The pandemic has provided the opportunity for many private labs to plunge into the market of molecular testing. During my time at Biocept, I was able to experience this emerging service firsthand, shaping key lab skills in a fast paced setting. My primary role at the company was to facilitate the extraction of viral RNA from received samples to be later processed by RT-PCR. This required skills such as attention to detail, the ability to multitask and work under pressure. The diagram below better describes the workflow of sample processing.
First, a swab is used to collect a mucous sample through the nose from the pharynx at a testing site (a). That swab is then placed in a tube with solution for preservation and sent to the lab.
The sample is transferred from the tube onto a plate where it is mixed with primers and a solution that contains polymerase, an enzyme that promotes DNA replication and is the key ingredient in PCR. However, it is important to note that the virus which causes COVID-19 has an RNA genome. In order to effectively leverage the function of polymerase, the RNA from the sample must be extracted and transformed via reverse-transcription into DNA(c). The extracted RNA is then placed into a thermocycler with a protein that promotes reverse transcription. This allows for the genetic code to be multiplied to detectable levels. Promoters within the mixture act as the railing on a bowling lane, only allowing for the reaction to take place within a region of interest on the DNA. The machine is looking for certain regions of DNA to become increasingly more present, typically regions containing genes known to be found within the viral genome. A "positive" is determined if certain quantities of these DNA regions are present, indicating virus within the sample (e).