Overview

Q. What is the principle of the real-time PCR test?

The assay to detect CSF viral RNA is a real-time RT-PCR method that utilizes a specific set of forward and reverse primers and fluorogenic probe hydrolysis chemistry for the detection of CSF viral RNA in samples. The assay has a specific set of oligonucleotide primers and a FAM/TAMRA probe that target the 5’-UTR of CSFV.

Q. What if I open a foil bag of eight tests and do not use all of them, can I reseal the bag and use the remaining tests at a later date?

Yes, these are dried tests that are stored in a special foil bag that does not allow the exchange of ambient gasses. Color-indicating Desiccants Packs are placed in the pouch containing dried tests to protect the tests from exposure to humidity. Under normal conditions, the desiccant pack should be blue in color. Should the color be pink, this indicates that the pouch has been damaged and the tests should not be used.

If the bag is opened, and some (but not all tests) are used:  The bag with the remaining tests and desiccants should be carefully resealed by folding over the open (several folds), and then taping the entire length of the folded area. The better the seal, the longer the tests will last.  The tests are still good as long as the color indicating desiccant packs remain blue inside the sealed pouch, or the expiration date of the kit, whichever comes first.

Q. I know that the ideal amplification signal should be sigmoidal in shape, but how do I interpret non-ideal curves? 

The package insert describes how to interpret the results. At a minimum, a curve representing PCR amplification must have a sharp rise in the positive direction. The point at which the sharpest rise occurs is called the inflection point. The inflection point corresponds to a second derivative peak that can be viewed by selecting the appropriate graph on the SmartCyler. Figure 1 below shows a low positive in two views, the primary curve and the second derivative plot.

If you have technical questions or concerns regarding this test, contact us.

Figure 1. Shown are the primary amplification curve and the second derivative view of the same curve.