DNA probes for the fast detection of SARS-CoV2 and influenza virus

The probes, which can be integrated into different types of devices, can detect RNA sequences of the targeted viruses within minutes, without the need for RNA extraction, purification and PCR amplification. The technology is currently available for further development through agreements with pharmaceutical and diagnostics industry partners.

With the COVID pandemic, real-time PCR (RT-qPCR) has become the gold standard test for population diagnosis. However, although PCR can detect SARS very specifically, it requires long processing times, as the sample needs to be extracted and the viral RNA amplified. In addition, tests must be performed in specialised laboratories, as specific instrumentation is needed, which further delays results.

Antigen kits, on the other hand, are faster but have less sensitivity and specificity, so they can produce false negatives or false positives if they detect viral RNA other than that of the virus in question.

Scientists from the Instituto de Química Avanzada de Cataluña of the CSIC, the University of Barcelona and CIBER have developed a rapid, sensitive and reliable biochemical strategy that allows a test to be performed at the point of patient care, on the spot, without specialised equipment or highly trained personnel. It can also be used in high-throughput multiplexed laboratory platforms to increase efficiency and reduce processing time.

The strategy is based on the use of innovative DNA probes containing polypurine reverse Hoogsteen hairpin (PPRH), a type of molecule that has a high affinity for SARS-CoV-2 RNA and influenza viruses.

Less than 20 minutes

The researchers have optimised the method in four different diagnostic devices (a thermal lateral flow device, an electrochemical PoC biosensor, an ELISA microplate and a fluorescent microarray) that can achieve detectability close to that achieved by other molecular methods, but without the need for PCR amplification. This makes the method a faster and cheaper option.

Quantification of viral RNA can be achieved in less than 20 minutes after sample collection. Among its advantages is its high sensitivity, as it has detection limits comparable to RT-PCR tests. It is highly specific, so it can differentiate SARS-CoV-2 from other viruses such as influenza (H1N1). The method is useful for routine on-site diagnosis of SARS-CoV-2 and influenza, as well as for high-throughput diagnostic screening.