Breaking Down PCR Diagnostic Testing

June 26, 2020

Many diagnostic tests for infectious diseases use a technology called polymerase chain reaction (PCR) to determine if a patient is infected with a virus or other pathogen. PCR-based testing works by amplifying a very small amount of genetic material to create millions to billions of copies so that there is enough for it to be detected and analyzed.

PCR testing — particularly when using high throughput instruments — requires far more than just the test itself. There are actually several different consumables required to get to the result, which we break down for you here.



What “Ingredients” Do You Need to Perform a PCR Test?

 

Sample Collection Components: Materials required for collecting a sample from a person’s throat or nose:

Nasal swab used to collect the sample by a healthcare provide. Sample collection swabs are designed specifically to be used for PCR testing and differ from household cotton swabs such as Q-tips
Testing tube containing a solution called viral transport media that protects the integrity of the sample within the tube during transport to the lab
Common laboratory tool known as a pipette used to transfer the sample from the collection tube into a secondary tube where it will be readied for analyzation with other patient samples. Note that not all samples need to be pipetted, as this depends on the type of test.

 

Test-Specific Components: Ready-to-use test kits that include all the components needed to extract the RNA from the patient sample and optimize it for PCR. Each kit includes:

A premixed solution, called a PCR master mix, that contains a complex blend of biochemicals, called reagents, and other components necessary to run the PCR test
Essential compounds to multiply and amplify the genetic material
Positive and negative controls that are run with every batch to ensure the test is functioning properly

 

Non-Specific Test Components: Also known as omni reagents because they are test agnostic

Manufacturer-specific racks for holding sample tubes, pipette tips to transfer samples onto processing and amplification plates. Up to 96 samples can be processed on a single plate
Manufacturer-specific chemicals that are typically kept readily available in labs as they are used for many kinds of tests used to detect pathogens – from HIV to the human papillomavirus (HPV) to SARS-CoV-2. They are used to prepare the sample for analysis by breaking open the cell, extracting the RNA and purifying it