The findings suggest that a component of this protein, called viral polymerase, could potentially be added to COVID-19 vaccines to elicit a long-term immune response and increase protection against new variants of the virus.
Most COVID-19 vaccines use part of the spike protein on the surface of the virus to make the immune system produce antibodies. However, newer variants – such as delta and omicron – carry mutations in the spike protein, which may make them less recognizable to immune cells and vaccine-stimulated antibodies. The researchers said a new generation of vaccines is likely to be needed to create a stronger and broad-based immune response capable of beating current variants and those that may emerge in the future.
One way to achieve this was to add to the vaccines a fragment of a different viral protein – one that is less prone to mutations than the spike protein and that activates T cells in the immune system. There are molecular receptors on the surface of T cells that recognize foreign protein fragments called antigens. When a T cell encounters an antigen recognized by its receptor, it replicates on its own and produces more immune cells, some of which target and kill the infected cells immediately and some that remain in the body for decades to fight the same infection if it ever returns.
The researchers focused on a viral polymerase protein found not only in SARS-CoV-2 but in other coronaviruses, including those caused by SARS, MERS, and the flu. Viral polymerases act as motors for the coronaviruses to make copies of themselves, allowing the infection to spread. Unlike the spike protein, viral polymerases are unlikely to change or mutate even if viruses develop.
To determine if there are T cell receptors in the human immune system capable of recognizing viral polymerase, the researchers exposed blood samples from healthy human donors (collected before the COVID-19 pandemic) to viral polymerase antigen. They found that certain T cell receptors actually recognized the polymerase. They then used a method they developed called CLInt-Seq to genetically sequence these receptors. Next, the researchers designed T cells to carry these receptors for polymerase, allowing them to study the ability of the receptors to recognize and kill SARS-CoV-2 and other coronaviruses.
More than 5 million people have died in COVID-19 worldwide. Current vaccines offer significant protection against serious diseases, but as new, potentially more contagious variants emerge, researchers realized that vaccines may need to be updated – and new findings from UCLA suggest a strategy that could help increase protection and long-term immunity. Researchers are now conducting further studies to evaluate viral polymerase as a potential new vaccine component.
Pavlo Nesterenko, A postgraduate student at UCLA, is the first author of the study; the responsible author is Dr. Owen Witte, who serves as president of the Department of Microbiology, Immunology, and Molecular Genetics at UCLA and is executive director of the Broad Stem Cell Research Center.
The research was supported by the Parker Institute for Cancer Immunotherapy, the Ruth L. Kirschstein Institutional National Research Service Award from the National Institutes of Health, and the UCLA WM Keck Foundationโs COVID-19 Research Award program.
Source: ANI
Source: The Nordic Page