LONDON (Reuters) London (Reuters) British researchers said on Wednesday they had identified coronavirus proteins that are recognized by T-cells of people who have been exposed to the virus but are able to resist infection, thereby providing an opportunity for new vaccine developers.
The multifaceted picture of immunity against COVID-19 is complex. There is evidence of a decrease in antibody levels six months after vaccination. However T-cells are believed play an important role in providing protection.
Researchers from the University College London (UCL), examined 731 health workers in two London hospitals during the initial wave COVID-19 pandemic. They found that the majority were not positive for the virus despite being exposed to coronavirus.
They discovered that, even though a subset of the workers didn’t generate antibodies or test positive with PCR tests, they had still generated a large and extensive T-cell response following possible exposure.
This suggests that people weren’t avoiding the coronavirus entirely. T-cells, however, had eliminated the virus prior to any symptoms or positive test results – a phenomenon known as “abortive infection” according to researchers.
“We know that some people are not infected, despite having exposure to the virus,” said Leo Swadling, lead author of the study, which was published in the science journal Nature.
“What’s particularly interesting is that the T cells that were detected in these people, in cases where there was no successful infection preferred to target different areas of the virus than the ones found after infection.”
Current vaccines, which provide the highest level of protection against severe illness but don’t completely stop the spread or re-infection focus on the spike protein of coronavirus.
Contrarily the T-cell response that led to abortive infections in the UCL study identified and targeted viral replication and transcription proteins that are highly conserved across coronavirus species.
Researchers stated that although T-cells are associated with protection against infections that are detectable, they weren’t sufficient to shield people from re-exposure.
They also suggested that previous exposure to other coronaviruses may be a factor in why certain health professionals were able to mount such quick T cell responses.
Researchers also stated that a vaccine targeting these proteins will be effective against a wide range of coronaviruses, including the dominant Delta variant.
Swadling stated to reporters, “This is a strong argument to include these proteins as a supplement to the next generation of vaccines.”
SOURCE: https://go.nature.com/3qqQoC8 Nature, online November 10, 2021.
