Scientists identify pan-variant neutralising antibody in humans to Omicron varia

The scientists said that this monoclonal antibody prevents binding to the receptor on host cells that the pandemic coronavirus usually commandeers. They also suggested that combining this antibody with others in a cocktail might reduce the chances of the virus becoming antibody treatment resistant.

Researchers team from University of Washington and Howard Hughes Medical Institute, and Humabs BioMed SA of Vir Biotechnology in Switzerland have looked at several aspects of the effects of exposure to earlier forms of the SARS-CoV-2 spike antigen – or immune-provoking protein — on the immune system’s reaction to the Omicron variants.

The findings have been published in the journal Science.

Omicron variants of the SARS-CoV-2 virus which was at the end of 2021 and have marked genetic differences from the ancestral SARS-CoV-2. The many, distinct mutations in their infection machinery have enabled them to escape from antibodies elicited from the original series of vaccines, from a history of infection, or from both of those two immune-system training events.

Past studies from the same team, according to the study, have noted that the BA.1 Omicron variant emerged as a “major antigenic shift due to the unprecedented magnitude of immune evasion associated with this variant of concern”.

They explained that mutations in two of the main antibody targets in the virus explain why there is a markedly reduced antibody neutralizing ability against these variants, especially in people who have not received booster doses.

“As a result, an increasing number of reinfections are occurring,” the scientists wrote in their paper, “even though these cases tend to be milder than in infections of immunologically naïve individuals”.

The evasive ability conferred by the mutations, they noted, also helps explain why most monoclonal antibody therapies given to patients in the clinic are less effective against these variants.

Through their experiments, the scientists learned that vaccine boosters and hybrid immunity, or immunity acquired through a history of an infection and vaccination, both induce neutralizing antibodies in the bloodstream against Omicron BA.1, BA.2, BA.2.12.1 and BA.4/5.

The scientists also determined that antibody responses to the pandemic coronavirus follows a pattern similar to the way the immune system responds to variations of the influenza virus. This phenomenon is called immune imprinting.

(With inputs from agency)