When our immune system comes into contact with the SARS-CoV-2 coronavirus, it fights back and produces antibodies. A similar immune response is caused by vaccines against Kovid-19. However, there is still little data available on the strength and durability of immune protection.
A team led by Professor Karsten Vatzl from the Leibniz Research Center for Work Environment and Human Factors of the Institute for Work Research (IfADo), in collaboration with the Max Planck Institute for Molecular Physiology (MPI) and Klinikum Dortmund, was now able to detect high levels of neutralizing antibodies in tested persons even 300 days after infection with the original variant of the coronavirus, writes Science daily.
After full vaccination, recovered individuals showed antibody levels about five times higher than those vaccinated without prior infection. This would provide much better protection against a severe form of the disease in the event of a new infection with other variants of the coronavirus, transmissions H1.
Our immune protection is provided by two systems that work hand in hand. When infected with a virus, the immune system responds by producing antibodies that can prevent the virus from infecting further cells. At the same time, so-called killer T-cells can recognize foreign components of the virus and thus destroy already infected cells.
During the immune response, the antibodies constantly improve and are finally "tailored" for the pathogen. The amount of these neutralizing antibodies shows how well the body can fight off a new infection.
A unique collaboration between biochemists, immunologists, clinicians and the Dortmund health department
"When the coronavirus pandemic broke out, we as immunologists were of course interested in how our immune system defends itself against the coronavirus. That's why, together with colleagues from the Max Planck Institute and the Dortmund Hospital, we developed a reliable test system for the detection of neutralizing antibodies," says the director of IfADo. Karsten Vacl.
He further explains "that a suitable 'bait' is needed, so that the antibodies can be extracted from the blood in a targeted manner".
One of the main targets of the immune system is the spike protein, which the virus uses to bind to and then infect human cells.
"We were able to produce part of this protein, specifically the cell-binding region, in high purity in a test tube," says Jan-Erik Hofmann, head of protein production at MPI Dortmund.
With this exact copy and blood samples from "Klinikum Dortmund", the researchers at IfADo were able to develop a reliable and meaningful system for the detection of antibodies to the coronavirus.
In a close exchange with the Dortmund health department and the Dortmund hospital, the scientists used this system to conduct a study with about 140 volunteers from a Dortmund health facility with several documented cases of SARS-CoV-2 infection at the beginning of the pandemic.
Five times higher antibody levels after vaccination in recovered patients
Effective amounts of neutralizing antibodies against the spike protein can be detected in almost all individuals who have tested positive for SARS-CoV-2. Even after 300 days, antibody levels barely decreased in three out of four subjects.
However, the tested persons were infected with the original variant of the coronavirus and neutralizing antibodies against the original spike protein were measured. As we know, the virus has now evolved in such a way that immunity to the original virus currently offers significantly less protection.
Therefore, the researchers also investigated the effect of vaccination with the AstraZeneca and Bayontek vaccines on the immune system.
Scientists have come to an astonishing result.
After full vaccination, recovered test subjects developed up to five times more neutralizing antibodies than vaccinated subjects without prior infection. This should also provide better protection than current variants.
"Now there are several studies on the immune response after covid-19. Our study differs from this one in that we had blood samples before and from the first weeks of the pandemic. So we knew exactly whether the tested person was already infected or not. In addition to these unbiased data, the long study period of almost a year is exceptional," says Vacl.
He adds that "the rules of the game have changed in the meantime, of course, because there are new variants like omicron".
However, it is important to know how long the immunity actually lasts, because it can also protect against a severe form of the disease in the event of a new infection with other variants of the coronavirus.
Vacl says they are also currently using jointly developed test systems to study immune responses to Covid-19 vaccines and their protection against different variants of the coronavirus.
"This study is an excellent example of successful interdisciplinary collaboration that not only brings important scientific findings, but is also very relevant to society," emphasizes Dr. Bernhard Schaaf, director of the Department of Pneumology and Infectious Diseases at the "Klinikum Dortmund".
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