Dr Salerwe Mosebi

In a major contribution by local researchers to provide home-grown solutions in response to the Covid-19 pandemic, Unisa's Dr Salerwe Mosebi is working with mineral research giant Mintek to develop rapid antigen-detecting and antibody-detecting tests with a remarkable 20-minute turnaround time.

Mosebi, a researcher in Unisa's College of Agriculture and Environmental Sciences, says that the intended solution targets the dual challenges of low test availability and slow results turnaround. "In the current and seemingly unyielding Covid-19 pandemic," says Mosebi, "diagnostic testing for SARS-CoV-2 has shown to be crucial to limiting the spread of the virus, identifying hotspots and appropriate management of infected patients. Reverse transcription polymerase chain reaction (RT-PCR) tests are currently the gold standard for the diagnosis of Covid-19. However, their availability remains a concern amid the rising global infections which has resulted in the shortage of these tests and their reagents."

Mosebi says that although molecular diagnostic tests are the gold standard, the need for material reagents, specialised equipment and trained personnel limits the number of tests that can be performed and this results in the saturation of the testing laboratories. "Moreover," he says, "RT-PCRs do not have a very rapid turnaround time."

Thus, in response to the challenges outlined above, Unisa and Mintek are collaborating on the development of Covid-19 rapid tests. Mosebi says that the expected outcomes of the project are clinically validated antigen-detecting and antibody-detecting rapid tests that can also be digitised to a portable test reader for results data management. "The antigen rapid test will also allow faster confirmation of clinical suspicion of Covid-19, leading to earlier isolation, contact tracing and appropriate clinical care of patients with positive results," says Mosebi.

Mosebi says that there is also a need to measure the population prevalence of past infection. "This is where the antibody rapid tests play an important role, as they are vital for the management and surveillance of the virus in the community," he says. "As such, highly specific and accurate antibody tests will help inform clinical and public health decisions about the safe opening of communities, schools, universities, and so forth. Other benefits envisaged include detecting antibodies that may neutralise the virus, identifying donors for convalescent plasma, establishing the prevalence of the disease in the population and, importantly, helping to verify the effectiveness of the vaccines as and when they become available to the general population."

To meet the deliverables, Mintek and Unisa have taken a holistic approach by partnering with other South African institutions and biotechnology companies to develop a local solution that will benefit the country. Mintek has developed a considerable body of trade secrets and know-how relating to the development of rapid diagnostic tests, including the sourcing and optimisation of rapid test materials and maximising sensitivity, and providing speedy results, stability and reproducibility using their gold nanoparticles formulations that enhance the performance of their offerings. The company also has an automated manufacturing facility with a production capacity of 20 million tests per annum.

Dr Mosebi in his natural habitat

With over 20 years’ experience of recombinant DNA technology for protein production and molecular biology techniques, Dr Mosebi has honed in on these areas of expertise to assist the country with Covid-19 diagnostics response solutions in collaboration with Dr Amanda Skepu from Mintek. He has so far successfully utilised the same technology and techniques as those used in his NRF-funded HIV drug discovery project to identify novel drug targets and inhibitors for HIV. Mintek is currently finalising the internal validations of prototypes before the kits are sent out for external validations as part of the South African Health Products Regulatory Authority regulatory requirements.

Additionally, a Mintek-Unisa collaborative proposal submitted in response to the SAMRC-RFA-SHIP-01-2020 Covid-19 diagnostics call, was approved for funding by the South African Medical Research Council (SAMRC) in 2020. Dr Skepu is the principal investigator of the project with Dr Mosebi as the co-investigator. The project was awarded a total of R3 355 325. "This was a grant call specifically for Covid-19 diagnostics projects responding to the pandemic – where only a handful applications were successful from tons of applications," says Mosebi. "This indeed is a feat that talks to the quality of the project and researchers involved."

Mosebi says that this intervention is expected to assist in easing the burden of sourcing testing kits internationally and reduce the reliance on importation. "The SARS- CoV-2 antibodies and antigens, which are key components to the test kits, used in this project will be produced in South Africa, ensuring the availability of the key reagents and circumventing issues of shipping and importation delays that are experienced with the current imported RT-PCR reagents and kits," he says. "The development and use of these tests will also assist in ramping up Covid-19 testing targeted for community surveillance. And lastly, these tests are rapid with a turnaround time of 20 minutes to obtain results. This will ensure that positive cases are identified immediately and isolated/quarantined whilst ensuring that contact tracing is initiated expeditiously."

* Article packaged by Philip van der Merwe, Editor: External Publications, Department of Institutional Advancement