Q-Plex™ SARS-CoV-2 Human IgG (5-Plex)

Q-Plex SARS-CoV-2 Human IgG (5-Plex)

For measurement of SARS-CoV-2 S1, SARS-CoV-2 S2, Sheep Fc (negative control), Anti-Human IgG (positive control), Nucleocapsid protein

  • Species Specificity: Human
  • Validated Sample Type: Human Serum, Plasma, and Dried Whole Blood Samples
  • Sample Volume Required per Well: 2 µL
  • Estimated Assay Length: 2 hours
  • Specificity: See assay validation below
  • Assay Type: Indirect
  • Detection Method: Chemiluminescent
  • Multiplex Format: 96-well plate
  • Catalog #: 721649HU
Analyte Assay Type Range Limit of Detection Precision (Inter-assay) Precision (Intra-assay) Average Linearity
S1 Indirect 1000 - 1.3 U/mL 1.3 U/mL 14% 6.2% 105%
S2 Indirect 1000 - 1.3 U/mL 1.3 U/mL 14% 13.2% 101%
NP Indirect 1000 - 1.3 U/mL 0.9 U/mL 13% 9% 103%
*Intra-assay and inter-assay precision are calculated with n=20 and n=10 replicates, respectively.
SARS-CoV-2 Spike Proteins S1 and S2 IgG Assay vs. Molecular COVID-19 Test
N=360 Confirmed Positive Confirmed Negative
IgG Test Positive 33 0
IgG Test Negative 1 326
SARS-CoV-2 Nucleocapsid IgG Assay vs. Molecular COVID-19 Test
N=360 Confirmed Positive Confirmed Negative
IgG Test Positive 32 19
IgG Test Negative 2 307
S1 and S2 vs. PCR S1 and S2 vs. PCR
Sensitivity (PPA) 97.1% 94.1%
Specificity (NPA) 100% 94.2%
Positive Predictive Value (PPV) 100% 62.7%
Negative Predictive Value (NPV) 99.7% 99.4%

Principle of the Assay

The Q-Plex SARS-CoV-2 Human IgG (5-Plex) array simultaneously recognizes human IgG antibodies to S1 and S2 subunits of the spike glycoprotein as well as antibodies specific for the nucleocapsid protein (NP). Whereas the spike glycoprotein is crucial for the virus’ ability to attach to a cell, the NP is the primary protein that makes up the shell, or capsid, of the virus. The assay also detects antibodies towards the Fc region of sheep antibody to control for cross-reactivity between sample and the assay components. Finally, the kit uses detection of anti-human IgG as a positive control to ensure the assay performs to expectations.

Why the nucleocapsid addition? 

The ability to measure antibodies towards NP as well as S1 and S2 provides an opportunity to distinguish antibody responses caused by vaccination versus those caused by infection. All currently authorized SARS-CoV-2 functional vaccines, such as the Pfizer and Moderna mRNA vaccines and the Johnson and Johnson DNA vaccine, use the spike glycoprotein as the immunogen to elicit a protective antibody response in the patient. Thus, detecting antibodies specific for NP in patients that have been vaccinated suggests that they have also been previously infected with SARS-CoV-2. This sort of tool is useful in seroprevalence studies, as well as in studies focused on elucidating the immune responses of vaccinated patients.

Kit Content

Each kit contains a 96-well plate, featuring the relevant biomarker panel in each well, and all reagents required to perform testing.

Reagents Include:

  • Detection Mix
  • Calibrators (High, Low, Negative)
  • Substrate
  • Sample Diluents
  • Streptavidin HRP
  • Wash Buffer


All Quansys Q-Plex™ Multiplex and Singleplex assays require the use of the Q-View™ Software to read and interpret the test results. A fully-functional, free trial version of the software is available to download, install, and use to analyze your first kit(s). At the end of the trial period, a purchased license is required to continue the use of the Q-View software.

Q-Plex™ Arrays are developed and optimized to work with Q-View™ Imagers. Quansys does not guarantee the results obtained from other imagers and not all imagers are compatible with Quansys Q-Plex Arrays.

Other Equipment Recommendations

Publication Library

Search our publication library for all the peer-reviewed journals and research products that have utilized Q-Plex™ technology here.

In-Kit Certificate of Analysis

Search and download Certificates of Analysis for your Quansys Biosciences kits here.

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Our Response to COVID-19

As new variants of SARS-CoV-2 arise, the global response must change and adapt. Tracking the infection and our immune response towards it becomes increasingly important. Learn more about our response to COVID-19.

Similar Kits Available

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GMCSF, IFNα, IFNγ, IL-1β, IL-1RA, IL-2, IL-2Rα, IL-6, IL-6r, IL-8, IL-10, IL-12p70, IL-13, MCP-1, MIP-1α, TNFα

Not Finding What You Need?

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Not seeing the biomarker or analyte you need? Customize your kit! The Q-Plex™ Custom Assays are fully quantitative ELISA-based Chemiluminescent assay kits allowing the concurrent measurement of up to 18 biomarkers or analytes.

Send in Your Samples

Choose up to 18 different biomarkers that will work best for your research. Send in your samples and let us run them for you. 

Contact a Representative

Have questions about the kit or interested in more information? Contact one of our representative to get all your questions answered. 

As researchers and problem solvers ourselves, we understand the value of sound data. We are proud to be a part of research that can better the world. We value the relationships, partnerships, and friendships that we have built with the people who trust and use our technology. We are committed to building these relationships. You can count on us to answer the phone and take time to thoroughly address questions or concerns about any of our products. In an industry that is reputed for grandiose claims, we trust that our quality standards and our customer service set us apart from the competition. If you’re happy with our products or if you think we can do something better, we hope you will let us know.