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T Cell Recognition of Cold Coronaviruses May Help in Protecting Against COVID-19

In unexposed blood samples, investigators discovered memory helper T cells that recognize cold coronaviruses also recognized SARS-CoV-2, and may help people fight off the virus.

A new study led by scientists at the La Jolla Institute for Immunology (LJI) shows that memory helper T cells that recognize common cold coronaviruses also recognize matching sites on SARS-CoV-2.

The research, published in Science, may explain why some people have milder COVID-19 cases than others—though the researchers emphasized that this is speculation and much more data is needed.

One of the coauthors of the new study, LJI Professor Alessandro Sette, Dr Biol, Sci, talked with Contagion® about it.

This latest paper builds upon a previous paper written by Sette, et al., on similar research that came out earlier this year.

At LJI, they had previous blood samples from years before SARS-CoV-2 existed. When Sette and his team took some of these samples and exposed them to the virus the samples had some immunity or protection against it because some of the memory T cells recognized SARS-CoV-2 as a virus.

“We detected responses against SARS-CoV-2 pieces in people who had not been exposed to SARS-CoV-2,” Sette explained.

While this was an important hypothesis, Sette and his team went to work to prove it.

“We mapped the specific amino acids recognized by T cells of non-exposed individuals. Then, we made synthesized corresponding pieces from the common cold coronaviruses and we proved that these T cells cross-recognized the common cold coronavirus and SARS-CoV-2.”

In addition, they were able to show these were memory T cells that induced an immunity response.

Sette also discusses how this preexisting reactivity might work to help fight the virus. “If you have this preexisting memory you may be able to mount a faster or stronger immune response, and this might explain in part why some people get more sick than others.”

While this might lay down a foundation for future work in the area, Sette acknowledges it still needs to be proven. In his discussion with Contagion®, he also lays out theories on how this could be done.