Anti-SARS-CoV-2 Neutralization Antibody Test Kit (Colloidal Gold) (A254396)

The Anti-SARS-CoV-2 Neutralization Antibody Test Kit (Colloidal Gold) is a rapid in vitro immunochromatographic assay, used for the semi-quantitative detection of neutralization antibodies against SARS-CoV-2 viral spike proteins, in human serum or plasma samples. The coronaviruses encode four major structural proteins, the spike (S), membrane (M), envelope (E), and nucleocapsid (N) proteins. The S protein contains a receptor-binding domain (RBD), which is responsible for recognizing and interacting with the cell surface receptor angiotensin-converting enzyme 2 (ACE2). ACE2 is widely expressed in the respiratory tract, on the cell surfaces in the alveoli, trachea, and bronchi, as well as on macrophages and other cell types. The ACE2-RBD interaction is essential for SARS-CoV-2 virus particle entry into the cytosol of host cells, and therefore viral replication and infection. Neutralizing antibodies secreted by B lymphocytes can bind to the RBD, blocking the interaction with ACE2, and granting the host strong immunity against the pathogen.

The test is a semi-quantitative membrane-based immunoassay. A sample of blood serum or plasma, mixed with a buffer solution, is dropped into the sample well, and the solution migrates up the membrane by the capillary effect. If there are neutralizing antibodies in the sample, these bind to colloidal gold labeled SARS-CoV-2 spike protein RBD contained within the membrane. Once the solution reaches the test (T) line, ACE2 coated on the membrane binds the free RBD and traps it at the T line, competing with the neutralizing antibodies for binding RBD. Therefore, the greater the amount of neutralizing antibodies in the sample, the more RBD is blocked from binding ACE2, the less colloidal gold accumulates at the T line, and the weaker the line observed. By comparing the T line strength to the colorimetric card, the presence and titer of neutralizing antibodies in the sample can be measured.

The solution also contains colloidal-gold labeled chicken IgY, which is captured by mouse anti-chicken IgY antibodies coated to the membrane at the control (C) line. If the C line does not appear after 10 minutes, the result is invalid, and the sample needs to be tested again using a new test cassette, carefully following the instructions. The C line appearing indicates the buffer and solution have been applied and proper membrane wicking has occurred, so its absence helps to identify false negative test results.

Anti-SARS-CoV-2 Neutralization Antibody Test Kit (Colloidal Gold) comes in packs of 25 tests and contains:

• 25 x Test Cassette.
• 25 x Buffer Vials (0.9ml/vial)
• 25 x Dropper
• 1 x Colorimetric Card

Clinical performance:

The performance of this kit was established using 626 clinical samples, with results compared to those from a plaque reduction neutralization test (111 positive, 515 negative). The kit displayed a sensitivity of 98.2% (109/111), and a specificity of 98.3% (506/515). Please refer to the datasheet for additional performance statistics.

Hook Effect:

The Hook effect is an immunological phenomenon in which the ability of antibodies to form immune complexes is sometimes impaired when concentrations of an antibody or an antigen are very high, resulting in false negatives or inaccurately low results. There was no hook effect observed within the titer range of positive samples.

Cross-reactivity:

There was no cross-reactivity observed with antibody/antigen positive sera samples from patients with other human coronaviruses (HCoV-HKU1, HCoV-OC43, HCoV-NL63, HCoV-229E), or non-coronaviruses, including influenza A virus (H1N1, H3N2, H5N1, H7N9), influenza B virus (Yamagata and Victoria lineages), respiratory syncytial virus, rhinovirus, adenovirus, enterovirus, Epstein-Barr virus, measles virus, human cytomegalovirus, rotavirus, norovirus, mumps virus, herpes zoster virus, or Mycoplasma pneumoniae.

Warnings:

• For in vitro diagnostic use only.
• For medical professional use only.
• Do not reuse any test components.
• Handle all samples cautiously as if they contain infectious agents. Observe established precautions against microbiological hazards throughout the procedure and follow the standard procedures for proper disposal of samples.
• Wear protective clothing such as laboratory coats, disposable gloves, and eye protection when samples are being assayed.
• The used tests, samples, and potentially contaminated items should be discarded according to the local regulation.
• Unreasonable sampling, transportation and handling, or low virus content in the sample will lead to false negative results. Humidity and temperature can adversely affect results.
• Each laboratory should build its own reference range.