How has PCR technology been used to diagnose viral infections?

In 2014, the Ebola virus terrorized the world with its deadly spread. PCR technology is an important way to quickly determine if a person is infected with a virus by rapidly replicating a specific section of DNA. This technology has been essential in the diagnosis of COVID-19 as well as Ebola, and has contributed significantly to the management and prevention of many infectious diseases.

 

Throughout 2014, the Ebola virus terrorized people around the world. The Ebola virus is deadly, with a fatality rate of 50-90% within a week of infection. But more important than its lethality is how quickly the virus spreads. In the 14th century, the Black Death swept across Europe, killing as many as one-third of Europe’s population. The Ebola virus started in West Africa, but like the Black Death, it has spread around the world and has been called the Black Death of the 21st century. In response, countries have implemented various tests for people traveling from abroad to prevent the virus from entering their countries. For example, on December 29, 2014, the U.S. Food and Drug Administration (FDA) approved the emergency use of the Light Mix Ebola Zaire rPT-PCR Test, a diagnostic kit that can identify infection with the Zaire-type Ebola virus, a type of Ebola virus, for rapid initial diagnosis. So, how is PCR technology applied to the Light Mix Ebola Zaire rPT-PCR Test, and how can it be used to detect infection with the virus?
When a virus invades a host cell, it replicates its nucleic acid and combines it with the host cell’s nucleic acid. Nucleic acids are the DNA and RNA that contain the genetic information of an organism. In the case of Ebola, the virus’ nucleic acid binds to a specific part of the nucleic acid of an infected person, which can be compared to that of a non-infected person. The problem with this is that the amount of nucleic acid needed is large, which is easily solved by using PCR technology. PCR is short for Polymerase Chain Reaction, which means polymerase chain reaction. DNA is made up of two strands linked together, and to replicate DNA, you need to separate the two strands and attach a nucleotide, the basic unit of DNA, to each single strand. Nucleotides are composed of phosphate-sugar-bases, and there are four types of bases, A, G, C, and T. The order in which these four types of bases are arranged determines the genetic information. The phosphoric acid and sugars act as a skeleton that wraps around and protects these bases. Also, bases on one strand are hydrogen bonded to bases on the other strand.
More specifically, PCR technology can be broken down into two steps. The first is DNA denaturation, which involves heating the DNA to 90 degrees Celsius to break the hydrogen bonds between the bases and separate the DNA into two single strands. Let’s call these two strands A and B, respectively. The second is DNA synthesis. A nucleotide is attached to the separated single strand A, and when the nucleotide is repeated, a new single strand is created that is exactly the same as single strand B. The amount of DNA is thus doubled from the original. The connections between nucleotides on the same strand are atom-to-atom covalent bonds, which are much stronger than hydrogen bonds and require a pool to support them. Taq DNA polymerase acts as this pool.
PCR is important because it can replicate specific sections of DNA at high speeds. It’s used to extract DNA from hairs left at crime scenes and replicate them in large quantities, and it’s also used to amplify DNA to test for viruses.
In early 2020, the COVID-19 pandemic hit the world. The COVID-19 virus was also diagnosed using PCR technology. Due to the high contagious nature of COVID-19 and its diverse clinical manifestations, early diagnosis and isolation were crucial. Countries tried to use rapid PCR tests to identify infected people and prevent the spread of the disease. PCR tests amplify the RNA of the COVID-19 virus to determine whether a person is infected, allowing for a quick and accurate diagnosis. As a result, PCR technology has become an essential tool for diagnosing and preventing the spread of the pandemic.
As such, PCR technology is an important way to quickly identify viral infections and has contributed to the management and prevention of many infectious diseases.