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Development and characterization of a new monoclonal antibody against SARS-CoV-2 NSP12 (RdRp) |
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| Authors: | Wen Meng Siying Guo Simon Cao Masahiro Shuda Lindsey R. Robinson-McCarthy Kevin R. McCarthy Yoko Shuda Alberto E. Paniz Mondolfi Clare Bryce Zachary Grimes Emilia M. Sordillo Carlos Cordon-Cardo Pengfei Li Hu Zhang Stanley Perlman Haitao Guo Shou-Jiang Gao Yuan Chang Patrick S. Moore |
| Affiliation: | 1. Cancer Virology Program, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania, USA;2. Cancer Virology Program, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania, USA Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA School of Medicine, Tsinghua University, Beijing, China;3. Cancer Virology Program, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania, USA Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA;4. Cancer Virology Program, University of Pittsburgh Medical Center Hillman Cancer Center, Pittsburgh, Pennsylvania, USA Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA;5. Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA Center for Vaccine Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA;6. Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA;7. Department of Microbiology and Immunology, University of Iowa, Iowa City, Iowa, USA |
| Abstract: | SARS-CoV-2 NSP12, the viral RNA-dependent RNA polymerase (RdRp), is required for viral replication and is a therapeutic target to treat COVID-19. To facilitate research on SARS-CoV-2 NSP12 protein, we developed a rat monoclonal antibody (CM12.1) against the NSP12 N-terminus that can facilitate functional studies. Immunoblotting and immunofluorescence assay (IFA) confirmed the specific detection of NSP12 protein by this antibody for cells overexpressing the protein. Although NSP12 is generated from the ORF1ab polyprotein, IFA of human autopsy COVID-19 lung samples revealed NSP12 expression in only a small fraction of lung cells including goblet, club-like, vascular endothelial cells, and a range of immune cells, despite wide-spread tissue expression of spike protein antigen. Similar studies using in vitro infection also generated scant protein detection in cells with established virus replication. These results suggest that NSP12 may have diminished steady-state expression or extensive posttranslation modifications that limit antibody reactivity during SARS-CoV-2 replication. |
| Keywords: | COVID-19 monoclonal antibody NSP12 RNA-dependent RNA polymerase, RdRp SARS-CoV-2 |