The Council of Scientific and Industrial Research (CSIR) has developed a faster way of testing for the severe acute respiratory syndrome coronavirus 2, which causes the Covid-19 disease. The CSIR’s achievement will replace a two-step testing process with a one-step test.
The CSIR is working with local company CapeBio Technologies, which has bought the licence for the technology, to commercialise and roll out the new test. This process is being funded by a grant from the Strategic Health Innovation Partnership (a joint initiative of the South African Medical Research Council and the Department of Science and Innovation – DSI).
The new test still needs the approval of the South African Health Products Regulation Authority. The CSIR hopes that the test will be approved and ready for use by the end of the year.
The current test, that uses samples collected by nasal and throat swabs, is called the polymerase chain reaction (PCR) test. The first step converts the genetic material of the virus – ribonucleic acid, better known as RNA – into deoxyribonucleic acid (DNA) using the reverse transcriptase enzyme. In the second step PCR is employed to produce thousands of copies of the DNA, until there are enough DNA molecules to be detected. Should the test detect this DNA, it means that the original sample must have contained the virus’ RNA, so the test gives a positive result (that is, it detects Covid-19).
The CSIR had previously created a most efficient technology to make the enzyme needed for the second step of the current test. “This enzyme is known as DNA Taq polymerase, and just three grams of the protein, produced in E. coli bacteria in as little as three days, is enough for a billion PCR reactions,” highlighted CSIR senior researcher Dr Lusisizwe Kwezi.
In practice, for a number of technical reasons, this does not mean that a billion people can be tested. One of these reasons is that diagnostic tests for each person must be replicated several times to make certain the results are accurate. What is does mean is that a great quantity of this essential reagent is available in South Africa, and at an affordable price.
Adding the reverse transcriptase enzyme will allow the two-step PCR test to become a one-step test. This will speed up the processing of the tests. For commercial production, plants will be used rather than E coli bacteria.
The expertise that developed this technology is the result of research the CSIR started years ago to supply the South African molecular biology market. “Back then, little did we know how important this would one day be,” he noted. “This just shows how research and development can translate concepts into technology solutions to emerging challenges whilst producing export products.”
“We have the potential in South Africa to respond to this pandemic,” emphasised Kwezi. “We have the know-how, and we are grateful for funding from the DSI.”
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