How TwistDX helps to detect biowarfare agents and infectious diseases in minutes
Cambridge company's technology can confirm presence of plague, ebola, anthrax, salmonella and more
At the height of the recent ebola epidemic in Africa, a consortium of academics and clinicians trialled a rapid diagnosis test for the disease in Sierra Leone.
Instead of taking hours, or even days, to get a blood sample or swab to a field laboratory and run the standard tests, they found reliable results could be achieved in minutes in the field. Given the infectious nature of ebola, such early diagnosis can be a life-saver.
Meanwhile in Germany, at Georg-August-University in Goettingen, ebola is just one of the infectious diseases – dengue and chikungunya viruses are others – that can be detected using a ‘suitcase lab’ in minutes.
And in Spain, researchers have developed similar rapid tests for biowarfare agents – including plague and anthrax.
All of these tests rely on extraordinarily versatile technology developed by TwistDX, an innovative and growing Cambridge company.
Its platform can be used for food testing – detecting salmonella, listeria and campylobacter – and in agriculture, where it can help find plant pathogens, detect foot and mouth disease or bovine tuberculosis in cattle, or find genetically-modified crops.
German researchers have also developed water hygiene testing using the technology, enabling contaminants to be detected in the field.
And pharmaceutical companies are deploying TwistDX’s platform to screen for cancer drugs.
“We have many proven uses and more than 250 peer-reviewed papers have been published on it,” commercial director Tony Hill tells the Cambridge Independent.
TwistDX’s patented technology uses enzymes to help ‘amplify’ specific DNA or RNA in a sample. Even with just a few copies of the target present, the reaction progresses rapidly, cloning it until it reaches detectable levels, typically within three to 10 minutes.
The technique is known as RPA – or Recombinase Polymerase Amplification – and has got scientists excited with its potential.
So much so, that the international research community has just voted the new liquid form developed by the company – TwistAmp Liquid Basic – as the best new life science product of the year in the Scientists’ Choice Awards 2018, organised by SelectScience.
RPA provides a game-changing alternative to a more established method of detection known as PCR, or polymerase chain reaction.
Offering speed, portability and fewer resources and equipment, it is ideally suited to field or point-of-care tests.
“The benefit of this process is that it occurs at one stable temperature – 37-42 degrees C and optimally at 39, so you have a very low energy demand into the reaction,” explains Tony. “With PCR, you’ve got a thermocycler which requires a lot of energy so it’s not such a portable process.
“RPA can be run at body heat – and there are papers that show this. This makes it portable and easily transferable into the field. It’s also cold chain independent.”
This means it doesn’t need to be refrigerated for short journeys.
“The other great benefit is speed,” adds Tony. “As soon as you’ve formed the daughter strand, the reaction continues exponentially until you run out of energy.” While RPA generates detectable levels within minutes, PCR processes – while getting quicker – can take an hour or more. And given that PCR requires thermal or chemical melting, it is typically done in the lab.
“One of the great benefits of RPA is that it’s far more robust in many applications so you have to do less purification or separation of your sample,” says Tony.
“You take your sample of interest – say a plant leaf – typically shake it up in some hydroxide, then put that into a tube, incubate it and put it into your lateral flow device. That process can take 10 minutes.”
The results can be delivered in a number of ways, including on a lateral flow strip, like a pregnancy test. This simplicity means you don’t need to be a molecular biologist to use RPA.
“The great advantage of our technology, given its speed and easy access, is the early identification of the target,” says Tony.
“In human healthcare this is increasingly important. It offers the ability to identify a disease sooner – such as when you’re in consultation with a doctor, so the necessary treatment can be applied.”
In Goettingen, Dr Ahmed Abd El Wahed’s team developed the fully mobile suitcase lab platform to help take this diagnostic power to areas where hospital and lab facilities are limited.
He says: “The suitcase laboratory tests that we have already developed are proving ideal for resource-lacking field settings where sending samples off to a central laboratory and waiting days for the results just would not be feasible. Our latest funded project is to develop a rapid assay as part of a malaria detection program in Nigeria.”
In addition to ebola and dengue, the suitcase lab also detects chikungunya viruses and the deadly visceral leishmaniasis, or kala-azar.
Researchers in Spain proved RPA can be used to detect the potential biowarfare agent Yersinia pestis – which causes bubonic and pneumonic plague.
“Our goal is to create something that will be available in every single part of the world to detect this,” says Olena Mayboroda, of the Universitat Rovira i Virgili. The team were also able to ‘multiplex’ the test, meaning they could detect the agent and other bacteria – such as the one causing deadly tularemia – at the same time.
“It was an extremely exciting moment when we saw the gel and had four clear bands for four different biowarfare agents that were amplified in just 25 minutes in one single tube,” adds Olena.
An anthrax test has also been developed using RPA which could help government agencies, border control and law enforcement separate a white powder hoax from a bioterrorism attack.
In the food and drink arena, RPA can be used to stop pathogens before they reach the consumer.
“We have developed a number of example tests,” says Tony. “They are not regulated for food testing but they show the application for major food pathogens like listeria, salmonella and campylobacter, with a variety of end-point detection methods. We are looking early in the food chain – at the production level. We have inquiries from interested companies in that sector because the economics of being able to clear a product at the point of it leaving the production line are tremendous.
“Our primary business model in food and many other areas is to work with researchers and look to get a product to partners who are active in the applied areas we work in, then ultimately grant commercial rights to the technology to bring a test to market.”
Given its versatility, it is little wonder that TwistDX is setting up a new, larger HQ at Coldhams Lane in Cambridge. Founded by chief executive officer Dr Niall Armes and chief scientific officer Dr Olaf Piepenburg, the company has been operating at Babraham Research Campus, The Officers’ Mess in Duxford and Cambridge Science Park, and is now positioned for growth.
Lead scientist Dr Matthew Forest says: “One of the great things about RPA is that we don’t know what people are going to do with it. The fact that it works at body temperature, it’s isothermal, it’s really easy to do...People are going to do things with it that we hadn’t even thought of.”
How it works
RPA, or Recombinase Polymerase Amplification, uses an enzymatic method to produce detectable levels of the specific nucleic acid being targeted.
It provides a cost-effective, more portable and faster alternative to PCR, or polymerase chain reaction, which uses thermal hybridisation to guide an oligonucleotide primer to its binding site in the template.
RPA uses an enzyme – a recombinase – to help the primer to find its target site using the template. The amplification reaction then progresses rapidly, producing many copies of the target.