In this cross-immunity, T cells appear to play an important role, which have formed in response to an infection with human corona cold viruses (huCoVs). For a long time, at least four coronavirus species have been circulating in mankind as causative agents of seasonal banal statements.
The hypothesis is not new. However, so far there has been a lack of convincing evidence, which has now been provided by scientists working with Rhia Kundu from Imperial College London, it said on Tuesday in the German pharmaceutical newspaper online. The scientists published their results on Monday in “Nature Communications” (DOI: 10.1038 / s41467-021-27674-x). “Our results suggest that cross-reactive memory T cells protect people without prior contact with SARS-CoV-d from such an infection,” the experts wrote in their abstract.
52 people examined
Since September 2020, when very few people in England were still suffering from Covid-19, the scientists had examined 52 people who had demonstrably had contact with SARS-CoV-2 infected people, but only half of them had not become infected . This was proven by a PCR test.
The next step: In the blood samples from these test subjects, the researchers then characterized T cells, the formation of which had been triggered by previous contact with a harmless corona cold virus. They checked whether these T cells also responded to SARS-CoV-2.
In any case, in subjects who had not become infected, cross-reactive T cells from survived huCoV infections were found in significantly higher concentrations than in the 26 persons who had become infected. The highlight: These T cells responded specifically to proteins from the interior of the SARS-CoV-2 or banal coronaviruses: to the protein that the capsule forms around the genetic material (nucleocapsid protein), to the membrane or Shell protein and the ORF1 protein. With regard to T-cell specificity against the spike protein (S protein), which serves as an antigen for most of the Covid-19 vaccines currently in use, there was no difference between the infected and non-infected groups.
Protecting cold viruses
Ajit Lalvani, senior author of the study and director of the NIHR Respiratory Infections Health Protection Research Unit at Imperial College London, was quoted in a press release from the research institution as saying: -Coronaviruses have a protective function against SARS-CoV-2 infection. These T cells offer protection by attacking proteins inside the virus and not the spike protein on the virus surface. “
But the T cell response is only part of the immunological protection. The expert emphasized that the previously available vaccination with the three partial vaccinations or booster vaccinations must therefore continue to be propagated.
The scientific study also paves the way for the development of more broadly acting SARS-CoV-2 vaccines. They should not only trigger antibodies and a T-cell response against the spike protein, but also lead to an immune response with antibodies and T-cells against the other SARS-CoV-2 proteins.
Lalvani: “The spike protein is under strong selection pressure from vaccine-induced antibodies, which is driving the development of vaccine escape mutants. In contrast, the internal proteins against which the protective T cells we have identified mutate much less They are very conserved between the different SARS-CoV-2 variants, including omicrons. New vaccines containing these conserved proteins from inside the virus would therefore elicit a broad protective T-cell response that will go on now and in the future SARS-CoV-2 variants should protect. “