Austrian scientists have developed a novel Covid-19 vaccine that has shown to be effective against all SARS-CoV-2 variants known to date, including Omicron.
The preclinical data for the antigen-based vaccine developed by a team at Medical University of Vienna showed that it targets the receptor binding domains (RBD) of the SARS-CoV-2, the virus causing Covid, and induces a robust and uniform RBD-specific IgG antibody response in animal models and in human tests.
This antibody response prevents the virus from docking onto and entering the body’s cells, so that infection cannot occur.
The findings, published in the leading journal Allergy, showed the vaccine to be effective even in those who have not yet built up any immunity as a result of vaccination.
“Our data give us grounds to hope that this readily producible protein-based vaccine antigen will be effective against all SARS-CoV-2 variants known to date, including Omicron,” said study leader Rudolf Valenta, from the varsity’s Centre for Pathophysiology, Infectiology and Immunology.
“The vaccine is designed to enable repeated injections to build up sustained sterilising immunity, is suitable for use in all age and risk groups and appears to be superior to currently available vaccines when it comes to inducing neutralising antibodies,” he added.
The SARS-CoV-2 subunit vaccine (PreS-RBD) is based on a structurally folded fusion protein consisting of two receptor binding domains (RBD) of the SARS-CoV-2 virus and the PreS antigen from hepatitis B, which serve as immunological carriers for each other, thereby strengthening the immune response.
Currently available genetic Covid vaccines induce mainly transient IgG1 antibody responses, whereas the PreS-RBD vaccine can additionally induce long-lived RBD-specific IgG4 antibodies.
PreS-RBD-specific IgG antibodies detected in blood and mucosal secretions reacted with SARS-CoV-2 variants, including the Omicron variant.
Antibodies induced by vaccination with PreS-RBD more potently inhibited the binding of RBD with its human receptor ACE2, and their virus-neutralising titres were higher than those in a random sample of individuals fully immunised with two vaccinations of currently registered vaccines or than those of Covid-19 convalescents (that is, individuals who had previously had Covid).
“The PreS-RBD vaccine has the potential to induce sterilising immunity to old and new SARS-CoV-2 variants by preventing infection by stopping viral replication and transmission through the inhibition of cellular virus entry,” Valenta said.