Researchers have identified a highly effective antibody that can neutralize a wide range of SARS-CoV-2 variants, as well as related coronaviruses, raising hopes for better treatments and vaccines against COVID-19 and future pandemics.
While COVID-19 is now considered endemic, much like the flu, scientists remain cautious due to Long COVID and the potential for dangerous mutations. This makes the discovery particularly valuable for public health.
The study, published in Cell Reports Medicine and led by researchers from the University of Texas at Austin and the University of North Carolina at Chapel Hill, focuses on an antibody called SC27. This antibody bridges the gap between vaccine-derived immunity and hybrid immunity, which refers to the stronger protection in individuals who have both recovered from infection and received a vaccine.
Typically, vaccine-induced antibodies target a small portion of the virus’s spike protein, which attaches to human cells. However, hybrid immunity tends to target the spike protein more broadly. SC27 follows this pattern by targeting the virus more comprehensively, enhancing its ability to neutralize the virus, even if it mutates.
“We found these antibodies cover the entire spike, including both the arc and stalk of the protein, similar to an umbrella,” explained Greg Ippolito, co-corresponding author and research associate professor in UT Austin’s Department of Molecular Biosciences. “The immune system sees the entire spike and works to neutralize it.”
SC27 was isolated from the blood of a person who had received an mRNA COVID-19 vaccine and later experienced a breakthrough infection. Laboratory tests confirmed that SC27 neutralized all major SARS-CoV-2 variants, including Omicron strains, which have largely evaded other antibody treatments. Additionally, it neutralized the original SARS virus from 2003 and several bat and pangolin coronaviruses, which could potentially cause future outbreaks.
In a statement from the World Health Organization (WHO) last month, the agency noted that despite COVID-19 no longer being a global public health emergency, the virus continues to circulate, with increased cases reported over the summer in Europe. The WHO emphasized the importance of updated vaccines to reduce hospitalizations and deaths, especially for high-risk groups such as older adults, immunocompromised individuals, and healthcare workers. Updated vaccines also offer greater protection against Long COVID, which can cause long-term health issues like brain fog and cardiovascular problems.
The researchers behind the SC27 study also highlighted the ongoing emergence of SARS-CoV-2 variants and the presence of zoonotic reservoirs—animals that host and allow the virus to evolve. This underlines the need for a comprehensive understanding of how to target these pathogens.
SC27’s broad potential stems from its ability to target a specific region of the spike protein that has remained relatively unchanged as the virus has evolved. Using advanced imaging techniques, the researchers visualized how SC27 binds to the virus, forming an unusually stable connection, which may explain its potency. SC27 exhibited a stronger binding affinity to the spike protein than any other known human antibody, including those previously approved for clinical use.
When tested in mice, SC27 prevented the virus from replicating in the lungs.
The discovery sheds light on how hybrid immunity produces broad and potent antibodies against coronaviruses. The study found that over 60% of the antibody response in people with hybrid immunity stemmed from their initial exposure to the virus, either through infection or vaccination. This “imprinting” effect helps explain why hybrid immunity provides enhanced protection.
The research team suggests that future vaccines could be designed to elicit SC27-like antibodies, offering broader protection against SARS-CoV-2 variants and related coronaviruses. However, further studies are required to determine if SC27 or similar antibodies can be developed into effective treatments or used to guide vaccine development.
