CSIR says it can make enough enzyme for one billion chemical reactions that can be applied in COVID-19 testing
After a two-day streak of cases below the 10 000 mark, South Africa’s new COVID-19 cases were at 11 362 on Wednesday.
This brings the total number of COVID-19 cases in South Africa to 471 123.
Gauteng tops the chart with 168369 cases recorded which accounts for 35.7% of the total infections.
The Western Cape comes in second with 98 737 cases followed by Eastern Cape with 75 872 cases.
Free State has 19207 cases, KwaZulu-Natal 71240, Limpopo 7840, Mpumalanga 12442, North West 18231, Northern Cape 4135, while 50 cases are yet to be allocated.
The country recorded a further 240 deaths bringing the total number of deaths to 7 497.
Eastern Cape accounts for 34 deaths, 156 from Gauteng, 27 from KwaZulu-Natal, and 23 from Western Cape.
“We convey our condolences to the loved ones of the departed and thank the health care workers who treated the deceased,” said Health Minister, Dr Zwelini Mkhize.
The number of recoveries currently stands at 297 967 which translates to a recovery rate of 63%.
The total number of tests conducted to date is 2 873 163 with 42 528 new tests conducted since the last report.
Meanwhile the Council for Scientific and Industrial Research (CSIR) says it can make enough enzyme for one billion chemical reactions that can be applied in COVID-19 testing, and researchers hope to begin supplying reagents for a faster, one-step test by the end of the year.
Current polymerase chain reaction (PCR) tests for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in nasal and throat swabs involve two steps.
Firstly, the virus’s genetic material, its RNA, must be converted to DNA using an enzyme called reverse transcriptase, in a reaction called RT-PCR.
Secondly, PCR is then used to make thousands of copies of the DNA, until there are enough of these tiny molecules to detect.
If the test detects the targeted DNA copies, there must have been viral RNA in the sample, hence the test is positive.
“The CSIR has already established a highly efficient technology to produce the enzyme needed for the second step,” says senior researcher Dr Lusisizwe Kwezi.
“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,” Kwezi said.
This does not equate to COVID-19 tests for a billion people because, among other technical reasons, diagnostic tests must be carefully repeated several times for each patient to ensure accurate results. But it does mean that a huge amount of this important reagent is available locally and affordably.
Another benefit of the reagent mix is that it contains a special antibody that stops the Taq enzyme from working when it is not needed. This makes it more specific when it has to amplify DNA during the PCR reaction, and more robust for potential future point-of-care testing devices.
Kwezi said earlier this month, the CSIR delivered a 3 g batch to local company CapeBio Technologies (Pty) Ltd, which has licensed and commercialised the technology.
It will be rolled out to support the national testing effort as soon as CapeBio gets approval from the South African Health Products Regulation Authority (SAHPRA).
Thanks to funding just awarded through the Strategic Health Innovation Partnership – a partnership between the South African Medical Research Council and the Department of Science and Innovation (DSI) – the CSIR and CapeBio are now working to add the reverse transcriptase enzyme to the mix as well, so that the two-step COVID-19 PCR test can be done in a single step. This will reduce the turnaround time of tests.
The antibody will be produced in plants rather than in E. coli, and Kwezi says the resulting one-step kit could be ready for national roll-out within six months, pending SAHPRA approval.
He said local availability of large amounts of such affordable ‘plug-and-play’ reagents, which also allow for faster results delivered to patients, will be critical in managing the pandemic in the long-term.