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What Are Antibody Detection Reagents?

Feb. 24, 2021

Recently several companies have designed and developed new coronavirus antigen/antibody detection reagents, which differ from the previously approved nucleic acid detection reagents in terms of test principles, test methods, and intended use.The next new coronavirus antibody test kit supplier will briefly introduce them.

1. What are antigen detection reagents?

Novel coronavirus genes encode several structural proteins, such as N protein, E protein and S protein, which include several antigenic epitopes, and by using the principle of specific binding of antigens to antibodies, the presence of antigens can be detected by antibodies, thus directly proving the presence of novel coronavirus in the sample. The type of sample for which antigen detection reagents are available is generally an infection site sample, such as a throat swab.

2. What are antibody detection reagents?

The above antigens of the novel coronavirus can be used as immunogens to stimulate plasma cells to produce specific antibodies after the virus infects the body. Using the principle of specific binding of antigens and antibodies, the presence of antibodies can be detected by antigens, thus indirectly proving that the body is infected with the novel coronavirus. The applicable sample type for antibody detection reagents is generally blood, including serum, plasma and whole blood.

The antibodies detected are divided into two main categories: IgM and IgG. There is a lack of systematic studies on the production and duration of these two classes of antibodies to novel coronaviruses. Usually, IgM antibodies are produced early, once infected, quickly, with short maintenance time and fast disappearance, and a positive test in blood can be used as an indicator of early infection. IgG antibodies are produced late, with long maintenance time and slow disappearance, and a positive test in blood can be used as an indicator of infection and previous infection.

 Novel Coronavirus Antibody Detection Kit

3. Methods used for antigen/antibody detection reagents

Antigen / antibody detection reagents are based on the immunological principle of specific binding of antigen and antibody, the commonly used methodologies are mainly colloidal gold, immunofluorescence chromatography, enzyme-linked immunoassay and chemiluminescence. Colloidal gold method is convenient, can be directly visual interpretation, generally 15 minutes to complete the test; immunofluorescence chromatography and colloidal gold method as convenient operation, rapid detection, but requires instrumentation interpretation; enzyme-linked immunoassay can be used for conventional enzyme standard reading, generally higher sensitivity, but the detection time is longer (about 1.5 hours or more), and more operational steps, the operation process should take measures to avoid infection. Chemiluminescence method is generally more sensitive, using fully automated chemiluminescence immunoassay analyzer, without too much manual operation can be completed detection, detection time is generally about half an hour.

4.The key to antigen/antibody detection reagents

The key to antigen / antibody detection reagents is to obtain highly sensitive and specific antigen and antibody for detection, but the antibody preparation process is tedious and time-consuming, recombinant antigen technology is relatively fast, but the selection of the best antigen also requires time and test basis. In addition, since the production and disappearance of antibodies is a dynamic process, it is crucial to choose a reasonable sampling time, but there is a lack of relevant research data.

5.Positioning of antigen/antibody detection reagents

In view of the characteristics and current status of the antigen/antibody test, its sensitivity and specificity are currently limited, and it cannot be used as the only basis for confirming and excluding the diagnosis of NCCP, and is not suitable for screening of the general population.

The intended use of the product is recommended to be limited to a supplemental test indicator for suspected cases with negative nucleic acid tests, or to be used in conjunction with nucleic acid tests in the diagnosis of suspected cases.

The combined application of nucleic acid, antigen and antibody assays can shorten the detection window and increase the positive detection rate, which is very important in the auxiliary diagnosis of new coronary pneumonia.