London: A specific area of the SARS-CoV-2 spike protein could be a promising target for a pan-coronavirus vaccine that could offer some protection against new virus variants, common colds, and help prepare for future pandemics, according to a team of scientists in the UK.
Developing a vaccine that provides protection against a number of different coronaviruses is a challenge because this family of viruses have many key differences, frequently mutate, and generally induce incomplete protection against reinfection.
This is why people can suffer repeatedly from common colds, and also be infected multiple times with different variants of SARS-CoV-2.
A pan-coronavirus vaccine would need to trigger antibodies that recognise and neutralise a range of coronaviruses, stopping the virus from entering host cells and replicating, said the team at the Francis Crick Institute.
In their study, published in Science Translational Medicine, they investigated whether antibodies that target the S2 subunit of SARS-CoV-2’s spike protein also neutralise other coronaviruses. This specific area of the spike protein tethers it to the virus membrane and allows the virus to fuse with the membrane of a host cell.
They found that after vaccinating mice with SARS-CoV-2 S2, the mice created antibodies that were able to neutralise a number of other animal and human coronaviruses, including the seasonal ‘common cold’ coronavirus HCoV-OC43, the original strain of SARS-CoV-2, the D614G mutant that dominated in the first wave, Alpha, Beta, Delta, the original Omicron, and two bat coronaviruses.
“The S2 area of the spike protein is a promising target for a potential pan-coronavirus vaccine because this area is much more similar across different coronaviruses than the S1 area. It is less subject to mutations, and so a vaccine targeted at this area should be more robust,” Kevin Ng, doctoral student in the Retroviral Immunology Laboratory at the Crick.
The S2 area of the spike protein has, until recently, been overlooked as providing a basis for vaccination. This is because certain critical targets in the S2 area are only revealed after the virus has bound to a cell, a process mediated by the S1 area.
As a result, there may be a narrower window of opportunity for S2 antibodies to neutralise the virus than for antibodies that target the S1 area.
“There’s a lot of research still to do as we continue to test S2 antibodies against different coronaviruses and look for the most appropriate route to design and test a potential vaccine,” said George Kassiotis, corresponding author and principal group leader at the Crick.
