JIR covid-19

Research Solutions for Coronavirus – Jackson Immunoresearch

Jackson ImmunoResearch Affinipure Anti-Human secondary antibodies are affinity purified polyclonal antibodies with specificity for human immunoglobulins.

We offer anti-human secondary antibodies in a range of host species including Alpaca, Donkey, Goat, Mouse and Rabbit. JIR secondary antibodies are available as whole IgG and F(ab’)2. Fab fragments can be an elegant component of multiple labeling and blocking protocols.

They are available with specificity for whole Ig, Fcγ and F(ab’)2 fragment, among other specificities.

Immunoassays for diagnostics testing

Serological tests are key assays for many health issues, including solid organ transplantation screening, crossmatching, disease diagnosis, monitoring and management. These assays play a crucial role in clinical decision-making. Immunoassays are among the most powerful and sensitive serological tests available, based on highly specific binding between antibodies and antigens, enabling qualitative and quantitative detection of analytes even at low concentrations. There are a variety of immunoassays available and the detection process varies from technique to technique. The most common of which are illustrated below showing a sandwich (Fig. 1A) and direct bind (Fig. 1B), respectively. When choosing an Anti-Human Secondary Antibody for use in sandwich format assays (Fig. 1A), it is important to consider the species in which the primary antibody was generated and to use a secondary antibody that has minimal cross-reactivity to that species.

Immunoassays are Important for a Variety of Diseases

Immunoassay techniques each have advantages and limitations. For example, rapid test assays like lateral flow provide qualitative results within minutes, allowing for point of care analysis, where as an ELISA can take hours to perform but provides quantitative information.

The benefits of lateral flow assays are highlighted by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Considering the fast spread and mortality rates of the disease, the FDA has taken action to allow states to launch new SARS-CoV-2 tests without FDA approval. This amendment allows the use of rapid test kits, which qualitatively detect IgG and IgM patient-generated antibodies to SARS-CoV-2, expanding the SARS-CoV-2 diagnostic capacity, with the aim of reducing the spread of the virus. Although there are clear advantages to lateral flow tests, these immunoassays don’t offer quantitative data, which is a key feature for some clinical tests.

Another critical application for which Anti-Human Secondary Antibodies are utilized is the transplant crossmatch assay. Flow cytometry crossmatch is an essential immunoassay when determining the suitability of a transplant patient for a donor organ. In these assays, the presence of donor-specific crossmatch antibodies in the organ recipient to human leukocyte antigens on the donor’s white blood cells, or on bead conjugates, is determined. The information provides the histocompatibility of the donor and the recipient and clinicians can then assess the suitability for organ transplantation.

Table 1. The detection process, immunoglobulin isotypes tested and the advantages and disadvantages of several types of immunoassays.

Immunoassay Detection Process Immunoglobulin Isotypes
Rapid test/ lateral flow Sample is loaded onto a test membrane and travels by capillary action. Analytes, including hyperimmune antibodies, present in the sample bind to color-coded Anti-Human detection antibodies as they travel. The complexes bind to either an immobilized sandwiching antibody (Fig. 1A) or an antigen in the form of a test line (Fig. 1B). A colored line provides a qualitative positive result. A common method of color-coding reporter antibodies is through conjugation to gold nanoparticles.
A control line is generally also included that indicates the assay is functioning properly.
IgG, IgM
Flow cytometry A serum sample is added to antigen-bearing cells or coated beads. A secondary antibody conjugated with a fluorescent probe is added and binds to any human antibody captured on the cell or beads (Fig. 1B). The fluorescence can then be analyzed by the flow cytometer to give quantitative data. IgG, IgM, IgA
Flow Injection Analysis (FIA) Similar to flow cytometry, the sample is injected into a column containing immobilized antigen, to which the antibodies of interest in the sample binds (Fig. 1B). A secondary antibody is added and binds to any human antibody captured on the column. This secondary antibody can either be conjugated to a fluorescent probe or an enzyme for colorimetric or fluorescent detection. IgG, IgM, IgA
ELISA A primary antibody is immobilized on a solid surface, typically a microtiter plate, which subsequently captures the antigen (Fig. 1A) or the antigen is coated directly onto the plate (Fig. 1B). Human antibodies from hyperimmune serum bind to the antigen. An enzyme-conjugated Anti-Human Secondary Antibody is added which binds to the human antibody from the sample. Finally, an enzyme substrate is added, which results in a colorimetric readout proportional to the analyte concentration. IgG, IgM, IgA
IPCR This process is similar to ELISA, but the secondary antibody is conjugated to an oligonucleotide. DNA amplification and detection are then performed by real-time PCR. IgG, IgM, IgA

Anti-Human Secondary Antibodies are Key Reagents in Immunoassays

While the function and purpose of immunoassays differ, high-quality reagents are essential when manufacturing any serological kit to produce accurate and reliable data that clinicians and patients can trust. The quality and characteristics of Anti-Human Secondary Antibodies are crucial considerations when developing an immunoassay. Secondary antibodies are preferred as they bind multiple epitopes on one primary antibody, which enhances the signal for higher sensitivity and selectivity.

Table 2 describes the many aspects to consider when selecting the most suitable secondary antibodies for an immunoassay.

Jackson ImmunoResearch Offers High-Quality Anti-Human Secondary Antibodies

Jackson ImmunoResearch Laboratories, Inc. specializes in providing secondary antibodies for immunological applications. Their wide range of products enables customers to select the most suitable secondary antibody for the development of their serological tests.

All Anti-Human Secondary Antibodies are manufactured to ISO 9001:2015 certification, providing quality, specificity and reliability of their products and these secondary antibodies can be purchased in standard and bulk quantities, which can be shipped worldwide.

Table 2. Considerations when choosing the appropriate secondary antibody characteristics in an immunoassay and features of Jackson ImmunoResearch products with regard to those considerations.

Consideration Jackson ImmunoResearch Secondary Antibodies
Host Species Serological tests for human samples should use Anti-Human Secondary Antibodies to minimize non-specific binding, which can lead to high background signals and false positives. Anti-Human Secondary Antibodies are developed in a range of host species including alpaca, donkey, goat, mouse and rabbit.
Product type Secondary antibodies are available as whole immunoglobulin (Ig)G, F(ab’)2 and Fab fragments. Whole IgG antibodies are often sufficient, but F(ab’)2 and Fab fragments are useful to avoid binding to live cells with Fc receptors. Secondary antibodies are available as whole IgG and F(ab’)2 and Fab fragment formats.
Specificity Depending on the specificity of the immunoassay required, secondary antibodies can be made to be specific to the whole Ig, Fc or F(ab’)2 domain. Anti-Human Secondary Antibodies offer specificity for whole Ig, Fc and F(ab’)2 domains.
Isotype Most immunoassays test for IgG isotypes, which constitute ~75% of the total serum Ig and are produced as part of the secondary immune response. However, IgM and IgA can be used, as these function in the primary immune response and protect mucus membranes, respectively. It is important that the secondary antibody has specificity for the isotype of the primary antibodies. Products are available with specificities to IgG, IgM, IgA, IgG+IgM and IgG+IgM+IgA.
Affinity purification and cross-adsorption Due to the high structure conservation in Ig domains, it is recommended to use class or species specific secondary antibodies that have been affinity purified and cross-adsorbed to reduce the possibility of cross-reaction. Immunoaffinity chromatography is used to isolate affinity-purified antibodies. Antibodies can be purchased which have been cross-absorbed against species and these details are provided in the parentheses of the product description with the term “min X” followed by abbreviations for the relevant species.
Conjugate Secondary antibodies are often conjugated to a reporter molecule e.g. an enzyme, fluorescent probe, or colored particle. The detection system of the immunoassay will determine the type of conjugate. Anti-Human Secondary Antibodies are available unconjugated or conjugated to a range of reporter types, including biotin, alkaline phosphatase, horseradish peroxidase, fluorophores and colloidal gold nanoparticles.

Serological tests enable disease surveillance from initial infection through to the development of immunity against infectious diseases. The power of serological testing comes from the specific detection of patient antibodies generated by the immune system. Here we discuss what serological tests are, why they are used and how the tests work

The development of serological tests is critical in the fightback against the novel coronavirus pandemic (covid-19).


What is a serological test?

A serological test is used diagnostically to identify antibodies in a sample of blood serum or other bodily fluid. As antibodies are raised as part of the immune response, the presence of an antibody specific for an infectious agent, (e.g. micro-organism or virion) indicates that the patient has (or has had) the infection. Other purposes of serological tests include diagnosis of autoimmune diseases or blood typing.


Why test?

Serological tests offer different insights into the nature of the disease than Polymerase Chain Reaction (PCR) or culturing the causative agent. They provide a measure of exposure to the virus even in individuals who are asymptomatic and who may not have been tested by a standard PCR-based assay. Determining exposure in patients who may be unaware they have been exposed but have developed immunity is especially important where environmental restrictions are in place to protect vulnerable or key individuals. An antibody-based serological test can provide results rapidly and cost-effectively.


How does a serological test work?

The principle method of a serological test is that the infectious agent is attached to a sample well or other surface, either directly or via a capture antibody. The sample is introduced and if present, antibodies will bind to the infectious agent. Unbound material is washed away, and any bound antibodies are detected with a secondary antibody conjugated to a reporter molecule.


Test kit formats

Enzyme immunoassay (EIA), Fluorescent Immunoassay (FIA), ELISA, ELISpot, Lateral Flow Test (LFT) (also known as Strip test or Rapid test) are different formats of serological tests. Some are designed for automated high throughput screening of hundreds of samples simultaneously, others are designed for easy and rapid use in point of care testing.


Anti-Human Antibodies for human diagnostics

JIR Anti-Human antibodies are suitable for the detection of human immunoglobulin isotypes by immunoassay. Manufactured to ISO 9001:2015 certification, JIR antibodies are available in standard and bulk quantities for worldwide shipment.

  • Anti-Human IgG
  • Anti-Human IgM
  • Anti-Human IgA

Anti-Human Secondary Antibodies

Anti-Human Antibodies for Serological Tests

Anti-Human secondary antibodies are an invaluable reagent in the development of high-throughput serological testing kits. JIR Anti-Human antibodies are manufactured to ISO: 2015 certification and are available in standard and bulk quantities for worldwide shipment.

JIR anti-human secondary antibodies are suitable for the detection of human immunoglobulin isotypes by immunoassay including ELISA, ELISPOT, Rapid test, Enzyme immunoassay (EI), Luminscent immunoassay (LIA), Fluorescent immunoassay (FIA) and lateral flow.


  • Anti-Human IgG
  • Anti-Human IgM
  • Anti-Human IgA


Available with specificities to IgG, IgM or IgA as well as IgG+IgM and IgG+IgM+IgA. Anti-Human products are highly cross-adsorbed.

Host species options include Alpaca, Donkey, Goat, Mouse and Rabbit.

Biotin, HRP and fluorescent dye conjugates available.

Anti-Human Secondary Antibodies are available with the following conjugates:

  • Unconjugated
  • Reporter enzymes (Alkaline Phosphatase (AP) or Horseradish Peroxidase (HRP)
  • Biotinylated (biotin conjugates)
  • Fluorophores (Alexa Fluor®, Brilliant Violet™, Cyanine and protein dye conjugates)
  • Colloidal Gold (Immunogold)

Affinity-purified antibodies are isolated from antisera by immunoaffinity chromatography using target antigens coupled to agarose beads. A proprietary elution process is used to dissociate antibodies from the antigen. Unconjugated affinity-purified antibodies are supplied sterile filtered in phosphate buffer without stabilizers or preservatives. Conjugated affinity-purified antibodies are freeze-dried in phosphate buffer with stabilizers and sodium azide, with the exception of horseradish peroxidase conjugates, which do not contain a preservative.

Cross adsorbed secondary antibodies (min X … Sr Prot)

Secondary antibodies against one species are likely to cross-react with other species unless they have been specifically adsorbed against the other species. Antibodies with “(min X … Sr Prot)” in the description have been tested and/or adsorbed against IgG and/or serum proteins of those species indicated in the parentheses. They are recommended when the presence of immunoglobulins from other species may lead to interfering cross-reactivities.

Example AffiniPure™ Anti-Human Secondary Antibodies


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