What Role Does DNA Polymerase Play In COVID-19 Detection?

2021-01-13 | Future Market Insights | Healthcare

DNA polymerase is one of the key enzymes found in nature that helps in binding of nucleotides. These nucleotides are the core building blocks of Deoxyribonucleic Acid, or what is more commonly known simply as DNA. DNA carries the essential genetic codes that are carried forward from generation to generation. For example, a baby carries the DNA of both its parents and hence has the genetic codes of its father and mother, while still being a unique individual; hence, the DNA of siblings is always similar but not same.

However, the function DNA polymerase assists in is not the genetic function, but rather the duplication function. DNA polymerase helps in creating duplicate copies of existing unique DNA strands, which are then passed on from one cell to another during the process of cell multiplication. This makes DNA polymerase vital for growth and cell rejuvenation in tissues, bones and all other organs. These factors can be applied beyond the human body as well and DNA polymerase has found wide application in DNA testing, cloning and other related biomedical fields.

For application in the biomedical field, DNA polymerase is used to artificially multiply a single DNA strand into numerous duplicates; this is exactly how the process of cloning works. Besides this, DNA polymerase is also used to check two different DNA strands to ensure that they match with each other through a screening process. The core principle in both these applications is that DNA polymerase can transform an undetectable quantity of DNA into a detectable quantity with a near-zero error probability. This same principle is used in the process of detecting a COVID-19 infection in an individual as well.

Incidentally, since COIVD-19 is a virus, it does not consist of DNA, but rather consists of Ribonucleic Acid (RNA). Though almost all organisms contain RNA, viruses are unique in that they consist only of RNA. RNA and DNA are similar in several aspects, but some key differences. For example, RNA consists of only one strand, while DNA has two strands. Similarly, though RNA and DNA each contain four nitrogen-based compounds, only three of them are common (guanine, adenine and Cytosine); the fourth nitrous compound in RNA is uracil, while in DNA it is thymine. However, key among these differences is that RNA contains ribose sugar molecules, while DNA contains deoxyribose sugar molecules, wherein lies the genesis of their nomenclature. Needless to say, DNA and RNA also perform different functions; while DNA transfers genetic data, RNA is only involved in the process of making proteins. Due to this factor, viruses are also sometimes referred to as ‘zombie’ cells.

Despite these key differences, the value of DNA polymerase in COIVD-19 testing hinges on the similarities between RNA and DNA. The key hurdle in COIVD-19 testing is that the polymerase chain reaction (PCR) test, which is widely regarded as a gold standard in testing of most biological materials, detects genetic data rather than proteins. Simply put, the PCR tests is reactive to DNA and not RNA. As a result the challenge is to transform the COIVD-19 virus into a DNA-type stand which can be detected by a PCR test. Fortunately, this is something that has commonly been done for the detection of various types of viruses in the past as well. The key ingredients required to transform COVID-19 virus’s RNA strand into a DNA-type strand is DNA polymerase, reverse transcriptase and other primers, probes and cofactors that can bind with the virus.

In this transformation process, the DNA polymerase first breaks down the RNA while the reverse transcriptase isolates the nucleotides. These nucleotides are then bound together to make DNA strands to which the primers, probes and cofactors can bind. Technically, at this stage the virus should be detectable by the PCR test. However, the response of different PCR tests is based on different minimum detectability thresholds. Hence, it is nearly always necessary to duplicate these DNA stands into adequate numbers for the PCR test to detect the virus. Once these processes are successfully completed, a PCR test will almost always give an accurate result.