Omicron and Delta variants ’neutralised’ by isolated antibodies

The Omicron and Delta variants of Covid-19 have been shown to be neutralised when using antibodies isolated from recovered patients

A team of researchers from Tel Aviv University has demonstrated that antibodies isolated from the immune system of recovered Covid-19 patients are effective in neutralising all known strains of the virus, including the Delta and the Omicron variants.

According to the researchers, this discovery may eliminate the need for repeated booster vaccinations and strengthen the immune system of populations at risk.

The research was led by Dr Natalia Freund and doctoral students Michael Mor and Ruofan Lee of the Department of Clinical Microbiology and Immunology at the Sackler Faculty of Medicine. The study was conducted in collaboration with Dr Ben Croker of the University of California San Diego. Professor Ye Xiang of Tsinghua University in Beijing. Professor Meital Gal-Tanamy and Dr Moshe Dessau of Bar-Ilan University also took part in the study.

The present study is a continuation of a preliminary study conducted in October 2020, at the height of the Covid-19 crisis. At that time, Freund and her colleagues sequenced all the B immune system cells from the blood of people who had recovered from the original Covid strain in Israel, and isolated nine antibodies that the patients produced. The researchers now found that some of these antibodies are very effective in neutralising the new coronavirus variants, Delta and Omicron. The discovery raises hopes of the global population becoming immune to Covid-19 and all its variants.

Very effective

Freund said: “In the previous study, we showed that the various antibodies that are formed in response to infection with the original virus are directed against different sites of the virus. The most effective antibodies were those that bound to the virus’ ‘spike’ protein, in the same place where the spike binds the cellular receptor ACE2. Of course, we were not the only ones to isolate these antibodies, and the global health system made extensive use of them until the arrival of the different variants of the coronavirus, which in fact rendered most of those antibodies useless.

“In the current study, we proved that two other antibodies, TAU-1109 and TAU-2310, which bind the viral spike protein in a different area from the region where most of the antibodies were concentrated until now (and were therefore less effective in neutralising the original strain) are actually very effective in neutralising the Delta and Omicron variants.

“According to our findings, the effectiveness of the first antibody, TAU-1109, in neutralising the Omicron strain is 92%, and in neutralising the Delta strain, 90%. The second antibody, TAU-2310, neutralises the Omicron variant with an efficacy of 84%, and the Delta variant with an efficacy of 97%.”

All known covid strains

According to Freund, the surprising effectiveness of these antibodies might be related to the evolution of the virus.

“The infectivity of the virus increased with each variant because each time, it changed the amino acid sequence of the part of the spike protein that binds to the ACE2 receptor, thereby increasing its infectivity and at the same time evading the natural antibodies that were created following vaccinations.

“In contrast, the antibodies TAU-1109 and TAU-2310 don’t bind to the ACE2 receptor binding site, but to another region of the spike protein – an area of ​​the viral spike that for some reason does not undergo many mutations – and they are therefore effective in neutralising more viral variants. These findings emerged as we tested all the known Covid strains to date.”

The two antibodies, cloned in Freund’s laboratory at Tel Aviv University, were sent for tests to check their effectiveness against live viruses in laboratory cultures at the University of California San Diego, and against pseudoviruses in the laboratories of the Faculty of Medicine of Bar-Ilan University in the Galilee; the results were identical and equally encouraging in both tests.

The study was published in the Nature journal Communications Biology.

Image: Dr Natalia Freund. Credit: Tel Aviv University.