Immune response against corona infection


How well can certain antibodies indicate immunity against the virus? A specific measuring technique makes it possible to determine their quality.

05/19/2020 · Lebenswissenschaften · Leibniz-Institut für Arbeitsforschung an der TU Dortmund · News · Forschungsergebnis

Immunologists at the Leibniz Research Centre for Working Environment and Human Factors (IfADo), in collaboration with local partners, are currently developing methods to detect antibodies against the novel coronavirus. Their aim is not only to determine whether antibodies are present in a person’s blood, but also to identify the actual role of these antibodies. Thus, the team is investigating how well certain antibodies can mediate immunity against SARS-CoV-2.

The coronavirus can infect cells because of its envelope proteins. This so-called spike protein binds to the ACE2 receptor on the surface of human cells, which opens up the virus the „infection pathway“ allowing the virus to introduce its genetic material into the cell. Antibodies, one of the weapons of the immune system, can bind to the envelope proteins and thus prevent the virus from infecting other cells. This neutralization function of antibodies is crucial for the development of protective immunity.

Immunologists at IfADo are currently investigating the type and concentration of antibodies relevant for immunity against SARS-CoV-2. Together with experts at the Max Planck Institute of Molecular Physiology (MPI) in Dortmund, they plan developing tests to detect virus-neutralizing antibodies against the spike protein. For this purpose, they are combining various immunological measurement techniques, such as flow cytometry. This technology makes it possible to determine the type and number of antibodies in a blood sample that interact with the envelope proteins of the virus. To study this interaction between envelope proteins and the antibodies, the scientists use so-called virus pseudo types, where the envelope protein of the coronavirus is incorporated into a less dangerous carrier virus that is no longer able to reproduce itself. This well-known procedure enables the scientists to safely and efficiently investigate the neutralization abilities of certain antibodies.

Close collaboration with local partners

For the last several weeks, the scientists have been in close contact with the municipal authorities, the Dortmund Health Authority and the Clinic Dortmund. Having a test system that can be used to assess the quality of antibodies contained in a blood sample could, for example, help the Clinic develop a more targeted antibody therapy. Since April, the Clinic Dortmund has been reaching out to patients who previously tested positive with SARS-CoV-2 and have now recovered to donate plasma, which will be used to treat patients with the antibodies in the plasma.

Reliable antibody tests (so-called ELISA tests) are also essential in order to determine whether a person was already (unnoticed) infected with the novel coronavirus. Although there are now a number of commercial ELISA tests on the market, their reliability is still an issue. IfADo, together with the Clinic Dortmund and the Max Planck Institute in Dortmund, recently began developing a detection system that could help bolster regional labs. As a basis for the test, the MPI Dortmund will produce an exact copy of the binding site of the spike protein, which will be used for the highly specific detection of antibodies against SARS-Cov-2. IfADo will develop various test systems and check their reliability. For this purpose, the team plans to use samples from the Clinic Dortmund’s blood bank that were already taken two years ago, i.e. before SARS-CoV-2, which will serve as negative controls. At the same time, the team will receive samples from patients who tested positive for SARS-CoV-2, which are then used as positive controls.

Further questions for basic research

For the IfADo-immunologists who are working together with Prof. Carsten Watzl, there are many research questions that they would like to pursue. „This concerns, for example, the question of how long immunity lasts. Do people still have antibodies after a few months or years or not? We are also interested in how certain immune cells such as natural killer cells react to infection with the new coronavirus“, explains IfADo-director Carsten Watzl.

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