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While traditional PCR-based assay remains as the golden standard for COVID-diagnosis, there is an increasing demand in other methods that enable quicker, easier, and more cost-effective tests. Lateral flow immunoassay (LFA) is an alternative platform that can be used to detect viral antigens in biological samples. Such tests rely on the availability of antibody pairs that can recognize the target antigen with desired specificity and sensitivity. Hundreds of antibodies against N and S proteins have been made available in recent months. Screening this large resource for a suitable pair has become a major speed limiting factor.
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In a recent study supported by The Global Good Fund and Global Health Labs (created by Gates Ventures and the Gates Foundation), authors from Global Health Labs, Intellectual Ventures Laboratory, and PATH systematically evaluated all commercially available antibodies using a high throughput screening process directly on nitrocellulose. The study identified a dozen pairs with the best potential to deliver optimal results in LFA assays.
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Index
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Capture antibody
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Detector antibody
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Average rank
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rd.1
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rd.2
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rd.3
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rd.4
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Average rank in clinical screen
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567
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Sino Biological
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Sino Biological
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1
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2.5
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25
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86.5
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–
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40143-MM08
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40143-R004
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527
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Sino Biological
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Sino Biological
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2
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30
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–
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–
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–
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40143-MM05
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40143-MM08
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564
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Sino Biological
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Sino Biological
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3
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4
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21.5
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14
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12
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40143-MM08
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40143-MM05
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111
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Creative Diagnostics
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Sino Biological
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4.5
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46.5
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–
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–
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–
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CABT-CS037
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40143-R004
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423
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Genemedi GMP-V-
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Sino Biological
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5.5
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–
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–
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8.5
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2.5
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2019nCoV-NAb001
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40143-MM08
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7
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Bioss
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Creative Diagnostics
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7.5
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–
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4
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5.5
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9
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bsm-41411M
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CABT-CS037
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534
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Sino Biological
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Bioss
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7.5
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–
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12.5
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27
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–
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40143-MM08
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bsm-41412M
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323
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Fitzgerald
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Bioss
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8
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–
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43.5
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32
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44.5
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10-2856
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bsm-41411M
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46
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Bioss
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Bioss
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9.5
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–
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–
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36
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23.5
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bsm-41413M
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bsm-41411M
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355
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Fitzgerald 10-2856
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Sino Biological
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9.5
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–
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3.5
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14
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14
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40143-MM08
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640
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Sino Biological
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Creative Diagnostics
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10.5
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14
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34.5
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13.5
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–
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40143-R040
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CABT-CS037
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33
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Bioss
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Sino Biological
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11
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–
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3
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5.5
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3
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bsm-41411M
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40143-MM08
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401
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Genemedi GMP-V-
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Bioss
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11.5
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–
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–
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23
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–
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2019nCoV-NAb001
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bsm-41413M
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517
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Novus Bio NB100-
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Sino Biological
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14.5
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87
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–
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–
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–
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56683
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40143-MM05
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666
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Sino Biological
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Novus Bio
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14.5
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100
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–
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–
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–
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40588-T62
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NB100-56683
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70
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Bioss
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Sino Biological
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16
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–
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–
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3
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3.5
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bsm-41413M
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40143-MM08
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Table: Antibody pairs selected to be screened against clinical samples are ranked according to average performance by S-N and S/N in the clinical screen. Average rank from all four robot screening rounds are also shown.
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Ref: David Cate, et al., Antibody Screening Results for Anti-Nucleocapsid Antibodies Towards the Development of a SARS-CoV-2 Nucleocapsid Protein Antigen Detecting Lateral Flow Assay. ChemRxiv.2020
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Antibody Pairs for SARS-CoV-2 N Protein
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Sino Biological has developed a large panel of antibodies against SARS-CoV-2 N protein. These pairs can be used to assemble detection assays for the corresponding antigen.
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Antibodies Specific to SARS-CoV-2 Antigen
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One of the main concerns for the antigen tests is whether the antibody pair also detects other circulating coronaviruses. To further validate the specificity, these antibodies were tested against a full panel of N proteins from the common coronaviruses. The result came back as all antibodies against the N proteins have no cross-reactivity in ELISA.
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