Latex Microsphere-Based Bicolor Immunochromatography for Qualitative Detection of Neutralizing Antibody against SARS-CoV-2

Abstract

Neutralizing antibody (NAb) is a family of antibodies with special functions, which afford a degree of protection against infection and/or reduce the risk of clinically severe infection. Receptor binding domain (RBD) in the spike protein of SARS-CoV-2, a portion of the S1 subunit, can stimulate the immune system to produce NAb after infection and vaccination. The detection of NAb against SARS-CoV-2 is a simple and direct approach for evaluating a vaccine’s effectiveness. In this study, a direct, rapid, and point-of-care bicolor lateral flow immunoassay (LFIA) was developed for NAb against SARS-CoV-2 detection without sample pretreatment, and which was based on the principle of NAb-mediated blockage of the interaction between RBD and angiotensin-converting enzyme 2. In the bicolor LFIA, red and blue latex microspheres (LMs) were used to locate the test and control lines, leading to avoidance of erroneous interpretations of one-colored line results. Under the optimal conditions, NAb against SARS-CoV-2 detection carried out using the bicolor LFIA could be completed within 9 min, and the visible limit of detection was about 48 ng/mL. Thirteen serum samples were analyzed, and the results showed that the NAb levels in three positive serum samples were equal to, or higher than, 736 ng/mL. The LM-based bicolor LFIA allows one-step, rapid, convenient, inexpensive, and user-friendly determination of NAb against SARS-CoV-2 in serum.

Research progress in methods for detecting neutralizing antibodies against SARS-CoV-2

“…Generally, the LFIA is based on an antigen-antibody reaction, while the detection of NAbs against SARS-CoV-2 is based on the protein‒protein interaction principle; that is, the interaction between the RBD or the S protein and ACE2. Additionally, the LFIA kit was developed by a competition method [ 89 , 90 ]. ACE2 receptor of human cell surface can bind to RBD of SARS-CoV-2, meanwhile, NAbs of SARS-CoV-2 can also specifically bind to RBD.…”

Gold-silver alloy hollow nanoshells-based lateral flow immunoassay for colorimetric, photothermal, and SERS tri-mode detection of SARS-CoV-2 neutralizing antibody

“…Finally, this tri-mode LFIA was successfully detected the serum samples from 98 vaccinated volunteers with 79 positive results, exhibiting great application value in neutralizing antibody detection. Compared with similar work for SARS-CoV-2 IgG [ 26 , 36 ] and neutralizing antibody detection [ 37 , 38 ], our method allows for photothermal, colorimetric and SERS tri-modal detection with higher sensitivity and accuracy.…”

Lateral Flow Immunoassay Based on Time-Resolved Fluorescence Microspheres for Rapid and Quantitative Screening CA199 in Human Serum

“…The mature LFIA has become a commonly used POCT technique in clinical diagnosis of various diseases, such as early-stage cancer [ 14 ], sexually transmitted diseases [ 15 ], AIDS [ 16 ], COVID-19 [ 17 ], and so forth. Our group have successfully developed LFIAs to rapidly detect SARS-CoV-2 nucleocapsid protein [ 18 ], IgG/IgM [ 19 ] and neutralizing antibody [ 20 ]. Colloidal gold nanoparticles (AuNPs) are the most commonly used tags in LFIA for colorimetric detection [ 21 ].…”