Vienna / La Jolla. The body’s own immune defense cells – so-called T cells – can recognize astonishingly large parts of the new Sars-CoV-2 virus. This was the finding of an international team of researchers led by the Tyrolean immunologist Daniela Weiskopf from the La Jolla Institute for Immunology in California. The findings open up additional opportunities for vaccine development, the researchers emphasize in the journal “Science Immunology”.
The team of scientists worked on blood samples from sick people in San Diego and later also in Rotterdam. The main focus was on T cells, a group of white blood cells that are tasked with identifying new threats and driving the acquired immune response.
No hiding game
As a rule, both T-helper and T-killer cells recognize “only very small virus parts – that is, pieces of eight or nine amino acids,” explains Weiskopf. In contrast to the B-lymphocytes, however, they do not produce specific antibodies, which then attack the virus, but must recognize their target structures directly on the surface of the intruders.
In the case of Sars-CoV-2, things seem to be different. The scientists found T-helper cells that reacted to the novel coronavirus in all ten closely examined patients, eight out of ten also had T-killer cells that positioned themselves against the pathogen. Their amount also increased over time.
“There has been speculation that the virus may be hiding from the immune system. But we have shown that it works well recognized,” emphasizes the Tyrolean researcher. The characteristic spike protein, which acts as a target for almost all vaccines under development, was also recognized by this part of the immune system in all examined infected persons. “This is good news for vaccine developers,” explains the immunologist.
Cross immunity hypothesis
The current study also showed that a total of 23 out of 25 proteins from the virus are recognized by T cells. This will bring more opportunities for future generations of vaccines because it could also use other proteins as target structures.
When the scientists also confronted older blood samples from 2015 to 2018 with the new virus, they also noticed that almost half of the T cells showed a reaction to virus parts. “The hypothesis is that these are cross-immunities that are caused by normal cold viruses circulating in the population,” says Weiskopf, who, among other things, continues to work on this question.
The very similar findings in the USA and the Netherlands indicate that the immune system can recognize Sars-CoV-2 relatively well in many regions. However, it is still important to find out whether this is actually the case: “It is important to us that we share the reagents freely. I have now distributed them to 60 different laboratories worldwide,” explains the researcher. (apa)
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