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Published On: April 25th, 2023Categories: Articles, PCR/DNA Extraction and Purification

General DNA Processes

The general public wasn’t too familiar with polymerase chain reaction (PCR) and antigen tests before the COVID-19 pandemic. The intricacies of both types of testing may still be a mystery to some folks—for many, the type of test that mattered was the one required by their employer or school. For example, in the early days of the COVID-19 pandemic when tests were first available, many institutions would only take PCR results to disprove the presence of COVID-19 because they are more authoritative.

Read on to learn more about PCR testing, how it differs from antigen testing, and equipment like robotic PCR machines that you need in your laboratory.

What Is PCR Testing?

While PCR and antigen testing have been used for testing for illnesses other than COVID-19, most people are familiar with them because of the pandemic. When testing for COVID-19, a nasal swab is used for both tests.

On this nasal swab is a sample of ribonucleic acid (RNA). Researchers amplify the RNA in a lab to detect the presence of a virus. A PCR test can detect even the smallest trace of a virus. To perform the PCR test, short single-stranded DNA that promotes the synthesis of a complementary strand of nucleotides is used as a primer, an enzyme (DNA polymerase) is used to aid in the synthesis, and a nucleotide solution mix containing adenine, thymidine, cytosine, and guanine are used to build duplicate DNA strands. The fourth reagent needed is the sample itself.
The PCR testing process has four steps:

  • Collection
  • Amplification (PCR machine steps occur here)
  • Amplification
  • Post-PCR cleanup

Using a liquid handling robot for PCR, there will be four additional steps during the amplification process: denaturation, annealing, and extension. Analysis with electrophoresis is the fourth and final step. During PCR, an automated PCR setup robot and PCR pipetting robots work together. DNA is placed in a tube along with the other reagents and chemicals. The tube is then placed in a thermal cycler or other PCR machines. The thermal cycler takes the DNA through the first three steps listed above. PCR is incredibly accurate, however, the major drawback is the time it takes to receive PCR test results, which typically range from 24 hours to several days.

What Is Antigen Testing?

Instead of looking for the virus as in a PCR test, an antigen test looks for proteins found outside a virus. An antigen test acts like an antibody, which is a “fighter” that attaches itself to antigen proteins. When the genetic material is taken from the sample swab and placed into a liquid, the liquid in the test strip will attach to the protein like an antibody if the virus is present. This indicates that a virus is in the body, but it is not as accurate as PCR testing. Proteins are not as conclusive as the actual virus itself.

However, in a post-COVID world, many institutions take antigen testing to disprove the presence of COVID-19. Also, results are available as quickly as 15 minutes later, and patients can self-administer the test at home.
Both tests certainly have their place; if speed is needed over accuracy, then an antigen test works well. However, PCR testing is the gold standard to accurately detect a virus if accurate results are needed without question (such as before a medical procedure).

What Equipment Is Needed in a PCR Testing Lab?

You’ll require certain equipment outfitted in the lab for PCR testing. Admittedly, even with automation, PCR can be a slow process, so automated PCR equipment is needed. In addition, you’ll need a PCR machine, such as a thermal cycler, and liquid handling robotics for setup and pipetting. Centrifuges, refrigerators and freezers, pipettes and pipette tips, and an electrophoresis system for analysis are staples of a PCR lab. Some more details of what you need include:

  • Pipette tips and other consumables. Opt for filter pipette tips for your PCR pipette, which avoids contamination and the entrance of aerosols. For other consumables, have vials on hand to aliquote PCR reagents into smaller containers.
  • Laminar flow or biosafety cabinet. This is where you set up PCR reactions to avoid contamination and the introduction of aerosols into the environment.
  • Bleach solution and distilled water. You should always have these items on hand to decontaminate consistently.

Interested in learning more about completing and setting up your lab for PCR testing? Contact a Hudson Robotics representative today for a quote.