Researchers at Sultan Qaboos University have developed a simpler, quicker and cheaper screening test for COVID-19 infections.
A team led by Dr Haytham Ali at SQU has developed the ready-to-use, rapid and sensitive colorimetric Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) based assay for the diagnosis of COVID-19 viral infection.
The test’s development was funded by the COVID-19 Research Programme of the Ministry of Higher Education, Research and Innovation.
“The test can be used in its current status as a screening assay with the advantages of being simpler, quicker (20-30 minutes) and cheaper than the Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR) assay,” Dr Ali, principal investigator of the research project, was quoted in a press release. qRT-PCR is the standard procedure currently in use all over the world, which requires expensive instrumentation.
The idea for the project emerged from the urgent need of a rapid and sensitive COVID-19 test for the prevention and control of the ongoing COVID-19 pandemic. “The colorimetric assay developed is highly sensitive and was able to detect as low as 80 viral genome copies with possible improvement through further adjustments,” Dr Ali said.
Three primer sets were designed by Dr Timothy Holton of SQU, co-principal investigator of the project, based on the complete genome sequence of 41 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, which causes COVID-19) isolat-ed in Oman, targeting the Spike protein gene and the M gene.
The primer set (CoV_S23258) was found to be the most sensitive and specific among the three designed sets.
The RT-LAMP assay was validated by testing 145 COVID-19 clinical samples obtained from SQU Hospital proving a sensitivity of 96.9 per cent and specificity of 94.7 per cent when compared to the validated real-time qRT-PCR assay.
The RT-LAMP assay specificity was tested against SARS-CoV Frankfurt-1 RNA virus and avian corona viruses as they tested negative with the developed assay.
The research team examined the possibility of directly using saliva samples spiked with SARS-CoV-2 RNA that gave the preliminary tests excellent results with the developed assay. Currently, Dr Ali’s team is trying to convert the test into a lyophilised (freeze dried) ready-to-use assay, where water and template need to be added to run the test. Results can be obtained by reading the colour change from red to yellow.
“Once we validate the lyophilised assay, we will proceed with implementing the assay as a point of care test in clinics, airports and other places,” Dr Ali added.
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