–
–
21.07.2021 12:49
SARS-CoV-2 variant B.1.617 makes it difficult for the immune system
Study with cell cultures shows that the mutant is less well inhibited by antibodies
SARS-CoV-2 still poses great challenges for mankind. The frequent emergence of mutants makes the threat posed by the virus difficult to predict. The SARS-CoV-2 variant B.1.617 has spread in India and produced the delta variant, B.1.617.2, which is now on the advance in many countries. Infection researchers from the German Primate Center (DPZ) – Leibniz Institute for Primate Research in Göttingen have examined the previously less known initial variant B.1.617 in more detail. In cell culture studies, they found out that the virus variant can infect certain lung and intestinal cell lines better than the virus of origin. In addition, the researchers were able to prove that B.1.617 is less well inhibited by antibodies from the blood of recovered or vaccinated people and by therapeutic antibodies. This could mean that B.1.617 and its subtypes will spread rapidly in the future and that incompletely vaccinated people and people with declining immune protection are exposed to an increased risk of infection compared to other currently circulating virus variants (Cell Reports).
The spike protein is built into the envelope of SARS-CoV-2 and mediates the entry of the virus into host cells. This is the only way for the virus to multiply in the body. The virus variants currently known all have different mutations in the spike protein, which in some cases make it easier for them to infect host cells and to escape the control of the immune system of infected people. The B.1.617 variant carries eight different mutations in the spike protein, including two within the receptor binding domain, which is essential for the attachment of viruses to cells and is the main target of neutralizing antibodies.
A team led by Markus Hoffmann and Stefan Pöhlmann, infection researchers at the German Primate Center, as well as scientists from the University Hospital Göttingen, the University of Erlangen and the Hannover Medical School, examined the effects of the mutations on the ability of the B.1.617 variant to enter Invade host cells and how efficiently this variant inhibits the antibody response in vaccinated and convalescent patients.
First, the researchers analyzed the host cell entry of the B.1.617 variant into various human cell lines. In two cell lines that originated from lung and intestinal tissue, they were able to demonstrate that the virus had a 50 percent increase in the efficiency of entry.
The researchers also examined the effectiveness of four different therapeutic antibodies that have been approved for the treatment of people with COVID-19. It turned out that the B.1.617 variant was completely resistant to one of these antibodies and was inhibited somewhat worse by another antibody.
As a third step, the scientists checked the effectiveness of antibodies from the blood of recovered and vaccinated people. Here they were able to determine a two to three-fold reduced protective effect against the B.1.617 variant.
“Our study suggests that the virus variant, through its mutations, can infect lung and intestinal cells more efficiently and is therefore probably more fit,” says Markus Hoffmann, first author of the study, summarizing the results. “In addition, the protective effect of antibodies is limited, as they block the cell entry of B.1.617 less than that of the original virus. Incompletely vaccinated people and people with a long history of infection who only produce small amounts of antibodies therefore probably have little protection against infection with the B.1.617 variant.
Stefan Pöhlmann, Head of the Infection Biology Department at the DPZ, adds: “It is advisable to quickly and completely immunize all persons willing to vaccinate with the available vaccines in order to prevent further spread of the B.1.617 variant, especially its subtype Delta, and its development to prevent new virus variants. In addition, it must be examined whether booster vaccinations with existing or optimized vaccines tailored to the current variants offer long-lasting and broad protection. ”
Scientific contact:
Prof. Stefan Pöhlmann
Tel.: +49 551 3851-150
Email: [email protected]
Dr. Markus Hoffmann
Tel.: +49 551 3851-338
Email: [email protected]
Originalpublikation:
Hoffmann M, Hofmann-Winkler H, Krüger N, Kempf A, Nehlmeier I, Graichen L, Arora P, Sidarovich A, Moldenhauer A-S, Winkler MS, Schulz S, Jäck H-M, Stankov MV, Behrens GMN, Pöhlmann S (2021): SARS-CoV-2 variant B.1.617 is resistant to Bamlanivimab and evades antibodies induced by infection and vaccination. Cell Reports. DOI:https://doi.org/10.1016/j.celrep.2021.109415
Additional Information:
http://medien.dpz.eu/pinaccess/pinaccess.do?pinCode=eOr6xsTScVii – Printable images
https://www.dpz.eu/de/aktuelles/pressemitteilungen.html – Press release on the DPZ homepage
Features of this press release:
Journalists
Biology
supraregional
Research results, scientific publications
Deutsch
–
