Health care providers need an assay that detects the nucleic acids, the DNA or RNA from the pathogen, in both biological and environmental samples at the point of care, offering a flexible “single source” solution. A tool that can detect multiple diseases would be valuable not only in terms of protection, but in terms of affordability. Costing upwards of $200 a test, traditional diagnostic tools are expensive at scale.
In an effort funded by the Defense Threat Reduction Agency’s Joint Science and Technology Office, Dr. Steven Benner from the Foundation for Applied Molecular Evolution (FfAME), is working to developing developing a turnkey, adaptable and cost-effective device to test for several pathogens in a single assay. The device will not require laboratory diagnostic tools and can be used with minimal training.
Molecular Beacons
As reported in the Journal of Virological Methods article “Standard and AEGIS Nicking Molecular Beacons Detect Amplicons from the Middle East Respiratory Syndrome Coronavirus,” the on-site reporting capability showed the adaptability of the diagnostic tool to detect a coronavirus (CoV) that causes the Middle East Respiratory Syndrome (MERS).
Dr. Benner utilized a previously discovered DTRA-supported tool, the artificially expanded genetic information system (AEGIS), to create the new, high sensitivity diagnostic tool with low noise. AEGIS works by adding nucleotides to the four found in standard DNA and RNA, pairing orthogonally to the A:T and G:C pairs.
Molecular beacons containing AEGIS then generate florescent light signals, detectable at points of sampling, where it can be read on the spot or captured by a cell phone camera for transmission to a remote site for evaluation and epidemiological use. Placing AEGIS components in the stems of molecular beacons lowers noise (thus reducing the ‘signal to noise’ ratio) by preventing unwanted cross-reaction with natural DNA that is abundant in natural environmental and human diagnostic samples.
As a further innovation, the diagnostic kit engineers the beacon so that a single target molecule turns over multiple copies of the beacon, allowing it to amplify the signal, increasing the sensitivity of the assay.
Combining these technologies allows the detection of as few as 50 copies of MERS-CoV RNA in the form of a green glow visible to the human eye, significantly stronger than existing point-of-sampling kits. In addition to detecting MERS, it provides accurate results in detecting influenza A and B, severe acute respiratory syndrome (SARS) and human respiratory syncytial virus (RSV); all viruses easily confused with the symptoms generated by MERS.
Adapted from DTRA Chemical and Biological Technologies Department
