• Anti-SARS-Cov-2 Multiplex Serology Assay: one of the most sensitive and reliable SARS-CoV-2 assays.

  • Flow cytometry SARS-CoV-2 multiantigen test simultaneously target four separate SARS-Cov-2 viral proteins and 3 immunoglobulins.

  • we are working every day to open opportunities for a better understanding of the immune response and its evolution over time after vaccination. 

SARS-CoV-2 Multiplex IgG+IgA+IgM kits

Multiantigen IgG+IgA+IgM Assay is a multiplex, microsphere-based, highly sensitive and specific assay that measure the presence or absence of antibodies against four different SARS-CoV-2 antigens simultaneously. 


Detecting SARS-CoV-2  neutralizing antibodies.


Identifying immune response after vaccination.


Identifying immune response to natural infection.


Identifying immune response to viral replication.

Three Reporter Channels Simultaneously

Figure 1: Graphical representation of Anti-SARS_CoV-2 flow cytometry bead-based assay procedure.

Differentiating immune response by virus and vaccination.

This serological bead-based assay has demonstrated to provide a wider range of information about the immune system response to SARS-CoV-2 than any other assay in the market, and it is performed in just 2 hours.

Figure 2: Histogram in cytometry comparing results of analysis of a positive vs. a negative sample for 4 viral proteins. (Mpro: Main virus protease or 3C-type protease (Mpro/3CLpro). | NP Nucleocapsid protein (N).  | S: Stable trimer of the spicule glycoprotein (S). | RBD: Receptor-binding domain (RBD) of S-glycoprotein) and 3 immunoglobulins (IgA, IgG, and IgM).

What is included:


12×8 well (12X8) black microtiter with lid. For  protocol with plate.


  • 0.16 ml IgG positive control. Contains CMIT/MIT 3:1 as preservative. Ready to use.
  • 0,16 ml IgG negative control. Contains CMIT/MIT 3:1 as preservative. Ready to use.


  • 80 μl calibrator. Contains CMIT/MIT 3:1 as preservative. Ready to use.


Magnetic polystyrene microspheres with a diameter (µm) 5.5 ±0.2 (CV<5%), coated with the following SARS-CoV-2 antigens:

  • RBD – bead population no. 1.
  • S – bead population no. 2.
  • N – bead population no. 3.
  • Mpro – bead population no. 4.


40 ml wash buffer (10X). PBS 10% BSA, pH 7.4 – 10X. Contains 10% albumin in 10mM sodium phosphate, 150mM NaCl, pH 7.4, contains KATHON™ anti-microbial agent.


  • 500 µl FITC-conjugated anti-human IgG antibody (5 µl/test). 
  • 500 µl PE-conjugated anti-human IgA antibody (5 µl/test).
  • 500 µl of PE-conjugated anti-human IgM antibody – Cyanine 7 – (5 µl/test).


10 ml of sample diluent buffer (1X – Ready to use).
Buffer that minimises non-specific binding, cross-reactivity and matrix interference, with blue dye. Contains CMIT/MIT 3:1 as preservative.

Qualitative and Quantitative Assay

Immunogenicity results are reported as an international standard unit. IU/mL for neutralising antibodies (RBD) and BAU/mL for S, N and Mpro Proteins.

Single Reagents available:

  • RBD coated beads


    Single Receptor-binding domain of S-glycoprotein (RBD) coated beads.

  • Spike coated beads


    Single stable trimer of the spicule glycoprotein (S) coated beads

  • Nucleocapsid coated beads


    Single Nucleocapsid protein (N) coated beads

  • Mpro coated beads


    Single Main virus protease or 3C-typeprotese (3CLpro,Mpro) coated beads.

  • Sample Diluent Buffer


    Contains < 0.0014 % [w/w] reaction mass of CMIT/MIT (3:1).

  • Wash Buffer Solution


    Contains 10 % albumin in 10mM sodium phosphate, 150 mM NaCl, pH 7.4, contains KATHON anti-microbial agent.



Qualitative  and quantitative analysis of the inmune response.

Different serology tests detect antibodies to different parts of the virus, after vaccination the antibodies formed will only be to one part of the virus (the spike protein). To understand if vaccination stimulated an antibody response, a test specifically designed for the antibodies of interest would need to be used.

This test presents a great opportunity because it gives so much information about the immune response based on the detection of 3 types of immunoglobulins and 4 specific SARS-CoV-2 antigens simultaneously, allowing us to differentiate the immune response for clinical infection and vaccination.


How do I place an order if I am a laboratory or distributor?

You can place an order via email writing us to order@immunostep.com. Simply choose a kit and send us your order with the reference number stabished in the table.  You can also  contact us in +34 923 29 48 27 (Spain). 

CE/IVD kits are only suitable for clinical use in European Union and countries with EU conformity recognition agreements. Manufactured in Spain by Immunostep under CSIC Patent Licence.

How are the antibodies quantified?

The SARS-CoV-2 multiplex assay has been calibrated against the WHO First International Standard for Anti-SARS-CoV-2 Immunoglobulin (Human), NIBSC Code 20/136.

In this sense, it is possible to quantitatively report the concentration of IgG immunoglobulins in International Units (IU / ml) against RBD or in United Antibody Units (BAU / ml) against S, N and Mpro. For this reason, the kit includes a calibrator or standard of known concentration with which to make a calibration line through serial dilutions to each of the viral antigens used in the test (RBD, S, N, Mpro) in which to interpolate the fluorescence values ​​resulting from the assay of the samples, thus obtaining the concentration in IU / ml or BAU / ml corresponding to each sample.

Can I perform this test at home?

These tests are for professional use only. If you are interested in acquiring these kits, please, contact us by  email info@immunostep.com, and we will contact you shortly.

How do I obtein the product if I am a particular?

If you are a particular and you want to acquire this test, please contact us in order to recieve a personalized proposal of distributors near you.

Do you work with a distributor in my country?

Our products are available through our extensive distribution network all over the world. Please contact us and we will give you all the information shortly.

Proyecto subvencionado por el Ministerio de Industria, Comercio y Turismo, como parte del programa de ayudas para la fabricación de material sanitario por la crisis de la COVID-19 (2020) con el objetivo de la creación de una línea de producción de test serológicos SARS-CoV-2 Multi-antígeno para citometría de flujo.