SCIENTISTS have designed a rapid, portable Covid-19 test that can provide results on a smartphone.
Its developers claim that it could broaden access to affordable testing in regions that lack expertise, infrastructure, and specialized equipment for laboratory-based testing.
SARS-CoV-2 — the coronavirus that causes Covid-19 — has infected more than 26 million people worldwide. Accurate testing is key to controlling the virus and reducing transmission.
Currently, the real-time reverse transcription-polymerase chain reaction (RT-PCR) test is the best way to test for SARS-CoV-2 infection.
In this test, the RNA — a single-strand molecule — goes through reverse transcription. In this process, an enzyme converts the RNA into double-stranded DNA.
After reverse transcription, scientists copy specific regions of the genome, using the PCR process. Then, they introduce primers, which are small sections of DNA that bind to particular DNA sequences of the SARS-CoV-2 genome.
The scientists then insert a fluorescent dye (also called a probe), the swab sample, and the primer into a PCR machine. The scientists register the sample as positive for SARS-CoV-2 if fluorescent signal marks appear.
The United States, Europe, and Asia use the RT-PCR tests widely. While these standard tests are highly scalable, their greatest limitation is that they require a laboratory set-up.
The test needs to run through different temperatures in each cycle to amplify the viral genetic material so that scientists can analyze it. This increases waiting times for results in regions that do not have access to the infrastructure and expertise required for RT-PCR tests.
The team of researchers explained how they developed a prototype test. According to their paper, the test can detect the SARS-CoV-2 virus in less than 40 minutes by using a hand-held reader, 3D-manufactured cartridge, and a smartphone.
Instead of relying on amplification of the viral genetic material by running it through 35–40 different cycles with varying temperatures, the new prototype test uses a far simpler process.
Known as loop-mediated isothermal amplification (LAMP), scientists developed this testing method 20 years ago and have used it as a more cost-effective alternative for amplifying DNA.
Scientists have already used this technique to detect the DNA in tuberculosis and malaria.
More recently, scientists have developed RT-LAMP (reverse transcription-LAMP) to detect RNA in viruses, such as HIV.
