Covid-19: Scientists identify antibodies to develop vaccine for different coronaviruses

New York - The antibodies have been detected in people who have recovered from Covid-19.

Scientists have discovered human antibodies that can neutralise several different coronaviruses and pave the way for a pan-coronavirus vaccine.

These antibodies have been detected in some people who have recovered from Covid-19, said the team at University of Washington.

The study, appearing in the journal Science, describes research on five such human monoclonal antibodies that can cross-react with a number of beta-coronaviruses.

The team examined certain memory B cells from Covid-19 convalescent donors. Memory B cells are white blood cells that recognise and respond to pathogens that have tried to attack the body during a previous encounter.

Out of five promising antibodies that they isolated, the scientists decided to concentrate on one designated one. Molecular structure analysis and functional studies showed that this human monoclonal antibody had impressive breadth: it was able to neutralise three different types of beta-coronaviruses.

These antibodies target a structure, called stem helix, in the spike protein of these viruses. The spike protein is critical to the virus' ability to overtake host cells.

The team went on to test if the stem helix antibody could protect against SARS-CoV-2 by administering it to hamsters 24 hours before exposure. They found that this antibody reduced the viral load of SARS-CoV-2 by inhibiting entry of the virus and by enhancing additional anti-viral and virus-clearing cellular immune responses.

Studies of the plasma from pre-pandemic human samples, as well as from Covid-vaccinated and Covid-recovered individuals were also analysed to see how the stem-helix targeting antibodies appeared.

The highest frequencies occurred in people who had recovered from Covid-19, then were later vaccinated.

Overall, however, the data from this study shows that, while it does occur, it is relatively rare for SARS-CoV-2 to elicit plasma stem-helix antibody responses.

• USA