Applications of Recombinase Polymerase Amplification technology

TwistDx’s TwistAmp® research kits provide ideal tools for researchers to develop tests, assays and kits relevant to their work in fields as diverse as water testing and biodefense, or food species verification and clinical or veterinary diagnostics. TwistDx can work with partners on specific assay development collaborations for research and commercial applications.

Below is a snapshot of why and how we think RPA is ideally suited to the development of rapid, highly sensitive and portable kits that can detect, diagnose and monitor in real-world settings.

Agriculture
RPA is a robust and highly sensitive technology for the development of seed testing, pathogen identification and other agricultural assays, including species authenticity testing. The isothermal amplification technology is relatively resistant to plant phenolics and other plant inhibitors of PCR, and for some applications RPA has been shown to work on crude plant samples with high specificity and sensitivity, removing the need for further nucleic acid purification. The ability to use RPA with simple, deployable lateral flow units and other disposable or battery-operated devices means that simple, highly portable assays might be developed for use in crop fields, forests and resource-limited laboratories or satellite facilities.

Biodefence
RPA could have huge potential to save lives in the biodefense sector, where assay portability, speed and reliability are essential both for routine and emergency applications. The technology could be used to develop highly sensitive and easy-to-use tests for environmental monitoring, and kits for use in pressured or volatile situations by first responders to test powders, liquids, surfaces and other materials or samples.

Water testing
RPA represents an ideal solution for on-site microorganism testing of both potable water and raw groundwater lakes and rivers. Generating results quickly and without the requirement for sample preparation, RPA could be adapted to highly portable, easy-to-use disposable test kits that water utility companies could use for scheduled or ad hoc coliform or Cryptosporidium testing of reservoirs and tap water, and environmental bodies could use to test natural water courses for polluting species.

Food testing
TwistDx has developed a range of TwistAmp®, TwistFlow® and TwistGlow® research-only assays for food testing. We currently offer ready-to-use kits for detecting Salmonella, Listeria and Campylobacter. These kits provide a flavour of the potential uses of RPA in the food industry, and we encourage our users and partners to harness the TwistDx reagents, TwistAmp® test kits and devices to develop their own food testing and species verification applications.

Medical diagnostics
Fast diagnosis of infectious diseases can literally save lives, both by enabling appropriate treatment to start immediately, and by controlling spread. It’s not hard to see how RPA could feasibly be harnessed to develop point-of-care, near-patient and field-use diagnostics that provide on-the-spot results. With on-site testing there is no need to recall patients back to a clinic or field site for their results and to give them their medication. Treatment can instead be started as soon as results are viewed. This is a major advantage in rural or remote areas where patients have to travel considerable distances and communication is difficult. Contrast the use of an on-the-spot RPA test with the requirement to send clinical samples off to centralised laboratories for PCR testing, or for microbiological culturing that can take 48 hours or more. We are encouraged that users are harnessing RPA to develop rapid tests for some of the world’s most deadly diseases. The work of one research group in the UK to develop an RPA-based field kit is described further on our Innovators page.

Microfluidics
RPA demonstrates a number of features that make it well suited to a diverse range of microfluidic devices. Published research has also demonstrated that RPA can easily be applied to standard digital formats. Unlike PCR, RPA is isothermal, works at a relatively low optimum temperature and can tolerate off temperatures and temperature fluctuations. This means that thermal control in very small, compartmentalised microfluidic device volumes is simplified. There is no need for preheating the master mix before delivery into the system, and at a low isothermal temperature the effects of evaporation and condensation are not a major problem. In addition, RPA has been shown to work well with surface-immobilised primers. These attributes are facilitating the design and engineering of new chip formats and structures.  

Veterinary
The advantages of RPA in veterinary medicine are similar to those for human diagnostics. Whether for detecting diseases in domestic pets or monitoring the prevalence of economically important infections in agricultural livestock, RPA can be harnessed to develop rapid, highly sensitive and specific tests that can be used in the lab, at a veterinary centre or at farms and other field sites. RPA-based tests could also be used at country borders, markets and other major sites of livestock sale and transportation, to monitor and potentially help to prevent the spread of infectious diseases on a national or international scale. Our Innovators page describes the work of one group of researchers who are exploiting RPA to develop a rapid, accurate test for bovine tuberculosis in cattle.