(Reuters) – In some people, past exposure to common-cold coronaviruses seems to prepare the immune system to fight the COVID-19 coronavirus, but it has not been clear why this is not true for everyone. Genes may play a role, according to a paper posted on bioRxiv ahead of peer review.

The authors analyzed small proteins, or peptides, on the SARS-CoV-2 virus that are known to be targets for killer T cells.

Compared to peptides on common-cold coronaviruses, some of the SARS-CoV-2 peptides were very different, but others were very similar, said study co-author Hashem Koohy of John Radcliffe Hospital and the University of Oxford. Most COVID-19 survivors’ killer T cells attack only peptides unique to SARS-CoV-2, his team found. Some survivors, however, have killer T cells that also attack the targets that closely resemble common-cold virus proteins.

Further analysis suggested to the researchers that people with certain versions of genes involved in the immune system may be more likely to make these “cross-reactive” killer T cells.

People with immune responses to the “shared” peptides may be at lower risk of severe disease, Koohy said.

Also, his team reported, some of the peptides they identified as being similar across multiple coronavirus strains could potentially be targets for vaccines and antibody drugs.

SOURCE: https://bit.ly/2Vc5s9u bioRxiv, online July 20, 2021.

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