Understanding RDT Mechanisms and Effects

The video tutorial explains how antigen detection rapid diagnostic tests (RDTs) work, focusing on the cassette format and the role of the conjugate, which is an antibody coupled to collidal gold particles. It describes the testing process with both infected and non-infected samples, highlighting the appearance of test and control lines. The tutorial also covers the prozone effect, where high antigen levels cause false negatives, and the backflow effect, where improper timing leads to false positives.

What is the primary function of the nitrocellulose membrane in an RDT cassette?

• To change color upon antigen detection

• To provide structural support

• To facilitate the immunochromatographic reaction

• To absorb excess liquid

What gives the conjugate its purple color in antigen detection RDTs?

• Silver particles

• Iron oxide particles

• Copper particles

• Collidal gold particles

In a sample without antigens, what is the expected result on the RDT?

• Both test and control lines appear

• Only the test line appears

• Only the control line appears

• No lines appear

What is the role of the control line in an RDT?

• To change color based on antigen type

• To confirm the presence of antigens

• To indicate a successful test run

• To measure the concentration of antigens

What happens to the conjugate antibodies that do not bind any antigen?

• They cause a false positive result

• They bind to the control line

• They remain at the test line

• They degrade and disappear

What causes the prozone effect in serological assays?

• Insufficient sample volume

• High antigen concentration

• Excessive antibody concentration

• Low antigen concentration

How does the prozone effect lead to a false negative result?

• By preventing antigen-antibody binding

• By causing antigen-antibody complexes to degrade

• By blocking the control line

• By allowing free antigens to migrate faster than complexes

What is the main risk associated with the backflow effect?

• False positive results

• False negative results

• Delayed test results

• Increased test sensitivity

What can cause the antibodies to migrate backwards in an RDT?

• High antigen concentration

• Excessive sample volume

• Drying out of the strip

• Low antibody concentration

What is the consequence of not reading the RDT within the recommended time?

• Increased test accuracy

• False positive results due to backflow

• False negative results due to prozone effect

• No visible lines on the test