The PCR test : more than a diagnostic tool – a trust-enabling technology.
Philippe GILLET, Chief Scientific Officer at SICPA, shares with us his thoughts on PCR as a trust-enabling technology that has made a positive impact in a multitude of diverse fields, causing a true paradigm shift.
During the pandemic new words have entered our vocabulary. Among them ‘PCR’. Previously used only by biologists and doctors, you might hear the term today in any pub or café – at least if they were open! Invariably it refers to the rather unpleasant nasal swab which is a key part of a Covid test. The full name is less useable, but rather more informative: polymerase chain reaction. It amplifies – or duplicates – a DNA sequence, of for example a virus. Above a certain threshold the virus is detectable and readable. It can thus give us information.
PCR is an excellent example of what we call technologies for trust. In its current use, the stakes are clear: we want to know whether or not we have contracted a potentially deadly virus. But PCR can do much more. It can serve to diagnose not only viruses but also bacterial and fungal infections. Scientists are working on its use for detecting cancer.
PCR is also an example of the application of technologies for trust in non-medical spheres. In forensics, it allows individuals to be identified on the basis of traces of DNA left at the scene of a crime. In food, simple cheap tests calibrated to identify horse DNA would have prevented the well-known lasagna scandal. The same approach can be used to identify or confirm fish species being sold. There is much at stake: whilst many species are threatened by over-fishing, more than 30% of sea food products is mis-labelled. The preservation of marine life depends on better traceability.
The PCR is the “swiss knife” of technologies for trust. It owes its versatility to the molecule which it amplifies: DNA. DNA is remarkably stable. It allows life in extreme environments – be it due to temperature, acidity, salinity or ionizing radiation. In good conditions, a DNA strand remains readable for around one and a half million years. By comparison, the durability of digital media can be measured in decades and Sumerian script is often unreadable after some thousands of years of erosion. But after three billion years of uninterrupted challenges – the beginning of life on earth is a disputed topic – DNA continues to prove its worth.
DNA is also surprisingly compact. A single gramme of this molecule can contain the equivalent of 215 million gigabytes – the equivalent of 400,000 average capacity laptops. This is the reason why a number of companies are working on projects which aim to store digital data in DNA.
Both miniscule and very hardy, DNA leaves millions of invisible, enduring traces in the environment. A multitude of messages all around us, a whole library of information to which PCR gives us access. Humans, animals and above all microorganisms reproduce and shed this molecule everywhere. In waste water we can find enough DNA of SARS-CoV2 to be able to estimate relatively precisely the progress of the pandemic in a given town.
Even more surprising, various types of microorganisms are the trademarks of local ecosystems. Every region, even every home, office or factory are different biotopes in themselves, carrying a unique DNA signature. This is why clothes made in Vietnam or Turkey do not have the same DNA – no more than Indian or American cotton. This is the basis for the Californian start-up Phylagen to develop a supply chain traceability system. The goal: to determine whether or not products have followed the official supply route, provide assurance that environmental norms have been respected, trace counterfeits, fight against the exploitation of workers.
Researchers at Harvard have taken the concept even further. They use DNA to label products. They introduce bacterial or yeast genomes into inactive DNA sequences. What they add has no biological role: it just contains information. Used to mark fruit or vegetables, the microorganisms carry this information all along the supply chain. With PCR we can detect this invisible barcode and thus trace the origin of products.
Tracing agri-food products this way may face resistance – even though such microorganisms are present in their billions in our environment, like beer yeast Saccharomyces cerevisiae for example. The same process can be used to mark a pair of shoes or any consumer good.
PCR is not an ancient technology. Since its invention in 1983, it has evolved in various ways becoming more precise and accessible. Among the new generation processes, we can mention the Swiss start-up SwissDeCode. Its technology for amplifying DNA is much less demanding that classical PCR in terms of equipment and temperature. SwissDeCode is currently developing its on solution for detecting food contaminants.
Before the discovery of CRISPR in 2012, DNA editing was a laborious and costly process, reserved for a small number of highly specialized laboratories. What used to take several months and costed thousands of dollars, can now be done in a few hours for fifty dollars. Any biological lab can modify whole genome sequences. It was the accessibility of this technology which earned its two inventors the Nobel prize for Chemistry in 2020. It is also this technology which opens the way to fraud. At the moment DNA cannot be changed as easily as text on a computer, but every year this prospect is getting closer.
Technologies for trust like PCR, but also credit cards, blockchain or GPS satellites or just good old bank notes, are part of a large system which we call ‘the economy of trust’. A system based on old and new technologies which allows us to verify that a client is solvent, that a product or a service is up to standard, that a transaction is secure. During the pandemic, PCR has helped ascertain the infectiousness of people – tourists, customers, workers.
Trust is not simply an economic “lubricant”, it is a necessity. This is why PCR has a key role to play. In 2019 it generated a USD 398 million turnover – in 2027 this will grow to over a billion dollars according to Research and Market. Such estimates are no doubt rather conservative and don’t take into account medical and forensic applications. Given its potential to certify supply chains and to assure the traceability of products, PCR has so many applications that its future can only be very bright.
The French Version of this article is available here: Au-delà du diagnostic, la PCR est une technologie de la confiance – Heidi.news