High-throughput isolation of SARS-CoV-2 nucleocapsid antibodies for improved antigen detection

Mizuki Fujisawa; Yu Adachi; Taishi Onodera; Nozomi Shiwa-Sudo; Naoko Iwata-Yoshikawa; Noriyo Nagata; Tadaki Suzuki; Shinji Takeoka; Yoshimasa Takahashi

doi:10.1016/j.bbrc.2023.06.067

High-throughput isolation of SARS-CoV-2 nucleocapsid antibodies for improved antigen detection

Biochem Biophys Res Commun. 2023 Sep 17:673:114-120. doi: 10.1016/j.bbrc.2023.06.067. Epub 2023 Jun 19.

Authors

Mizuki Fujisawa¹, Yu Adachi², Taishi Onodera², Nozomi Shiwa-Sudo³, Naoko Iwata-Yoshikawa³, Noriyo Nagata³, Tadaki Suzuki³, Shinji Takeoka⁴, Yoshimasa Takahashi⁵

Affiliations

¹ Research Center for Drug and Vaccine Development, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan; Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
² Research Center for Drug and Vaccine Development, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan.
³ Department of Pathology, National Institute of Infectious Diseases, 4-7-1, Gakuen, Musashi-murayama-shi, Tokyo, 208-0011, Japan.
⁴ Department of Life Science and Medical Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan; Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan.
⁵ Research Center for Drug and Vaccine Development, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan. Electronic address: ytakahas@niid.go.jp.

Abstract

SARS-CoV-2 nucleocapsid protein (NP) is the main target for COVID-19-diagnostic PCR and antigen rapid diagnostic tests (Ag-RDTs). Ag-RDTs are more convenient than PCR tests for point-of-care testing or self-testing to identify the SARS-CoV-2 antigen. The sensitivity and specificity of this method depends mainly on the affinity and specificity of NP-binding antibodies; therefore, antigen-antibody binding is key elements for the Ag-RDTs. Here, we applied the high-throughput antibody isolation platform that has been utilized to isolate therapeutic antibodies against rare epitopes. Two NP antibodies were identified to recognize non-overlapping epitopes with high affinity. One antibody specifically binds to SARS-CoV-2 NP, and the other rapidly and tightly binds to SARS-CoV-2 NP with cross-reactivity to SARS-CoV NP. Furthermore, these antibodies were compatible with a sandwich enzyme-linked immunosorbent assay that exhibited enhanced sensitivity for NP detection compared to the previously isolated NP antibodies. Thus, the NP antibody pair is applicable to more sensitive and specific Ag-RDTs, highlighting the utility of a high-throughput antibody isolation platform for diagnostics development.

Keywords: Antigen test; COVID-19; Nucleocapsid protein; SARS-CoV-2; Single B-cell culture.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antibodies, Viral
COVID-19* / diagnosis
Epitopes
Humans
Nucleocapsid
SARS-CoV-2*
Sensitivity and Specificity

Substances

Antibodies, Viral
Epitopes