COVID 19 Antigen Rapid Test - Animated Video

Summary

This video explains the process of detecting SARS-CoV-2 using rapid antigen tests, focusing on the detection of the nucleocapsid protein. The test involves swabbing the patient's nasal passage to collect respiratory secretions, which are then mixed with a buffer to extract the antigen. The extracted sample is applied to a test cassette, where it interacts with antibodies that cause a visible color change if the nucleocapsid protein is present. The test results in two lines for a positive result, one line for negative, and no lines indicate an invalid test.

Takeaways

• 😀 SARS-CoV-2 has four structural proteins: spike protein, membrane protein, envelope protein, and nucleocapsid protein.
• 😀 Nucleocapsid protein is the most predominantly expressed structural protein in SARS-CoV-2, making it a primary target for rapid antigen tests.
• 😀 Rapid antigen tests are designed to detect the nucleocapsid protein antigen in respiratory secretions.
• 😀 Anterior nasal swabs or nasopharyngeal swabs are used to collect samples for antigen detection.
• 😀 The swab is rotated inside the nostril to collect secretions containing the nucleocapsid protein.
• 😀 After collection, the swab is placed in an extraction buffer tube to extract the antigen.
• 😀 The extracted sample is applied to a test cassette, which contains a sample well, test line, and control line.
• 😀 The test uses a lateral flow immunochromatographic assay to detect the presence of the antigen.
• 😀 Gold nanoparticles are used as visual indicators to show a red color when the antigen-antibody complex forms.
• 😀 A positive result shows two colored lines: one in the control line region (C) and another in the test line region (T), indicating COVID-19 positivity.
• 😀 A negative result shows only one colored line in the control line region (C), and no line in the test region (T). A missing control line indicates an invalid test.

Q & A

What are the four structural proteins of SARS-CoV-2 mentioned in the script?

The four structural proteins of SARS-CoV-2 are the spike protein, membrane protein, envelope protein, and nucleocapsid protein.

Why is the nucleocapsid protein important in the context of antigen rapid tests?

The nucleocapsid protein is predominantly expressed in SARS-CoV-2 and is targeted by most antigen rapid tests because it holds the RNA genome of the virus.

How is the sample for the rapid antigen test collected?

The sample is collected using an anterior nasal or nasopharyngeal swab, which is inserted into the nostril and rotated to collect secretions containing the nucleocapsid protein.

What happens after the swab is collected during the test?

The swab is placed into an extraction buffer tube and stirred to extract the antigen, after which the swab is removed and the tube is sealed.

What is the purpose of the test cassette in the antigen test?

The test cassette contains a sample well, a test line, and a control line. It is used to detect the presence of the nucleocapsid protein antigen through a visual process.

What is a lateral flow immunochromatographic assay, and how does it work in the antigen test?

A lateral flow immunochromatographic assay is a method where the sample flows across a test strip. The sample interacts with antibody complexes, and the presence of a specific antigen results in a visible colored line.

How is the antigen detected in the test?

If the nucleocapsid protein antigen is present, it binds to the gold anti-SARS-CoV-2 antibody complex, and the resulting mixture migrates across the test strip, creating a visible colored line.

What do the two colored lines in the test result indicate?

The presence of two colored lines, one in the control line region (C) and one in the test line region (T), indicates a positive result for COVID-19.

What does a single colored line in the control region indicate?

A single colored line in the control region (C) indicates a negative result for COVID-19.

What does it mean if no line appears in the control region?

If no line appears in the control region (C), the test is invalid and cannot be relied upon for accurate results.

How is the quality control performed in the test?

Quality control is performed using gold-labeled chicken IgY antibodies in the conjugation pad, which help ensure the test's validity and reliability.