID-19 [39][40][41]. Hence, Pd-Ir nanocubes were conjugated with antibodies to investigate the detection sensitivity for NP of SARS-CoV-2 compared with standard HRP-based immunoassay.…”