What is SARS-CoV2 | COVID-19 RT-PCR testing ?
In living organisms such as animals, plants, and microorganisms including viruses, their genetic material exists in two forms. One form is known as DNA (deoxyribonucleic acid), while the other form is known as RNA (ribonucleic acid). While humans have DNA as their genetic material, the SARS-CoV2 (COVID-19) virus has RNA as its genetic material. When the COVID-19 virus infects the host cells, it replicates its RNA genome, to produce complete full length copies of its genome that are then incorporated into new viral particles. These new viruses then infect additional host cells, and the viral infection-replication cycle subsequently repeats over and over. The SARS-CoV2 (COVID-19) RNA genome is about 27 to 32 kilobases in size and it contains six (6) main functional Open Reading Frames (ORFs). These ORFs are essentially physical regions of the SARS-CoV2 (COVID-19) RNA genome which encode genes. The six (6) main genes of the SARS-CoV2 (COVID-19) genome are: ORF1a/ORF1b (encodes the replicase protein), S (encodes the spike protein), M (encodes the membrane protein) and N (encodes the nucleocapsid protein). There are also seven potential additional ORFs that encode accessory proteins, and these are scattered among the locations of the six (6) main ORFs of SARS-CoV2 (COVID-19) RNA genome. When a person’s specimen, such as nasal swab, throat swab, nasopharngyeal swab or even saliva is collected, scientific and/or diagnostic methods are used to detect the absence or presence of a genetic region or fragment that is specific to the SARS-CoV2 (COVID-19) RNA genome; such as in one or more of the Open Reading Frames (ORFs) described. SARS-CoV2 | COVID-19 RT-PCR testing is currently considered the gold standard for the detection of SARS-CoV2 | COVID-19.
Polymerase chain reaction (PCR) is an outstanding technique used to amplify, or copy small fragments of genetic material into larger quantities thereby making it easier for the genetic material being examined to be detected by various scientific, or medical diagnostic equipment. PCR could also be thought of as making photocopies of small fragments of genetic material. In fact, PCR is very accurate and sensitive in doing so to detect the absence or presence of genetic material in a specimen. However, PCR can only be undertaken on DNA fragments. Since the SARS-CoV2 (COVID-19) virus has RNA as its genetic material, the SARS-CoV2 (COVID-19) RNA is first converted into DNA in a process called reverse transcription (abbreviated as RT). Small pieces of DNA fragments known as PCR primers and probes are then used to bind to specific regions of the SARS-CoV2 (COVID-19) DNA genome made by reverse transcription. The region between the sites of the SARS-CoV2 (COVID-19) genome that is bound by the PCR primers and probes is then amplified or copied in repeated cycles of up to 45 times, in a process known a RT-PCR (Reverse Transcriptase Polymerase Chain Reaction). When the RT-PCR amplification process occurs, the fluorescent dyes attached to the PCR primers and probes can be detected and quantified in Real time. If SARS-CoV2 (COVID-19) genetic material is not present in the specimen examined, then after all the cycles of RT-PCR amplification are completed, there will be no or extremely very low background levels of detection of the fluorescent dyes and probes used in the RT-PCR. If SARS-CoV2 (COVID-19) genetic material is present in the specimen examined, then at early to moderate stages of the cycles of RT-PCR amplification, there will be the detection of the SARS-CoV2 (COVID-19) genetic material.
What do the results mean with COVID-19 RT-PCR testing ?
A positive result means that the SARS-CoV2 (COVID-19) genetic material was detected in the specimen examined in the duration of cycles used in the RT-PCR amplification process.
A negative result means that the SARS-CoV2 (COVID-19) genetic material was not detected in the specimen examined in the duration of cycles used in the RT-PCR amplification process.
A false positive result means that there was detection of genetic material in the specimen examined in the duration of cycles used in the RT-PCR amplification process. However, this could be caused by the presence of interfering or similar genetic material to the SARS-CoV2 (COVID-19) genome that was collected with the person’s specimen.
A false negative result means that the SARS-CoV2 (COVID-19) genetic material was not detected in the specimen examined in the duration of cycles used in the RT-PCR amplification process. However, this could occur when the there is not enough SARS-CoV2 (COVID-19) genetic material in the specimen for the RT-PCR test to detect it. This can happen early after a person is exposed.
Both false positives and false negative results very rarely occur. However, in general, false negative results are much more likely to occur than false positive results.
To learn more about CEN4GEN COVID-19 RT-PCR testing options or to order a test, contact CEN4GEN at [email protected], and a representative will guide you with the testing process and provide relevant information for you and your healthcare provider. CEN4GEN is an award winning corporation with global recognition and leadership in molecular medicine / molecular diagnostic medicine; and offers COVID-19 RT-PCR testing services in Edmonton, Alberta, Canada.