The world may have left Covid-19 behind but the scars of the pandemic are still fresh in the minds of millions who lost their loved ones to the virus that brought the world to its knees a few years ago. To better mitigate any such global health challenge in future, scientists at the University of Texas have made a groundbreaking discovery of a potent antibody that could offer protection against all known variants of the SARC-CoV-2 as well as SARS-like coronaviruses that infect other animals.
Scientists have raised caution over long-term COVID-19 conditions that continue to trigger and that a dangerous mutation may yet be a possibility in future. Therefore the discovery is of significant value for public health. As part of a new study on hybrid immunity to the virus, the team of scientists discovered and isolated a broadly neutralising plasma antibody called SC27, from a single patient.
The researchers have used a technology developed over several years of research into antibody response and obtained the exact molecular sequence of the antibody. The team claims that the discovery has opened the possibility of manufacturing the antibody type on a larger scale and future treatments.
Jason Lavinder, a research assistant professor in the Cockrell School of Engineering’s McKetta Department of Chemical Engineering said, "The discovery of SC27, and other antibodies like it in the future, will help us better protect the population against current and future COVID variants.” Lavinder, is one of the leaders of the new research, which was recently published in Cell Reports Medicine.
The research has come amid another summer COVID spike. It shows that while the worst of the pandemic may have passed, there’s still a need for innovative solutions to help people avoid and treat the virus.
What is SC27 antibody?
The virus has rapidly evolved in the last four years since the COVID-19 outbreak in December 2019 in China. Each variant has shown different characteristics, many of which made them more resistant to vaccines and other treatments. SC27 recognises the different characteristics of the proteins found in the many COVID variants. These capabilities of SC27 were verified by researchers who first decoded the structure of the original spike protein and developed the way for vaccines and other treatments.
The technology used to isolate the antibody termed Ig-Seq, gave researchers a closer look at antibody response to infection and vaccination using a combination of single-cell DNA sequencing and proteomics – a study of proteins to determine their structure, function, and interaction.
Will Voss, who co-led the study explains that one of the goals of this research and vaccinology in general is to have a 'universal vaccine' that can "generate antibodies and create an immune response with broad protection to a rapidly mutating virus."
Testing of the antibody
To develop the antibody that can protect against all COVID-19 variants, the antibody was isolated from the blood of a person who had received an mRNA COVID-19 vaccine and later experienced a breakthrough infection. When researchers tested the SC27 in the laboratory, they confirmed the hypothesis that it could neutralise variants at large.
During the research, it potently neutralised all major Sars-CoV-2 variants, including recent Omicron strains that have largely evaded existing treatments.
Apart from the COVID-19 virus, the antibody even neutralised the original Sars virus from 2003 and the pangolin coronavirus that could potentially spark future outbreaks.
During the testing, SC27 exhibited an extremely strong binding affinity to the spike protein, surpassing all other known human antibodies against Sars-Cov-2, including those previously approved for clinical use across the world.
When the antibody was given to mice for testing before infection with Sars-CoV-2, SC27 prevented the virus from replicating in the lungs.
How does the SC27 antibody work?
The protective antibodies developed by the team of UT scientists bind to a part of the virus called the 'spike protein' that acts as an anchor point for the virus to attach to and infect the cells in the body. The antibody will block the spike protein, preventing this interaction between the body cells and the virus, therefore it will prevent infection.
SC27 antibody appears to bridge the gap between vaccine-derived immunity and what is known as hybrid immunity.
Hybrid immunity – a combination of both infection and vaccination offers increased antibody-based protection against future exposure compared with infection or vaccination alone. Hybrid immunity is intended even for those who have recovered from a natural infection and have also had vaccine shots, they will have strong protection.
The discovery of SC27 emphasises how hybrid immunity - resulting from both vaccination and previous infection - can produce potent antibodies against the COVID-19 virus.
Put simply, the existing vaccine antibody typically targets a small portion of the spike protein of the virus that directly attaches to human cells. The antibodies in those with hybrid immunity will have SC27 target the spike protein more broadly. This antibody targets the virus more broadly, thus becoming better able to neutralise the pathogen even if it mutates.
Implications of SC27 antibody
A statement released by the World Health Organisation last month said that even though it has been more than 12 months since COVID-19 was declared to no longer be a public health emergency, the virus has remained in circulation all around. It triggered a summer wave in Europe with many patients complaining of respiratory illness who had Sars-CoV-2 in primary care. The number of patients hospitalised with COVID-19 increased as well.
UN health body in its statement said that "an updated and effective COVID-19 vaccine is required to reduce hospitalisation and deaths in high-risk individuals. The updated vaccine is required, especially for those with multiple underlying medical conditions, pregnant women, and health professionals who may be easily exposed."
When will SC27 be available?
According to the study, hybrid immunity existed in over 60 per cent of the antibody response in people, which originated from the initial exposure, whether from vaccination or infection. This effect explains why hybrid immunity provides more protection.
The team also suggests that future vaccine strategies could potentially be designed to include SC24-like antibodies, which might offer broader protection against Sars-CoV-2 variants and related coronaviruses.
The researchers have filed a patent application for SC27. As of now, while the results are promising, the effectiveness of the newly discovered antibody is yet to go under massive trial before it’s finally available for people to benefit from. The trial follow-up will continue for at least two years to assess the validity of the vaccine and the protection it will provide.
Unlike COVID-19 vaccines which were given for emergency use, this antibody is more likely to undergo several trials for its bold claims. Further studies would follow to determine if SC27 or similar antibodies could be developed as an effective treatment.
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